Welcome To My Presentation On

Moisture Control & Breathable Finish.

Submitted by Avik Kumar Dhar ID-2016-2-3-002 M.sc. In Textile Engineering Wet Processing Engineering

Submitted to Dr. M. Forhad Hossain Associate Professor & Head Dept. Of Wet Processing Engineering Bangladesh University Of Textiles

Contents Introduction of Moisture control & Breathable finish.Wetting ,Wicking and MVTR & RET.Aims of Breathable FinishDesired Attributes of Moisture Management FabricHow to Make a Waterproof and Breathable Fabric??? Perspiration Rates and Activities.Moisture Transport Mechanism. Factor Affecting Moisture Transport. Types of Waterproof Breathable Fabric.Water Proof Fabric Made From Different Fibers. Functional fields of moisture management technique.Gore –Tex In Active Sportswear.Why breathable fabrics fail???Conclusion

Breathability:-It is the ability of a fabric to allow moisture vapour to be

transmitted through the material. Moisture control & breathable finish can be defined as the controlled movement of water vapour & liquid water (perspiration) from the surface of the skin to the atmosphere through the fabric.

Wetting, wicking, and moisture vapor transmission (MVT) properties are the critical aspects for evaluating the comfort performance of textiles .

Wetting ,Wicking and MVTR

• Wettability can be defined as interaction between liquid and the substrate before wicking.

• Wickability can be defined as the ability to sustain capillary flow.

• MVTR is a measure of how quickly (or slowly) moisture passes through a fabric or other substance. It is usually measured in g/m2/day or the mass of moisture that passes through a square meter of fabric in 24 hours

RET• RET (Resistance to Evaporative Transfer) test

This test is also known as the “sweating hot plate test.” The test measures how much a fabric resists letting moisture vapor through.

Since performance is based on how much vapor is blocked, the lower the number is the better.

The test is performed by first saturating the fabric. The fabric is then placed over a heated and porous metal plate. This plate is intended to mimic human skin. The volume of the evaporated water is then measured.

Aims of Breathable Finish

To increase comfort by evaporating humidity as early as possible. To protect skin from weather. To transport the humidity to the atmosphere as

fast as possible. To make the skin feel dry.

Desired Attributes of Moisture Management Fabric

• Optimum heat and moisture regulation.• Good air and water vapour permeability.• Absence of dampness.• Rapid drying to prevent catching cold.• Rapid moisture absorption and conveyance capacity.• Dimensionally stable even when wet.• Breathability and comfort.• Lightweight , soft and pleasant touch.

How to Make a Waterproof and Breathable Fabric???

We want to prevent water molecule (liquid) to get it the fabric and allow water vapour (gas) to pass from skin to fabric. The size of water droplet (liquid) is 100 μm and the water vapour (gas) is 0.0004 μm and we need to make a fabric with porous space around 10 μm. In this way, it allows water vapour to pass through (from skin to fabric) and prevent water droplet to penetrate (from outside to fabric).

Perspiration Rates and Activities

Moisture Transport MechanismMoisture transportation 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 or the greater the surface energy, the greater the tendency of a liquid to move up the capillary.

• Hence, the narrower the spaces between these fibres, the greater the ability of the textile to wick moisture.

Factor Affecting Moisture Transport

• Fiber type• Cloth/ Fabric construction• Weight /thickness of the material.• Presence of chemical treatment.

Types of Waterproof Breathable Fabric

1. Closely woven fabric2. Micro porous membranes and coatings.3. Hydrophilic membranes and coatings.4. Combination of micro porous and hydrophilic

membranes and coating.5. Retro-reflective microbeads.6. Smart breathable fabrics.7. Fabrics based on Biomimetics

Closely Woven Fabric• It was developed in 1940s for military purposes and is known

as Ventile.• Ventile fabric uses the finest cotton yarn, combed and piled

together.• The yarn is woven using oxford weave.• It can be produced from micro-denier synthetic filament yarn

also.

Micro Porous Membranes -are extremely thin films -made from polymeric material -they have very high resistance to liquid water penetration-allow the passage of water vapour. -A typical membrane is only 10 μm thick.- provide the necessary mechanical strength.

-The micro porous membranes have tinyholes on their surface smaller than a raindrops but larger than water vapourmolecule.-The pore sizes ranges from 0.1 to 50mm.-Some of the membranes are made fromPolytetrafluoroethylene PTFE polymer,Poly-vinylidene fluoride PVDF, acrylics,polyamino acids etc .

PU (Polyurethane) is the most popularpolymer because of toughness, flexibility ofthe film.

Various methods of generating micro porousmembranes and coatings are as follows :-

Mechanical fibrillation(only for membrane)

Wet coagulation process. Thermo coagulation. Foam coating

(only for coating). Solvent extraction. Solubilizing one component in the mixture

(only for coating). RF /ion /UV or E beams radiation. Melt blown / Hot melt technology. Point bonding technology Fig- Micro porous Coating

Hydrophilic Membranes

-Thin films of chemically modified polyesteror polyurethane.-These polymers are modified by theincorporation of poly.-The poly (ethylene oxide) constitutes thehydrophilic part of the membrane by formingamorphous region in the main polymersystem.-This amorphous region acts as intermolecularpores allowing water vapour molecules to passthrough but preventing the penetration ofliquid water due to the solid nature of themembrane.

