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The material difference

August 9th, 2021 / By: / Feature

A U.S. Army Paratrooper, part of the 173rd Airborne Brigade, engages targets with an M240B machine gun during a live-fire exercise. Photo: U.S. Army/ Paolo Bovo.

New technologies in anti-ballistics are just beginning to emerge, offering opportunities in this protection market. 

by Seshadri Ramkumar, Ph.D.

As tensions and danger prevail in many parts of the world, ballistic protection technologies are an important and integral part of countermeasures to threats. This segment within the advanced textiles sector is a growing market due to prevailing social and political tensions, and its importance in saving lives. 

According to the 2020 annual report of BAE Systems plc., the U.S. is the single largest defense market, fueled primarily by government defense spending. A cursory look at reports by a few market and research analysis firms peg the annual growth rate of the antiballistic sector to be about 6-7 percent. While the U.S. leads in defense spending and innovation, countries such as China, India and Saudi Arabia are also investing heavily in countermeasures against threat scenarios. 

Limited commercialization

The industry has more recently dedicated efforts towards improving the design of soft and hard armors, but developments in the ballistics protection sector have been mostly incremental for a time, with major breakthroughs in raw material dating back to the invention of aramids in the late 1960s. Apart from a few commercially viable synthetics, disruptive fiber technologies have not occurred in the recent past. Three major fiber chemistries are generally used today: aramids, ultra-high molecular weight polyethylene and polyphehylenebenzobisoxazole (PBO). Although there have been developments in the research, commercial success has been limited beyond these three fibers. 

Given this situation, there is room right now for developing new ballistic protection products to enhance performance characteristics with improved design. Additional functional chemistries added via finishing, as well as hybrid composite structures, are possibilities. But any alterations must be accomplished without affecting the impact resistance of materials.

The basics

The antiballistic field can be classified broadly into personnel protection, vehicular protection and infrastructure protection. The materials used to develop the protection products and the design depend on the type and severity of the threats. Antiballistic structures such as vests, chest shields, helmets, lower and upper extremity coverings are countermeasures used in personnel protection. 

Antiballistics for personnel protection involving soldiers, law enforcement, first responders and civilians are governed by standards formulated by the U.S. National Institute of Justice (NIJ). NIJ standard-0101.06 sets the minimum requirements for protection against different threat levels (Type IIA to Type IV). This standard sets the performance capability of antiballistics for projectiles ranging from a 9 mm FMJ bullet to an armor-piercing bullet. To reach NIJ Level III (rifle ammunition and above), rigid plates of ceramic and/or relevant inorganic materials are needed. 

The improvement pathway

One of the failure modes of antiballistics is slippage between layers; however, the interlocking of fibers between layers will help prevent this. Design developments to reduce slippage have resulted in logistically improved soft armor shields. These improved structures make it possible to reduce the number of impact resistant layers, which reduces overall weight and cost. 

Needlepunching technology has been useful in enhancing the performance characteristics of armor shields by improving interlocking in the third dimension, giving enhanced “Z-directional” strength. North Carolina-based Tex Tech Industries Inc., in fact, developed and patented an enhanced antiballistic panel using the concept of Z-directional strength. The technology was recently acquired by DuPont. 

Research work carried out at Texas Tech University, Lubbock, Texas, focused on imparting cut and/or strike resistance to sharp objects, in addition to utilizing needlepunching to vertically interlock fibers to impart three-dimensional strength. The structure consisted of panels of woven antiballistic layers interlocked by staple fibers. Such structures tend to have less slippage resulting in improved impact resistance. As the bonding is by interlocking of fibers from needled webs, drapability and flexibility of the structure provides better fit and shape. 

On the horizon

Deemed a wonder material with two-dimensional lattice structure and high surface area, graphene is finding a range of applications in electronics, biomedical engineering and high-strength applications. Graphene-incorporated impact resistant structures have been researched, but their commercial viability must be thoroughly analyzed. 

Graphene’s high strength and Young’s modulus should help with the development of hybrid structures that can find applications in heavy duty and impact-resistance products. Additionally, as its theoretical surface area is higher, impact energy can be absorbed and dissipated, which is an important requirement for impact-resistant materials. 

Recently, biomimetic approaches are being examined to model the strength and other mechanical properties of spider silk. The protein fiber from spider dragline is showing promise as a high-strength material with tenacity that is comparable to that of alloys. By analyzing the structure of extended filaments, bioengineered filaments can be generated in laboratories. Imitating such natural materials using synthetic and sustainable materials are already leading to improved engineered products.

In addition to bioengineering approaches, emerging manufacturing disciplines like high-energy plasma physics, supercritical liquid extraction, and three-dimensional printing provide varied opportunities for new products. Atmospheric pressure plasma finishing methods could be considered to impart performance-enhancing attributes. High-impact resistant fibers are affected by humidity and temperature and hence functional finishing treatments can be helpful to counter negative effects by ambient influences. 

It is in the interest of the antiballistics market sector to continue to pursue disruptive technologies regarding raw materials, particularly high-performance fibers that are influenced to a lesser degree by outside environmental conditions. The industry can focus on design improvements, such as reducing shear slippage, and improving stitch and bond strength. From a commercial point of view, reduced weight and cost reductions will go a long way in supporting the acceptance of new high-performance products. 

Dr. Seshadri Ramkumar is a professor in the Nonwovens and Advanced Materials Laboratory, Texas Tech University, and a frequent contributor to Advanced Textiles Source.