V-378A, A New Modified Bismaleimide Matrix Resin for High Modulus Graphite

Abstract

V-378A is a modified bismaleimide matrix resin which exhibits significant advantages over previously available bismaleimides and 350°F curing epoxy resins. The Tg of this new resin is in excess of 700°F. It has excellent tack at ambient temperatures and is available at prepreg resin solids contents as low as 30% for “net” resin (i.e. no bleed) cures. High modulus graphite unidirectional tapes based on V-378A exhibit excellent uncured or wet transverse strength. V-378A can be cured under standard low autoclave pressure of 100 psi and temperatures of 350°F similar to current 350^°F curing epoxy systems. Unrestrained post cure at temperatures of 475 – 500°F are required to maximize elevated tem-perature strength retention. Cured V-378A/high modulus graphite composites exhibit strength retention at temperatures up to 600°F, excellent resistance to conditions of high humidity, no microcracking after repeated thermal spikes, and excellent tensile, compressive and shear strength. V-378A offers easy, epoxy-like processing characteristics with no volatile condensation products given off during cure with significantly su-perior high temperature strength retention after severe humidity aging.