Advantages of Hydrophilic Coatings over Laminated and Micro Porous

It has good adhesion on textile substrate.High gloss.Water and solvent resistance.High moisture permeable properties and It is less expensive. A major problem with both coated and laminated breathable

fabrics is their poor wet abrasion resistance.• Polyethylene glycol can be utilized as a relocking aid with e-

Caprolactum. Using this approach, in the present day, various polyethylene glycols of molecular weight 400, 1000, 3000 and 6000 are used for Hydrophilic polyurethane coating.

Combination of Micro Porous and Hydrophilic Membranes and Coating.

The fabrics are coated with copolymers having both hydrophilic and hydrophobic segments. The hydrophobic parts provide the resistance to liquid water droplets while the hydrophilic part allows for water vapor permeability.

Few advantages of bicomponent micro porous films are that - It provides added strength and toughness to films.- It reduces the stretch which may be caused by opening of the pores and also the moisture vapor transfer is more by mechanical means than by chemical adsorption means.

Some drawbacks of the films including - Increased cost - Stiffness and- Reduction of breathability of the fabric.

Retroreflective Microbeads.

This fabric possesses a print or coating havingretroreflective pattern areas of aligned, hemisphericallycoated retroreflective microbeads.

One patent describes how abreathable fabric was adhered to anarray of dots, where each one of the dotshad coated retroreflective microbeads, insuch a way that the fabric breathesfrom the interstices between the dots.

Fabric with Retroreflective Microbeads

Smart Breathable Fabrics.

A breathable fabric with temperature dependent response may be desirable for certain applications where there are huge variations in temperature over a short period of time. Such fabrics are called smart breathable fabrics.Phase change materials are also an important

category of smart breathable textiles. The incorporation of these phase change materials

leads to improvements in thermal and moisture management.

PCMs

Phase Change is the process of going from one state to another, e.g. from solid to liquid and vice versa. Any material that experiences the process of phase change is named as Phase Change Materials (PCM)

Spacer Structure Two separate fabric webs are joined together by spacer

threads or fibres of varying rigidity. The intermediate zone creates a layer of air, which has an insulating and thermoregulatory effect. Modifying the structure of the knitted construction can alter the amount of air incorporated in the assembly.

Spacer fabrics are 3D fabrics . This creates a ventilated layer of air, allowing heat and

moisture to escape. Advantage is the low weight in proportion to the large

volume.

Spacer Structure

Fabrics Based on Biomimetics

Biological mechanisms are mimicked to get desired functions.

For a breathable fabric the analog of leaf stomata, this opens when the plant needs to increase water vapor intake and closes when its needs to reduce, can be used.

Pine cone and watch whether the spines open and close. In rain, the spines close up to protect the seeds inside. In dry, the spines open up to improve the chances of the seeds

escaping. Researchers at England's Bath University and the London College

of Fashion are trying to design biomimetic clothes that could work the same way. The fabric could be made with an outer layer of tiny spikes. When it's hot, the spikes would open up to let out the heat, cooling you down. When it's cold, the spikes would flatten back down to trap air and provide more effective insulation.

Water Proof Fabric Made From Different Fibers

• Polyester -Air fine Field sensor -Polyester coolmax-Coolpass-Thermopile-Microfibers

• Polypropylene• Nylon

-Hyrofil-Tactel

• Silk• Wool• Cotton• Viscose rayon

Functional fields of moisture management technique

1. Inner wears1. Athletic wear

(active sportswear) 1. Performance wear

(climbing, walking, skiing) 1. Comfort wears

(nightwear) 1. Military

(multi-climate clothing) 1. Health

(hospital bed linens, wound dressings) 1. Agricultural technology

(Geo-textiles, greenhouse screening panels, soil moisture control) 1. Technical solutions

(Formula 1 protective clothing, fire fighting, industrial clothing) 1. Industrial

(filter & valve technology, building, packaging) 1. Upholstery

(transport)

Gore –Tex In Active Sportswear Gore –Tex membrane is used for developing active sportswear.

Gore-Tex membrane is a film like laminate with billions ofmicro pores per square inch. Each pore is smaller than a waterdrop, bigger than a molecule of water vapour.

The more active we become, the more heat and moisture areproduced by our body. Breathable outerwear and footwear aids ourbody’s natural cooling process by allowing perspiration vapour toescape.

Apparel that is not breathable causes excess moisture toaccumulate next top our body, which makes one feeluncomfortable.

Wetness next to our skin can be even worse in cooler temperatures,when you become susceptible to getting chilled. These are why allthe breathing is necessary. With Gore-Tex outerwear and footwear,you stay dry and comfortable when you are active and there is noperspiration build up to make you cold.

Gore-Tex fabric is waterproof-• Gore-Tex fabric is waterproof-

Raindrops hitting the fabric’s outersurface are bouncing right off the topbecause the fabric is totallywaterproof. They could be bigraindrops, pounding raindrops, andthey would still be bouncing off thesurface. No moisture can penetrate theGore- Tex fabric because the waterdrops are always bigger than the micropores in the Gore- Tex membrane.

Why breathable fabrics fail???

• Moisture may not move through the fabric fast enough.

• The “outside” humidity is too high. • The fabric can “wet out” or become saturated

with water.

ConclusionMoisture control and breathable fabric is the greatestinvention among the most useful invention for humanbeing. When water proof breathable fabric wasdiscovered, textile world realized that there is norestriction is the textile world. Water proof breathablefabric is very important because of playing vital role insportswear. This study went through the basicmechanism and idea of moisture management andbreathable fabric, different types of breathable fabric,the application of breathable fabric in different sectorsspecially in sportswear and the impact of fiber inbreathable behaviour also. But there are still severalsectors in which breathable finish to be studied.

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