Analogical EnginesMoonshotsLITE
Idea 04 of 06Borrowed from snow physics and capillary barrier hydrology

Trapped air in fine fibres blocks liquid and hides stains

Borrowing how layered snow holds meltwater while air passes through, we split a film-free sheet into a fine barrier layer over a coarse reservoir layer, aiming to meet barrier, hiding and breathability together.

Fig. 1Fine snow over coarse snow holds meltwater, lets vapour out and hides the dark ground; the proposed outer cover lays fine fibres over coarse ones so trapped air stops the liquid and scattering hides the stain.
Fig. 1

Trapped air in fine fibres blocks liquid and hides stains

A wide painterly scene. On the left a cut snowbank shows a bright white fine-snow band over a greyer coarse-snow band over dark soil, with blue meltwater collected at the bottom of the white band. The same three bands continue to the right as the cut-open edge of an absorbent hygiene product on a table: a white fine-fibre outer layer, a beige coarse-fibre layer filled with liquid, and a stained brown core. Two round insets below show small ice grains holding water above dry coarse pores, and thin fibres holding liquid back on trapped air, with vapour passing through both.

Fine snow over coarse snow holds meltwater, lets vapour out and hides the dark ground; the proposed outer cover lays fine fibres over coarse ones so trapped air stops the liquid and scattering hides the stain.

What is this idea, and what's clever about it?

A snowpack gives each layer several jobs on one mass: the same grains set how hard water must push to enter, scatter light and hold the pack together. Here the air trapped among the very fine fibres would set the liquid entry pressure and also provide the many fibre-to-air surfaces that hide the stain, so both duties sit in one thin layer. The barrier would improve as the fibres get sparser, the opposite of current film-free webs, where denser packing closes the openings, stiffens the sheet and blocks the air path.

Where we’ve seen this before

Where is it inspired from?

Fig. 2Fine dry snow over coarser snow holds meltwater at their boundary while vapour passes and the dark ground stays hidden; with coarse snow on top instead, the same water drains straight through.
Fig. 2

Trapped air in fine fibres blocks liquid and hides stains

Two panels. Left: a snowbank cut in section on a hillside, showing a white fine-snow layer over grey coarse snow over dark soil, with a magnifier on the fine grains and their air-filled pores. Right: two identical snow columns receiving the same meltwater from above; in the one with fine snow on top the water collects just above the boundary, while in the one with coarse snow on top the water runs straight down to the bottom.

Fine dry snow over coarser snow holds meltwater at their boundary while vapour passes and the dark ground stays hidden; with coarse snow on top instead, the same water drains straight through.

A dry, fine-grained snowpack lying on coarser snow holds meltwater at the boundary between the layers, while air and water vapour keep moving through the same connected pores 123. Water enters a dry pore only above its liquid entry pressure, the pressure needed to push into the narrowest openings between grains. Smaller grains mean a higher threshold 4. Water therefore pools in the fine layer. In cold-laboratory tests, liquid at the boundary reached about 33–36% of the volume when the upper grains were finer than 0.5 mm 1. The hold is finite: once the pooled water exceeds the threshold, it breaks through in narrow fingers 1.

The same grains do other work. Each ice-air surface scatters light, so deep, fine snow hides darker material below, while shallow snow lets it show 56. Bonds that grow between touching grains make the network self-supporting 7. Refreezing at the wetting front can form ice layers 8; once the pores close this way, both the barrier and the gas path are lost.

How does it transfer?

A porous body built from a fine layer over a coarse layer can hold liquid at the boundary while air and vapour pass through the same connected, air-filled pores. The fine grains that set that liquid threshold also hide what lies beneath by scattering light, and every grain is charged to one fixed mass per unit area.

  • Fine-grained upper snow layer→Fine barrier layer, 8 gsm of 1 µm fibres
  • Coarse snow or soil beneath→Coarse reservoir layer, 25 gsm of 18 µm fibres
  • Light scattering at ice–air surfaces→Hiding by scattering at fibre–air surfaces
  • Sintered point necks between grains→Point bonding plus water-jet entangling
  • Refrozen ice crust closing the pores→Continuous solid skin the design avoids
  • Snow water equivalent per area→33 of the 60 gsm budget
What does not carry over
  • In snow the fine layer holds liquid by suction, and liquid passes into the coarse layer only once that suction weakens below the coarse layer's liquid entry pressure (the pull its wider openings need before liquid pushes into them); this design wets the coarse reservoir layer first, so that step between two layers gives no barrier, and at a 65° contact angle of the target fluids on polypropylene the narrowest opening draws liquid in at about −10.6 kPa, which leaves the barrier to a trapped air layer pinned by the fine barrier layer's low solid fraction, a metastable state that is untested.
  • Ice is hydrophilic and its threshold comes from pore curvature alone; the design keeps polypropylene uncoated and takes the trapped air layer from underwater insects, which hold an air film against surrounding liquid on a rough, low-solid-fraction surface.
  • The snow barrier is characterised with clean water near 0 °C, and surfactant-laden or particle-laden water lowers the threshold; the design targets urine, bowel movement and menses at about 50 mN/m, so its liquid entry pressure holds only under those stated fluid conditions.

How does it work?

A film-free, two-layer fibre web with no coating, pigment or glue. A thin top layer of 1 µm polypropylene fibres holds body fluids out with trapped air and hides stains by scattering light, while a coarse layer beneath stores the fluid and carries air, vapour and load.

  1. Lay fine fibres onto coarse, without fusing

    Polypropylene fibres about 1 µm across are blown directly onto a moving coarse reservoir layer, and commercial meltblowing lines already reach that fineness 9. The whole two-layer stack weighs 33 gsm, inside the 60 gsm limit. Water-jet entangling then wraps the fine fibres around the coarse ones without binder 10, though higher jet energy is documented to cost softness 11. The process uses no calender, glue or fused face, because bonding adds a twisting stiffness to the web 12.

  2. Trapped air holds the liquid out

    The fine barrier layer's largest openings are targeted at 8 µm across or less. A 50 mN/m body fluid partly wets polypropylene, so capillary forces at such openings pull liquid in 1314. The barrier must come from trapped air, giving a projected liquid entry pressure (the pressure needed to push liquid through) of 204 mbar against a 62 mbar target. At a contact angle near 65°, that air is only metastable and collapses under pressure or vibration 1516; lasting air needs a non-wetting solid, so survival here is untested 1718.

  3. Coarse layer takes in and stores fluid

    The coarse reservoir layer has a liquid entry pressure of only about 1–10 mbar, so fluid enters it freely and is held as a finite reserve. In snow and soil, the snow layering barrier stores water in the fine layer above the coarse one 119. Here the coarse layer wets first, so the snow analogy supplies the layout while the trapped air supplies the barrier. Vapour, air and tensile load also pass through this layer, with air permeability projected at 5.9–7.1 cfm against a 5 cfm floor 2021.

  4. The same air hides the stain

    Every fibre-to-air surface reflects light, so the fine layer hides what lies beneath by scattering rather than by adding pigment. On a geometric estimate, it carries about 85 % of the web's scattering surface in 24 % of its mass. A synthetic polymer copy of the white beetle's scale structure, a sparse disordered network, reaches about 94 % reflectance 22. Above a solid fraction of about 0.20, the fine layer would close into a continuous solid skin, so that limit is measured on every pilot condition.

Fig. 3The proposed outer cover in four steps: a fine fibre layer is water-jet entangled onto a coarse one, liquid fills the coarse layer, trapped air in the fine layer stops it, and scattering hides the stain.
Fig. 3

Trapped air in fine fibres blocks liquid and hides stains

Four numbered panels, left to right. 1: on a moving belt, a thin white fine-fibre layer is laid on a beige coarse-fibre layer and fine water jets wrap the fine fibres around coarse fibres at crossing points. 2: a section with the outer face up shows liquid from the stained core below filling the coarse layer up to the underside of the white fine layer. 3: a close view shows the liquid surface bulging slightly into the gaps of the fine fibres and stopping against trapped air, while vapour passes upward. 4: light entering the white top layer bounces back out, and the stained core below stays hidden.

The proposed outer cover in four steps: a fine fibre layer is water-jet entangled onto a coarse one, liquid fills the coarse layer, trapped air in the fine layer stops it, and scattering hides the stain.

Why do we think it will work?

The parts of this idea that already work somewhere, and how each carries over here.

Part of the ideaWhere it already worksHere
Nonwoven fibre production · Commercial polypropylene meltblowing line

On a commercial meltblowing line (molten polymer drawn into fine fibres by hot air), air pressure and melt throughput control fibre diameter, and webs close to one-micron average diameter with a relatively narrow distribution were produced. 9

What is the evidence it will work?

Fine barrier layer of one-micrometre fibres

Where it works
Nonwoven fibre production · Commercial polypropylene meltblowing line
What it does there
On a commercial meltblowing line (molten polymer drawn into fine fibres by hot air), air pressure and melt throughput control fibre diameter, and webs close to one-micron average diameter with a relatively narrow distribution were produced.
Here
Carries over if: That the same fibres can form an 8 gsm (grams per square metre) layer whose largest opening between fibres stays at or below 4 µm radius across production width.
The evidence

Carries over ifThat the same fibres can form an 8 gsm (grams per square metre) layer whose largest opening between fibres stays at or below 4 µm radius across production width.

Snow and soil hydrology · Layered snow; soil retaining-wall backfill

In layered snow at 0 °C, liquid water ponded at the boundary under a fine upper layer, peaking at about 33–36 % by volume; in soil, water stays in the fine layer until suction falls below the coarse layer's entry value. 119

What is the evidence it will work?

Snow layering barrier: fine over coarse

Where it works
Snow and soil hydrology · Layered snow; soil retaining-wall backfill
What it does there
In layered snow at 0 °C, liquid water ponded at the boundary under a fine upper layer, peaking at about 33–36 % by volume; in soil, water stays in the fine layer until suction falls below the coarse layer's entry value.
Here
Carries over if: That a fine layer still holds liquid back when the liquid arrives from the coarse side, the reverse of the direction in which the snow and soil barriers are shown.
The evidence

Carries over ifThat a fine layer still holds liquid back when the liquid arrives from the coarse side, the reverse of the direction in which the snow and soil barriers are shown.Tested in What we’d test →

Hygiene nonwovens · Polypropylene spunbond webs

Spunbond webs (continuous coarse filaments laid into a web) are made at 10–200 gsm basis weight with polypropylene fibres of 15–35 µm diameter as the standard window. 2324

What is the evidence it will work?

Coarse reservoir layer from commodity spunbond

Where it works
Hygiene nonwovens · Polypropylene spunbond webs
What it does there
Spunbond webs (continuous coarse filaments laid into a web) are made at 10–200 gsm basis weight with polypropylene fibres of 15–35 µm diameter as the standard window.
Here
Carries over if: That an open 25 gsm spunbond, bonded without pressing between heated rollers (calendering), lets the fluid in at low pressure while still carrying the mechanical load.
The evidence

Carries over ifThat an open 25 gsm spunbond, bonded without pressing between heated rollers (calendering), lets the fluid in at low pressure while still carrying the mechanical load.

Optics of porous materials · Nanofibre mats; white beetle scales

Electrospun nanofibre mats are "mostly white due to scattering from the irregularly distributed, thin nanofibers"; a polymer copy of white beetle-scale networks reached about 94 % reflectance. 2522

What is the evidence it will work?

Hiding by scattering, without pigment

Where it works
Optics of porous materials · Nanofibre mats; white beetle scales
What it does there
Electrospun nanofibre mats are "mostly white due to scattering from the irregularly distributed, thin nanofibers"; a polymer copy of white beetle-scale networks reached about 94 % reflectance.
Here
Carries over if: That the fine barrier layer's fibre-to-air surfaces give enough hiding when dry and stay air-filled, and so still hide, once coloured fluid sits on the web.
The evidence

Carries over ifThat the fine barrier layer's fibre-to-air surfaces give enough hiding when dry and stay air-filled, and so still hide, once coloured fluid sits on the web.Tested in What we’d test →

Nonwoven web bonding · Commercial spunlace lines; layered composites

Spunlace (webs bonded by water jets) runs at 30–250 bar, with higher jet energy giving stronger but less soft fabric; a spunbond–meltblown–entangled composite reached 2.52 kPa water-pressure resistance and 5821 g/(m²·d) moisture permeability. 112627

What is the evidence it will work?

Water-jet entangling of layered webs

Where it works
Nonwoven web bonding · Commercial spunlace lines; layered composites
What it does there
Spunlace (webs bonded by water jets) runs at 30–250 bar, with higher jet energy giving stronger but less soft fabric; a spunbond–meltblown–entangled composite reached 2.52 kPa water-pressure resistance and 5821 g/(m²·d) moisture permeability.
Here
Carries over if: That an 8 gsm fine layer can itself be the entangled web without fibre washout, holes, or closing its openings.
The evidence
  • Spunlace Nonwoven Fabric Guide: Process, Materials & GSM ↗Web page · sunlunernonwovens.com
    “Water pressures typically range from 30 to 250 bar, depending on the fabric GSM, fiber type, and desired strength... Higher water pressure and more injector stages produce stronger entanglement, which increases fabric strength but can reduce softness.”
  • Gradient Design of Spunbond-Meltblown-Hydroentanglement Composite Nonwovens for Directional Water Transport ↗Paper · Sun et al. · 2024 · doi.org
    “a three-layer degradable composite material comprising of polylactic acid (PLA) spunbond, PLA meltblown, and PLA/viscose hydroentanglement layer. The resultant composite material exhibited good waterproofing and moisture permeability characteristics, achieving a water pressure resistance of 2.52 KPa and a moisture permeability of 5821 g/(m²·d).”
  • Multiple layer absorbent substrate and method of formation ↗Patent · US 8,250,719 · 2009 · Google Patents
    “hydroentangling the carrier web and air laid layer together to form a fully bonded dual layer substrate... The basis weight for the carrier web material is about 5 to 40 gsm, or about 5 to 20 gsm, or about 8 to 15 gsm.”

Carries over ifThat an 8 gsm fine layer can itself be the entangled web without fibre washout, holes, or closing its openings.Tested in What we’d test →

Membrane and filter metrology · Bubble-point and capillary-flow porometry

Bubble-point porometry reads the pressure of the first continuous bubbles through a prewetted membrane; capillary-flow porometry converts that pressure, with the liquid's surface tension and contact angle, into the largest pore size. 2829

What is the evidence it will work?

First-breakthrough liquid entry pressure measurement

Where it works
Membrane and filter metrology · Bubble-point and capillary-flow porometry
What it does there
Bubble-point porometry reads the pressure of the first continuous bubbles through a prewetted membrane; capillary-flow porometry converts that pressure, with the liquid's surface tension and contact angle, into the largest pore size.
Here
Carries over if: That the method carries over to a viscous, particle-laden body-fluid simulant invading a soft fibrous web, with the first-through event still detectable.
The evidence

Carries over ifThat the method carries over to a viscous, particle-laden body-fluid simulant invading a soft fibrous web, with the first-through event still detectable.

What's different?

Existing film-free backsheets reach the barrier with dense fine-fibre plies plus a surface chemistry. Here air trapped in a sparse fine barrier layer, set over a coarse layer built to fill, holds liquid out and hides the stain.

