Bullet-resistant Wool Heads Toward Commercialization

Researchers at RMIT University, Australia, have developed ballistic materials containing a
wool/Kevlar® blend for applications such as bullet-resistant vests that are expected to cost less,
weigh less 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 some 20 percent of its efficacy when wet and therefore must be treated with an
expensive waterproofing agent. They also found that 28 to 30 layers of the blended material provide
the same 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 fewer layers suffice 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 support from Australian Wool Innovation and Australian Defence
Apparel. Padhye and Arnold are working with ballistics vest makers in hopes of commercializing the
wool/Kevlar material.

May/June 2011