In-Situ Composite Processes from PEI/TLCP Blends

Abstract

Blends of isotropic polymers and liquid crystalline polymers have been studied for their potentials to generate in-situ composites yielding high strength/modulus characteristics^1,2. In this composite, the thermotropic liquid crystalline polymer (TLCP) reinforcing agent comes out as a low viscous melt during the compounding process, and crystallizes upon cooling to form needle-like reinforced structures in the final fabrication step. This in-situ composite process is advantageous since melt processability and mechanical properties can be simultaneously improved. Also in in-situ composite, the geometry of reinforcement can be easily controlled, through which mechanical properties are abruptly increased. These are great advantages over conventional composite in which geometry of reinforcement is fixed prior to processing and the aspect ratio of reinforcement is reduced during conventional processing such as extrusion. Whereas in the in-situ composite process, reinforcement is deformable so that the aspect ratio of reinforcement can be increased by the extensional flow field^3,4: the aspect ratio of reinforcement as well as reinforcement volume is crucial factor for improving mechanical properties of composites⁵. Also this process can be applicable to blow molding⁶ and film processing⁷, which never be achieved in conventional composite processes.