The threat posed by global terrorism, at home and abroad, often means that police and army personnel, journalists reporting from war zones and civilian rescue workers have to wear body armour capable of stopping high velocity projectiles such as bullets and bomb shrapnel.

Integral body armour has evolved significantly since the 1960s when the ability of alumina ceramics to withstand bullet impacts was discovered. Modern armour is now much more sophisticated, using advanced materials such as Kevlar and glass fibres together with ceramic and carbon epoxy. The current armour can take multiple hits, provides good fire and smoke resistance and has low toxicity characteristics – vast improvement on that of the 1960s. However, modern armour generally relies on a ceramic layer to take almost all of the ballistic impact. The use of such materials compromises the weight and flexibility of armour in the field.

A research team based at the Science and Technology Facilities Council (STFC) Daresbury Laboratory, together with researchers from Tuskegee and Florida Atlantic universities in the USA, are evaluating new nanocomposite materials which can be woven into fabrics to provide greater flexibility as well as better ballistic protection. They have found that incorporating spherical nanoparticles of carbon nanotubes, silicon dioxide or titanium dioxide in a plastic or epoxy matrix offers improved ballistic resistance together with greatly improved flexibility.

Daresbury Laboratory's role has been to investigate ways to make the new materials as strong as possible. The manufacturing process used to make the new body armour can introduce impurities which limit the amount of nanoparticles that can be incorporated and so reduce its effectiveness.

Researcher Dr Vin Dhanak said, "We're using the synchrotron light source, or SRS, and the photoelectron spectrometer at the National Centre for Electron Spectroscopy and Surface Analysis, both based at Daresbury. These world-leading instruments let us analyse how the nanoparticles bond with the matrix materials in which they're embedded. This will help improve the manufacturing process to eliminate impurities and make the materials stronger."

Although still in development, these new materials are already catching the attention of security services and promise to have wide-ranging potential for protecting society, both at home and abroad.

The research is also being funded by the US National Science Foundation. 

Image explanation
Upper image: High speed streak camera images of a bullet impacting on a neat Polypropylene sandwich.
Lower image: High speed streak camera images of a bullet impacting on a nanophased polypropylene sandwich layer. Measurement of the bulge height as a function of time shows that the nanocomposite resists the impact better.