LARC-IA: A flexible backbone polyimide

A new linear, aromatic, thermoplastic polyimide, prepared from oxydiphthalic anhydride (ODPA) and 3,4'-oxydianiline (ODA) in diglyme and identified as LARC-IA, was synthesized and evaluated. The monomers are relatively inexpensive and physiologically safe. Molecular weight was controlled by use of a monofunctional anhydride, phthalic anhydride (PA), in order to promote controlled flow and wetting properties. The polymer is considered a safe alternative to commercially available LARC-TPI which is prepared with an expensive diamine of uncertain carcinogenicity. The evaluation was based primarily on the polymer's adhesive properties as determined by thermal and water boil exposure of lap shear specimens. Strengths were determined at room temperature, 177, 204 and 232 C before and after exposure to determine the adhesive system's durability to adverse environments over a period of time. Other properties (FWT, G(1c), film and composite properties) were examined which were determined to be typical of a high temperature polyimide. Results of the study show a favorable comparison to LARC-TPI, a commercially available polyimide.