The collaboration of science in developing smarter textiles has consistently resulted in new technologies with improved efficiency and better functionality. While clothes are primarily meant to protect the wearer from various discomforts like sunlight, dust, wind, rain, snow, and temperature extremes, phase change materials (PCMs) have emerged as a valuable innovation in this regard. PCMs have the unique ability to absorb or release heat in significant quantities, making them suitable for various applications, including outerwear, sports gear, military uniforms, and bedding products.

The application of PCMs dates back to the late 1970s and early 1980s when NASA (National Aeronautics and Space Administration) utilized them for developing new materials capable of protecting equipment and delicate instruments from extreme temperature variations in space. This groundbreaking work led to the use of PCMs in creating spacesuits for astronauts. PCMs, such as paraffinic hydrocarbons, were employed to help astronauts maintain a steady body temperature in the harsh and fluctuating conditions of outer space.

The human body generates heat through muscle activity, which is released through the skin. A garment worn by an individual must be designed to facilitate heat evaporation when the body becomes overheated and conserve heat when the wearer is exposed to cold conditions to maintain a consistent body temperature. The normal body temperature of an individual is approximately 98.6 degrees Fahrenheit (37 degrees Celsius). Deviations from this temperature range can lead to fever or hypothermia. PCMs are engineered to maintain the wearer's body temperature close to the ideal average.

Phase-change materials undergo a transformation from solid to liquid when the temperature of the fabric they are encapsulated in exceeds a certain threshold. The significant heat released during this phase transition is absorbed and stored by the PCMs, effectively cooling the skin. Conversely, when the body temperature becomes excessively cold, the PCMs crystallize and release stored heat to keep the body warm. To prevent PCMs from leaking in their liquid state, they are encapsulated within plastic beads or other suitable materials.

Hence, phase change materials are substances capable of absorbing, releasing, and storing heat as they transition between different states. They absorb heat when transitioning to a liquid state and release heat when transitioning to a solid state. These unique substances have found applications in various fields, including clothing for mountaineers and skydivers. Unlike regular clothing with excessive layering that can burden wearers and drain their energy, PCMs with their auto-thermo-regulating properties reduce the load on the wearer and enhance efficiency.

The substances used to achieve such temperature maintenance are microcapsules made of paraffin, which is petroleum jelly; inorganic substances like salt hydrates; and hygroscopic materials are used in fabrics, fibers, and foams to create textile products. There are various ways in which they are incorporated into textile and apparel industry.


One is to apply microcapsules in a coating on foam or a textile material and another is to pad them on non-wovens. Using micro PCMs which have high affinity to fibres and pass through regular textile processes easily can be used for developing various textile products. These embedded micro phase change materials do not affect dyeing properties of textile even after diffusing into the fabric.


Micro-encapsulation of PCMs can be done in three different ways which depends on its final application in a product. One way is to infuse microcapsules with PCMs. Products manufactured using this method are generally close to skin. It can be used to coat fabrics to increase its functionality and as foam in products like shoes and helmets. These microcapsules can be fixed to fibres and can resist functioning for several washes. However, 30 percent microcapsules are lost after ten washes.


This technology when used to make garments and protective outerwear can manage moisture, prevents overheating and overcooling, absorbs extra heat, reduces perspiration, and adapts in response to the changing temperature in the environment. There are garments, shoe soles, and bedding products available in the market currently using PCMs in different forms. But the only constraint is that these materials have a temporary effect on the wearer and do not last longer to protect from temperature differences. Hence developing something more long-lasting and durable in order to overcome the existing limitations and perform better PCM textile products is the focus of many companies.


References:


1. Textileworld.com

2. Indiantextilejournal.com