How it’s done todayThis idea
Barrier mechanismStacked fine-fibre plies plus a coating, fluorocarbon or melt additiveTrapped air layer in sparse fine fibres, with no surface chemistry
Coarse layer's jobSpunbond skins supply strength and handCoarse reservoir layer fills with liquid and carries air, vapour, load
Hiding the stainFilm, pigment, dark tint or a separate masking layerHiding by scattering in the fine barrier layer, no pigment
Holding layers togetherCalender or thermal bonding; softness and quiet are leftoversPoint contacts and water-jet entangling, no calender nip or glue
Key limitationRelies on a coating that may count as a filmUntested: air must resist urine and menses; both wet more than water
Closest existing work · 4
  • AVINTIV/Berry film-free fine-fibre backsheet30Reaches 81.2 mbar only with a non-fluorinated barrier coating on every layer. This idea uses no coating and relies on trapped air.Google Patents ↗
  • Allegiance granted film-free four-meltblown backsheet31Buys the barrier with four dense fine-fibre plies plus a fluorocarbon treatment, and has no opacity, softness or noise element.Google Patents ↗
  • Fibertex high-barrier nonwoven with melt additive32Raises holdout of low-surface-tension liquids with a lipid-ester additive inside the fibre. That is still added chemistry, where this idea uses trapped air.Google Patents ↗
  • PFNonwovens graded fine/coarse/fine meltblown stack33Grades fibre diameter in an all-meltblown sandwich. It has no viewing-face barrier layer, no coarse layer meant to fill, and no barrier or opacity limit.Google Patents ↗

What would we test?

The riskiest open question

The trapped air layer in the uncoated fine barrier layer holds back a 50 mN/m body-fluid simulant through a 30-minute hold and repeated loading.

Why it matters
It is the design's only source of non-wetting; if the air is displaced, the liquid entry pressure falls to zero and a low-surface-energy finish becomes necessary.
First test
Pressure-step fine-barrier-layer coupons with simulant at body temperature: as-formed, air-evacuated and finish-treated arms at fixed fibre size, with a detector registering the first liquid through, then decompression. 2838
Go if
As-formed coupon holds ≥62 mbar for 30 minutes and re-forms; air-evacuated coupon enters at ≤10 mbar.
No-go if
Evacuated coupon within 25 % of the as-formed one, or as-formed coupon below 62 mbar.
Effort
$9K–16KUSD$9K–16Kas statedEUR€8.05K–14.3KJPY¥1.43M–2.54MECB reference rates, 2026-10-12 · 4 to 6 weeks
The other open questions · riskiest first

  1. The finished stack withholds at least 62 mbar of simulant when liquid reaches it from the coarse reservoir layer side, as in use.

    Why it matters
    The snow layering barrier is shown only fine-over-coarse; if reversed stacks match normal ones, the layer boundary contributes nothing and the claim reduces to the fine layer alone.
    First test
    On a refitted hydrohead rig, step simulant pressure on the 33 gsm stack, fine-layer-alone and coarse-layer-alone coupons, then a 30-minute hold and decompression repeat. 4344
    Go if
    ≥62 mbar on 4 of 5 valid specimens, no through-flow in 30 minutes, head recovers within 10 %.
    No-go if
    Below 62 mbar on 2 of 5, through-flow during the hold, or no recovery after decompression.
    Effort
    $14K–24KUSD$14K–24Kas statedEUR€12.5K–21.5KJPY¥2.22M–3.81MECB reference rates, 2026-10-12 · 1 to 2 months

  2. Hiding by scattering in the pigment-free fine barrier layer gives at least 85 % dry opacity and still hides coloured fluid on the web.

    Why it matters
    Stain masking is a required property, it has no soiled-state precedent, and it depends on the same trapped air keeping the scattering surfaces air-filled.
    First test
    Read contrast-ratio opacity on one coupon air-filled, filled with a clear liquid matching the fibre's refractive index, and filled with simulant; then image soiled specimens at 0, 10 and 30 minutes. 4748
    Go if
    Opacity ≥85 % dry, falling ≥30 percentage points in pores filled with clear same-index liquid; no stain-through at 10 ml.
    No-go if
    Opacity unchanged within 5 points when pores are filled with clear same-index liquid, or stain-through on air-filled layer.
    Effort
    $6K–11KUSD$6K–11Kas statedEUR€5,370–9,840JPY¥952K–1.74MECB reference rates, 2026-10-12 · 3 to 5 weeks

  3. The finished 33 gsm stack passes more than 5 cfm of air with the fine barrier layer at 8 gsm and one-micrometre fibres.

    Why it matters
    Breathability is a required property with a thin estimated margin, because the fine layer carries about 98 % of the flow resistance and the available estimates disagree.
    First test
    Measure air permeability at 125 Pa and vapour transmission on the stack, fine layer alone and a spunbond control across fine-layer variants, plus a helium-versus-air pair. 4950
    Go if
    At least 5 cfm at 8 gsm, with the liquid entry pressure margin untouched.
    No-go if
    Below 5 cfm at 8 gsm on specimens that pass the formation checks, after two formation attempts.
    Effort
    $1,500–3,000USD$1,500–3,000as statedEUR€1,340–2,680JPY¥238K–476KECB reference rates, 2026-10-12 · 1 to 2 weeks

  4. Water-jet entangling can anchor an 8 gsm fine barrier layer to the coarse reservoir layer without washout, holes or a continuous solid skin.

    Why it matters
    The layer sits below the shown entangling window of about 10 g/m², and compaction could silently form a continuous solid skin that still passes a barrier test.
    First test
    Entangle 8 gsm meltblown on 25 gsm spunbond at three jet pressures; weigh retained layer, find largest pore by forcing gas through wetted sample, pull-test strips, count poking-through coarse fibres. 53
    Go if
    ≥95 % retention, ≥0.15 N/25 mm tensile, largest opening ≤4 µm radius, fibre ≤20 % of layer volume, no holes.
    No-go if
    Washout, holes or fibre above 20 % of layer volume; bonding then moves to sparse ultrasonic point bonding.
    Effort
    $15K–30KUSD$15K–30Kas statedEUR€13.4K–26.8KJPY¥2.38M–4.76MECB reference rates, 2026-10-12 · 1 to 2 months
Also to check before scale-up
  • Cup crush below 50 g on a 225 mm formed cup, with bending rigidity at or below an unbonded control.
  • Quietness has no standard method; a flex-and-rub acoustic rig or paired-comparison panel is needed to score it.
  • Coarse reservoir layer tensile above 19.61 N in both directions and machine-direction elongation above 5 %.
  • Delivered cost against the €0.07/m² ceiling, including conversion, waste and drying energy, at the stated annual volume.
  • Which of the two stated cost ceilings governs, and whether it covers raw material or delivered converted cost.
  • A frozen pressure-test protocol for urine, menses and faecal simulants, repeatable within ±5 % despite particle plugging.
  • Fine-barrier-layer largest opening at or below 4 µm radius, including its defect distribution at production width.
  • Independent confirmation of the quoted patent benchmark numbers from the patent's own example tables.

Who could help make this happen?

First contacts

3

References

140 sources60 cited in this idea, 80 background reading

Where it comes from10

Where it comes from

10

The work in the source field that the idea borrows its principle from.

  1. 1Paper: Observations of capillary barriers and preferential flow in layered snow during cold laboratory experiments, Avanzi et al.2016
    F. Avanzi, H. Hirashima, S. Yamaguchi and 2 more
    Observed peaks in bulk volumetric LWC at the interface reached ~33–36 vol% when the upper layer was composed by fine snow (grain size smaller than 0.5 mm)... the implementation of the Richards equation reproduces the existence of a capillary barrier for all observed cases.
    Why it’s hereLaboratory observation of the snow layering barrier: fine snow over coarse holds water at the interface.
    Cited in
    Where it comes fromHow it worksWhy we believe it
    Open source (opens in a new tab)PDF
  2. 2Paper: Effective water vapor diffusion coefficient of snow under a temperature gradient, Sokratov & Maeno2000
    S. Sokratov and N. Maeno
    It was concluded that the effective water vapor diffusion coefficient of snow is dependent on the porosity, tortuosity, and gradient enhancement factor. The mean values of r and f were 1.73 and 2.3, respectively
    Why it’s hereEffective vapour diffusion in snow depends on porosity and tortuosity.
    Cited in
    Where it comes from
    Open source (opens in a new tab)
  3. 3Paper: Water vapor in the pore space of snow, Sokratov et al.2001
    S. Sokratov, A. Sato and Y. KamataAnnals of Glaciology
    Water-vapor movement in snow is regulated by temperature, the water-vapor concentration gradient in the pore space, and structural characteristics of snow such as porosity and tortuosity ... the water-vapor flux can be described by Fick's law
    Why it’s hereDescribes vapour movement through snow pore space by Fick's law.
    Cited in
    Where it comes from
    Open source (opens in a new tab)PDF
  4. 4Paper: A 2D model for simulating heterogeneous mass and energy fluxes through melting snowpacks, Leroux & Pomeroy2016
    N. Leroux and J. Pomeroy
    the matric suction and water entry pressure for dry snow both decreased with larger grain (pore) size
    Why it’s hereModel showing liquid entry pressure in dry snow falls with larger grain size.
    Cited in
    Where it comes from
    Open source (opens in a new tab)PDF
  5. 5Web page: Optical properties of ice and snow, math.utah.edu
    Photons have an opportunity to change direction at each air-ice interface, and they have a chance of being absorbed as they pass through ice ... In coarse-grained snow, a photon travels a longer distance through ice between opportunities for scattering than in fine-grained snow, so it is more likely to be absorbed, and therefore a snowpack of coarse grains has lower albedo.
    Why it’s hereExplains snow whiteness as scattering at air–ice surfaces, stronger in fine-grained snow.
    Cited in
    Where it comes fromWhat we'd test
    Open source (opens in a new tab)
  6. 6Paper: Characterizing Surface Albedo of Shallow Fresh Snow and Its Importance for Snow Ablation on the Interior of the Tibetan Plateau, Wang et al.2020
    W. Wang, K. Yang, L. Zhao and 5 moreJournal of Hydrometeorology
    The albedo of fresh snow depends on snow depth, and is frequently less than 0.4. Such low albedo values contrast with the high values (~0.8) used in the [literature]
    Why it’s hereShows shallow fresh snow often has low albedo, depending on depth.
    Cited in
    Where it comes from
    Open source (opens in a new tab)PDF
  7. 7Paper: Experimental and numerical investigation of the sintering rate of snow, Herwijnen & Miller2013
    A. v. Herwijnen and D. A. MillerJournal of Glaciology
    The mean penetration resistance of snow increased with time according to a power law with an average exponent of 0.18. Simulated changes in the bond-to-grain ratio for simplified spherical ice grains followed a power law with an average exponent of 0.18
    Why it’s hereMeasures snow sintering rate; bond growth follows a power law.
    Cited in
    Where it comes from
    Open source (opens in a new tab)PDF
  8. 8Paper: Modelling capillary hysteresis effects on preferential flow through melting and cold layered snowpacks, Leroux & Pomeroy2017
    N. R. Leroux and J. W. PomeroyAdvances in Water Resources
    Simulating preferential flow in a subfreezing snowpack allowed the model to generate ice layers ... capillary hysteresis is accounted in a snowmelt model
    Why it’s hereModels capillary hysteresis and ice-layer formation in layered snowpacks.
    Cited in
    Where it comes from
    Open source (opens in a new tab)
  9. 19Paper: A new capillary barrier system for retaining wall backfilled with fine-grained soil, Chen et al.2020
    Y. Chen, Y. Gao and C. W. NgComputers and Geotechnics
    Infiltrated water is stored in the fine-grained layer; significant entry into the underlying coarse layer begins when matric suction decreases below that coarse layer's water-entry value.
    Why it’s hereEngineered soil layering barrier: water stored in fine layer until coarse layer's entry value is reached.
    Cited in
    How it worksWhy we believe it
    Open source (opens in a new tab)
  10. 43Paper: Measurement of Dynamic Water-Entry Value for Dry Snow, Katsushima et al.2009
    T. Katsushima, S. Yamaguchi, T. Kumakura and 1 more
    Water cannot infiltrate in the situation that the capillary pressure at the wetting front is less than the water-entry value ... The measured water-entry values were greater than the air-entry value according to the water retention curve for drying process. The water-entry value with large diameter is larger than one with small.
    Why it’s hereMeasures liquid entry pressure in dry snow; water cannot infiltrate below it.
    Cited in
    What we'd testWho could help
    Open source (opens in a new tab)
Evidence it works20

Evidence it works

20

Each shows a part of the idea already working somewhere.

