Most of us are familiar with the liquid crystal display, which has become ubiquitious on watches and electrical devices. The liquid crystal bulletproof vest is among the less well known applications.
Liquid crystallinity is an intermediate state of matter, with neither the precisely ordered molecular arrangement characteristic of a solid, or the amorphous random state of a liquid. In some conditions a liquid crystal behaves like a liquid, in others like a solid. When a voltage is applied, the molecules become aligned in a particular orientation with a degree of structural order.
Once the crystals line up, they can be chemically linked to form long chains of molecules which can form the basis of high tensile fibres. To make a bulletproof vest, the fibres are woven into a material and then set in resin to be moulded into shape.
`The secret of the material’s strength lies in the chemical bond which is among the strongest known to exist,’ says Professor Harry Coles of the new Southampton Liquid Crystal Institute.
The institute will take a multidisciplinary approach to understanding the properties and behaviour of the materials and finding new uses for them.
Meanwhile, Hoechst, of Germany, has announced improved grades of the liquid crystal polymer Vectra, which it says will assist in further miniaturisation in electronics.
Vectra has the unusual property of increasing in strength with decreasing wall thickness, making it ideal for complex, thin walled components in the electronics industry. Applications include components exposed to high mechanical and thermal stress such as intricate connector systems, smart card readers and moulded interconnect devices.