US navy develops transparent TPE armour

Washington - The US Naval Research Laboratory is actively seeking licensees to manufacture its patented transparent thermoplastic elastomer armour.

The new, lightweight armour reduces the weight inherent in most bullet-resistant glass while maintaining superior ballistic properties, according to the NRL.

Furthermore, because thermoplastic elastomers are converted by physical means into solids rather than by chemical processes, the new transparent armour can be repaired in the field when damaged, the NRL said.

"Heating the material above the softening point, around 100 degrees Celsius, melts the small crystallites, enabling the fracture surfaces to melt together and reform via diffusion," said Mike Roland, senior scientist for Soft Matter Physics at the NRL.

A hot plate, similar to an iron, can be used to repair the smooth, flat surface of the armour with negligible effect on the material's bullet-resistant properties, Roland said.

Previously, NRL scientists have tested layers of polyurea and polyisobutylene to enhance the ballistic performance of armour and helmets, the laboratory said.

By using thermoplastics in lieu of polyurea and polyisobutylene, it said, NRL scientists can replicate their ballistic properties while achieving transparency, lighter weight and repairability.

"Because of the dissipative properties of the elastomer, the damage due to a projectile strike is limited to the impact locus," Roland said. "This means that the effect on visibility is almost inconsequential, and multi-hit protection is achieved."

Commercial sources supplied the thermoplastic elastomers for project, an NRL spokesman said. He declined to name the suppliers.