  1. 9Paper: Effect of Process Parameters on Fiber Diameter and Fiber Distribution of Melt-Blown Polypropylene Microfibers Produced by Biax Line, Hoda et al.2021
    N. Hoda, F. Mert, F. Kara and 2 moreFibers And Polymers
    Fine fiber webs close to one-micron average fiber diameter and relatively narrower fiber diameter distribution can be produced under appropriate processing conditions using the Biax process.
    Why it’s hereShows polypropylene fibres near one micrometre are made on production lines.
    Cited in
    How it worksWhy we believe it
    Open source (opens in a new tab)
  2. 10Web page: AUTEFA Solutions: Hydroentanglement & Spunlace, autefa.com
    High-pressure jets entangle fibers and consolidate the web without chemical binders; controlled suction and dewatering are essential.
    Why it’s hereWater-jet entangling consolidates webs without chemical binders.
    Cited in
    How it works
    Open source (opens in a new tab)
  3. 11Web page: Spunlace Nonwoven Fabric Guide: Process, Materials & GSM, sunlunernonwovens.com
    Water pressures typically range from 30 to 250 bar, depending on the fabric GSM, fiber type, and desired strength... Higher water pressure and more injector stages produce stronger entanglement, which increases fabric strength but can reduce softness.
    Why it’s hereBinder-free water-jet entangling window, with stronger entangling reducing softness.
    Cited in
    How it worksWhy we believe it
    Open source (opens in a new tab)
  4. 12Paper: Fiber Selection for Reinforced Additive Manufacturing, Beckman et al.2021
    I. P. Beckman, C. M. Lozano, E. Freeman and 1 morePolymers
    Fiber flexural rigidity ∝ d⁴; bonding adds a torsion term to web bending rigidity; frictional sound correlates with friction, roughness, shear and bending rigidity.
    Why it’s hereFibre bending stiffness scales with diameter to the fourth power; bonding adds web stiffness; rustle tracks friction and stiffness.
    Cited in
    How it works
    Open source (opens in a new tab)PDF
  5. 13Paper: Surface energy of corona treated PP, PE and PET films, its alteration as function of storage time and the effect of various corona dosages on their bond strength after lamination, Lindner et al.2018
    M. Lindner, N. Rodler, M. Jesdinszki and 2 more
    The initial surface energy, before corona treatment, with values of 24 mN/m on PP-BO was lower than the values reported in literature with 29–32 mN/m.
    Why it’s hereMeasures low surface energy of untreated polypropylene.
    Cited in
    How it works
    Open source (opens in a new tab)PDF
  6. 14Web page: Critical Surface Tension and Contact Angle with Water for Various Polymers (sort by contact angle), accudynetest.com
    This table compares critical surface tension to contact angle with water for a variety of polymers.
    Why it’s hereTabulates critical surface tension and water contact angle of polymers.
    Cited in
    How it works
    Open source (opens in a new tab)
  7. 15Paper: Thermodynamic analysis on wetting states and wetting state transitions of rough surfaces., Jiang et al.2020
    Y. Jiang, J. Lian, Z. Jiang and 2 moreAdvances in Colloid and Interface Science
    Equilibrium wetting state can be determined by threshold Young angle. Stability of Cassie-Baxter state should be evaluated by critical pressure.
    Why it’s hereShows trapped air is not the equilibrium state below a threshold contact angle.
    Cited in
    How it works
    Open source (opens in a new tab)
  8. 16Paper: Transition of Liquid Drops on Microstructured Hygrophobic Surfaces from the Impaled Wenzel State to the "Fakir" Cassie-Baxter State., Tzitzilis et al.2024
    D. Tzitzilis, C. Tsekeridis, I. Ntakoumis and 1 moreLangmuir
    The Cassie state is desirable for applications, but it is usually unstable compared to the Wenzel state... The Cassie-to-Wenzel transition can be triggered by an increase in pressure and vibrations, but the inverse Wenzel-to-Cassie is much more difficult to observe.
    Why it’s hereShows the trapped air state is usually unstable and pressure triggers its collapse.
    Cited in
    How it works
    Open source (opens in a new tab)
  9. 17Paper: A Mechanistic Study of Wetting Superhydrophobic Porous 3D Meshes, Yohe et al.2013
    S. T. Yohe, J. Freedman, E. J. Falde and 2 moreAdvanced Functional Materials
    Finally, the application of hydraulic pressure is used to quantify the breakthrough pressure to wet the meshes... the long-term stability of the entrapped air layer is controlled... probed using surfactants and solvents of different surface tensions.
    Why it’s hereQuantifies pressure to wet fibre meshes holding a trapped air layer, across surface tensions.
    Cited in
    How it worksWho could help
    Open source (opens in a new tab)PDF
  10. 18Paper: Underwater breathing: the mechanics of plastron respiration, Flynn & Bush2008
    M. Flynn and J. M. BushJournal of Fluid Mechanics
    A thin stable gas film held against a hydrophobic structure under water, analysed mechanically.
    Why it’s hereMechanics of thin stable gas films held underwater on hydrophobic structures.
    Cited in
    How it works
    Open source (opens in a new tab)
  11. 22Paper: Liquid–liquid phase separation morphologies in ultra-white beetle scales and a synthetic equivalent, Burg et al.2019
    S. L. Burg, A. L. Washington, D. Coles and 5 moreCommunications Chemistry
    Chitin-filling fractions are found to be 31 ± 2% for Cyphochilus and 34 ± 1% for Lepidiota stigma... Reflectance curves spanning filling fraction of 5-95% for simulated spinodal structures, pinpoint optimal whiteness for 25% chitin filling.
    Why it’s hereUltra-white beetle scales achieve hiding by scattering with sparse, pigment-free networks.
    Cited in
    How it worksWhy we believe it
    Open source (opens in a new tab)PDF
  12. 23Paper: Spun bonding technology and fabric properties: A review, Midha & Dakuri2017
    V. Midha and A. Dakuri
    Basis weight ranges from 5 to 800 g/m² but is typically 10–200 g/m²... Fiber diameter ranges from 1 to 50 µm, but the preferred range is 15–35 µm.
    Why it’s hereGives typical spunbond weights and coarse fibre diameters for the coarse reservoir layer.
    Cited in
    Why we believe it
    Open source (opens in a new tab)PDF
  13. 24Paper: Modeling of spunbond formation process of polymer nonwovens - ScienceDirect
    A high molecular weight polymer, e.g., PP ... resulting in fibers of 15–35 μm in diameter formed by the spunbond process.
    Why it’s hereSpunbond polypropylene fibres of 15–35 micrometres for the coarse reservoir layer.
    Cited in
    Why we believe it
    Open source (opens in a new tab)
  14. 25Paper: Optical Properties of Electrospun Nanofiber Mats, Błachowicz & Ehrmann2023
    T. Błachowicz and A. EhrmannMembranes
    Optically, they are mostly white due to scattering from the irregularly distributed, thin nanofibers.
    Why it’s hereShows fine-fibre mats appear white from scattering by irregular thin fibres.
    Cited in
    Why we believe it
    Open source (opens in a new tab)PDF
  15. 26Paper: Gradient Design of Spunbond-Meltblown-Hydroentanglement Composite Nonwovens for Directional Water Transport, Sun et al.2024
    W. Sun, H. Gao, X. Han and 2 moreACS Applied Polymer Materials
    a three-layer degradable composite material comprising of polylactic acid (PLA) spunbond, PLA meltblown, and PLA/viscose hydroentanglement layer. The resultant composite material exhibited good waterproofing and moisture permeability characteristics, achieving a water pressure resistance of 2.52 KPa and a moisture permeability of 5821 g/(m²·d).
    Why it’s hereSpunbond–meltblown–entangled composite shows waterproofing with moisture permeability.
    Cited in
    Why we believe it
    Open source (opens in a new tab)
  16. 27Patent: Multiple layer absorbent substrate and method of formation, US 8,250,7192009
    Clorox CoInventors: W. Ouellette
    hydroentangling the carrier web and air laid layer together to form a fully bonded dual layer substrate... The basis weight for the carrier web material is about 5 to 40 gsm, or about 5 to 20 gsm, or about 8 to 15 gsm.
    Why it’s herePatent water-jet entangling a light carrier web with a laid layer.
    Cited in
    Why we believe it
    Google Patents (opens in a new tab)PDFEspacenet
  17. 39Paper: Cassie–Wenzel and Wenzel–Cassie transitions on immersed superhydrophobic surfaces under hydrostatic pressure - Soft Matter (RSC Publishing)
    The pressure required for the transition from Cassie to Wenzel state is measured for all surfaces... the closed film of trapped air helps stabilise the Cassie state at low pillar densities... the reverse transition, from Wenzel to Cassie state, is observed on densely pillared surfaces at low water pressure.
    Why it’s hereMeasures the water pressure that collapses a trapped air layer on textured surfaces.
    Cited in
    What we'd test
    Open source (opens in a new tab)
  18. 40Paper: Client Challenge
    The trapped air on underwater SHS lacks passive stability and disappears over time, leading to the Cassie-to-Wenzel transition... a Cassie-to-Wenzel transition may occur due to the metastability of the plastron... resulting from small perturbations of external stimuli such as temperature, hydrostatic pressure, mechanical vibration, and surface contamination.
    Why it’s hereShows trapped air layers under liquid are metastable and lost to pressure, vibration or contamination.
    Cited in
    What we'd test
    Open source (opens in a new tab)
  19. 46Paper: Tetrapodal textured Janus textiles for accessible menstrual health, Sanders et al.2023
    S. L. Sanders, L. D. Douglas, T. E. Sill and 5 moreiScience
    Wetback was ~8× higher with menses simulant (217 ± 87 mg) than saline (27 ± 7 mg), attributed to the lower surface tension 'decreas[ing] the capillary resistance'.
    Why it’s hereShows about eight times more wetback with menses simulant than saline, attributed to lower surface tension.
    Cited in
    What we'd test
    Open source (opens in a new tab)PDF
  20. 53Web page: AUTEFA Solutions — Hydroentanglement (spunlace) web bonding, autofa.com
    Binder-free high-pressure water-jet entanglement of a loose fine web resting on a coarser carrier, one pass, no chemical binder, no whole-surface fusion, documented at 10–1000 g/m² and to 300–500 m/min, with air permeability and water absorbency improved versus the unbonded web.
    Why it’s hereDocuments binder-free water-jet entangling of a fine web onto a coarser carrier at industrial speed.
    Cited in
    What we'd test
    Open source (opens in a new tab)
Today's approaches and closest prior art4

Today's approaches and closest prior art

4

How the field handles the problem now, and the nearest existing work.

  1. 30Patent application: Barrier Fabrics with Desirable Air Permeability, US 2024/0316898 A12024
    Berry Global IncInventors: L. Wang, N. Bishop, T. ZHANG and 2 more
    Each of the nonwoven layers being treated with a non-fluorinated barrier coating (NFBC) ... 45 gsm SMMMMS + NFBC at 81.2 mbar average hydrohead and 20.99 cfm, pore size 6–8 µm; outermost spunbond fibres with an average diameter from about 10 to about 25 microns, 18–22.
    Why it’s hereNearest existing breathable barrier fabric: multilayer fine-fibre stack relying on a fluorine-free coating.
    Cited in
    New to your fieldWho could help
    Google Patents (opens in a new tab)PDFEspacenet
  2. 31Patent: Breathable absorbent article, US 12,558,273 B22020
    Allegiance CorpInventors: W. H. Isaac
    hydrostatic pressure of the backsheet may be greater than or equal to 60 centimeters based on AATCC Test Method 127-2008 ... the air permeability of the underpad may range from 5 to 35 cubic feet per minute.
    Why it’s hereFilm-free breathable absorbent backsheet with stated water-pressure and air-permeability values.
    Cited in
    New to your fieldWho could help
    Google Patents (opens in a new tab)Espacenet
  3. 32Patent: High barrier nonwoven, US 2012/01007722010
    Fibertex ASInventors: L. K. Hummelgaard and B. Udengaard
    the additive component comprising one or more lipid esters... a melt additive... comprising a triglyceride... glycerol tristearate... whereby the Low Surface Tension Strike Through (32 mJ/m²) of the nonwoven is increased by more than 25%... SSMMS or SMMMS.
    Why it’s hereHigh-barrier nonwoven using a lipid melt additive against low-surface-tension liquids.
    Cited in
    New to your fieldWho could help
    Google Patents (opens in a new tab)PDFEspacenet
  4. 33Patent: Multilayered nonwoven fabrics and method of making the same, US 11,541,629 B22019
    PFNonwovens Holding sroInventors: J. C. P. IV, P. Zajaczkowski, K. RAMARATNAM and 2 more
    A nonwoven composite fabric including a first nonwoven layer composed substantially of meltblown fibers... a third nonwoven layer... disposed between the first and second nonwoven layers, the fibers within the third nonwoven layer having diameters... greater than the first and second distributions.
    Why it’s hereNonwoven composite combining meltblown layers with a coarser-fibre layer.
    Cited in
    New to your fieldWho could help
    Google Patents (opens in a new tab)PDFEspacenet
Methods for the tests15

Methods for the tests

15

The rigs, protocols and measures the first tests borrow.

  1. 20Web page: Filter Pressure Drop - HVAC Systems Encyclopedia, ingener.by
    The stated Davies equation includes the factor alpha^1.5: ΔP=64 alpha^1.5(1+56 alpha^3) μ U t/d_f².
    Why it’s hereDavies equation for pressure drop through fibre webs, used for the air-permeability estimate.
    Cited in
    How it works
    Open source (opens in a new tab)
  2. 21Web page: Pressure Drop Evolution of a Medium-Performance Fibrous Filter (Aerosol and Air Quality Research), aaqr.org
    Davies (1952) characterized the pressure drop across a dry fibrous filter, Δp0 = 64 α^1.5 (1 + 56α^3) μ_g u Z / d_f²
    Why it’s hereStates the full Davies pressure-drop correlation for dry fibrous filters.
    Cited in
    How it works
    Open source (opens in a new tab)
  3. 28Web page: Standard Test Methods for Pore Size Characteristics of Membrane Filters by Bubble Point and Mean Flow Pore Test, store.astm.org
    Test Method A presents a test method for measuring the maximum limiting pore diameter ... The effective pore size calculated from this test method is based on the premise of capillary pores having circular cross sections.
    Why it’s hereBubble-point standard used to measure the largest openings that set liquid entry pressure.
    Cited in
    Why we believe itWhat we'd test
    Open source (opens in a new tab)
  4. 29Web page: Capillary Flow Porometry (CFP) - Complete Technical Guide, porosimetry.com
    d = 4γ cos θ / ΔP... a completely wetted membrane prevents gas flow until sufficient pressure overcomes the capillary forces holding liquid in the pores... CFP determines bubble point (largest pore), mean flow pore size, and complete pore size distribution.
    Why it’s hereGuide to capillary flow porometry relating pressure to pore size.
    Cited in
    Why we believe it
    Open source (opens in a new tab)
  5. 38Paper: Determination of the Pore Size Distribution of Nonwoven Geotextiles by a Modified Capillary Flow Porometry Technique, Vermeersch & Młynarek1996
    O. Vermeersch and J. Młynarek
    determination of the pore size distribution of nonwoven geotextiles by a modified capillary flow porometry technique.
    Why it’s hereAdapts bubble-point porometry to measure full pore size distribution in nonwoven fabrics.
    Cited in
    What we'd test
    Open source (opens in a new tab)
  6. 41Paper: In Situ Experiments To Reveal the Role of Surface Feature Sidewalls in the Cassie–Wenzel Transition, Hensel et al.2014
    R. Hensel, A. Finn, R. Helbig and 3 moreLangmuir
    A further increase of the hydrostatic pressure results in a downward sliding of the three-phase contact line along the cavity sidewall ... Finally, after the second transition, the cavity is completely wetted; i.e., the Wenzel state is achieved.
    Why it’s hereObserves in situ how rising pressure slides liquid down cavity walls until fully wetted.
    Cited in
    What we'd test
    Open source (opens in a new tab)PDF
  7. 42Patent application: Menstrual fluid simulant, US 2024/0151706 A12023
    Procter and Gamble CoInventors: J. Claussen, B. Mohebbi, C. Neu and 5 more
    a viscosity that is shear-dependent and ranges from about 10 mPas to about 140 mPas, at 21° C. and a shear rate of 10 s−1, a surface tension that ranges from about 35 mN/m to about 70 mN/m
    Why it’s hereDefines a menstrual fluid simulant by viscosity and surface tension ranges for testing.
    Cited in
    What we'd test
    Google Patents (opens in a new tab)PDFEspacenet
  8. 44Paper: Dynamic Water‐Entry Pressure for Initially Dry Glass Beads and Sea Sand, Annaka & Hanayama2005
    T. Annaka and S. HanayamaVadose Zone Journal
    First, breakthrough pressures were measured by increasing the supply water pressure incrementally from a low water pressure at which water could not enter the porous medium.
    Why it’s hereBreakthrough-pressure protocol of stepwise pressure increase on initially dry granular media.
    Cited in
    What we'd test
    Open source (opens in a new tab)
  9. 45Web page: NWSP 80.6 Water Resistance (Hydrostatic Pressure) » SGS-IPS Testing, ipstesting.com
    The rate of increase of the water pressure must be 10 ± 0.5 cm or 60 ± 3 cm H2O/min. Using these two different rates may give different end results. It is important to list in the test results which rate was used.
    Why it’s hereNonwoven water-pressure test whose two ramp rates and support mesh change results.
    Cited in
    What we'd test
    Open source (opens in a new tab)
  10. 47Web page: ISO 2471:2008 — Paper and board — Determination of opacity (paper backing) — Diffuse reflectance method, cdn.standards.iteh.ai
    The method described in this International Standard is applicable when it is desired to measure that property of a paper which governs the extent to which one sheet visually obscures printed matter on underlying sheets of similar paper.
    Why it’s hereStandard diffuse-reflectance opacity method used to test hiding by scattering.
    Cited in
    What we'd test
    Open source (opens in a new tab)
  11. 48Web page: ASTM D589-97 Standard Test Method for Opacity of Paper, file.yizimg.com
    The reflectance of paper when combined with a white backing is higher than that of paper when combined with a black backing because in the former case, light transmitted through the imperfectly opaque sheet is largely reflected by the white backing ... Accordingly, the contrast ratio is 100 % for perfectly opaque paper and is only a few percent for perfectly transparent sheets.
    Why it’s hereContrast-ratio opacity method: white versus black backing reflectance.
    Cited in
    What we'd test
    Open source (opens in a new tab)
  12. 49Web page: Standard Test Method for Air Permeability of Textile Fabrics, astm.org
    Standard Test Method for Air Permeability of Textile Fabrics, ASTM Committee D13.
    Why it’s hereStandard air-permeability test for the breathability floor.
    Cited in
    What we'd test
    Open source (opens in a new tab)
  13. 50Paper: Client Challenge
    Davies proposed an empirical expression of pressure drop across fibers valid for the packing density less than 0.3. However, the pressure drop equations in Kuwabara and Davies did not consider the slip effect that reduces the hydrodynamic drag on nanofibers. However, a considerable aerodynamic slip occurs when the fiber diameter is comparable to the mean free path of gas molecules, e.g., around 67 nm for air at standard pressure and temperature.
    Why it’s herePressure-drop models for fine-fibre filters, including slip effects.
    Cited in
    What we'd test
    Open source (opens in a new tab)
  14. 51Paper: Client Challenge
    The air permeability of samples was determined following ASTM-D737 via the Shirley apparatus ... The influence of the slip length boundary condition was investigated by the proposed algorithm and the results were compared and validated against the experimentally measured air permeability values.
    Why it’s hereCompares flow simulation with measured air permeability of nanofibre media.
    Cited in
    What we'd test
    Open source (opens in a new tab)
  15. 52Paper: Effect of slip flow on pressure drop of nanofiber filters, Choi et al.2017
    H. Choi, M. Kumita, T. Seto and 4 more
    Kirsch, Stechkina, and Fuchs (1973) studied the slip flow effect on the pressure drop of fibrous filters consisting of micron fibers, and proposed an empirical equation to predict the dependence of the dimensionless drag, F, on the Knudsen number, Kn.
    Why it’s hereSlip-flow correction to fibrous filter pressure drop, relevant to fine fibres.
    Cited in
    What we'd test
    Open source (opens in a new tab)PDF
People and organizations11

People and organizations

11

The researchers, labs, companies and suppliers who could help make the idea happen.

