New Technology Pres

7/31/2019 New Technology Pres

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ENGINEERING OF TEXTILES

USING

NEW TECHNOLOGIES

Manisha A. Hira

Scientist CThe Synthetic & Art Silk Mills Research Association

Sasmira Marg, Worli,Mumbai 400 030

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What is Human Comfort?

A pleasant state of physiological, psychological and

physical harmony between a human being and the

environment

Thermal comfort:

One should be comfortable in a thermally neutral

condition, neither gaining nor losing body heat content

and with normal skin temperature in all areas

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Factors Influencing Thermal Comfort

Metabolic heat generated by the body of the

wearer

Wind chill in the environment

Thermal insulation ability of the garment

Air permeability of garment

Water vapour permeability of the garment

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Mechanism of Deriving Thermal Comfort

Clothing is expected to provide thermal

comfort by:

Thermal Insulation

Thermal regulation

Air is the best thermal insulator

Textile structures entrap air to provide thermal

insulation

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Need for Engineering Thermal Comfort

A few examples to the temperature fluctuations thatone could experience are as below: The astronauts in the space shuttle traveling around the

earth periodically come across the sunny side and the shady

side and the corresponding temperature rise and drop. A worker in the industrial freezer compartment is equipped

with clothing to protect from the freezing temperature.When this worker comes out into the normal industrialclimate, he experiences overheat.

Under such periodic changes in the environmentaltemperature, it is practically inconvenient for thevictim to keep adjusting his clothing as per theclimatic demands.

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TECHNIQUES TO ENGINEER

THERMAL COMFORT IN CLOTHING

Thermal insulation

High loft fibres

Hollow fibres

Polymeric coating

Shape Memory Polymers

Thermo-regulation

Electroconductive Polymers

Phase change materials

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Thermal Insulation through High

loft fibres

Traditional method of providing thermalinsulation

Thermal insulation is directly proportional to

Fabric thickness High loft fibre provide scope for air

entrapment and better insulation

Down fibres are commonly used Limitation is the loss of thermal capacity of

these structures on wetting.

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Thermal Insulation through Hollow

fibres

Synthetic hollow fibres are found to higher heat

conductivity ability in the fibre axis direction as

compared to transverse direction

This anisotropic behaviour of hollow fibres is utilisedfor providing thermal insulation

Hollow fibres of nylon, polyester, polypropylene and

acrylic are available and can be used.

This can be coupled with other insulation techniques

for developing thermal protective clothing.

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Thermal Insulation through

Polymeric Coating Coating of textile substrates with expanded forms of

polymers

These coatings in expandable form (foams) providescope for air entrapment

Popular coating used for this purpose: Poly vinyl chloride

Poly urethane

Poly tetra fluoroethylene

They are termed as breathable coating with necessary airand water vapour permeability along with water proofbehaviour.

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Thermal Insulation using Shape

Memory Polymers (SMPs)

Class of polymers synthesized to respond dynamically to thethermal stimuli by altering their shape.

These coating are active near their glass transition temperature(Tg)

These coatings have a permanent parent shape and alter to a

temporary shape in response to temperature change The temporary shape alteration provides for scope of air

entrapment and thermal insulation.

The engineering of SMPs with Tg close to the activitytemperature is essential.

Available SMPs in the range are active in the range -30 C to260 C.

Styrene acrylate, cynate esters and epoxy polymer systems aregenerally used

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Thermo-regulation using

Electroconductive Polymers

Particulate filler are added to polymers to

regulate temperature

Generally, ceramics are used in this case

Absorb solar radiation and generate infra-red

radiation to maintain body temperature.

Zirconium carbide, magnesium oxide, ironoxide are popularly used

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Thermo-regulation using Phase

Change Materials

Certain materials posses the ability to change their

physical state from solid to liquid and vice versa

within a given temperature range.

In doing so, they absorb or release certain amount of

heat equivalent to their latent heat and keep the

substrates temperature unaltered.

These chemicals, termed as Phase Change Materials(PCM), can be used for obtaining the thermo-

physical comfort characteristics in the fabric.

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Thermal Behaviour of PCM

TEMPERATURE (O C)

30 35 4037

HEAT OF FUSION

PHASE CHANGE TEMP.

150

125

100

75

50

25

HEATFLOW(mW

)

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Thermal Effects of PCMs

A cooling effect, caused by heat absorption of the PCM; A heating effect, caused by heating emission of PCM;

A thermo-regulating effect, resulting from either heatabsorption or heat emission of the PCM helping to keep

the temperature of a surrounding substrate nearlyconstant;

An active thermal insulation effect, resulting from eitherregulating the heat absorption or the heat emission of the

PCM regulating the heat flux though the substrate whileadapting to the thermal surrounding.

