NEEW Generation Smart Textile

.

New Generation Smart Textiles Containing

Phase Change Materials

Gagan Sachdeva and Surbhi Gupta

B.Tech, Textile Technology

Panipat Institute of Engineering & Technology,

2 www.technicaltextile.net

New Generation Smart Textiles Containing Phase Change Materials

Gagan Sachdeva and Surbhi Gupta, B.Tech, Textile Technology,

Panipat Institute of Engineering and Technology, Samalkha, Panipat-132102

ABSTRACT

Smart textiles are materials and structure that sense and react to environmental conditions or

stimuli, such as those from mechanical, thermal, chemical, electrical, magnetic or other sources.

The Phase Change Materials are those which change their phase from solid to liquid upon

heating and back to solid from liquid when temperature is drop down. During their phase change

from Solid to liquid they absorb, distribute and store the heat, and release it when going a phase

change from liquid to solid. Thus it keeps the wearer skin’s temperature constant by absorbing

the excess heat and releasing it when required. PCM possesses the ability to change their phase

with a certain temperature range which can be controlled by choosing the various phase change

material according to the end use of the product. This paper discuss about the principle of Phase

Change Material, Its different type available. The different technology used for the incorporation

of phase change materials into textile substrate and their application with limitation is also been

discussed.

Keywords: Phase Change Temperature, Technical textiles, Microclimate, Microencapsulation,

Perspiration, Temperature, Thermocules and Thermal Regulation.

1. INTRODUCTION

The textile industry has reached a highly advanced stage with the different types and qualities of

fabrics that can be manufactured. The history of textiles and fibers spans thousands of years,

beginning with the style change from animal skins to the first fabric used to clothe humanity. But

during the relatively short period of the past 50 years, the fiber and textile industries have

undergone the most revolutionary changes and seen the most remarkable innovations in their

history. Technical textiles are reported to be the fastest growing sector of the textile industrial

sector [6]. In recent years, significant progress has been achieved in the area of technical textiles,

fibers, yarns, fabrics and other structures with added-value functionality have been successfully

developed for technical and/or high performance end-uses. Technical textiles were promoted as

alternative materials for a limitless range of applications, including civil engineering, the

automotive industry, aerospace and the medical industry. The huge advancement in the

Technical textiles industry and the accurate control on the mechanization process offer an

innovative environment for new product, namely Smart textiles. Smart textiles are materials and

structure that sense and react to environmental conditions or stimuli, such as those from

mechanical, thermal, chemical, electrical, magnetic or other sources [15]. In the last decade one

of emerging technologies is microencapsulated Phase Change Materials which are being


developed to provide significantly enhanced thermal management for fibers, foams and textiles

with application to apparel and technical textiles.

The different types of Smart textile materials are:

1) Phase Change Material,

2) Chromic Colors,

3) Shape memory materials,

4) Auxetic material,

5) HoIofiber,

6) Stomatex,

7) Stimuli-responsive hydrogels and membranes and

8) Electronic textile [1, 4].

Suitable technical equipment is becoming more and

more important for authorities and the military. Not

only are electronics, hard and software playing a large

role, there are also increasing demands for apparel.

The call for Smart fabrics is becoming more and more

insistent. A new generation of these fabrics features

Phase Change Materials (PCMs) which are being

developed to provide significantly enhanced thermal

management for fibers, foams and textiles. These

Phase Change Materials are able to absorb, store and

release excess body heat when the body needs it

resulting in less sweating and freezing, while the

micro climate of the skin is influenced in a positive

way and efficiency and performance are enhanced.

An Outlast Jacket Containing Phase Change Material

is shown in Fig: 1, which maintain the wearer skin

temperature in a comfortable zone.