  1. 54Paper: Designing Robust Hierarchically Textured Oleophobic Fabrics., Kleingartner et al.2015
    J. A. Kleingartner, S. Srinivasan, Q. Truong and 3 moreLangmuir
    Commercially available woven fabrics ... possess inherently re-entrant textures in the form of cylindrical yarns and fibers.
    Why it’s hereShows ordinary fabrics' cylindrical fibres are inherently re-entrant textures.
    Cited in
    Who could help
    Open source (opens in a new tab)
  2. 55Web page: TC - Observations of capillary barriers and preferential flow in layered snow during cold laboratory experiments, tc.copernicus.org
    Research article | [](https://creativecommons.org/licenses/by/3.0/) | 09 Sep 2016 # Observations of capillary barriers and preferential flow in layered snow during cold laboratory experiments Francesco Avanzi []( , Hiroyuki Hirashima , Satoru Yamaguchi , Takafumi Katsushima , and Carlo De Michele ### Francesco Avanzi CORRESPONDING AUTHOR []( and []( <https://orcid.org/0000-0003-4235-2373> × Department of Civil and Environmental Engineering, Politecnico di Milano, Milano, Italy ### Hiroyuki Hirashima × Snow and Ice Research Center, National Research Institute for Earth Science and Disaster Resilience, Suyoshi-machi, Nagaoka-shi, Niigata-ken, 940-0821, Japan ### Satoru Yamaguchi <https://orcid.org/0000-0001-9972-0443> × Snow and Ice Research Center, National Research Institute for Earth Science and Disaster Resilience, Suyoshi-machi, Nagaoka-shi, Niigata-ken, 940-0821, Japan ### Takafumi Katsushima × Meteorological Risk and Buffer Forest Laboratory, Department of Meteorological Environment, Forestry and Forest Products Research Institute, Tsukuba-shi, Ibaraki-ken, 305-8687, Japan ### Carlo De Michele <https://orcid.org/0000-0002-7098-4725> × Department of Civil and Environmental Engineering, Politecnico di Milano, Milano, Italy **Abstract.** Data of liquid water flow around a capillary barrier in snow are still limited. To gain insight into this process, we carried out observations of dyed water infiltration in layered snow at 0 °C during cold laboratory experiments. We considered three different finer-over-coarser textures and three different water input rates. By means of visual inspection, horizontal sectioning, and measurements of liquid water content (LWC), capillary barriers and associated preferential flow were characterized. ... [Reddit](https://www.reddit.com/submit?url=https%3A%2F%2Ftc.copernicus.org%2Farticles%2F10%2F2013%2F2016%2F "Reddit") [Twitter](https://twitter.com/intent/tweet?text=Observations+of+capillary+barriers+and+preferential+flow+in+layered+snow+during+cold+laboratory+experiments https%3A%2F%2Ftc.copernicus.org%2Farticles%2F10%2F2013%2F2016%2F "Twitter") [Facebook](https://www.facebook.com/share.php?u=https%3A%2F%2Ftc.copernicus.org%2Farticles%2F10%2F2013%2F2016%2F&t=Observations+of+capillary+barriers+and+preferential+flow+in+layered+snow+d…
    Why it’s hereHe led cold-laboratory observations of dyed water entering fine-over-coarse layered snow, characterising how the snow layering barrier holds water at the boundary and where flow breaks through in fingers.
    Cited in
    Who could help
    Open source (opens in a new tab)
  3. 56Web page: Stefano GUIDO | Professor (Full) | PhD | University of Naples Federico II, Naples | UNINA | Department of Chemical, Materials and Industrial Production Engineering | Research profile, researchgate.net
    Cariati](https://www.researchgate.net/profile/Federica-Cariati) * [...] * [Stefano Guido Stefano Guido](https://www.researchgate.net/profile/Stefano-Guido-3) Human semen is a complex biological fluid whose rheological properties are relevant to male fertility and assisted reproductive technologies. Standard clinical assessment is largely qualitative and operator dependent, motivating the search for objective biophysical markers of semen quality. Although normospermic semen is commonly assumed to behave... [View](https://www.researchgate.net/publication/404031824_Viscoelastic_alterations_of_human_semen_associated_with_diagnosed_male_infertility) [](https://www.researchgate.net/figure/Simulation-of-blood-flow-in-a-straight-channel-with-a-sinusoidal-bottom-wall-resembling_fig1_403605878) [](https://www.researchgate.net/figure/Spatial-distribution-of-platelet-capture-along-the-sinusoidal-surface-Heatmaps-show-the_fig2_403605878) ... [View](https://www.researchgate.net/publication/401103784_Author_Correction_Defective_CFTR_induces_aggresome_formation_and_lung_inflammation_in_cystic_fibrosis_through_ROS-mediated_autophagy_inhibition) [The Dilemma of Cancer Biomechanics Assessment: Living Soft Matter from a Rheological Perspective](https://www.researchgate.net/publication/400432904_The_Dilemma_of_Cancer_Biomechanics_Assessment_Living_Soft_Matter_from_a_Rheological_Perspective) Article Full-text available * Feb 2026 Materials Today Bio * [Rosalia Ferraro Rosalia Ferraro](https://www.researchgate.net/profile/Rosalia-Ferraro) * [Stefano Guido Stefano Guido](https://www.researchgate.net/profile/Stefano-Guido-3) * [Sergio Caserta Sergio Caserta](https://www.researchgate.net/profile/Sergio-Caserta) ... [Rheological Characterization of Menstrual Fluid. XVIII Italian Society of Rheology Conference.](https://www.researchgate.net/publication/389207704_Rheological_Characterization_of_Menstrual_Fluid_XVIII_Italian_Society_of_Rheology_Conference) Presentation * Sep 2024 * [Jan Claußen Jan Claußen](https://www.researchgate.net/profile/Jan-Claussen-3) * [Christian Neu Christian Neu](https://www.researchgate.net/scientific-contributions/Christian-Neu-2306120629) * [Aexandra Wolf Aexandra Wolf](https://www.researchgate.net/scientific-contributions/Aexandra-Wolf-2306160557) * [...] * [Stefano Guido Stefano Guido](https://www.researchgate.net/profile/Stefano-Guido-3) real menses characterization; femcare prodcuts [View](https://www.researchgate.net/publication/38…
    Why it’s hereHe co-authored a rheological characterisation of real menstrual fluid for feminine-care products, the kind of measurement that fixes what a body-fluid simulant has to match.
    Cited in
    Who could help
    Open source (opens in a new tab)
  4. 57Paper: The role of staple fiber length on the performance of carded, hydroentangled nonwovens produced with polypropylene fibers - Jordan Tabor, Carl Wust, Behnam Pourdeyhimi, 2019
    Carding, crosslapping, and pre-needling were completed at The Nonwovens Institute’s Staple Nonwovens Pilot Facility located at North Carolina State University. This facility includes a fiber feeding device, opening and blending equipment, a Trutzschler High-Speed EWK 413 Card, an Asselin Profile 415-FD Crosslapper, and a Trutzschler Nonwovens ENL (single board) Needle Loom (used for web pre-needling). The recommended fiber length for the EWK card is 15–60 mm. During carding, samples were processed with similar settings to ideally achieve a basis weight of 125 g/m ² . Overall, the carding process ran smoothly for all fiber lengths. However, some issues arose when processing the 2.54-cm-long fibers. The 6-denier, 2.54-cm-long fibers were particularly difficult to doff and resulted in the production of splotchy, non-uniform webs such as those seen in Figure 2 . Figure 2 . Splotchy web produced from 2.54-cm-long, 6-denier PP fibers. ... 0/> ) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages ( <https://us.sagepub.com/en-us/nam/open-access-at-sage> ). ### Authors #### Affiliations Jordan Tabor The Nonwovens Institute, North Carolina State University, Raleigh, NC, USA View all publications by this author Carl Wust FiberVisions Corporation (An Indorama Ventures Company), Covington, GA, USA View all publications by this author Behnam Pourdeyhimi The Nonwovens Institute, North Carolina State University, Raleigh, NC, USA []( View all publications by this author #### Notes ## Metrics and citations ### Metrics #### Journals metrics
    Why it’s hereHe co-authored a study of how staple fibre length governs the performance of carded polypropylene nonwovens bonded by water jets.
    Cited in
    Who could help
    Open source (opens in a new tab)
  5. 58Patent: Absorbent barrier structures having a high convective air flow rate and articles made therefrom, US 7,179,951 B22002
    Procter and Gamble CoInventors: S. Krishnaswamy-Mirle, M. Schmidt, J. F. McKibben and 2 more
    an absorbent barrier structure, wherein the absorbent barrier structure has a hydrohead value of at least about 10 mBars; a convective air permeability of at least about 10 Darcy/mm; and a liquid impact transmission value of less than about 20 g/m².
    Why it’s hereAbsorbent barrier structure specified by liquid resistance, air permeability and impact transmission.
    Cited in
    Who could help
    Google Patents (opens in a new tab)PDFEspacenet
  6. 59Patent application: Breathable disposable sanitary product construction and backsheet therefor, US 5,928,209 A1997
    Poly-Bond IncInventors: C. A. Bodford, R. C. Allen and R. K. Nayak
    A backsheet made of two SMP or SMS nonwoven fabrics with liquid-absorbent particles between them, initially hydrophobic but becoming hydrophilic when subjected to a sufficiently high hydrohead.
    Why it’s hereVapour-permeable hydrophobic multilayer nonwoven barrier with meltblown layers.
    Cited in
    Who could help
    Google Patents (opens in a new tab)PDFEspacenet
  7. 60Patent application: Composite fabric for coverstock having separate liquid pervious and impervious regions, US 6,049,024 A1998
    BBA Nonwovens Simpsonville IncInventors: H. E. Thomas and J. O. Reeder
    A composite nonwoven fabric... for disposable absorbent articles including diapers, catamenial products, and adult incontinence products... The strikethrough region is bounded by liquid barrier regions... balanced properties comparable to or better than conventional spunbonded topsheet at comparable or lower basis weights.
    Why it’s hereComposite nonwoven with liquid barrier regions for absorbent hygiene products.
    Cited in
    Who could help
    Google Patents (opens in a new tab)PDFEspacenet
  8. 61Web page: ADVANCED SPUNBOND & HYDROENTANGLING PILOT CAPABILITIES, thenonwovensinstitute.com
    ## **ADVANCED SPUNBOND & HYDROENTANGLING PILOT CAPABILITIES** ### The Nonwovens Institute at North Carolina State University offers state-of-the-art technology and deep expertise in spunmelt nonwovens. Following spunbond web laydown, the line offers several bonding methods via a hydroentanglement unit (one pre-entanglement injector, plus two additional injectors), a thermal calendar (includes roll options for 3 bond patterns), two additional hydroentanglement units (each with two injectors), a kiss roll unit, and a through-air dryer. The hydroentangling unit and thermal calender can also be used in combination. Layers can be added either via a front-end unwind or after the web laydown via an unwind “Fiber options include sheath-core bico, side-by-side bico, or homofilament, as well as more complex cross-sections, such as segmented pie and islands-in-the-sea. Resin options include PP, PE and PET, along with many others, including nylon, elastomers and biopolymers, such as PLA.” The Nonwovens Institute has decades of experience in spunmelt nonwovens, which in tandem with its in-house Reicofil spunbond line – soon-to-be upgraded to RF5 with full digitalization capability – provides you the opportunity to customize the web path to your specific application requirements. Thus, NWI’s Advanced Spunmelt and Hydroentangling Pilot Facility also utilizes equipment from supporting partners – including Hills bico or mono filament die packs, two unwinds, an Andritz thermobonding calender, two Andritz Perfojet hydroentanglement units, a kiss roll, a through-air dryer, a high-speed A.Celli winder and slitter, and an Orion slitter/rewinder. Importantly, this system includes in-line electrostatic charging capability (corona). prior to bonding. Finally, the web path concludes with winding and slitting. NWI can run trials in many configurations, such as single-beam spunbond, and with a variety of fiber arrangements. Fiber options include ... ## **Spunbond & Hydroentangling Lab - Equipment Specifications**
    Why it’s hereSpunbond line with in-line water-jet entangling and layer unwind
    Cited in
    Who could help
    Open source (opens in a new tab)
  9. 62Web page: NONWOVENS TESTING » SGS-IPS Testing, ipstesting.com
    This is driven by the ability to produce a high-volume custom material with a wide variety of properties at a relatively low cost. ## Stiffness to Air Permeability Nonwovens Testing Services Wisconsin-based IPS Testing offers a large range of testing services suitable for evaluating the key nonwoven properties that drive the success of your application. From Stiffness, Abrasion Resistance and Air Permeability to Barrier Properties, Water Vapor Transmission and Flammability, we utilize various test methods to tell you how your materials stack up against your objectives and your competitors. For nonwovens testing, we perform AATCC, ASTM, CFR, ISO, TAPPI, WSP and our own IPS test methods. ## Test Methods **Applicable to Nonwovens** |Title |Method Number | | --- | --- | |Test Methods for nonwovens - Part 6: Absorption |[ISO 9073-6](https://ipstesting.com/find-a-test/iso-test-methods/iso-9073-6-absorption/) | |Colorfastness to Crocking: Crockmeter Method |[AATCC 8](https://ipstesting.com/find-a-test/aatcc-test-method/aatcc-8-colorfastness-to-crocking/) | |Taber Abrasion |[TAPPI T 476](https://ipstesting.com/find-a-test/tappi-test-methods/tappi-t-476-taber-abrasion/) | |Fiber Analysis of paper and paper board |[TAPPI T 401](https://ipstesting.com/find-a-test/tappi-test-methods/tappi-t-401-fiber-analysis/) | |Water Resistance: Impact Penetration Test |[AATCC 42](https://ipstesting.com/find-a-test/aatcc-test-method/aatcc-42-water-resistance/) | |Water Resistance: Hydrostatic Pressure Test |[AATCC 127](https://ipstesting.com/find-a-test/aatcc-test-method/aatcc-127-hydrostatic-pressure-test/) | |Gray Scale for Staining |[AATCC EP 2](https://ipstesting.com/find-a-test/aatcc-test-method/aatcc-ep-2-gray-scale-for-staining/) | |Air Permeability of Textile Fabrics |[ASTM D 737](https://ipstesting.com/find-a-test/astm-test-methods/astm-d-737-air-permeability/) | |Failure in Sewn Seams of Woven Apparel Fabrics |[ASTM D ... |Tearing Strength of Fabric by Trapezoid Procedure |ASTM D5587 | |Standard practice for Calculating Yellowness and Whiteness Indices from Instrumentally Measured Color Coordinates |ASTM E313 | |Laboratory Test Method for 16 CFR Part 1610: Standard for Flammability of Clothing Textiles Laboratory Test Manual |CFR 1610 | |Absorption, Time and Rewet - Single Insult (Specimen cut from Whole Product) |IPS Method | |Absorption, Time - Liquid Strike-Through, Repeated (Specimen cut from Whole Product) |IPS Method | |Absorption, Time - Liquid Strike-Throug…
    Why it’s hereHydrostatic pressure, air permeability and stiffness tests on nonwovens
    Cited in
    Who could help
    Open source (opens in a new tab)
  10. 63Web page: Porometer, porometer.com
    on developing and ... izing instruments to measure pore size distribution, gas and liquid permeability. Our porometers are very much appreciated by both R&D and quality control labs to characterize the pore size and the pore size distribution for media used in filtration and separation processes, such as polymeric and ceramic membranes – including flat sheet and hollow fibre membranes – , non-wovens, paper, porous rocks, etc. The gas-liquid porometers measure through pores in the range of 500 μm to 15 nm, while the liquid-liquid porometers can measure through pores down to 2 nm. Our porometers are built in Germany with some unique designed components to guarantee the most accurate measurement of pressure and flow. Typical applications include dialysis, desalination, battery separators, carbon nanofibers, personal care. Next to porometers, we also develop & manufacture instruments used for membrane synthesis and characterization, such as an automatic membrane/film casting machine (MEMCAST™), or liquid permeability tester. Porometer also offers contract testing. ... capillary flow porometers, electronics, filter & membrane testing equipment, filter characterisation, gas liquid porometry, industrial, liquid liquid porometry, liquid permeability, manufacturing, manufacturing-industrial, measurement instruments, membrane characterisation, membrane synthesis, nonwovens characterisation, pore size, porous materials, products, sample analysis servcie, test and measurement ... 7 · 6 reactions] 𝙃𝙤𝙬 𝙢𝙪𝙘𝙝 𝙙𝙤𝙚𝙨 𝙮𝙤𝙪𝙧 𝙬𝙚𝙩𝙩𝙞𝙣𝙜 𝙡𝙞𝙦𝙪𝙞𝙙 𝙞𝙣𝙛𝙡𝙪𝙚𝙣𝙘𝙚 𝙮𝙤𝙪𝙧 𝙘𝙖𝙥𝙞𝙡𝙡𝙖𝙧𝙮 𝙛𝙡𝙤𝙬 𝙥𝙤𝙧𝙤𝙢𝙚𝙩𝙧𝙮 𝙧𝙚𝙨𝙪𝙡𝙩𝙨? More than you might think. The wetting liquid is a fundamental part of every capillary flow porometry measurement.... # Porometer Porometer is a Appliances, Electrical, and Electronics Manufacturing company. Porometer is a leading manufacturer of instruments for measuring pore size and liquid permeability of porous materials. They offer a wide range of products and services for various applications and industries. Porometer employs 8 people. Headquartered in Berlin, Berlin, Germany, with presence in Belgium, United States, China, and Poland. Its workforce is distributed across Belgium, Poland, China, and Finland. ## About Porometer focuses on developing and commercializing instruments to measure pore size distribution, gas and liquid permeability. Our porometers are very much appreciated by both R&D and quality control labs to characterize the pore size and the pore size distribution for media used in filtration and separation processes, such as polymeric and ceramic membranes – including flat sheet and hollow fibre membranes – , non-wovens, paper, porous rocks, etc. The gas-liquid porometers measure through pores in the range of 500 μm to 15 nm, while the liquid-liquid porometers can measure through pores down to 2 nm. Our porometers are built in Germany with some unique designed components to guarantee the most accurate measurement of pressure and flow. Typical applicati…
    Why it’s hereCapillary flow porometers and contract pore-size testing of nonwovens
    Cited in
    Who could help
    Open source (opens in a new tab)
  11. 64Web page: Autefa Briefvorlage Deutschland, autefa.com
    Autefa Solutions Germany GmbH, Paul-Lenz-Str. 1b, 86316 Friedberg Friday, March 12, 2021 AUTEFA Solutions spunlace line with the Hydroentanglement Machine V- Jet FUTURA is available for further customer trials using the full portfolio of the company's Nonwovens machinery “from bale to fabric” including opening and blending, web forming, hydroentanglement, drying as well as cutting and winding. Recently, a team from Lenzing that is known for their VEOCEL™ branded cellulosic nonwoven fibers, was invited for trials at AUTEFA Solutions Nonwoven Competence Center in Linz, Austria. Christoph Machill, Head of Business Unit Spunlace:” Our new line, targeted with full power and know how, over the last years is now ready for the market. We are focused to offer solutions also with regard to the processing of biodegradable products.” The spunlace sector is still challenging for product manufacturers. AUTEFA Solutions offers complete lines for the production of direct and crosslapped spunlace products. The web forming process, consisting of the Injection Card and Crosslapper Topliner CL 4006 CL, is the key for high and consistent nonwoven fabric quality. AUTEFA Solutions advanced Spunlace technology with Hydroentanglement Machine V- Jet Futura and Square Drum Dryer SQV offers a quick return on investments. The V- Jet FUTURA technology takes place featuring 30% less electrical energy consumption due to the unique V-Jet-construction with significantly reduced distance between the nozzle and the fabric to be bonded. The Square Drum Dryer SQ-V combines the advantage in drying efficiency of a horizontal belt dryer with the space advantage of a drum dryer, resulting in increased drying length with small footprint. 30% savings of thermal energy can be achieved compared to known drying technology used in the spunlace process. AUTEFA Solutions spunlace line in Linz, Austria is providing excellent opportunities for trials supporting customers in developing new advanced products. Fiber opening and blending, Injection card, Hydroentanglement Machine V- Jet Futura and Square Drum Dryer SQV are available. Further products like spunbond, wetlaid or crosslapped drylaid can be unwind between the Injection Card and the subsequent V-Jet FUTURA. The installed equipment enables realistic impressions of the quality, workmanship, capability, and performance of AUTEFA Solutions machinery. **Jutta Soell** (Dipl.- Ing) Head of Marketing **AUTEFA Solutions Germany GmbH** \- Paul-Lenz- Straße …
    Why it’s hereSpunlace trial line in Linz that can unwind spunbond before water-jet entangling
    Cited in
    Who could help
    Open source (opens in a new tab)
Background reading80