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PHASE CHANGE MATERIALS

Plastic crystals

Hydrated Inorganic salts like Calciumchloride hexahydrate, lithium nitratetrihydrate, etc

Polyhydric alcohols like 2,2- dimethyl,1,3-propandiol (DMP), etc

Paraffin waxes Linear chain hydrocarbon, C8 - C24

Polyethylene Glycol,Molecular weight range 600 to 2000

PET PEG block copolymer

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Application areas for PCMs

Solar thermal energy storage for room heating

Electronic circuitry to insulate the circuits from

environment

Textile industry to provide thermo-regulation intextiles

Techniques for introducing PCMs in

textiles

Coating of substrates

Microencapsualtion in substrates

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SASMIRAs approach towards

Thermo- regulatory textiles Developing Phase Change Material formulations in

various active temperatures ranges

High altitude applications

Active wear applications High temperature applications

Optimising techniques of incorporating PCM

formulations in textiles

Standardising technique of evaluating thermo-

regulatory behaviour of textiles with incorporated

PCMs

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Microencapsulation

Finishes normally adhere to the surface of textiles

and are washed off on repeated use.

Microencapsulation helps to

Achieve permanency of the finishes.

Also protects the core from atmospheric conditions.

CAPSULE MICROCAPSULES

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MICROENCAPSULATION

A TECHNIQUE BY WHICH MICRO PARTICULATESOR DROPLETS OF MATERIALS CAN BEENCLOSED IN AN IMPERVIOUS CAPSULE

GENERALLY, THE CAPSULE DIAMETER RANGESFROM 1 TO 60

THE CAPSULE WALL DOES NOT HAMPER THEFUNCTIONING OF PARTICULATES WITHIN IT

THE PROCESS CAN BE CARRIED OUT USING

POLYMERIC COATING OF DMDHEU, PU, etc

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Techniques of Microencapsulation

Phase separation

Insitu polymerisation

Air suspension

Spray drying

Microencapsulationmethod

Core material Approximateparticle size(m)

Phase separation Solid, liquids 2 - 1200

Air suspension Solids 35 - 5000

Spray drying Solids, liquids 6 - 600

Insitu polymerisation Solids, liquids 1 - 1500

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NANOTECHNOLOGY

THE TECHNOLOGY DEALS WITH DEVELOPMENT &USE OF DEVICES THAT HAVE SIZE IN THE RANGEOF NANOMETERS(10-9)

SUCH MATERIALS ARE FINE IN SIZE GREATERSURFACE AREA AND RAPID IN ACTION

LAYERED SILICATE, ALUMINA FIBRE, NANOTUBESOF CARBON, SILICON DUST ARE EXAMPLES OF

NANOMATERIALS

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Nanoproducts

1. Nano-spun fibres Fine fibres of nano-diameter, 100 500 nm

Spun by electrospinning technique

Resultant fibres in the form of

Yarns

Fibre webs

Conductive fibres, filtration textiles, wound

dressings and scaffolds.

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2. Nano-composites Formed using Nanoclay or Carbon Nano tubes

(1

50 nm) in matrix

Composites for aerospace

Tougher and stiffer composites, ~ 500 MJ/m3

toughness and `1000 MPa modulus

Improved fire resistance

Polyester barrier packaging

Dyeable polypropylene

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NANOMATERIALS

Two Tetrahedral Si Sheet per OneAluminium Octahedral sheet.

Polymer compositewith nanoplates

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3. Nano-finishes

Thin nano-scaled finishes

Polymer dispersion with nanoparticle additives

Provide low surface energy and minimisation

of surface contact area Self cleaning finishes - Imparting stain and water

resistance to fabrics

Imparting hydrophilicity to the synthetic fibres

Thin responsive films

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APPLICATIONS OF NANOTECHNOLOGY

INTEGRATION OF SMART DEVICES LIKENANOCOMPUTERS, SOLAR CELLS, MICROMETERSIN GARMENTS

CONTROLLED DRUG RELEASE WITHNANODISPERSED HYDROGELS OF DRUGS

AEROSPACE COMPOSITES

DYEABLE POLYPROPYLENE

NANO FINISHES LIKE ANTICREASE

ANTISOIL

ANTIMICROBIAL

THERMOREGULATORY

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