Lyotropic Liquid Crystalline Polymers for Extreme Temperature Structural Applications

This Small Business Innovation Research Phase I program will test a solution processing scheme for fabricating shaped structural components, such as sheets and tubes, from a class of rigid-chain lyotropic liquid crystalline polymers. This class of polymers includes rigid-rod polymers such as poly(p-phenylene benzobisthiazole) (PBZT) and extended-chain polymers such as poly(p-phenylene terephthalarnide) (PPTA). These polymers usually do not melt upon heating to their degradation temperature at approximately 500¿C. Therefore, normally, they are extruded and coagulated from their liquid crystalline solutions into high-strength, high-modulus fibers. In this Phase I research program, the rigid-chain lyotropic liquid crystalline polymers will be processed into monolithic, shaped structural components via a thermally reversible phase transformation of their concentrated solutions. The thermal formation of the structural components can be carried out by conventional extrusion and molding techniques used for thermoplastic and thermosetting polymers. The highly anisotropic liquid crystalline solutions allow the shaped structural components to be processed with significant molecular orientation, giving rise to self-reinforcing mechanical properties. These structural components are expected to have the essential thermal and mechanical properties for stringent applications at both cryogenic and elevated temperatures.