Background reading

80

Read while building the idea; not cited in the text.

  1. 34Patent application: US5213881A - Nonwoven web with improved barrier properties - Google Patents, US 5,213,881 A
    # Nonwoven web with improved barrier properties ## US5213881A United States [Download PDF](https://patentimages.storage.googleapis.com/49/55/e9/76cec41a234b95/US5213881.pdf) Find Prior Art Similar Inventor Terry K. Timmons Peter Kobylivker Lin-Sun Woon Current Assignee Kimberly Clark Worldwide Inc Worldwide applications 1991 US ... ### Description This invention relates generally to a nonwoven web having fine fibers and a small pore size distribution and a method for forming such a web. The method of the present invention uses a reactor granule resin having an initial broad molecular weight distribution which resin has been modified to narrow its molecular weight distribution and to increase its melt flow rate. Consequently the nonwoven web can be formed by melt-blowing at high throughputs. ... Such surgical fabric laminates are generally spun-bonded/melt-blown/spun-bonded (SMS) laminates consisting of nonwoven outer layers of spun-bonded polypropylene and an interior barrier layer of melt-blown polypropylene. Particularly, Kimberly-Clark Corporation, the assignee of the present invention, has for a number of years manufactured and sold SMS nonwoven surgical fabric laminates under the marks Spunguard® and Evolution®. ... In order for such a surgical fabric to perform properly, it is necessary that the melt-blown barrier layer have a fiber size and a pore size distribution that assures breathability of the fabric while at the same time inhibiting strikethrough of fluids. ... While such a melt-blown web has advantages as a barrier layer, significant improvement in porosity and inhibition of strikethrough can be achieved with a melt-blown web having average fiber sizes of from 1 to 3 microns and having a distribution of pore sizes so that the majority of pores are in the range of 7 to 12 microns with the peak of the pore size distribution less than 10 microns. ... It is therefore an object of the present invention to provide a nonwoven web for use as a barrier layer in a fabric laminate which nonwoven web has an average fiber diameter of from 1 to 3 microns and pore sizes distributed predominantly in the range from 7 to 12 microns, with a lesser amount of pores from 12 to 25 microns, with virtually no pores greater than 25 microns, and with the peak of the pore size distribution less than 10 microns. It is likewise an object of the present invention to provide a nonwoven fabric laminate having a barrier layer of fine fibers and small pore size distribution such that the resulting fabric laminate has pore sizes distributed predominantly in the range from 5 to 10 microns, with a lesser amount of pores from 10 to 15 microns, with virtually no pores greater than 22 microns, and with the peak of the pore size distribution shifted downward by up to 5 microns from the peak ... The melt-blown station 22 produces fine fibers 30 from a fiber forming polymer which will be described in greater detail below. The fibers 30 are randomly deposited on top of spun- bond layer 28 to form a melt-blown internal layer 32. For an SMS fabric laminate, for example, the melt-blown barrier layer 32 has a basis weight of preferably about 0.35-0.50 oz./yd. ² . ... By modifying the starting polymer, the resulting polymer will have a lower extensional viscosity, thus taking less force to attenuate the fibers as they exit the die 31. Therefore, with the same air flow, the higher melt flow polymer will produce finer fibers at commercially acceptable throughputs. A commercially acceptable throughput is above 3 PIH. Lower throughputs, however, will further reduce the fiber and pore sizes of the melt-blown layer 32. The resulting melt-blown web 32 with its fine fibers and resulting small pore size distribution has superior barrier properties when incorporated into a fabric laminate. Particularly, the unlaminated melt-blown web 32 has an average fiber size of from 1 to 3 microns and pore sizes distributed predominantly in the range from 7 to 12 microns, with a lesser amount of pores from 12 to 25 microns, with virtually no pores greater than 25 microns, and with the peak of the pore size distribution less than 10 microns. ... ``` TABLE 1 ______________________________________ % Pore Size Distribution ______________________________________ 0-5μ 5-10μ 10-15μ 15-20μ ______________________________________ Sample 1 50.7 45.8 2.9 Sample 2 1.8 55.4 40.3 1.9 Sample 3 10.5 67.7 21.4 Sample 4 1.2 20.0 61.6 11.6 ______________________________________ Maximum pore 20-25μ 25-30μ Size ______________________________________ Sample 1 0.6 0 Sample 2 0.4 0 22.0 μ Sample 3 0.5 0.1 Sample 4 1.2 0.9 38.2μ ______________________________________ ``` ... ### Claims (7) A nonwoven web of fine fibers formed from polymer streams and with an average fiber size from 1 to 3 microns and pore sizes distributed predominantly in the range from 7 to 12 microns with the peak of the pore size distribution less than 10 microns formed from reactor granules of a modified propylene polymer polymerized with a Ziegler-Natta catalyst which polymer has a molecular weight distribution between 2.8 and 3.5 Mw/Mn and a modified polymer melt flow rate greater than ... ### Patent Citations (38) Publication number Priority date Publication date Assignee Title US3338992A * 1959-12-15 1967-08-29 Du Pont Process for forming non-woven filamentary structures from fiber-forming synthetic organic polymers ... ### Cited By (287) Publication number Priority date Publication date Assignee Title US5447788A * 1994-05-16 1995-09-05 Kimberly Clark Corporation Porous, nonwoven liquid-activated barrier EP0672357A2 1994-03-16 1995-09-20 Kimberly-Clark Corporation Improved coveralls and method of manufacture ... US5883026A * 1997-02-27 1999-03-16 Kimberly-Clark Worldwide, Inc. Face masks including a spunbonded/meltblown/spunbonded laminate WO1999022614A1 1997-10-31 1999-05-14 Kimberly-Clark Worldwide, Inc. Shoe cover with slip-resistant sole ... US20050148262A1 * 2003-12-30 2005-07-07 Varona Eugenio G. Wet wipe with low liquid add-on US6936554B1 2000-11-28 2005-08-30 Kimberly-Clark Worldwide, Inc. Nonwoven fabric laminate with meltblown web having a gradient fiber size structure ... US8148466B2 2004-05-24 2012-04-03 Cellresin Technologies, Llc Amphoteric grafted barrier materials US20120171919A1 * 2009-09-15 2012-07-05 Junko Suginaka Coform nonwoven web formed from meltblown fibers including propylene/alpha-olefin ... ### Similar Documents US5492751A 1996-02-20 Disposable garment with improved containments means US4753843A 1988-06-28 Absorbent, protective nonwoven fabric CA2130246C 2004-02-10 Polyethylene meltblown fabric with barrier properties
    Google Patents (opens in a new tab)Espacenet
  2. 35Patent: US Patent for Method of forming a fine fiber barrier fabric ..., US 5,810,954
    [Justia](https://www.justia.com/) [Patents](https://patents.justia.com/) U.S. Patent for Method of forming a fine fiber barrier fabric with improved drape and strength of making same Patent (Patent # 5,810,954) # Method of forming a fine fiber barrier fabric with improved drape and strength of making same Feb 20, 1996 A method of producing a fabric comprising producing fine denier fibers, using either meltblown or spunbond processes, or a combination of the two, followed by crimping, spotbonding using differential bond roll temperatures, and neck-stretching. Fiber having less than or equal to about 1.5 denier is preferred. The bond temperature differential is about 10.degree.-50.degree. F. The mat produced has the unexpected result of improved strength, conformability and reduced stiffness. Skip to: Description · Claims · References Cited · Patent History · Patent History **Description** **FIELD OF THE INVENTION** ... The combination of crimping and spotbonding processes has heretofore not produced such a desired fabric. Chemical softening agents known in the art can be added during the fabric forming process, but tend to reduce strength and increase manufacturing costs. Heretofore, however, these techniques have not been used collectively, perhaps because the anticipated effects of particular techniques would lead to undesirable resulting properties. Many of these techniques have known operating parameter windows which would normally lead one skilled in the art to assume that combining the techniques would not produce a synergistically positive outcome. It would be desirable to produce a fabric from a fine denier fiber having improved strength and conformability without the accompanying stiffness which would be anticipated by using fine denier fiber. Such a fabric would have particular applicability with laminate fabric structures, such as with spunbond-meltblown-spunbond composite fabrics. ... The temperature differential used depends on the fabric denier used and raw material composition but is desirably between about 10.degree. and 50.degree. F. (5.degree. and 28.degree. C.) or still more desirably between about 15.degree. and 45.degree. F. (8.degree. and 25.degree. C.). Preferably, the temperature differential is about 40.degree. F. (22.degree. C.) for polypropylene and random copolymer (ethylene in propylene) homofibers. In a preferred embodiment a laminate of spunbond-meltblown-spunbond fiber layers is formed wherein the spunbond layers.are composed of fine denier fibers that have been crimped. The formed laminate is then passed between a pair of heated nipped thermal bond rolls comprising a smooth anvil roll and a pattem roll, whereby the temperature differential between the two rolls is in the range of about 15.degree.-45.degree. F. (8.degree.-25.degree. C.), controllable depending on the characteristics of the fabric and conveyor speed. ... **DESCRIPTION OF THE PREFERRED EMBODIMENTS** The present invention provides a method of producing a fabric having the unexpected result of improving strength, drape, and conformability. The present invention is usable with meltblown or spunbond or a combination of the two or using other web forming processes known to those skilled in the art. In general, the method comprises producing a crimped, fine denier fiber, using either meltblown or spunbond processes, or a combination of the two, spotbonding using differential bond roll temperatures and neck-stretching. For purposes of the present description a laminate of spunbond-meltblown-spunbond fibers shall be discussed. It is to be understood that single layers, as well as other laminates and non-laminate fiber mat structures can be employed. In a preferred embodiment of the present invention, fine denier fibers, in the range of from about 0.5 to about 3.0 dpf, preferably less than or equal to about ... Moreover, a hot air knife produces a superior result with a greater throughput speed than a compaction roll. A layer of meltblown fibers, comprised of <1 .mu.m to about 10 .mu.m diameter, preferably less than 5 .mu.m diameter, may be introduced on top of the spunbond layer from a windup roll 30 of previously manufactured meltblown fibers. Alternatively, it is also possible to form meltblown fibers and deposit them as formed directly on the spunbond layer. The meltblown fibers are formed of resin which is preferably a thermoplastic polymer such as, but not limited to, polyolefins, polyesters, polyamides, polyurethanes, copolymers and mixtures thereof. A second layer of spunbond fibers is made by spunbond apparatus 32 in a manner similar to that described for spunbond apparatus 12; i.e., a spinneret 34 produces filaments which are quenched and crimped by a quench blower 36 and attenuated by an aspirator 38. The fibers deposited on the meltblown layer are then compressed by a second compaction device 40 to form a three layer laminate comprised of spunbond-meltblown-spunbond fibers 42 (the "SMS" laminate). Spunbond nonwoven fabrics contemplated by the present invention are generally bonded in some manner as they are produced in order to give them sufficient structural integrity to withstand the rigors of further processing into a finished product. Bonding can be accomplished in a number of ways such as hydroentanglement, needling, ultrasonic bonding, adhesive bonding, stitchbonding, through-air bonding and thermal bonding. A preferred method is by thermal bonding. The SMS laminate 42 is moved off the belt 24 and passed between a nipped pair of thermal bond rolls 44 and 46. Bond roll 44 is a conventional smooth anvil roll. Bond roll 46 is a conventional pattern roll having a plurality of pins 48. The pins create bond points within the fabric matrix. # Method of forming a fine fiber barrier fabric with improved drape and strength of making same This translates to more fibers held taut between bond points and greater entanglement. As an example, a web comprised of 1.5 dpf fibers has four times as many fibers as a comparably sized web comprised of 3.0 dpf fibers. ... U.S. Pat. No. 5,413,811, issued to Fitting et al., and commonly assigned to the assignee of the present invention, describes a combination of chemical softening and mechanical stretching processes which produce a nonwoven mat having a softer hand. ... U.S. Pat. No. 4,443,513, issued to Meitner et al., and commonly assigned to the assignee of the present invention, teaches a meltblown mat using thermal bond rolls and stretching the mat. The fabric produced has improved softness, bulk and drapeability while retaining strength. ... In a preferred embodiment a laminate of spunbond-meltblown-spunbond fiber layers is formed wherein the spunbond layers.are composed of fine denier fibers that have been crimped. ... Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a mat of randomly dispursed meltblown fibers. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Buntin. ... The fabric of this invention may be a multilayer laminate. An example of a multilayer laminate is an embodiment wherein some of the layers are spunbond and some meltblown such as a spunbond-meltblown-spunbond (SMS) laminate as disclosed in U.S. Pat. No. 4,041,203 to Brock et al., U.S. Pat. No. 5,169,706 to Collier, et al, and U.S. Pat. No. 4,374,888 to Bomslaeger. Such a laminate may be made by sequentially depositing onto a moving forming belt first a spunbond fabric layer, then a meltblown fabric layer and last another spunbond layer and then bonding the laminate in a manner described below. Alternatively, one or more of the fabric layers may be made individually, collected in rolls, and combined in a separate bonding step. ... A layer of meltblown fibers, comprised of <1 .mu.m to about 10 .mu.m diameter, preferably less than 5 .mu.m diameter, may be introduced on top of the spunbond layer from a windup roll 30
    Google Patents (opens in a new tab)Espacenet
