High Thermal Conductivity Fibers from PBO

摘要

This project proved that, unlike other precursor fibers (rayon, polyacrylonitrile (PAN) and pitch), phenylenebenzobisoxazole (PBO) can be directly converted to carbon fiber without prior stabilization. More importantly, when directly carbonized, the PBO-based carbon fibers developed moduli and thermal properties similar to pitch-based carbon fibers. This ability to develop high moduli and thermal conductivity could make PBO an attractive reinforcing fiber for many carbon/carbon applications. Thus, a process for forming potentially low-cost carbon/carbon composites using PBO fibers was also evaluated. In this process PBO fibers were coated with phenolic and high melting pitches using a novel suspension coating technique, and then directly thermoformed into carbon/carbon composites. No stabilization step was needed, and the fibers and matrices were carbonized simultaneously. The resulting carbon/carbon composites exhibited properties similar to those of many commercial composites. Thus, the project demonstrated that PBO can be suspension coated with either a phenolic or pitch matrix, formed into a complex preform and directly carbonized to produce a carbon/carbon composite. This process eliminates the lengthy stabilization period and carbonizes both the fiber and the matrix in a single step.