Developments in auxetic materials that could revolutionize blast mitigation textiles may find wider market applications.
By David O’Keefe
Part II of a series by speakers at the Advanced Textiles Conference 2010. Part I covers developments in advanced textiles, Part III addresses electrical conductive nanocoatings and Part IV covers the potential of nanomaterials in creative applications. Part V examines the push for sustainability.
What are the newest, most exciting or intriguing developments in advanced textiles?
Every now and then, a technology comes along that completely changes the approach to solving a particular problem or addressing a specific market need and moving beyond the inventor’s original intent. This may be the case with Advanced Fabric Technologies’ (AFT) Xtegra™, which could have a transformational impact on a number of industries, from construction to medicine.
Initially developed as a blast-mitigation fabric, Xtegra automatically adjusts its strength and permeability as external force is applied because of its “power threads”—elastic yarn wrapped in non-elastic fiber. When stretched, the yarn bulges between wraps, creating an auxetic helix structure. Weaving bundles of these power cords together creates a fabric that thickens and stretches when subjected to external forces, such as the blast from an explosion.
Security applications run the gamut from spall liners that stop shrapnel from killing or injuring soldiers in military vehicles hit by explosives, to improved ballistic protection clothing (bullet-proof vests and helmets). Wider applications beyond the security realm may include better seat belts and surgical sutures, improved hurricane and blast protection for petrochemical plants and offshore platforms, remotely adjustable tourniquets and bandages, and self-adjusting filtration systems.
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?
Xtegra employs revolutionary technology, and since it is in its early developmental stages and is designed to save lives, much testing is required before the fabric can begin to gain widespread acceptance. Blast and ballistic testing must be performed in special facilities, and explosives are closely regulated. Introducing it into the military arena requires jumping many bureaucratic hurdles as well. For example, the U.K.’s Ministry of Defense has classified some of the tests it has performed on Xtegra as secret, and even AFT can’t obtain detailed results of those trials. Also, the military generally tests products, not components such as fabrics, no matter how promising they are.
Collaboration is imperative for progress in all industries. AFT continues to work with companies that already have government contracts to introduce Xtegra into existing product lines, such as tents, seating systems, spall liners and body armor. As testing is completed in the security area, results are being shared with other industries in an effort to get them thinking about new applications.
Who is driving new developments, the researchers or the market?
In the case of Xtegra, both researchers and the market were driving forces. The global war on terror and the existence of various explosive devices and suicide bombers have sparked a need for lighter, better and cheaper armor protection. Although Xtegra was not designed to stop bullets, testing is underway on employing the fabric behind ceramic strike plates in place of, or in conjunction with, current materials such as Kevlar®, to lighten and otherwise improve personal armor.
Federal buildings, embassies, and military and police facilities are seeking better protection from bomb blasts as well. Xtegra was originally envisioned as a material for blast curtains to prevent flying glass and other explosion debris from injuring people inside structures; however, it soon became apparent that the material had other applications.
What is the market demanding, and how is your company responding?
The blast-curtain market currently is dominated by sheer fabrics. These materials stop glass kinetically by moving with the fragments much as a sheet on a clothesline moves when struck by a baseball. But the sheer materials do not mitigate a blast’s shock wave, whereas Xtegra has been shown in tests to dissipate as much as 25 percent of the blast wave energy. However, while current-generation Xtegra does allow some light to pass through, it is generally opaque. This works fine for heavy drapery applications, but the market is demanding a wider range of fabric options—sheer blast curtains, in particular. Research is underway to develop more translucent versions of Xtegra that still mitigate the shock wave.
For some armor applications, more rigid materials are often required. Testing of multiple layers of Xtegra bonded together with resins and epoxy is being conducted by AFT, the U.K. Ministry of Defense and by various manufacturers of protection products.
Xtegra is also being marketed to other industries for testing and product development. Potential medical uses include improved sutures, medication delivery systems, and remotely adjustable bandages. AFT is also looking into incorporating other materials into the weave of future Xtegra generations, including fiber optics, telemetry and metal screening. Imagine, for example, a military battle uniform that is bullet- and blast-resistant, changes color and camouflage patterns using fiber optics, tracks a soldier’s location and vital signs, delivers medication, emits a signal to prevent friendly-fire accidents, and can be tightened remotely as a bandage or tourniquet.
What new products or processes are being developed now that will have the most profound impact on the way in which end-product manufacturers do business tomorrow?
Future-generation Xtegra may involve micro-weaving for medical applications, or interweaving other components, as discussed. Because the concept upon which Xtegra is based is completely novel, applications that haven’t even been considered will likely be developed as products cross-pollinate among various industries.
Applications currently envisioned include seat belts, bandages, dental floss, surgical sutures, self-adjusting filters, torque-measuring systems, oil-spill recovery systems, hurricane- and blast-resistant sheetrock, medicine-delivery systems, breathable, anti-fungal and anti-microbial clothing, tents and shelters, and construction materials. As new Xtegra-derivative products begin to appear in the marketplace, AFT expects the range of applications to expand exponentially.