US Naval Research Laboratory (NRL) researchers have created a transparent thermoplastic elastomer armour, which is designed to help reduce weight.

Thermoplastic elastomers are soft, rubbery polymers that can be converted into a solid by using physical means instead of a chemical process.

The solidification is also reversible, and facilitates the repair of damaged armour surfaces ‘on-the-fly’ in the field.

NRL Soft Matter Physics senior scientist Dr Mike Roland said: “Heating the material above the softening point of around 100 degrees Celsius melts the small crystallites, enabling the fracture surfaces to meld together and reform via diffusion.

“This can be accomplished with a hot plate, akin to an iron, that moulds the newly forming surface into a smooth, flat sheet with negligible effect on integrity.”

NRL scientists have so far tested polymeric materials for use as a coating to obtain enhanced impact resistance of hard substrates.

The ballistic performance of armour and helmets can be improved with the application of polyurea and polyisobutylene layers, along with attaining enhanced ballistic effectiveness and mitigation of blast waves.

"Heating the material above the softening point of around 100 degrees Celsius melts the small crystallites, enabling the fracture surfaces to meld together and reform via diffusion."

NRL scientists have also used thermoplastic elastomers to recreate superior ballistic properties of polyurea and polyisobutylene coatings. Advantages include that the material is lighter than conventional bullet-resistant glass, as well as being transparent and easily repairable.

Roland added: “Because of the dissipative properties of the elastomer, the damage due to a projectile strike is limited to the impact locus.

“This means that the effect on visibility is almost inconsequential, and multi-hit protection is achieved.

The transparent thermoplastic elastomer armour technology of NRL is covered by US Patent #9,285,191; 'Polymer Coatings for Enhanced and Field-Repairable Transparent Armour.'

Image: NRL-developed transparent polymer armour comprises alternating layers of elastomeric polymer and a harder material substrate. Photo: courtesy of US Naval Research Laboratory.