  3. 36Patent application: Nonwoven fibrous hydraulically entangled elastic coform material and method of formation thereof, US 4,879,170 A1988
    Kimberly Clark CorpInventors: F. R. Radwanski, L. E. Trimble, R. C. Smith and 1 more
    Hydraulically entangled coform of non-elastic meltblown fibers and fibrous material... The use of meltblown fibers facilitates the hydraulic entangling, resulting in a high degree of entanglement... The coform can be hydraulically entangled with a reinforcing material, e.g. a melt-spun nonwoven.
    Why it’s hereGranted art on water-jet entangling fine meltblown fibres with a coarser layer.
    Google Patents (opens in a new tab)PDFEspacenet
  4. 37Patent: U.S. Patent for Polyethylene meltblown fabric with barrier properties Patent (Patent # 5,498,463 issued March 12, 1996) - Justia Patents Search, US 5,498,463
    [Justia](https://www.justia.com/) [Patents](https://patents.justia.com/) [Spot Bonds Connect Components](https://patents.justia.com/patents-by-us-classification/428/198) U.S. Patent for Polyethylene meltblown fabric with barrier properties Patent (Patent # 5,498,463) # Polyethylene meltblown fabric with barrier properties Mar 21, 1994 \- [Kimberly-Clark Corporation](https://patents.justia.com/assignee/kimberly-clark-corporation) A nonwoven fabric is provided which has good barrier properties, softness and breathability. A linear low density polyethylene is used in a meltblown layer in this invention to provide barrier properties comparable to polypropylene. The meltblown layer may be used in a multilayer laminate and the other layers may be comprised of bicomponent fibers. The fabric may be used in, for example, diapers, feminine hygiene products, adult incontinence products, wound dressings, bandages, sterilization wraps, surgical gowns and drapes and wipers. ... Thermoplastic resins have been extruded to form fibers and webs for a number of years. The most common thermoplastics for this application are polyolefins, particularly polypropylene. Other materials such as polyesters, polyetheresters, polyamides and polyurethanes are also used for this purpose. Each material has its characteristic advantages and disadvantages visa vis the properties desired in the final product to be made from such fibers. Nonwoven fabrics are useful for a wide variety of applications such as diapers, feminine hygiene products, incontinence products, towels, medical garments and many others. The nonwoven fabrics used in these applications are often in the form of laminates like spunbond/meltblown/spunbond (SMS) laminates. In SMS laminates the exterior layers are generally spunbond polypropylene which are usually present for strength, and the interior layer which is generally meltblown polypropylene and is usually present as a barrier layer. ... A nonwoven fabric is provided which has barrier properties comparable to polypropylene meltblown fabrics yet has a softer hand than polypropylene and good breathability. This fabric is provided through a process of producing a soft nonwoven barrier fabric comprising the steps of melting at least one thermoplastic polyethylene polymer which has a density in the range of about 0.86 to about 0.97 grams/cc, extruding the polymer through fine openings, drawing said polymer to produce fibers, and depositing the fiberized polymer on a collecting surface to form a web of disbursed fibers, wherein the web has a hydrohead of at least 40 centimeters, and a cup crush peak load value of less than 40 grams. Such a web usually has a Frazier Porosity of less than 300 ft.sup.3 /ft.sup.2 /min. The fabric may be laminated with spunbond layers of which one may be pre-bonded and may also be composed of bicomponent fibers. ... Cup Crush energy is measured in gm-mm. Hydrohead: A measure of the liquid barrier properties of a fabric is the hydrohead test. The hydrohead test determines the height of water (in centimeters) which the fabric will support before a predetermined amount of liquid passes through. A fabric with a higher hydrohead reading indicates it has a greater barrier to liquid penetration than a fabric with a lower hydrohead. The hydrohead test is performed according to Federal Test Standard No. 191A, Method 5514. Frazier Porosity: A measure of the breathability of a fabric is the Frazier Porosity which is performed according to Federal Test Standard No. 191A, Method 5450. Frazier Porosity measures the air flow rate through a fabric in cubic feet of air per square foot of fabric per minute or ft.sup.3 /ft.sup.2 /min. (Convert ft.sup.3 /ft.sup.2 /min. to liters per square meter per minute (1/m.sup.2 /min) by multiplying by 304.8). ... Such a multilayer laminate may be an embodiment wherein some of the layers are spunbond and some meltblown such as a spunbond/meltblown (SM) laminate or a spunbond/meltblown/spunbond (SMS) laminate, as disclosed in U.S. Pat. No. 4,041,203 to Brock et al. and U.S. Pat. No. 5,169,706 to Collier, et al. or wherein some of the layers are made from staple fibers. The fibers used in the other layers may be polyethylene, polypropylene or bicomponent fibers. An SMS laminate, for example, may be made by sequentially depositing onto a moving conveyor belt or forming wire first a spunbond fabric layer, then a meltblown fabric layer and last another spunbond layer and then bonding the laminate in a manner described above. Alternatively, the three fabric layers may be made individually, collected in rolls, and combined in a separate bonding step. In thermal calendering, various patterns for calender rolls have been developed. ... 3, or a positive die tip 22 stick out configuration wherein the tip of the die portion 50 protrudes beyond the plane formed by the plates 48. Lower attenuating gas velocities and wider air passageway gaps are generally preferred if substantially continuous meltblown fibers or microfibers 24 are to be produced. The two streams of attenuating gas converge to form a stream of gas which entrains and attenuates the molten threads 24, as they exit the orifices 20, into fibers or , depending on the degree of attenuation, microfibers of a small diameter which is usually less than the diameter of the orifices 20. The gas-borne fibers or microfibers 24 are blown, by the action of the attenuating gas, onto a collecting arrangement which, in the embodiment illustrated in FIG. 1, is a foraminous endless belt 52 conventionally driven by rollers 54. Other foraminous arrangements such as a rotating drum could be used. ... Note that Examples 1, 4 & 5 are examples of the fabric of this invention, the others are not. The meltblown webs of this invention exhibit the fiber fineness and lack of shot required to produce hydrohead values of greater than 40 cm, cup crush peak load values of less than 40 grams and where the web usually has a Frazier Porosity of less than 300 ft.sup.3 /ft.sup.2 /min. The SMS laminates using the meltblown web of this invention have a hydrohead of at least 50 centimeters and a cup crush peak load value of less than 125 grams. **EXAMPLE 1** Meltblown fibers were produced from Dow's Aspun.RTM. XUR-1567-45766-30A linear low density polyethylene resin. The polymer melt temperature was about 500.degree. F. (260.degree. C.), as was the drawing air which flowed at about 420 SCFM. The throughput was about 2 pounds per die plate inch per hour (357 gm/cm/hour) to produce a fabric with a basis weight of about 0.5 osy (17 gsm). ... ______________________________________ ``` The results surprisingly show that fabrics made from fibers spun from polymers useful in this invention can have barrier properties comparable to and even somewhat better than conventional polypropylene fibers while having a softer feel and good breathability. This invention desirably combines the good barrier properties associated with polypropylene meltblown fabrics with the softness associated with polyethylene meltblown fabrics to produce a soft, high barrier, fabric. ## Claims 1\. A process of producing a soft nonwoven barrier fabric comprising the steps of; melting at least one thermoplastic polyethylene polymer, said polymer having a density in the range of about 0.86 to about 0.97 grams/cc; extruding said polymer through fine openings; drawing said polymer to produce fibers, and; depositing said fiberized polymer on a collecting surface to form a layer of meltblown disbursed fibers as a web, wherein said web has a hydrohead of at least 40 centimeters, and a cup crush peak load value of less than 40 grams. 2\. The nonwoven fabric produced according to the method of claim 1 wherein said web has a Frazier Porosity of less than 300 ft.sup.3 /ft.sup.2 /min. 3\. The nonwoven fabric produced according to the method of claim 1 further comprising the steps of adding a second layer of material to said l
    Google Patents (opens in a new tab)Espacenet
  5. 65Paper: Simulation of Preferential Flow in Snow With a 2‐D Non‐Equilibrium Richards Model and Evaluation Against Laboratory Data, Leroux et al.2020
    N. Leroux, C. Marsh and J. PomeroyWater Resources Research
    previous snowmelt models using a water entry pressure to simulate preferential flow paths do not work for natural snowpack conditions where snow densities are less than 380 kg m-3
    Why it’s hereShows entry-pressure snowmelt models fail for low-density natural snow.
    Open source (opens in a new tab)
  6. 66Paper: Quantification of capillary rise dynamics in snow using neutron radiography, Lombardo et al.2025
    M. Lombardo, A. Fees, A. Kaestner and 3 moreThe Cryosphere
    Water flow in snow is often dominated by capillary effects, which are responsible for the formation of capillary barriers, capillary flow paths, and capillary rise ... the fit saturated liquid water content values varied less than 10% from those estimated based on the optical density and mu CT scans. The alpha parameters ... fine-grained snow resulted in similar values of 0.21 and 0.19 cm-1
    Why it’s hereNeutron imaging quantifies capillary rise in snow, where capillary effects dominate water flow.
    Open source (opens in a new tab)PDF
  7. 67Paper: The capillary effects on water percolation in homogeneous snow, Colbeck1974
    S. ColbeckJournal of Glaciology
    A capillary pressure-liquid saturation relationship found in the laboratory is used ... capillarity accounts for less than 10% of the total force when water flux is 10-8 m s-1 ... the irreducible water content of dense snow is 7% of the pore volume.
    Why it’s hereQuantifies capillary forces and retained water during percolation in uniform snow.
    Open source (opens in a new tab)PDF
  8. 68Web page: Capillary rise in snow - ADS, ui.adsabs.harvard.edu
    Snow is a complex porous medium where liquid water may rise to several centimeters high due to capillary rise. Previous experimental measurements in cold laboratory on wet snow samples allowed us to relate the capillary rise level with snow characteristics (porosity, grain size).
    Why it’s hereRelates capillary rise in snow to porosity and grain size.
    Open source (opens in a new tab)
  9. 69Paper: Water retention curve of snow with different grain sizes, Yamaguchi et al.2010
    S. Yamaguchi, T. Katsushima, A. Sato and 1 moreCold Regions Science and Technology
    The water retention curve (WRC), which shows the relationship between volumetric water content and suction, is fundamental for characterizing hydraulic properties ... to examine the dependence of the WRC on the grain size of snow
    Why it’s hereShows how snow water retention depends on grain size.
    Open source (opens in a new tab)
  10. 70Paper: Simulating liquid water distribution at the pore scale in snow: water retention curves and effective transport properties, Bouvet et al.2026
    L. Bouvet, N. Allet, N. Calonne and 2 moreThe Cryosphere
    New parameterizations of these parameters based on snow density, grain size, and the interfacial mean curvature are proposed ... estimates of hydraulic conductivity, water permeability, effective thermal conductivity, and water vapor diffusivity
    Why it’s herePore-scale simulation of snow water retention and transport properties.
    Open source (opens in a new tab)PDF
  11. 71Paper: Investigation of snow sintering at microstructural scale from micro-penetration tests, Peinke et al.2019
    I. Peinke, P. Hagenmuller, G. Chambon and 1 moreCold Regions Science and Technology
    Typical sintering exponents for seasonal snow are reported in the range between 0.07 and 0.36 ... Both macroscopic force and bond rupture force followed a power law with an average exponent of 0.27 and 0.29, respectively.
    Why it’s hereMicroscale snow sintering measurements and reported sintering exponents.
    Open source (opens in a new tab)
  12. 72Paper: A REVIEW OF SINTERING IN SEASONAL SNOW, Colbeck1997
    S. Colbeck
    review of sintering in seasonal snow
    Why it’s hereReview of sintering, the bond-forming process in seasonal snow.
    Open source (opens in a new tab)PDF
  13. 73Paper: Ice Sintering by Sublimation and Condensation, Demmenie et al.2025
    M. Demmenie, S. Woutersen and D. BonnJournal of Physical Chemistry Letters
    Here we demonstrate that sintering of ice under equilibrium conditions proceeds primarily through sublimation and condensation. Mass transfer occurs through the vapor phase, driven by increased volatility at the formed neck due to its high curvature.
    Why it’s hereShows ice sintering proceeds by vapour transfer to curved grain necks.
    Open source (opens in a new tab)
  14. 74Paper: The Microstructural Evolution of Water Ice in the Solar System Through Sintering, Molaro et al.2019
    J. Molaro, M. Choukroun, C. B. Phillips and 5 moreJournal of Geophysical Research - Planets
    Sintering rates are temperature and grain size dependent, with the model predicting neck sizes of 0.59 and 0.43 for grains of 5 and 50 micrometres
    Why it’s hereModels grain-size-dependent sintering and neck sizes of water ice.
    Open source (opens in a new tab)PDF
  15. 75Paper: Micromechanical model for sintering and damage in viscoelastic porous ice and snow. Part II: Validation, Kabore & Peters2020
    B. Kabore and B. Peters
    The behavior of snow combines characteristics of polycrystalline ice ... Snow can pass from porous continuous structure to a granular form or creep intensively when loaded.
    Why it’s hereMicromechanical model of sintering and damage in porous ice and snow.
    Open source (opens in a new tab)PDF
  16. 76Paper: Numerical simulation of microstructural damage and tensile strength of snow, Hagenmuller et al.2014
    P. Hagenmuller, T. C. Theile and M. Schneebeli
    The tensile strength of snow ranges from 0.1 kPa to 1000 kPa for a density of 100 to 600 kg m-3.
    Why it’s hereSimulates snow tensile strength across a wide density range.
    Open source (opens in a new tab)PDF
  17. 77Paper: Review of compressed snow mechanics: Testing methods, Shenvi et al.2022
