High Temperature Modulus and Structure of Poly (P-Phenylene Benzobisthiazole) Fibers.

摘要

A high modulus and high-temperature properties are of great importance for fibers used in aerospace composites. We have developed a method which uses laser-generated ultrasound to measure the Young's modulus of fibers as a function of temperature and static tensile stress. For fibers of poly (p-phenylene benzobisthiazole), measurements have been made to 580C and 1.7 GPa. They exhibit nonlinear elasticity which changes systematically with temperature, tensile stress and processing conditions. They exhibit a relaxation associated with a structure change at about 300-400C. We have also used x-ray diffraction to measure aspects of the ultrastructure such as crystal orientation, crystal size and unit cell. The measurement of the unit cell dimensions as a function of temperature to 500C shows a structure change at about 300-400C. It is consistent with an oscillation of the phenyl and bisthiazole moities around the connecting single bonds. Keywords: Rigid rod; Polymers; Reprints.