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Protecting against ballistic threats with nanofibre combat clothing

Materials World magazine
,
3 Sep 2020

A novel nanofibre material designed to protect against extreme heat and ballistic threats could offer soldiers a lighter suit of armour. Shardell Joseph reports.

A lightweight multi-functional material that provides the same impact protection but also 20 times the thermal insulation of existing armour is being developed by a Lieutenant Colonel in the United States Army Reserve, who is also a Professor at Harvard University, USA. 

Kit Parker says, ‘When I was in combat in Afghanistan, I saw…how heavy body armour could limit mobility. As soldiers on the battlefield, the three primary tasks are to move, shoot and communicate. If you limit one of those, you decrease survivability and you endanger mission success.’

Researchers from the University, in collaboration with the US Army Combat Capabilities Development Command Soldier Center (CCDC SC) and the United States Military Academy (West Point), believe they have overcome one of the ongoing limitations with protective armour whereby materials that are strong enough to protect against ballistic threats usually cannot protect against extreme temperatures and vice versa. This leads to equipment that comprises layers of different materials leading to bulky armour that limits the wearer’s mobility. 

The new material made up of para-aramid nanofibres and air between the fibres, using a Kevlar polymer and aerogels, could reinvent personal protective equipment such as gloves, jackets and ballistic resistant vests to safeguard soldiers, but also others working in extreme environments such as firefighters and astronauts.

‘Our idea was to use this Kevlar polymer to combine the woven, ordered structure of fibres with the porosity of aerogels to make long, continuous fibres with porous spacing in between,’ says Grant Gonzalez, Postdoctoral Fellow at the School of Engineering and Applied Sciences of Harvard University. ‘In this system, the long fibres could resist a mechanical impact while the pores would limit heat diffusion. ‘In our material, we combined the structure-function relationships of aerogels and impact resistant fibre to enable a multi-functional material with thermal and mechanical protection.’

This was achieved by controlling the polymer structure-function relationship using rheology and the team’s immersion Rotary Jet-Spinning nanofibre platform.
‘By understanding the rheology of the precursor material, we used the immersion Rotary Jet-Spinning platform to engineer the structure-function relationship of para-aramid fibres providing multi-functional protection,’ says Gonzalez. 

The material was compared to commercial Kevlar and Twaron products by using fragment simulating projectiles and thermal heat testing. The team believes the material and production method are scalable and close to commercialisation and are seeking non-academic funding to achieve this next phase in development.

‘Scientifically, the next steps are to improve the mechanical protective performance of the material by improving the polymer structure within the fibre itself,’ Parker explains. 

‘We’ve shown that you can develop highly protective textiles for people that work in harm’s way. Our challenge now is to evolve the scientific advances to innovative products for my brothers and sisters in arms.’