Waterproof breathable fabrics allow water vapor to pass through while preventing liquid water from penetrating. There are three main types: densely woven fabrics, membranes/laminated fabrics, and coated fabrics. Densely woven fabrics use very fine fibers and tight construction to reduce pore size. Membranes use thin polymeric films with micro pores or hydrophilic regions that block liquid water but allow vapor. Coated fabrics apply porous or hydrophilic polymeric coatings to fabrics. These fabrics are widely used in sportswear and outdoor clothing to transport moisture away from the skin while resisting liquid water.

1. Breathable Fabrics
or waterproof breathable/waterproof-breathable
Some important points
Waterproof fabric completely prevents the penetration and absorption of
liquid water.
Breathable fabric is actively ventilated and it passively allow water vapor to
diffuse through them yet prevents the penetration of liquid water.
Waterproof breathable fabrics resist water droplets from passing through
while at the same time allowing water vapor through. The breathability of
almost all waterproof breathable fabrics is very dependent upon weather
conditions, especially temperature and humidity.
Waterproof breathable fabrics are widely used in sportswear and similar
Application.

3. Breathable Fabrics
or waterproof breathable/waterproof-breathable
Breathability is measured by the rate at which water vapor passes through in
the units of grams of water vapor per square meter of fabric per 24 hours
period (g/m2/d), often abbreviated to just ‘g’. In recent years some of the
sporting goods manufacturers have begun including this information on their
labels. Typical mid-range fabric tends to have values of 5000 mm of water
resistance and 5000g of breathability. The highest end materials boast
20000 mm and 20000 g.

4. Breathable Fabrics and Applications
or waterproof breathable/waterproof-breathable

5. Waterproof Breathable Fabric
Drops of water (10000-2000000A diameter)
are too big to penetrate the membrane
wind
Perspiration vapor (3.5A) passes through
inter-molecular opening easily

6. Uses of Waterproof Breathable Fabric
Leisure Work
Heavy duty, foul weather clothing: Anoraks,
cagoules, packs , over-trousers, hats, gloves,
gaiters
Foul weather clothing: survival suits, special
military protective clothing, clean room
garments, surgical garments, hospital drapes,
mattress and seat covers, specialized
tarpaulins, packaging, wound dressings
,filtration
Domestic and transport: non-allergic bedding, car
covers, fire smoke curtains in ships, cargo wraps
in aircraft
Fashionable weather protection: rainwater,
skiwear, golf suits, walking boot linings,
panels and inserts, sport footwear linings,
panels and inserts
Tents
Sleeping bag covers

7. Examples of Breathable Fabrics
Anorak
Cagoule
Gaiter
Gaiter

8. Examples of Breathable Fabrics

9. Types of waterproof breathable fabric
There are several types of waterproof breathable fabric. These can be divided
into three groups:
Densely woven waterproof breathable fabrics
Membranes/Laminated waterproof breathable fabrics
Coated waterproof breathable fabrics

10. Waterproof Breathable Fabric
Densely Woven
• For cotton, the finest type of long staple are selected so that there are
very small space between the fibers. The cotton is processed into
combed yarn, which is then plied. This improves regularity and ensures
that the fibers are as parallel as possible to the yarn axis, and that there
are no large pores where water can penetrate. The yarn is woven using
an oxford weave, which is a plain weave with two threads acting together
in the warp. This gives maximum crimp in the weft, again ensuring that
the fibers are as parallel as possible to the surface of the fabric. When
the fabric surface is wetted by water, the cotton fibers sell transversely
reducing the size of the pores in the fabric and requiring very high
pressure to cause penetration. This fabric is thus become waterproof
without the need for water-repellent.

11. Waterproof Breathable Fabric
Densely Woven
Densely woven fabric can be made from synthetic microfilament yarns. The
individual filaments are less than 10 micrometer in diameter, so that fiber
with very small pores can be engineered. Microfilaments are usually made
from polyamide or polyester. The latter is particularly useful as it has
inherent water-repellent properties. The water penetration resistance of the
fabric is improved by application of silicone or fluorocarbon finish.
The use of very fine fibers and microfilaments and dense construction (sett)
results in fabric with very small pores size compared with conventional
fabrics. Typical pores size for a waterproof fabric is about 10um compared to
60um for a conventional fabric. Fabric made from microfilaments is claimed
to have up to 7000 filaments per centimeter.

12. Waterproof Breathable Fabric
Fig: Maximum crimp in weft
Warp
Weft

13. Microscopic View
Scanning Electron
Micrograph of Densely
woven Fabric
Photomicrograph of
Densely woven Fabric
(Dry)
Photomicrograph of
Densely woven Fabric
(Wet))
Scanning Electron
Micrograph of
Microfilament Fabric

14. Waterproof Breathable Fabric
Membranes/Laminated waterproof breathable fabrics: are made by application
of membranes into textile product. These thin membrane made from polymeric
materials. This offer high resistance to water penetration but allow water vapor.
The maximum thickness of the membrane is 10micron. They are two types:
Micro porous membranes
Hydrophilic membranes
• Micro porous membranes
Micro porous membrane is a thin film of expanded polytetrafluoroethylene
• The membrane contains tiny holes which are much smaller than the finest raindrop
but much larger than a water vapor molecule.
• The hydrophobic nature of the polymer and small pore size requires very high
pressure to cause water penetration.

