Phase Change Materials (PCM) in textile
In the textile sector is the protection against extreme environmental conditions, will be crucial. Clothing that protects us from water, extreme cold, intense heat, flames high tension, the balls driven, toxic chemicals, nuclear radiation, biological toxins, etc. are just some of the illustrations.

These garments, as a sportsman and that the defense, firefighters wearing flak jackets and other professional wear and use. TextileThe products can be made more comfortable if the properties of textile materials that can adapt to all types of environments.

At present, for compliance with the requirements of phase change materials (PCM) is a smart material. It absorbs, stores and the heat of the discharge in accordance with the various changes in temperature and is applied more often to make intelligent materials.

Phase Change Materials
stat "Phase Change" is the process of transition from one to another, such asfrom solid to liquid. Any material, experiences, the process of phase change is known as phase change materials (PCM).

These materials absorb collect, discharge or heat in the range between solid and liquid. They waste heat, as it turned into a solid state and absorb as they walk in a liquid state. There shall be established three basic phases of matter, liquid and gas, but other phases such as crystalline, colloid, glassy, amorphous, and plasma are consideredpresent.

This basic phenomenon of science was originally developed and used to build the spacesuits of astronauts for the space program of the United States. This suits the astronauts kept warm in the black void of space and cool in the transition of the solar system. Phase change materials are compounds that solidifies the merger and certain temperatures and are therefore able to receive or download large amounts of energy.

The storage of heat by the phase of a material at a constantThe temperature is called latent heat, "that is classified, from a liquid to solid. When a PCM is undergoing a change, a huge amount of energy is needed. The most important feature is that the latent heat is the transfer of large amounts of energy as a transfer of sensible heat.

Quiet a few of these stages of change PCM in a temperature range above and below the temperature of human skin. This property of certain substances used in the manufactureProtective measures during the year and clothing for the environment suddenly changes. Fiber, fabric and foam with built-in PCM store body heat and then release back to the body because the body requires. Because the method is the dynamic phase change, the materials are continually passing from solid to liquid and back to the physical movement of the body and the outside temperature. In addition, phase change materials are used, but never get used.

Phase change materials areWaxes, that the distinctive character of water and energy they emit heat without changing temperature. These waxes are eicosane, octadecane nonadecane, hexadecane and heptadecane. They all have different points of freezing and melting and mixing the microcapsules into a thermal energy storage and release of thermal energy and maintain their temperature range of 30-34 ° C, which is very convenient for the body.

The amount of heat absorbed by a PCM in an era of changethe amount of heat that can be included in a common heating process, using water as a PCM are analyzed. The melting of the ice where the water for the absorption of latent heat of almost 335 J / g. When the water boiled in a sensible heat of only 4 J / g is absorbed, while the temperature rises one degree. Therefore, absorption of latent heat in phase change of ice into water is about 100 times greater absorption of heat sensitive.

Assimilate as PCM in textiles?
L 'Accounts can be woven with encapsulated PCM, non-woven or knitted fabric are combined.

The capsules may be the fabric in various ways, added to:

Microcapsules: Microcapsules in different shapes – round, square, triangular, the fibers within the polymeric phase. The PCM microcapsules are permanently fixed in the structure of the fiber during the spinning process to wet the fiber production. Microencapsulation provides a softer hand, more stretching, more breathability and air permeabilitysubstances.

Matrix coating during processing, the PCM microcapsules in a coating material such as acrylic, polyurethane, etc., and are applied to the embedded tissue. There are many coating methods are available as a knife roll, knife-over-air, pad-dry-cure, gravure, dip coating and transfer.

Foam dispersion: microcapsules are in a mix of water-blown polyurethane foams and these are mixed in a fabric in a lamination process, which applies waterremoved from the system through the drying process.

Body and groups
The thermal insulation of clothing required, which depends largely on physical activity and environmental conditions such as temperature and relative humidity. The amount of heat produced by humans is highly dependent on physical activity and can vary from 100W while resting to over 1000W during maximum physical performance.

Especially during the cold season (0 ° C), proposedIsolation is defined to ensure that the body is sufficiently warm while sleeping. In extreme activities and is often the case with the winter sports, the body temperature increases as the heat increases. For this increase within a specified period, the body sweats to withdraw energy from the body by evaporative cooling. If the thermal insulation of clothing during exercise is reduced, some of the heat generated can be removed by convection, so that theBody should not need to sweat so much.

The quality of insulation in a garment in terms of heat and cold will be managed in large part the thickness and density of component materials. thickness of high and low density make better insulation. It is, in many cases, the thermal insulation air pockets between the layers of clothing is offered observed.

