Processing and Properties of IM7/PETI Composites

Abstract

A phenylethynyl terminated imide (PETI) oligomer from the reaction of 3,3',4,4'-biphenyltetracarboxylic dianhydride, an 85:15 molar ratio of 3,4'-oxydianiline and 1,3-bis(3-aminophenoxy)benzene and 4-phenylethynylphthalic anhydride as the end-capper at a theoretical number average molecular weight (Mn) of - 5,000 g/mol was evaluated as a composite resin matrix. Unidirectional prepreg was made by coating an N-methylpyrrolidinone solution of the amide acid oligomer onto unsized IM7. The thermal and Theological properties and the solvent/volatile depletion rates of the amide acid/NMP system were determined. This information was used to successfully design a molding cycle for composite fabrication. Composites molded under 1.38 MPa at 371°C consistently yielded good consolidation as measured by C-scan and optical photomicrography. Composite mechanical properties at various temperatures included short beam shear strength, flexural strength and modulus, longitudinal compression strength and modulus (IITRI), longitudinal tensile strength and modulus and open hole compression (OHC) strength. These composites exhibited excellent resin dominant properties. The OHC strength values, in particular, suggested that PETI composites have excellent damage tolerance.