Bullet-Resistant Wool Softens the Blow
Researchers at RMIT University in Melbourne, Australia are developing wool-Kevlar blends for ballistic materials, in a bid to create lighter, cheaper, and more effective bullet-resistant vests that work in both dry and wet conditions.
Dr Rajiv Padhye and Dr Lyndon Arnold, from RMIT's School of Fashion and Textiles, have found a vest made of wool-Kevlar blend works better in the wet and needs fewer layers compared with existing ballistic vests, potentially reducing manufacturing costs.
Dr Padhye said Kevlar was a strong but expensive fabric that lost about 20% of its effectiveness when wet, requiring a costly treatment to waterproof the material.
"While a typical Kevlar vest is made of about 36 layers, our wool-Kevlar blend only needs 28 to 30 layers to achieve the same bullet-resistant effect," Dr Padhye said.
"And because wool fibres expand naturally in water by up to 16%, the wool-Kevlar blend actually becomes more effective in wet conditions.
"The result is a cheaper, bullet-resistant vest that works even better when it's wet."
Woven bullet-resistant vests are designed to prevent blunt trauma injury by slowing bullets within the layers of fabric to dissipate their energy.
Dr Arnold said tight weaves were needed to ensure the bullets dissipate their kinetic energy by breaking the fibres, rather than sliding past them.
"By adding wool to Kevlar, we increase the friction and hold the yarns more closely together, enabling us to reduce the number of layers required," he said.
"With Kevlar averaging about $70 per kilogram, compared to about $12 for wool, reducing the amount required to make a vest is a real incentive for manufacturers."
The research found the optimum blend for the wool-Kevlar ballistic material was 20-25% wool and 80-75% Kevlar.
Funded by Australian Wool Innovations, the project has received material support including ballistics testing from Melbourne-based Australian Defence Apparel. The researchers are currently working with ballistics vest manufacturers towards the commercialization of the product.