Fig: 1 Outlast Phase Change Jacket

According to this definition textiles containing PCM are considered as smart because they react

immediately to changes in environmental temperature and adapt to the prevailing hot or cold

condition [2]. Phase change technology originates from the NASA (National Aeronautics and

Space Administration’s) research program of the 1970s.The aim of this program was to provide

astronauts and instruments with better protection against extreme fluctuation of temperature in

space and since then research work has been carried out by scientists and now textiles with phase

change materials (PCMs) are used in numerous products and applications from apparel,

underwear, socks, accessories and shoes to bedding and sleeping bags. PCMs can even be found

in specialty items, such as antiballistic vests, automotive, medical or special industrial

applications, where warmth and energy play a role.


2. PRINCIPLE WORKING OF PCM FABRIC

The principal function of clothing assembly is to provide the wearer with protection against

undesirable environments. Due to the fact that a human being is homeo thermal, the human body

regulates temperature in narrow limits around 370C [2]. But Fabrics containing PCMs appear to

be effective in contributing to apparel comfort by buffering and reducing overheating, the cause

of perspiration. The fabrics with PCM react immediately to changes in environmental

temperature and adapts to the prevailing hot or cold conditions. The Phase Change Materials

changes their phase from solid to liquid upon heating and back to solid from liquid when

temperature is drop down. During their phase change from Solid to liquid they absorb, distribute

and store the heat, and release it when going a phase change from liquid to solid. When

temperature rise occurs as a result of body activity or a higher environmental temperature, PCM

reacts by absorbing the heat. Storing this surplus energy the PCM liquefies. This phase change

produces a temporary cooling effect in the clothing layers. The Working of Phase Change

Material is also shown in Fig: 2. Once the PCM has completely melted, the storage of heat stops.

The PCM releases the stored heat with a drop of environmental temperature or when the body is

at rest, and a temporary warming effect occurs in clothing layers. This heat exchange produces a

buffering effect in clothing layers, minimizing changes in skin temperature.

Fig: 2 Working Principle of PCM

The PCMs keep the wearer more comfortable by absorbing excess body heat when it creates too

much heat and by releasing stored heat when the body needs it most. The Thermocules work

with the body to regulate temperature and humidity better than fabrics or insulation alone.


3. BENEFITS OF PCM:

The followings are the benefits that can be obtained by incorporation of PCM into a textile

substrate:

a) A cooling effect, caused by absorption of heat by the PCM.

b) A heating effect, caused by release of heat from the PCM.

c) A thermo-regulating effect, resulting from either absorption of heat or release of heat by the

PCM which keeps the temperature of wearer constant in the comfort zone.

d) An active thermal barrier effect resulting from either heat absorption or heat emission of

the PCM and creating a thermal barrier in surrounding substrate, which, regulates through

the substrate and adapts the heat flux to thermal needs.

e) The cross-linked PEG treated fabric have antibacterial activity, resiliency/antiwrinkling,

wear, toughness, absorbency and exsorbency of liquids, improved abrasion and linting

resistance, decreased static propensity and increased oily soil release[5].

4. TYPES OF PHASE CHANGE MATERIALS

There are different types of phase change material which change their phase over a specific

temperature range. So according the end use we can have different PCMs. Few example of phase

change materials with their phase change temperature (PCT) and their Heat storage capacity:

4.1. Hydrated Inorganic Salt:

Hydrated inorganic salt is an inorganic salt crystal with n water molecules. The hydrated

inorganic salt that can be used in the manufacture of heat-storage and thermo-regulated textiles

and clothing usually has a heat-absorbing and -releasing temperature interval of about 20 to 40

°C. Table: 1 shows some of the hydrated inorganic salts.

Table: 1, Hydrated Inorganic Salts [5]


4.2. Hydrocarbons:

The Phase Change Temperature (PCT) or

Melting temperature for the hydrocarbons can

be manipulated by selecting no. of carbon

atoms. The PCT can be achieved from -5ºc to

60ºc by having no. of carbon atoms from 13-28.

