This page was printed from https://advancedtextilessource.com

Complete comfort

January 9th, 2019 / By: / Feature

Paratroopers jump with the 517th Airlift Squadron during airborne training over Malemute drop zone, Joint Base Elmendorf-Richardson, Alaska, Jan. 9, 2018. The Soldiers are trained to execute airborne maneuvers in extreme cold weather/high altitude environments in support of combat, training and disaster relief operations. Photo: U.S. Air Force by Alejandro Pentildea.
A systems approach is needed to meet all the requirements of high-performance garments.

Comfort for the human body needs to be comprehensive. This complicates the technologies that are available to reach the ultimate goal of providing physiological, environmental and psychological comfort. A definition that fits technologically well to clothing is a “feeling of relief.” In light of this definition, the fiber and textile industry will need to plan carefully, given expectations, in developing the next-generation of comfort clothing structures.

Fibrous structures are necessary to provide protection from external natural and/or manmade environmental conditions, while also focusing on physiological suitability, sensory perception and performance requirements. In order to achieve this, a “systems-of-systems” approach is required.

The defense concept

Among different aspects of comfort, thermal, sensory (feel) and bulk (weight) are closely related. These factors are mutually interconnected and hence need to be balanced. This approach was adopted years ago by the U.S. Dept. of Defense, resulting in the Integrated Protective Fabric System, with the goal of reducing the load for the warfighter, while providing maximum protection.

This was achieved using a “systems-of-systems,” approach, treating each required protection characteristic as a separate system, while the fabric structure will be a single comprehensive system. In the case of chemical and biological protective fabric, this could be achieved using technologies that can combat chemical and biological threats individually, while the integrated suit will have the capability to counter both chemical and biological threats.

Such an approach is needed to develop comfort clothing. While this may look complicated, multidisciplinary collaborations can lead to developing integrated comfort systems. Fiber science, manufacturing systems engineering, electrical and electronics engineering all have a role to play in its development.

The ingredients needed

Three main ingredients need to be considered in the development of thermal or any other comfort-providing suits: fibers, fabric structure and external gadgets. With the advent of wearable technologies, use of microchips and sensors can be effectively integrated to develop lightweight, active comfort clothing.

In terms of fibers for enhanced comfort, developments have been incremental. Chemistry advances have enabled phase change materials that respond and adapt to external ambience and environmental conditions to provide balanced comfort.

Major developments have occurred in finishing treatments that can alter the surface characteristics to develop improved clothing. A well-established technology is imparting variable surface properties on each side of the fabric making one side to be hydrophilic and the other side hydrophobic. This approach is useful for thermal comfort suits, as the microclimate between the fabric and the skin is an important factor that alters the thermal balance, and hence the protection.

Atmospheric plasma finishing technology is commercially viable and such burgeoning processes can be tried to develop sustainable manufacturing methods for developing next generation comfort fibrous structures.

Apart from fibers, fabric structures play an important role. Thermal comfort depends on the transfer of moisture vapor and trapping of air and gas molecules, which necessitates bulky, but lightweight structures. Typically, nonwoven, high-loft structures are used as lining materials. Improved fibers, such as hollow fibers, sheath- and core-structured fibers, can be tried in nonwoven structures, which again will be incremental in development.

New developments
Excessive heat and humidity can put first responders at risk of heat-related illness, stress and injuries. PhaseCore cooling vests from First Line Technology are designed to mitigate these risks. Photo: First Line Technology.

Systems-of-systems approaches are being used today in the advanced textiles industry in developing next-generation suits. For example, Chantilly, Va.-based First Line Technology LLC has been developing heat stress-reducing clothing for warfighters and firefighters. Its PhaseCore technology involves a cooling vest and follow-up immerse cooling equipment to provide enhanced heat stress-reduction capability. This systems approach utilizes phase-change material in the cooling vest, which reduces the weight for the user. Unlike ice packs that may lead to vasoconstriction, the phase-change chemistry does not overcool the wearer.

“It is essential that we focus on preventing heat stress rather than treating heat stress after it occurs. Going into 2019, and with the heat just a couple of months away, we must revisit how we manage and prevent heat stress—from the football field to the battlefield. Cooling systems, such as the PhaseCore Cooling Vests and the Immersion Cooling Equipment, are available that allow professionals to not just put in policies and procedures to prevent heat stress, but to also equip themselves with the tools to put those policies and procedures in effect,” says Amit Kapoor, the company’s president and CEO.

A key point, he adds, is that the advanced textile sector is heavily dependent on investments in research and must keep on inventing to improve the product.

Wearables are slowly entering slowly the advanced textiles sector. Electrically activated fabric structures are on the horizon, which could influence comfort technologies. These advancements are occurring rapidly in the biomedical sector, such as for wound healing.

Recently, in an article published in American Chemical Society’s ACS Nano, scientists from the University of Wisconsin-Madison and researchers from Chinese institutes in Chengdu and Wuhan have shown how they were successful in developing efficient wound-healing patches.

They have harnessed an electric field created in-situ, due to the mechanical motion of the patch on the skin. This has helped with rapid wound closures by creating a balanced thermal ambience between the patch and the skin. This development illustrates the need for multidisciplinary collaborations in developing new thermal balance systems.

Going forward, the industrial fabric sector needs to follow the “systems of systems,” approach in designing next generation comfort clothing and should embrace multiple fields, including science, technology and engineering.

 

Seshadri Ramkumar, Ph.D., is the director of the Nonwovens and Advanced Materials Laboratory, Texas Tech University, and a frequent contributor to Advanced Textiles Source.