16. Hydrophilic membranes
• Hydrophilic membranes are very thin films of chemically modified
polyester or polyurethane containing no holes which therefore are
sometimes referred to as non-poromeric.
• The polyester or polyurethane polymer is modified by incorporating
up to 40% by weight of poly(ethylene oxide)
• The poly(ethylene oxide) constitutes the hydrophilic part of the
membrane by forming part of the amorphous regions of the
polyurethane polymer system.
• These amorphous regions are described as acting like intermolecular
pores’ allowing water vapor molecules to pass through but
preventing the penetration of liquid water owing to the solid nature of
the membrane.

19. Figure that differ coated Laminated fabric

22. Methods of Membrane incorporation
There are four main methods of incorporating membranes into
textile articles. The method employed depends on cost, required
function and processing condition,
1 Laminate of membrane and outer fabric (Fig. a) –
The membrane is laminated to the underside of the outer fabric to
produce a two-layer system.
Advantage:1.Has very effective protective properties like waterproof,
wind resistance.
Disadvantage:1.This method produces a rustling ,paper-like handling
apparel.
Use: mainly used in protective clothing.

23. Methods of Membrane incorporation
Liner or insert processing (Fig. b) – The membrane is laminated
to a light- weight knitted material or web. This structure is then loosely
inserted between the outer fabric and the liner. The three materials
(outer, laminate and lining) are joined together by concealed stitch
seams.
Advantage :1.This method gives soft handle good drape properties
2.In this method ,the outer fabric can be modified to suit
fashion demand.

24. Methods of Membrane incorporation
Laminate of membrane and lining fabric (Fig. c)
– The laminate is attached to the right side of the lining material.
-The functional layer is incorporated into the garment as a
separate layer independent of the outer fabric.
Advantage: In this method the fashion aspects can be maximized.

25. Methods of Membrane incorporation
Laminate of outer fabric, membrane and lining (Fig. d) –
This produces a three-layer system, which gives a less
attractive handle and drape than the other methods and, therefore, is
not commonly used.

26. Coated waterproof breathable fabrics: consist of
polymeric material applied to one surface of fabric.
Polyurethane is used as coating material. The
coatings are of two types:
Micro porous Coating
Hydrophilic Coating

27. Figure of Micro porous coating

28. • Micro porous Coating
• Micro porous coatings have a similar structure
to the micro porous membranes.
• The coating contains very fine interconnected
channels, much smaller than the finest
raindrop but much larger than a water vapour
molecule
Micro porous Coating

29. Hydrophilic coating
• Hydrophilic coating: It uses the same basic water
vapour permeability mechanism as the hydrophilic
membranes.
• These coatings are all based on polyurethane, which
has been chemically modified by incorporating
polyvinyl alcohols and polyethylene oxides. These
have a chemical affinity for water vapour allowing
the diffusion of water vapour through the
amorphous regions of the polymer

30. Figure of Waterproof coating

31. Desirable Attributes of WBF for Sportswear
Optimum heat and moisture regulation
Good air and water vapor permeability
Rapid moisture absorption and conveyance capacity
Absence of dampness
Rapid drying to prevent catching cold
Low water absorption of the layer of clothing just positioned to the skin
Dimensionally stable even when wet
Durable, Easy care lightweight, Soft and pleasant touch
Does it possible to maintain above mentioned qualities in one fabric?

32. How to get these attributes?
Two layer structures are needed. The first layer closed to skin should be of the
wicking property, made of synthetic fibers, e.g., micro-denier polyester. The
outer layer usually cotton that absorbs and evaporates the perspiration/water
vapor. The first layer is ideal for wicking perspiration away from the skin.
Wicking refers to technical property in fabrics that move sweat away from the skin to the outer surface
of the fabric where it evaporates

33. Moisture Transport Mechanism
The mechanism by which moisture is transported in textiles is similar to the
wicking of a liquid in capillaries. Capillary action is determined by two
fundamental properties of the capillary:
Its diameter, and
Surface energy of its inside face.
The smaller the diameter of the greater the surface energy (hydrophilic
action), the greater the tendency of a liquid to move up the capillary. In textile
structures, the space between the fibers effectively form capillaries. Hence,
the narrower the spaces between these fibers, the greater the ability of the
textile to wick moisture. Fabric constructions, which effectively form narrow
capillaries, pick up moisture easily. Such constructions include fabrics made
from micro fibers are packed closely together. However, capillary action
ceases when all parts of a garments are equally wet.

35. Factors affecting Moisture Transport
There are several factors, which affect moisture transport in a fabric. The
most important are:
Fiber type
Cloth construction or weave
Weight or thickness of the materials
Presence of chemical treatments

36. Assessment Techniques
Assessment of the effectiveness of waterproof breathable fabrics
requires measurement of three properties:
Resistance to penetration and absorption of liquid water
Wind resistance
Water vapor permeability.