By selecting the no. of carbon atoms the PCT

could be control as shown in Fig: 3. The

Melting temperature of Hydrocarbons increases

with increase in no. of carbon items. As shown

in Fig: 3 the 20 number of carbons gives the Tm

of 37.5º C which means the hydrocarbon which

is having 20 number of carbon atom will

change its phase from solid to liquid over 37.5º

C temperature and back from liquid to solid

below 37.5º C temperature. Fig: 3, PCT vs No. of Carbon atoms [2]

4.3. Polyethylene glycol:

Paraffin waxes have the heat storage capacity of 150-200kj/kg with the PCT or melting

temperature ranges from 35º C to 63º C. According to the end use of product different phase

change temperature for PEG can be chosen as per Table: 2. The melting temperature for

polyethylene glycol increases with increase in molecular weight.

Table: 2, Molecular weight and melting temperature of Polyethylene glycol [2]

4.4. Fatty acids and Vegetable oils:

Fatty acid and mineral oils their heat Storage capacity range 153-182 kj/kg with Phase change

temperature range(PCT)/Melting temperature of 30º-60ºc.


5. INCORPORATION OF PCM INTO FABRICS [2,5,7]:

Since the process of phase change is dynamic; therefore, the materials are constantly changing

from a state to another depending upon level of physical activity of the body and outside

temperature. The thermo-regulating characteristic is possible in manmade fiber by adding PCM

microcapsules to a polymer solution prior to fiber extrusion. In the process, PCM microcapsules

are integrated inside the fiber itself. These PCM is first microencapsulated by a polymer coating

in a sphere shape. The diameter of molecule is as small as 15-40µm. Then these microcapsules

can be applied to textile substrate by any of the following method.

5.1. Fiber technology

The first step in any technology of PCM is Microencapsulation. The microencapsulated PCM

fibers could store heat over long periods .Microencapsulation is the process of capturing small

amounts of phase change materials in a shell material so that the phase change materials are

permanently enclosed and protected. The protective polymer shell is very durable and designed

to withstand textile production methods used in fiber, yarn spinning, weaving, knitting, and

coating applications.

5.2. Coatings

PCM could be incorporated into the textiles by coating using polymer such as acrylic,

polyurethane, etc, and applied to the fabric. There are various coating processes available such as

knife-over-roll, knife-over-air, pad-dry-cure, gravure, dip coating, and transfer coating. To prepare the coating composition, microspheres containing phase change material are wetted

and dispersed in a dispersion of water solution containing a surfactant, a dispersant, an antifoam

agent and a polymer mixture. The coating would be then applied to a textile substrate. In an

alternative embodiment, an extensible fabric would be coated with an extensible binder

containing microencapsulated phase change material to form an extensible, coated fabric.

Preferred phase change materials include paraffinic hydrocarbons.

5.3. Lamination

In this technology microcapsules would be mixed into a water-blown polyurethane foam mix and

these foams are applied to a fabric in a lamination process, where the water is taken out of the

system by drying process. The excellent honeycomb structure obtained during foam formation

made considerable amount of still air trapping possibility, thus, leading to an increased passive

insulation. Although the presence of PCM micelles in cells can easily be distinguished.

Beside chemical protective suits the PCM can also improve the thermo-physiological wearing

comfort of other protective garments made of nonwovens such as surgical gowns, uniforms, or

garments worn in clean rooms. The cooling effect of the PCM can delay the temperature rise

and, hence, the moisture rises in the microclimate substantially. As a result, the wearing time of

the garments can be extended significantly without the occurrence of heat stress as a serious

health risk.


5.4. Microencapsulation:

Microencapsulation is a process in which tiny particles or droplets are surrounded by a coating to

give small capsules many useful

properties. In a relatively simplistic form,

a microcapsule is a small sphere with a

uniform wall around it.

Microencapsulation is also known as

micro packaging of solids and liquids.

The material inside the microcapsule is

referred to as the core, internal phase, or

fill, whereas the wall is sometimes called a

shell, coating, or membrane. The Fig: 4

show microencapsulated paraffin by a

polymer. It is an innovative technology for

packing of solids and liquids. Fig: 4 Microcapsule containing paraffin [2]

The microcapsules are produced by depositing a thin polymer coating on small solid particles or

liquid droplets, or on dispersion of solid in liquids. The core particles (active substance) from

microcapsule can be released under controlled conditions to suit a specific purpose. The core

substance from the microcapsule can be released by friction, by pressure, by dissolution through

the polymer wall coating or by biodegradation. Most microcapsules have diameters between a

few micrometers and a few millimeters.