But the outside temperature also affects the effectiveness of the insulation. The most extreme temperature, whether it be a highor very low, less effective the insulation. Thus, a habit developed because of its ability to heat or cold is chosen by the wearer awaiting the climate where you wear the protective clothing.

Although, a dress made from a dense tissue will have more weight, and freedom of movement of the support is limited. Clearly then, a dress designed by an intelligent substance whose nature can change the outside temperature, supplyexcellent protection. However, such a garment to be comfortable for the user.

Effect of temperature change of PCM
PCM microcapsules can be small, temporary heating and cooling effects of the layers of clothing when the temperature of the PCM layers reaches the transition temperature. The effect of phase change materials on the thermal comfort of protective clothing systems is probably the highest, when the carriers are often caused by temperature transients (ie, to andforth between warm and cold) or touch from time to time, or handling cold objects. The temperature of the PCM layers of clothing often have to vary the damping effect to continue.

The most obvious example is the change in water vapor and ice at 0 ° to 100 °. There are many products that phase change near the body temperature and are being incorporated into fibers and sheets or coating substrates, the phase is equal to or close to body temperature, and then changeHold the balance of body temperature and keeps it more stable. E 'for athletes in extreme conditions and the people involved in extreme sports such as mountaineering and trekking. E 'used in industrial applications where the people are very mobile, can be used, for example, to and from the cool room.

The effects on tissue

If the PCM condensate is heated to the melting point, it absorbs heat as it moves from a solid to liquid. This phase changeproduced a short-term slowdown in the layers of clothing. The thermal energy can come from the body or from a hot environment. Once the PCM is completely melted, the heat-retaining stops

If the head of PCM in a cold environment where the temperature below the freezing point of the PCM and the fuel temperature is taken below the transition temperature, the micro-encapsulated PCM liquid back to solid state, generating heat and a heating current. L 'The developers say that this heat is a damping effect, makes the clothes, to minimize changes in skin temperature and continue with the thermal comfort of the wearer.

The layer of clothing (s) from PCM has to change with the temperature range before the transition phase and PCM is to produce or absorb heat. As a result, change the carrier of a burden to the temperature of some material PCM. PCM is a transient phenomenon. They have no effect in constant thermalEnvironment.

Active microclimate cooling systems require batteries, pumps, give fluids circulating and the latest control devices satisfactorily cool the body, but their performance can be adjusted and made to continue for a long time. They are expensive and complicated. This change in passive micro-climate of latent stage by using equipment, both gas and liquid by evaporation of water (Hydroweave), a massive shift of the liquid phase of a gel of cornstarch, water or wax,contained in plastic bubbles.

The dress of liquid evaporation is more economical, but give only found minimal or short-term slowdown in the environment of high humidity in protective clothing. You also need to re-wet clothes, renew for reuse. The water / starch gel-type head cooling is currently preferred by the military, and can offer a satisfactory and long-term cooling near 32 ° F (0 degrees Celsius) but can also feel very cold on the skin and needs a very coldFreezer (5 ° F) completely rejuvenate or to recharge the garment. If it is fully charged, its something gel-PCM rigidly clamped, and the head is limited breathability.

The other leaders paraffin PCM are relatively cheaper, but their plastic bubbles to split so dripping its contents or to a serious fire hazard. Moreover, their paraffin-PCM melts above 65 ° F (18 ° C) and must be at temperatures below 50 ° F (10 ° C) in the refrigerator or chargedRefrigerator. Its cooling rate also decreases the time in which paraffin blocks are thermal insulation and heat control that can be transferred to or from them. The plastic used to contain the bubbles PCM also severely restrict the airflow and breathability, resulting in their comfort.

Used by PCM

Automotive textiles

The scientific theory of temperature control of the PCM has been used in various ways for the production of fabrics. In the summer ofcan increase the temperature inside the car of a motor vehicle clear if the car is parked outside. To adjust the temperature while driving, many cars are equipped with air conditioning, but a required cooling capacity needs a lot of energy. Hence the application of the technology of phase change materials in various applications for domestic automotive sector could provide energy savings, as well as an increase in the thermal comfort of the carInterior.

Dressed Active

Active wear is expected that a thermal equilibrium between the heat produced by the body during the execution of an activity and the heat released into the environment. active wear clothing normally do not meet these needs are. The heat from the body in the hard work is often not released in the required amount, resulting in a situation of stress. On the other hand, during periods of rest between activities,less heat is produced by the body. Considering the same amount of heat is expected to hypothermia. Application Support PCM in the clothes in the regulation of heat shock, heat stress, and then support and help to improve their work efficiency under high load.