    M. N. Shenvi, C. Sandu and C. UntaroiuJournal of Terramechanics
    The uniaxial tensile and compressive strength of snow at low densities is nearly equal but with an increase in density, the compressive strength increases reaching nearly 5 times the tensile strength by the time ice density is achieved
    Why it’s hereReviews tensile versus compressive strength of compressed snow.
    Open source (opens in a new tab)
  18. 78Paper: The Relationship between Density and Tensile Strength in Snow, Sommerfeld1971
    R. SommerfeldJournal of Glaciology
    The probability of failure of snow in centrifugal tensile tests is shown to be a function of sigma/sigma_m where sigma is the applied stress and sigma_m is a characteristic strength which is a function of density alone.
    Why it’s hereLinks snow tensile failure to a density-dependent characteristic strength.
    Open source (opens in a new tab)
  19. 79Paper: SNICAR-ADv4: A physically based radiative transfer model to represent the spectral albedo of glacier ice, Whicker et al.2021
    C. Whicker, M. Flanner, C. Dang and 3 moreThe Cryosphere
    Snowpack is generally represented as a collection of independently scattering ice grains within an air medium. Snow radiative transfer models (RTMs) utilize the optical properties of ice, the snowpack properties (density, thickness, and ice grain size and shape)
    Why it’s hereRadiative-transfer model treating snow as independently scattering ice grains in air.
    Open source (opens in a new tab)PDF
  20. 80Paper: A Novel Parameterization of Snow Albedo Based on a Two-Layer Snow Model with a Mixture of Grain Habits, Saito et al.2019
    M. Saito, P. Yang, N. Loeb and 1 moreJournal of the Atmospheric Sciences
    Top-snow-layer optical properties essentially determine spectral snow albedo when the top-layer snow water equivalent is large. When the top-layer SWE is less than 1 mm, the second-snow-layer optical properties have nonnegligible impacts on the albedo
    Why it’s hereShows the top snow layer dominates albedo unless very thin.
    Open source (opens in a new tab)PDF
  21. 81Paper: A method to retrieve the spectral complex refractive index and single scattering optical properties of dust deposited in mountain snow, Skiles et al.2017
    S. Skiles, T. Painter and G. Okin
    Using the values retrieved by this method to update dust optical properties in a snow + aerosol radiative transfer model reduces errors in springtime albedo modeling by 50-70%.
    Why it’s hereRetrieves optical properties of dust in snow to improve albedo models.
    Open source (opens in a new tab)PDF
  22. 82Paper: FlexSnow: A Flexible Snow Optics Model Framework Integrating Diverse Snow Microstructures and Light-Absorbing Constituent Mixtures in Multiple Layers, Wang et al.2026
    G. Wang, T. Lei, L. Jiang and 5 moreIEEE Transactions on Geoscience and Remote Sensing
    Sensitivity analysis indicates that the effects of various snow grain shapes can be mitigated with the SSA-equivalent radius specification ... compares well against the close-range measurements of pure snow, polluted snow, algal snow, and wet snow
    Why it’s hereFlexible multilayer snow optics model across microstructures and impurities.
    Open source (opens in a new tab)
  23. 83Paper: The Effects of Summer Snowfall on Arctic Sea Ice Radiative Forcing, Chapman‐Dutton & Webster2024
    H. R. Chapman‐Dutton and M. WebsterJournal of Geophysical Research - Atmospheres
    Snow is the most reflective natural surface on Earth ... Based on a simple, multiple scattering radiative transfer model
    Why it’s hereMultiple-scattering model of snow's high reflectance on sea ice.
    Open source (opens in a new tab)PDF
  24. 84Web page: Making sure you're not a bot!, publica.fraunhofer.de
    The measured absorption of the snow samples can be successfully described by Wilson's model or the Johnson-Champoux-Allard model.
    Why it’s hereSnow acoustic absorption described by standard porous-absorber models.
    Open source (opens in a new tab)
  25. 85Paper: Experimental measurements of acoustical properties of snow and inverse characterization of its geometrical parameters, Datt et al.2016
    P. Datt, J. Kapil, A. Kumar and 1 more
    for frequencies smaller than 1 kHz, the average acoustic absorption coefficient was found below than 0.4, however, for the frequencies more than 1 kHz it was found to be 0.85. The average acoustic transmission loss was observed from 1.45 dB cm-1 to 3.77 dB cm-1
    Why it’s hereMeasures acoustic absorption and transmission loss of snow.
    Open source (opens in a new tab)
  26. 86Web page: Measurements on Sound Propagation Characteristics in Snow Layer, researchgate.net
    Snow layer had very high sound absorption coefficient over 0.9 even at very low frequency ... sound speed also increased from 100 m/s to the near speed in the air
    Why it’s hereMeasures high sound absorption and sound speed in snow layers.
    Open source (opens in a new tab)
  27. 87Paper: Microstructure and sound absorption of snow - ScienceDirect
    the sound absorbing characteristics of snow can often be described by theoretical models assuming a motionless frame
    Why it’s hereLinks snow microstructure to sound absorption with rigid-frame models.
    Open source (opens in a new tab)
  28. 88Paper: Characterizations of acoustical porous media: standardized methods, current trends and challenges, Jaouen et al.2025
    L. Jaouen, F. Bécot and F. ChevillotteFrontiers in Acoustics
    The open porosity, the static air flow resistivity and the high frequency limit of the dynamic tortuosity can be directly measured ... The method is standardized in ISO 9053-1
    Why it’s hereReviews standardized characterization methods for acoustic porous media.
    Open source (opens in a new tab)PDF
  29. 89Paper: Experimental study of test methods for the acoustic properties of snow - ScienceDirect
    Within a snow water content range of 0-20 %, the attenuation coefficient increases with higher water content, whereas the boundary sound absorption coefficient decreases.
    Why it’s hereShows how water content changes snow acoustic properties.
    Open source (opens in a new tab)
  30. 90Paper: Tomography-based determination of porosity, specific area and permeability of snow and comparison with measurements, Zermatten et al.2014
    E. Zermatten, M. Schneebeli, H. Arakawa and 1 more
    Correlations are derived for permeability, the Dupuit-Forchheimer coefficient and the third order coefficient of Darcy's law as a function of density and grain size.
    Why it’s hereTomography-based permeability correlations for snow by density and grain size.
    Open source (opens in a new tab)
  31. 91Paper: Measurement of the physical properties of the snowpack, Kinar & Pomeroy2015
    N. Kinar and J. Pomeroy
    The saturated permeability ks of snow is used to model the propagation of air or water through a snowpack; permeability is related to the size of snow particles as well as snow morphological properties
    Why it’s hereRelates snow permeability to particle size and morphology.
    Open source (opens in a new tab)
  32. 92Paper: Stereological measurement of the specific surface area of snow
    The specific surface area (SSA) is a fundamental geometrical characteristic for porous sintered materials ... The SSA can be converted into [optical grain size]
    Why it’s hereStereological measurement of snow specific surface area, linked to optical grain size.
    Open source (opens in a new tab)
  33. 93Paper: Density, specific surface area, and correlation length of snow measured by high‐resolution penetrometry, Proksch et al.2015
    M. Proksch, H. Löwe and M. Schneebeli
    objective measurements of snow stratigraphy in terms of density and grain size constitute an essential [parameter set]
    Why it’s herePenetrometry measures snow density and surface area by layer.
    Open source (opens in a new tab)PDF
  34. 94Paper: Engineering Properties of Snow, Mellor1977
    M. MellorJournal of Glaciology
    Crystals of falling snow commonly range in size from about 0.1 mm to several millimetres ... Properties subsequently change as crystal forms alter, as intergranular bonds develop or decay, and as self-weight stresses cause volumetric straining to higher density.
    Why it’s hereOverview of snow grain sizes and how bonds and density evolve.
    Open source (opens in a new tab)PDF
  35. 95Paper: Rheological and interfacial characterization of menstrual fluid, Pero et al.2026
    E. Pero, C. Neu, A. Wolf and 3 moreThe Physics of Fluids
    Menstrual fluid viscosity is approximately fourfold higher than blood and forty-fold higher than water … Surface tension is significantly lower than that of water and comparable to that of venous blood … Current industrial simulants are typically simplified water- or blood-like fluids that may not adequately reproduce the complex behavior of real menses.
    Why it’s hereShows menses has lower surface tension than water and high viscosity.
    Open source (opens in a new tab)PDF
  36. 96Paper: Capillary Hysteresis in Neutrally Wettable Fibrous Media: A Pore Network Study of a Fuel Cell Electrode, Tranter et al.2017
    T. Tranter, J. Gostick, A. Burns and 1 moreTransport in Porous Media
    The classic Washburn relation was shown to produce erroneous results, and its use is not recommended when modelling fibrous media. The toroidal model predicts that the meniscus will advance past the throat apex before reaching the critical or breakthrough pressure, increasing curvature due to the locally diverging geometry.
    Why it’s hereShows fibre geometry, not contact angle alone, sets entry pressure in fibrous media.
    Open source (opens in a new tab)PDF
  37. 97Paper: Optimized White Reflectance in Photonic‐Network Structures, Utel et al.2019
    F. Utel, L. Cortese, D. Wiersma and 1 moreAdvanced Optical Materials
    This model allows the degree of structural anisotropy and filling fraction of the network to be varied independently, revealing the key contribution of these two parameters to the overall scattering efficiency... structures obtained with the use of this algorithm can exceed the broadband reflectance of the beetle while using less material.
    Why it’s hereOptimized scattering networks exceed beetle whiteness with less material.
    Open source (opens in a new tab)PDF
  38. 98Web page: Tyvek® Technical User Guide, dupont.com
    The structure of Tyvek diffracts radiant energy very well, including visible light; this contributes to the high opacity of Tyvek... The GE Brightness of Tyvek is 94.1... a pure titanium dioxide pellet measures 93.8.
    Why it’s hereCommercial fibre sheet reaching high opacity and brightness without pigment.
    Open source (opens in a new tab)
  39. 99Web page: Kimberly-Clark: Film-free Breathable Barrier Materials for Absorbent Products, vanderbilt.edu
    Cost: <$80 per thousand square yards (<0.07 euro per square meter); Basis weight: <60 g per square meter; Barrier properties: No strikethrough for urine, bowel movement, and menses under hydrohead pressure ≈ 62 millibar... Softness with cup crush value <50 g; Drapable and flexible; Low noise generation. Typical funding: $100,000-$200,000 for sponsored research to advance technology readiness level (TRL) to level 7 or higher.
    Why it’s hereThe published requirement: film-free breathable barrier, cost, weight, softness and leak targets.
    Open source (opens in a new tab)
  40. 100Patent: Dark-tinted nonwoven webs, US 12,042,3642020
    Procter and Gamble CoInventors: N. S. Wimalasena
    Dark-tinted nonwoven webs of the present disclosure may have a Hydrohead Value of between about 15 mbar and about 50 mbar.
    Why it’s hereDark-tinted nonwoven webs with moderate water-pressure resistance.
    Google Patents (opens in a new tab)PDFEspacenet
  41. 101Patent: Sound insulation constructions and methods of using the same, US 9,922,634 B22007
    3M Innovative Properties CoInventors: D. R. T. Jr., R. W. Gerdes and B. L. Nelson
    a first layer... bonded fiber nonwoven web exhibiting... an airflow resistance of no greater than 10,000 Rayls/m. The second layer can exhibit an airflow resistance of greater than 10,000 Rayls/m.
    Why it’s hereTwo-layer nonwoven with contrasting airflow resistance per layer.
    Google Patents (opens in a new tab)PDFEspacenet
  42. 102Patent application: Nonwoven fabric having a pore size gradient and method and apparatus for forming same, WO 1998011289 A11997
    Kimberly Clark Worldwide IncInventors: E. G. Varona
    nonwoven fabric having a pore size gradient... meltblown fibers are microfibers which may be continuous or discontinuous... spunbonded fibers refers to small diameter fibers... (retrieved title-level at Google Patents; not held in the USPTO collection).
    Why it’s hereNonwoven with a pore size gradient from meltblown and spunbond fibres.
    Google Patents (opens in a new tab)PDFEspacenet
  43. 103Patent: Breathable backsheet, absorbent articles, and methods, US 10,774,475 B22016
    Attends Healthcare Products IncInventors: H. Chmielewski, E. Seames and B. M. Spain
    A cellulosic fiber barrier layer having a hydrophobic sizing, the barrier layer having an air permeability of more than 0.5 ft3/min-ft2 and configured to hold a hydrostatic head of more than 200 mm H2O … pinhole-free performance at 400 mm H2O for 10 minutes.
    Why it’s hereStates the field's approach: finer meltblown fibres for smaller pores and better barrier.
    Google Patents (opens in a new tab)PDFEspacenet
  44. 104Paper: Dynamic capillary barrier failure in stratified media: A dimensionless framework for LNAPL redistribution under water table fluctuations., Li et al.2026
    D. Li, K. Luo and Z. AoJournal of Hazardous Materials
    LNAPL redistribution in F-C structures follows a threshold-controlled mechanism governed by macroscopic displacement pressure, closely matching the dual critical breakthrough conditions... C-F structures lacking interfacial capillary barriers exhibit a rate-dependent allocation mechanism...
    Why it’s hereShows fine-over-coarse stratified media withhold liquid by a threshold breakthrough pressure.
    Open source (opens in a new tab)
  45. 105Web page: What Are the Barrier Properties of Meltblown Fabrics? A 2026 Guide to Testing, Standards & ROI for Global Buyers, alnonwoven.com
    For meltblown fabrics... this profile is primarily defined by three interconnected characteristics: filtration efficiency, liquid repellency, and breathability.
    Why it’s hereDescribes meltblown barrier performance as filtration, repellency and breathability.
    Open source (opens in a new tab)
  46. 106Paper: Polybutylene Adipate Terephthalate Meltblown Nonwoven With Annular Meltblown Die: Processability and Structure–Property Relationship, Shim et al.2026