6. APPLICATION OF PHASE CHANGE MATERIALS

Fabrics containing micro PCMs have been used in a variety of technical textile applications such

as apparel, automotive textiles, domestic textiles, medical products,

6.1. Apparel:

Major end-use of textile containing PCM in Apparel includes:

6.1.1. Life style apparel - Smart jackets, Vests, Men's and

Women's hats, Gloves.

Some peoples have jobs where they go to and from a cold

storage facility or transport vehicle and a warm building or

outside environment on an intermittent basis.

PCM protective garments improve the comfort of workers as

they go through these environmental step changes. It has been

observed that garments made with PCMs or “dynamic

insulation” will keep a person warm longer than conventional

insulation when worn in cold environment.

Fig: 5 Jacket Containing PCM


6.1.2. Outdoor active wear apparel -jackets and jacket lining, boots, golf shoes, trekking

shoes, socks, ski and snowboard gloves.

Safety helmets have a thermal resistance of approximately 1.0 m2 k/w and due to their structure

the heat generated by the wearer can be dissipated only by means of convection. But with the

incorporation of micro PCM in the helmet liner leads to substantial reduction of the microclimate

temperature in the head area.

6.1.3. Protective garments.

In the case of chemical or biological protective clothing a

conflict between the protective function of clothing and the

physiological regulation of body temperature may occur.

The conflict led to discomfort and physical strain and in

extreme cases can put the person at risk from heat stress.

The Outlast Protective garment (Body Armor) contains the

microencapsulated PCM thus providing more comfortable

Protective textile. The Outlast provide many kinds of

protective clothing which contains the microencapsulated

PCM ranges from Vest to Body Armor. The Fig: 6 show an

Outlast Body armor containing Phase Change Material.

Fig: 6 Outlast Body Armor

6.2. Automotive Textiles:

A Car Interiors containing Phase Change Material is

shown in Fig: 7. During the summer, the temperature

inside the passenger compartment of an automobile

can rise substantially-for instance, when the car is

parked outside. In order to stabilize the interior

temperature while driving the car, many models are

equipped with air conditioning systems; however,

providing sufficient cooling capacity requires a lot of

energy. On the other side, during the winter months,

the driver and the passengers are often confronted

with low temperatures, especially as they first get in

the car.

Fig: 7 Car Interior containing PCM

As result, some models have heating systems installed in the driver’s seat which are supplied by

the car’s battery. Due to additional systems for monitoring and controlling various functions in

cars, the power supply needed for their operation has steadily increased over the past years. In

order to prevent further demands on the battery’s capacity, manufacturers are searching for all

kinds of energy savings.


6.3. Aerospace:

Phase change technology originates from the NASA

(National Aeronautics and Space Administration’s)

research program of the 1970s.The aim of this

program was to provide astronauts and instruments

with better protection against extreme fluctuation of

temperature in space and since then research work

has been carried out by scientists. In Aerospace the

PCM is used in space suits and as a cover protection

for instruments against the severe temperature

changes of outer space.

Fig: 8, Space Suit with PCM

6.4. Medical Products:

PEG-treated fabric may be useful in medical and hygiene

applications where both liquid transport and antibacterial

properties are desirable, such as surgical gauze, nappies and

incontinence products [5]. Textile containing PCM can keep

the skin temperature within the comfort range, so they can

be used as a bandage. If a therapeutic blanket made of a

flexible PCM composite contains a micro PCM having a

transition temperature below normal skin temperature, it can

be used for cooling febrile patients in a careful and

controlled manner.

Fig: 9, Wound Care bandage

A careful selection of the phase change temperature makes it possible to avoid the danger of

overcooling the patient that is inherent with ice packs. Alternatively, a blanket with PCM can be

useful for gently and controllably reheating hypothermia patients.

6.5. Others:

There are numerous others application for textile containing Phase Change Material, Some of the

popular uses of PCM in textile are:

The PCM is used in tarpaulin cloth so that temperature of inside the tarpaulin can be maintained

as shown in Fig: 10.


