DEVELOPMENT OF HIGH TEMPERATURE RESISTANT GRAPHITE FIBER COUPLING AGENTS

摘要

Ten surface treatments were investigated as potential coupling agents to improve the elevated temperature shear strength retention of polyimide/graphite and polyphenylquinoxaline/ graphite composites. The potential coupling agents were evaluated by fiber strand tensile tests, fiber and composite weight losses at 533 and 588K, and by interlaminar shear strength retention at 533 and 588K. The two surface treatments selected for more extensive evaluation were a coating of Ventromer T-l, a complex organometallio reaction product of titanium tetrachloride and trim ethyl borate, and a polyphenylquinoxaline (PPQ) sizing which was paralyzed in nitrogen to form a carbonaceous layer on the fiber.nParalyzed polyphenylquinoxaline is a very satisfactory coupling agent for polyimide/ Thornel 300 graphite fiber composites. During 1000 hours aging at 588K such composites lose a little over half their transverse tensile strength, and suffer a slight loss in flexural modulus. However, no degradation of flexural strength or interlaminar shear strength occurs during 1000 hours aging at 588K.