Advancements in protective clothing applications include super-repellent coatings, nanotechnology and intelligent textiles.
By Dr. Eugene Wilusz
What are the most exciting or intriguing developments in the industry in advanced textiles?
The category of protective textiles is broad, and the applications demanding. Textiles are expected to provide protection against ballistic and blast events, flames, chemicals, biological agents, punctures, insects, rain, cold, ultraviolet (UV) radiation and extreme heat. Furthermore, defense must be provided without entirely compromising on comfort. Traditional textiles provide a degree of protection, but when more is needed, it can come from blends, laminates, additives, coatings, finishes, novel fibers and novel-textile structures.
Some of the most interesting developments involve super repellent coatings, electrospun nanofibers, fibers with novel cross sections, intelligent textiles, and biomimetic (inspired by nature) materials. Super repellent coatings can make fabrics superhydrophobic, where water rolls off as spherical droplets. These materials mimic the structure of lotus leaves and other materials found in nature. Recent work has demonstrated that it’s possible to construct fabrics that are oleophobic (oil repellent) and even superoleophobic.
One of the ways novel fibers are being developed is through the extrusion of fibers with unique cross-sectional shapes. The channels and added surface area in these fibers make them useful as wicking fibers and, in apparel for sun protection, incorporating UV-absorbing material. Other novel fibers are multicomponent, and the arrangements may include sheath/core, islands-in-the-sea and pie cross-sections.
Some of the most exciting or intriguing developments are in smart or intelligent textiles, including the integration of electronics. These include flexible antennas, sensors and soft keyboards. Fibers can be fabricated by a new method of drawing a cylinder of polymer containing electronics or photonics within its core.
Electrospun nanofibers can increase the efficiency of air filters, can be used in medical applications, such as wound dressings, masks and gowns, and serve as matrix layers for adsorbents and catalysts.
Who is driving new developments, the researchers or the market?
Both. The market expects increased performance from its materials, and research investment in areas like nanotechnology and intelligent materials continues to lead to new technologies.
What is the market demanding and how is your research team responding?
The market is demanding sustainable, high-performance textiles that are lightweight and reasonably priced. The military needs textiles that can provide a high level of protection against bullets, fragment projectiles, blasts and flames, which requires textiles made of high-modulus fibers and other performance materials.
Some of these materials, such as aramids (strong, heat-resistant synthetic fibers), are expensive, so cost-effective alternatives are needed. Chemical-protective clothing, including fully encapsulated suits, is heavy and uncomfortable and necessitates the development of lighter-weight ensembles. The proliferation of electronics has fueled the demand for integrating textiles and electronics. Market demands such as these have led to a steady investment in research and development toward multifunctional protective clothing applications.
Are new technologies finding their applications and markets? If so, where is the most robust growth occurring or likely to occur in the near future? If not, what’s holding up the implementation of new technologies?
New technologies are steadily finding their markets, including medical applications, military and civilian protective clothing, clothing for active sports and outdoor activities, tents and soft shelters. The markets for some of these applications are tempered by the added cost of the particular technology.
Fast-drying fabrics with high moisture-vapor transport have become very popular. In these fabrics, two technologies are combined in one fabric: a water-repellent treatment on the outside and a moisture-absorbent function inside. Hollow-core fibers are being utilized for their lightweight insulation properties. Similar to polar bear hair, they provide extraordinary insulation with minimal weight, and their increased surface area allows for fast wicking and evaporation of moisture. Microencapsulated phase-change materials have been incorporated into gloves, apparel, bedding and outdoor gear for cooling or warmth, depending on the choice of material.
Sensors such as physiological status monitors have been developed and integrated into the clothing systems for firefighters and can be monitored via wireless communication, and they’ve been used in sports clothing. Flexible solar panels have been integrated into backpacks and other items to generate power for electronic devices.
What new products and/or processes are being developed now that will have the most profound impact on the way in which end product manufacturers do business tomorrow?
The manufacture of electrospun nanofibers on a commercial scale is expanding and evolving as demand increases. These fibers can also be produced by splitting of bicomponent fibers and by nozzle-free centrifugal spinning. Reactive extrusion has the potential to produce a variety of multifunctional products. Coatings of metal oxides by atomic layer deposition have been used to modify the properties of fabrics, such as their surface energy.
The drawing of fibers from polymer cylinders containing electronics and photonics within their cores has produced fibers that are being used in military and medical applications. Among them is one that serves as a diode. The potential exists for more materials to be incorporated within the cores of fibers for other applications.
Processes to produce electronic textiles continue to evolve but challenges remain, some related to power and controls, others associated with mobile-device integration.