Researchers at RMIT University, Australia, have been developing materials containing a blend of wool and Kevlar® for ballistic applications such as bullet-resistant vests that are expected to cost less, be lighter-weight and have greater efficacy than traditional Kevlar vests.

RMIT School of Fashion and Textiles professors Dr. Rajiv Padhye and Dr. Lyndon Arnold report that a vest made with the blended material has greater efficacy when wet than a 100-percent Kevlar vest, which loses approximately 20 percent of its efficacy when wet and therefore must be treated with an expensive waterproofing agent. They also found that only 28 to 30 layers of the blended material are needed to provide the level of protection offered by 36 layers of 100-percent Kevlar material.

"And because wool fibres expand naturally in water by up to 16 percent, the wool-Kevlar blend actually becomes more effective in wet conditions," Padhye said. "The result is a cheaper bullet-resistant vest that works even better when it's wet."

Arnold noted that when wool is added to Kevlar, the friction is increased and the yarns hold together more closely, so that fewer layers are needed to dissipate a bullet's kinetic energy. "With Kevlar averaging around $70 per kilogram, compared to about $12 for wool, reducing the amount [of Kevlar] required to make a vest is a real incentive for manufacturers," he added.

A blend comprising 20- to 25-percent wool and 75- to 80-percent Kevlar provides the optimal performance, according to research findings.

The project has received funding from Australian Wool Innovation and material support, including ballistics testing, from Australian Defence Apparel. Padhye and Arnold now are collaborating with ballistics vest manufacturers in hopes of commercializing the wool/Kevlar material.

April 5, 2011