Lifestyle clothing – stylish fleece jacket, men and women, hats, gloves and rainwear.

Outdoor sports – Jackets Clothing and trim jacket, boots, golf shoes, sports shoes, socks and skiSnowboard gloves.

Real-world applications in space suits and gloves for phase change materials are used in consumer products.

Aerospace Textile

phase change materials in consumer products have been used primarily for protection for use in space suits and gloves to protect astronauts from temperature fluctuations during production of the highest made spacewalks in space.

The usefulness of the isolation resulting from the micro-encapsulated phase change materials (PCM accounts)created primarily to heat the gloved hands of astronauts walk in space. The materials have been accepted as an ideal glove, while the extreme temperatures of space to support the environment.

Medical Textiles

Fabrics with phase change materials (PCM) may soon find use in the medical field. To increase the physical comfort thermo-surgical clothing such as dresses, hats and gloves. In bed as mattress covers, tents and blankets. A product that helps theCosts of patient stay quite warm in operation, isolating tailored to your body temperature.

Other uses of PCM

Phase change materials are used in the textile sector, at the time, the ends are: gloves, boots, hats, etc. A number of PCM can be selected for different applications. For example, the skin near the body temperature of about 33 ° C (91 ° F). Even if the skin temperature of about 30 meters -31 ° C. PCM materials can be usefulup to 16 ° C, sufficient to ensure the comfort of someone with a ski boot in the snow. Are increasingly applied in the protection of the central body, and in areas of displacement blankets, sleeping bags, mattresses and mattress pads.

Types of PCM

Phase Change Materials standards are usually a polymer / carrier with thermally conductive filler which is filled by a solid changes to a highly viscous liquid (or semi-solid) state at a certain critical temperature. These materials are consistent withwell to irregular surfaces and their wetting properties such as thermal compound, which significantly reduced the contact resistance to the distinctive character of interfaces. Because of this composite structure, phase change materials are death-than-life forces during mechanical shock and vibration, providing or component from mechanical damage. Moreover, in semi-solid state of these materials at high temperatures given issues related to "pump" under thermo-mechanicalFlexion.

In one passage, the specific heats the material to a much softer close to liquid as the physical condition in which the thermally conductive material expands in volume. This growth makes the material more thermally conductive volume to replace the river and in the microscopic air gaps between the heat sink and electronic components. With the air filled gaps between the thermal surfaces, reducing a high degree of wetting of the surfaces of the twoContact resistance.

There are generally two types of material phase transitions:

. Thermally conductive and electrically insulating.
. Electrically conductive.

The main difference between the thermally and electrically conductive material, the film or the carrier, the polymer phase change is covered. With the insulation, electric insulation properties of the lowest voltage are achieved.

The analysis of the thermal barrier function of the phaseChange Materials in Textiles

Manufacturers can now enter the PCM thermal comfort in a wide range of clothing. But knowing them to be seen how much and what type of PCM, as well as changes in the textiles sector, a piece of clothing served its purpose to do, is essential to quantify the effect of active thermal insulation material provided by this level.

The total heat capacity of PCM in many products depends on its specific heat capacity and its quantity. The required amount canexpected operating conditions, the desired thermal effect and its duration and the specific heat of PCM. The structure of the transport system and finished products will also affect the thermal performance of PCM, which are measured in terms of selection of material needs and product design.

Perspective PCM

The biggest challenge for the development of textile structural PCM is the method of their use. Encapsulation of PCM in a polymer shellan obvious choice, but adds weight to drive the active material. Efficient encapsulation, the core-to-wall ratio, encapsulation, stability, set during the application and installation of capsules on fabric structure are some of the technological aspects will be measured.
Although PCM is funded with different types of clothing and related products, are the applications where they can really work is limited. As test methods developed for more than PCM, the PCM material producersand clothing must continue to carefully target the markets where their products do not work well.

Conclusion

Since a large amount has been invested in research and development in these areas in developed areas is to assume that very soon all the clothes of the season will be produced in mass production. For example, in Britain, scientists is an acrylic fiber with the integration of micro-capsules of phase change materials have been designed. These fibers are used throughout the year for the production of lightweightCeilings.

many garment companies in the U.S. are now producing many of such garments, like thermal underwear and socks knitted inner layer, shirt or sweater and a jacket with an insulating layer PCM interlining to the outer layer, as well as helmets and other headgear and gloves . such clothing can keep temperatures mild and pleasant, in the extreme case, both the weather. There is no doubt that the textiles PCM integrate their way into various applications available in the near future.