7/28/2019 Application of Waterproof Breathable Fabric

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APPLICATION OF

WATERPROOF BREATHABLEFABRIC

SUBMITTED BY: ADITYA KUMAR

4TH SEM , DFT

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o Waterproof fabric completely prevents the penetration andabsorption of liquid water , incontrast to water-repellent fabric,which only delays the penetration of water.

o Waterproof breathable fabric arehighly water resistant and designedfor use in garments that provide

protection from weather , which isfrom wind , rain and loss of bodyheat.

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o The term waterproof should mean , literally, something thatis impervious to water.

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o Traditionally, fabric were made waterproof by coating it withcontinuous layer of impervious flexible material.

o The materials used were animal fat, wax and hardened vegetableoils.

o Nowadays synthetic polymers such as polyvinylchloride(pvc) andpolyurethane are used..

How it is done ?

o Coated fabric are considered tobe more uncomfortable to wear than water-repellent fabric, asthey are relatively stiff and do notallow the escape of perspirationvapour

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o The term breathable implies that the fabric is activelyventilated.

o Breathable fabric passively allow water vapour to diffusethrough them yet still prevent the penetration of liquid water.

How it works ?

o During physical activity the body provides cooling partlyby producing insensible perspiration.

o If the water vapour cannot escape to the surroundingatmosphere the relative humidity of the microclimate

inside the clothing increases causing a correspondingincreased thermal conductivity of the insulating air, andclothing becomes uncomfortable.

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o If the body loses heat more rapidly than it is able toproduce it, causes Hypothermia.

o If perspiration cannot evaporate and liquid sweat (sensibleperspiration) is produced, the body is prevented fromcooling at the same rate as heat is produced.

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TEMPREATURE

HEAT LOSSHEAT GAIN

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o The body to remain at the physiologically requiredtemperature , clothing has to permit the passage of water

vapour from perspiration at the rates under the activityconditions.o The ability of fabric to allow water vapour to penetrate is

commonly known as breathability.o Although perspiration rates water vapour permeability are

usually quoted in units of gram per square metre per dayor grams per day.

TYPES OF WATERPROOF BREATHABLE FABRIC

Densely wovenfabric. Membranes. Coatings.

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Densely woven water breathable fabric

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The densely woven waterproof breathable fabrics of cotton or synthetic microfilament yarns with compact weave structure.o Usually combined yarns are weaved parallel to each other with no

pores for water to penetrate. usually oxford weave is used.

HOW IT WORKS?

o When fabric surface is wetted by water the cotton fibers swelltansversely reducing the size of pores in the fabric andrequring very high pressure to cause penetration.

o Therefore waterproof is provided without the application of anywater-repellent finishing treatment.

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LAMINATED WATERPROOF BREATHABLE FABRICS OR MEMBRANE

o Laminated waterproof breathable fabrics made by application of membrane into textile product

o These are thin membrane made from polymeric materials, which

offer high resistance to water penetration but allow water vapour at the same time.o Maximum thickness of membrane is 10 micron.o They are of two types: Microporous membrane

Hydrophilic membrane

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o The microporous membranes have tiny holes on their surface smaller than rain drop but larger than water vapour molecule.

o They are made from polytetrafluroethylene (PTFE) polymer or polyvinylidene fluoride (PVDF).

o The hydrophilic membranes are thin films of chemically

modified polyester or polyurethane, modified by incorporationof poly.o The poly (ethylene oxide) constitutes the hydrophilic parts of

the membrane by forming amorphous region in the mainpolymer system.

o This amorphous region act as intermolecular pores allowingwater vapour molecules to pass through but preventing thepenetration of liquid water due to solid nature of membrane.

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COATED WATERPROOF BREATHABLE FABRIC

o Coated waterproof breathable fabric consist of polymericmaterials applied on the surface of fabric. E.g. polyurethane

o The coating are of two types: Microporous membrane Hydrophilic membraneo In microporous membrane coating contains very fine

interconnected channels much smaller than finest raindropbut larger than water vapour molecule.

o The hydrophilic coating is same as hydrophilic membrane butthe difference between the microporous and hydrophilicmaterial is the former water vapour passes through thepermanent air-permeable structure whereas the later transmits vapour through mechanism involving adsorption-diffusion and de-sorption.

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CONCLUSION

o The outer surface of most laminatedwaterproof breathable fabric is treated witha durable water-repellent coatings(DWR) and improving the overallperformance.

o DWR coating will began to degrade after extended use and as the garment becomessoiled.

o Water vapour transfer in waterproof breathable fabrics decreases as raintemperature increases.

o However, the breathability of most of themultimately ceases after long exposure toprolonged severe rainy condition.

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THANK YOU