Fig: 10 Tarpaulin fabrics with PCM

The PCM is also used in the Covering cloth for some sensitive items which require a maintained

and control temperature as shown in Fig: 11.

Fig: 11 Cover Fabric for sensitive items

The PCM can also be used in baterry warmers, agriculture, building material and geotextile[17].


7. LIMITATION

Besides the very important functions and application of Textile containing PCM, It posses few

limitation due to which the textile containing phase change material are not so popular, the

limitation of textile containing phase change materials are:

a) The limitation with phase change materials is that this phenomenon only occurs over a

specific temperature or temperature range for any specific PCM and When the Latent

heat of the PCM is fully absorbed or released the thermo regulating effect stops. b) The clothing structure should be carefully engineered otherwise it can release the

absorbed heat to the environment rather than to the wearer’s body.

c) If the amount of PCM presence is more to get higher heat storage, the fabric become very

stiff because of higher amount of PCM.

8. CONCLUSION

The intelligent textiles and smart clothing is emerging field in the world of textiles. The textile

industry has already focused for several years on enhancing the functional properties of textiles.

Phase Change Material, Chromic Colors, Shape memory materials, Auxetic material, HoIofiber,

Stomatex, Stimuli-responsive Hydrogels and membranes and Electronic textile are examples of

Smart textiles that are already commercially available in the market. The textiles containing

phase change materials (PCMs) are used in many products and applications from apparel,

underwear, socks, accessories and shoes to bedding, sleeping bags, car Seats, Wound care

bandages, space suit and protective garment. PCMs are even find their application in some

specialty items, such as antiballistic vests, automotive, medical or special industrial applications,

where warmth and energy plays a vital role.


9. REFERENCES

1) International Journal Of Clothing Science And Technology Vol.18 No.2,2006 pp. 108-128,

An Overview of smart technologies for clothing design and engineering By: S Lam Po Tang

and G.K.Stylios.

2) S.Mondal, Phase change materials for smart textiles-An overview, Appl. Them. Eng (2007),

doi:10.1016/j.applthermaleng.2007.08.009.

3) Information on http://www.outlast.com

4) Smart and Intelligent Textile and fibres By: H MEINANDER, Tampere University of

Technology, Finland

5) Smart Fibres, Fabrics and Clothing Edited by: Xiaoming Tao, Heat Storage and thermo-

regulated textile and clothing By: Xingxiang zhang, pp 34-57

6) Handbook of Technical Textile, Woodhead Publishing limited, Edited By: A.R Horrocks and

S.C Ananad

7) Phase Change Materials: Overview By: Aravine Prince, http://www.fibre2fashion.com

8) Information on http://en.wikipedia.org/wiki/Phase_change_material

9) PCM Thermal Solutions, http://www.pcm-solutions.com

10) Smart Textiles & Clothing, Synergies for innovation By: Miloslav Ohlidal-Brno University

of Technology & Pavel Malcik-textile Testing Institute, Brno

www.czelo.cz/dokums_raw/Ohlidal.pdf

11) http://www.textileworld.com/Articles/2004/March/Features/Phase_Change_Materials.html

12) Advances in Technolgy: Smart & Engineered Textile Jose A. Gonzalez, Protective Clothing

Research Group, Department of Human Ecology,University of Alberta

www.ualberta.ca/~jag3/smart_textiles/Page_5.html

13) Information on http://en.wikipedia.org/wiki/Micro-encapsulation

14) Journal of Technical textiles international, Berbara Pause of textile Testing, March 2002

International Newsletter.

15) Smart Textiles: The Innovative Road to the future by: Sungmee park and Sundaresan

Jayaraman, Textile & Fiber Engineering, Atlanta, USA

16) Technical Textiles, volume 44, February 2001.

17) Phase Change Materials (PCMs) and Applications, Space Hardware Design Final Project by:

Benn Mottinger, University of Colorado, Aerospace engineering

http://www.fibre2fashion.com/

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