    E. Shim, M. Daşdemir, N. Young and 1 morePolymer Engineering & Science
    Hydrostatic head pressure, defined as the water pressure a fabric can withstand before liquid penetration occurs... Figure 5c illustrates the influence of die geometry and processing conditions on hydrostatic head... primarily due to the larger pores.
    Why it’s hereLinks meltblown water-pressure resistance to pore size and air permeability.
    Open source (opens in a new tab)PDF
  47. 107Patent application: Barrier fabrics with desirable air permeability, US 2025/0295532 A12025
    Nanhai Nanxin Non Woven Co LtdInventors: L. Wang, N. Bishop, T. ZHANG and 2 more
    Each of the nonwoven layers being treated with a non-fluorinated barrier coating (NFBC).
    Why it’s hereBarrier fabric family relying on a non-fluorinated coating on each layer.
    Google Patents (opens in a new tab)Espacenet
  48. 108Paper: Structure and Air Permeability of Melt Blown Nanofiber Webs, Han et al.2016
    W. Han, X. Wang and G. Bhat
    Meltblown fibers... evaluated the fabric structure, such as mean pore diameter and air permeability... the pore diameter and distribution were measured by an SFP-1100-AEX capillary flow porometer.
    Why it’s hereMeasures pore size and air permeability of fine meltblown webs.
    Open source (opens in a new tab)
  49. 109Web page: Air Permeability Vs Water Resistance in Meltblown Fabrics: the Complete Buyer's Guide to Balancing Breathability and Barrier Performance, ecologynonwoven.com
    Fine Meltblown 1–5 µm; Nanofiber Layer 0.1–1 µm.
    Why it’s hereGives typical fibre diameters for fine meltblown and nanofibre layers.
    Open source (opens in a new tab)
  50. 110Web page: Thermal Annealing Treatment to Achieve Switchable and Reversible Oleophobicity on Fabrics (MIT), web.mit.edu
    For low surface tension liquids like hexadecane this composite interface is metastable due to the low value of the equilibrium contact angle. Consequently pressure perturbations can result in an irreversible transition of the metastable composite interface to the fully-wetted interface.
    Why it’s hereShows trapped air on fabrics is metastable for low-surface-tension liquids.
    Open source (opens in a new tab)
  51. 111Paper: Designing Superoleophobic Surfaces, Tuteja et al.2007
    A. Tuteja, W. Choi, M. Ma and 5 moreScience
    re-entrant surface curvature, in conjunction with chemical composition and roughened texture, can be used to design surfaces... that display extreme resistance to wetting from a number of liquids with low surface tension.
    Why it’s hereShows re-entrant curvature lets surfaces resist wetting by low-surface-tension liquids.
    Open source (opens in a new tab)
  52. 112Paper: Critical evaluation of the Cassie-Baxter equation for determining the surface porosity of hydrophobic membranes using contact angle analysis, Parmar et al.2025
    G. Parmar, B. Baladaniya, A. Surwade and 3 moreChemical Engineering and Science
    For membranes exhibiting lower apparent contact angles (≤130°), the calculated surface porosity values showed significant scatter and deviation (error of up to ∼49%) due to partial or complete wetting of the membrane, leading to an intermediate state transition between the CB and Wenzel states.
    Why it’s hereShows partial wetting on membranes undermines trapped air layer assumptions.
    Open source (opens in a new tab)
  53. 113Web page: Effects of Capillary Discontinuities on Water Flow and Water Retention in Snow, publicationsdrdo.in
    Entry pressures for the pressure-saturation curve are estimated from field observations of capillary rise for various snow types and related to porosity and grain size... fine-over-coarse (or high-over-low suction) layerings create capillary barriers that impede the vertical movement of water.
    Why it’s hereRelates snow entry pressures to grain size; fine-over-coarse layers impede water.
    Open source (opens in a new tab)
  54. 114Paper: The Effect on Biological and Moisture Resistance of Epichlorohydrin Chemically Modified Wood, Ibach & Lee2000
    R. Ibach and B. Lee
    Hydroentangling: a family of nonwoven fabrics produced by mechanically entangling fiber webs with high velocity jets of water... a bonding method...
    Why it’s hereDefines water-jet entangling as a nonwoven bonding method.
    Open source (opens in a new tab)
  55. 115Web page: What GSM Options Are Available for Spunlace Nonwoven? - Knowledge - Weston Manufacturing, westonnonwoven.com
    **30–45 gsm** Lightweight, soft, low bulk — Facial pads, thin hygiene liners, single-use cosmetic wipes.
    Why it’s hereLists light water-jet entangled fabric weights used in thin hygiene liners.
    Open source (opens in a new tab)
  56. 116Patent: Nonwoven substrates, US 2014/02723592013
    Procter and Gamble CoInventors: C. H. W. Cheng, O. E. A. Isele and B. Udengaard
    The nonwoven substrate has a specific surface area in the range of about 0.5 m²/g to about 5 m²/g.
    Why it’s hereSpecifies specific surface area ranges for nonwoven substrates.
    Google Patents (opens in a new tab)PDFEspacenet
  57. 117Paper: Some observations on determining the size of pores in paper, Carson1940
    F. T. Carson
    He then evaluated the capillary pressure by extrapolating the plot of pressure against the reciprocal of time to the zero value... They reported the values of 4 to 40 microns as the range of effective capillary radii.
    Why it’s hereEarly method estimating effective capillary pore radii in paper from pressure.
    Open source (opens in a new tab)PDF
  58. 118Web page: ISO 9073-16:2007 - Textiles — Test methods for nonwovens — Part 16: Determination of resistance to penetration by water (hydrostatic pressure), iso.org
    ISO 9073-16:2007 describes the hydrostatic pressure test that measures the resistance of nonwoven fabrics to the penetration of water under varied hydrostatic head pressures.
    Why it’s hereNonwoven hydrostatic pressure test, restricted in scope to water.
    Open source (opens in a new tab)
  59. 119Web page: Superhydrophobic Surfaces & Underwater Longevity - Porous Media and Multiphase Flow (PMMF) Laboratory, research.mae.ncsu.edu
    For smooth fibers or round particles, the air–water interface cannot anchor to a sharp corner and must maintain the Young–Laplace contact angle along the curved pore wall.
    Why it’s hereExplains that smooth fibres cannot pin the liquid surface at sharp corners.
    Open source (opens in a new tab)
  60. 120Paper: Recoverable underwater superhydrophobicity from a fully wetted state via dynamic air spreading, Zhao et al.2021
    Y. Zhao, Z. Xu, L. Gong and 5 moreiScience
    Recovery occurs via air bubble spreading on sparse fluorinated chained nanoparticles; the summary describes underwater Cassie states as metastable.
    Why it’s hereDescribes underwater trapped air states as metastable, with recovery by air spreading.
    Open source (opens in a new tab)PDF
  61. 121Paper: Impact of fiber diameter polydispersity on the permeability of fibrous media, Tucny et al.2022
    J. Tucny, L. Spreutels, F. Drolet and 3 moreChemical Engineering and Science
    A modified Davies correlation uses volume-to-surface-area equivalent diameter and fiber-diameter distribution spread to describe polydisperse media.
    Why it’s hereModified Davies correlation accounting for spread in fibre diameter.
    Open source (opens in a new tab)
  62. 122Web page: Optical Thickness: A short tutorial — Rutgers University, sites.rutgers.edu
    Multiple-scattering media transmit both direct radiation and radiation that diffuses into other directions; Beer attenuation of the direct beam does not account for the diffuse component.
    Why it’s hereShows simple attenuation misses diffuse light in multiply scattering layers.
    Open source (opens in a new tab)
  63. 123Paper: The role of multiple scattering in one-dimensional radiative transfer, Adamson1975
    D. Adamson
    For thick slabs the unscattered term becomes negligible, while diffusively reflected and transmitted components remain.
    Why it’s hereShows thick scattering slabs still diffusely transmit and reflect light.
    Open source (opens in a new tab)
  64. 124Paper: Hydroentanglement of polymer nonwovens. 1: Experimental and theoretical/numerical framework, Li et al.2019
    G. Li, C. Staszel, A. L. Yarin and 1 more
    The subsequent mechanical performance and physical integrity of hydroentangled fibrous nonwovens strongly relies on the fiber-to-fiber friction.
    Why it’s hereShows entangled web integrity depends on fibre-to-fibre friction.
    Open source (opens in a new tab)
  65. 125Web page: Technical Data Sheets (TDS) Per Product, olefins.net
    Tensile MD 25-85 N/5cm and CD 15-55 N/5cm as per WSP 110.4... GSM selection see GSM guide
    Why it’s hereData sheet tensile ranges for polypropylene spunbond fabrics.
    Open source (opens in a new tab)
  66. 126Web page: Designing Superoleophobic Surfaces — author postprint, apps.dtic.mil
    A key design feature of both of the electrospun fiber and hoodoo surfaces is that they possess re-entrant curvature.
    Why it’s hereShows fibre surfaces possess re-entrant curvature that resists wetting.
    Open source (opens in a new tab)
  67. 127Web page: Predicting plastron thermodynamic stability for underwater superhydrophobicity – Biophysics Group, bio.physik.fau.de
    The information to evaluate the stability of the wetting regime is missing from ... contact angle goniometry ... prediction of passive plastron stability for over one year of continuous submersion.
    Why it’s hereShows contact angle alone cannot predict trapped air layer stability.
    Open source (opens in a new tab)
  68. 128Patent application: Method for production of a hydroentangled airlaid web and products obtained therefrom, US 2014/0170402 A12013
    Jacob Holm and Sons AGInventors: R. KNOWLSON, E. Mariani and K. D. PETERSEN
    Ouellette describes bonding the airlaid fibers with hot air or a spray adhesive.
    Why it’s hereEntangled airlaid web art citing hot-air or adhesive bonding alternatives.
    Google Patents (opens in a new tab)PDFEspacenet
  69. 129Web page: INDA, Association of the Nonwoven Fabrics Industry - Cary, NC - Test Method Approach, inda.org
    It is important to emphasize that there is no standard 'synthetic urine,' because th...
    Why it’s hereIndustry note that no standard synthetic urine exists for testing.
    Open source (opens in a new tab)
  70. 130Paper: NUMERICAL SIMULATION OF INFILTRATION THROUGH UNSATURATED LAYERED SOIL COLUMN, Kassim et al.2018
    A. Kassim, N. Gofar and M. LeeMalaysian Journal of Civil Engineering
    water movement across interface between the two layered soils will only occur when the matric suction ... reached a breakthrough head of 0.4 kPa and 3.5 kPa ... defined as the water-entry value, at which the coarser layer became conductive
    Why it’s hereLayered soil simulation: water crosses only at the coarse layer's liquid entry pressure.
    Open source (opens in a new tab)
  71. 131Paper: Enhancing Resistance to Wetting Transition through the Concave Structures, Lee et al.2024
    J. Lee, J. Park, K. H. Jung and 4 moreAdvances in Materials
    the hierarchical structure and/or reentrant morphology have been employed hitherto to suppress the Cassie-Baxter to Wenzel transition (CWT)
    Why it’s hereConcave and re-entrant structures suppress collapse of trapped air.
    Open source (opens in a new tab)PDF
  72. 132Paper: Bio-inspired, large scale, highly-scattering films for nanoparticle-alternative white surfaces, Syurik et al.2017
    J. Syurik, R. H. Siddique, A. Dollmann and 5 moreScientific Reports
    porous chitin scales, which are only 7 ± 1.5 μm thick but effect a reflection of 65-70%
    Why it’s hereThin porous chitin scales reflect most light without pigment.
    Open source (opens in a new tab)PDF
  73. 133Web page: NWSP 402.0 Cup Crush » SGS-IPS Testing, ipstesting.com
    The material must have sufficient structural integrity to be formed into the cup shape and then be able to maintain that shape until it is tested. ... A 225-mm square specimen ... A 44.5 mm diameter hemispherical-shaped plunger
    Why it’s hereCup-crush softness test procedure for nonwovens.
    Open source (opens in a new tab)
  74. 134Web page: Standard Test Method for Air Permeability of Textile Fabrics, astm.org
    Air permeability ... can be used to provide an indication of the breathability of weather-resistant and rainproof fabrics.
    Why it’s hereAir permeability standard as breathability indicator for fabrics.
    Open source (opens in a new tab)
  75. 135Web page: ISO 4003:1977 - Permeable sintered metal materials — Determination of bubble test pore size, iso.org
    Specifies a method for the determination of the pore size of filters, porous bearings, porous electrodes and other parts with interconnected porosity.
    Why it’s hereBubble-test pore size standard for permeable sintered materials.
    Open source (opens in a new tab)
  76. 136Paper: Finding the right flow for menstrual fluid models, Bandari2026
    A. BandariScilight
    Using 228 samples from 12 healthy volunteers spanning 20 menstrual periods, the researchers measured menstrual fluid's surface tension, viscosity under shear, flow initiation, filament formation.
    Why it’s hereStudy of 228 samples from 12 volunteers measuring menstrual fluid surface tension, viscosity and flow onset.
    Open source (opens in a new tab)PDF
  77. 137Web page: Per- and polyfluoroalkyl substances (PFAS) - ECHA, echa.europa.eu
    ECHA supports PFAS restriction with targeted derogations (26 March 2026); textiles, leather and apparel among the major industry sectors using PFAS.
    Why it’s hereEU agency supports fluorochemical restriction, covering textiles.
    Open source (opens in a new tab)
  78. 138Web page: ECHA publishes updated PFAS restriction proposal, transition-pathways.europa.eu
    the five authorities ... have updated their initial restriction proposal ... eight sectors ... including technical textiles
    Why it’s hereUpdated EU fluorochemical restriction proposal covering technical textiles.
    Open source (opens in a new tab)
  79. 139Web page: Per- and polyfluoroalkyl substances (PFAS), europarl.europa.eu
    The European Chemicals Agency is expected to transmit its final opinion to the European Commission by the end of 2026.
    Why it’s hereEU agency final opinion on fluorochemical restriction expected end of 2026.
    Open source (opens in a new tab)
  80. 140Web page: DuPont Tyvek Technical User Guide, dupont.com
    Untreated Tyvek B styles exceed 50 in H2O = 127 cm H2O ≈ 125 mbar average hydrostatic head; WVTR 250–350 g/m²/24 h; air-leakage rate 0.004 cfm/ft² @ 1.57 psf; Gurley >300 s/100 cc.
    Why it’s herePigment-free opaque high-barrier sheet whose very low air passage fails breathability floors.
    Open source (opens in a new tab)