Processing of In Situ Composites and Microcomposites Based on Thermotropic Liquid Crystalline Polymers and Thermoplastics

摘要

Tbe purpose of this work was to determine how to obtain the maximum reinforcement from thermotropic liquid crystalline polymers (TLCPs) when blended with other thermoplastics to produce light weight, wholly thermoplastic composites. Towards this goal, the research first focused on the spinning of thermoplastic/TLCP composite strands and fibers using a novel dual extrusion technique developed in our laboratory. It was found that the high degree of extensional deformation achieved in spinning and the ability to utilize the supercooling behavior of the TLCPs allowed a wide variety of thermoplastic/TLCP composite systems to be produced with properties matching or exceeding theoretical expectations. The strands and fibers generated in the spinning step were then subjected to a variety of post-processing techniques. This was done to expand the processing options available while retaining the high mechanical properties of the pregenerated TLCP fibrils. These post-processing techniques included: (1) manufacturing and consolidating woven thermoplastic/TLCP composite preforms, (2) injection molding of pregenerated microcomposites, and (3) rapid prototyping. Each of these techniques was shown to produce composites with higher mechanical properties than those of the neat matrix resins.