A new flexible backbone polyimide adhesive

Abstract

A new linear, aromatic, thermoplastic polyimide, identified as LARC-IA, has been synthesized and evaluated, primarily as an adhesive, which is physiologically safe and relatively inexpensive. The polymer was prepared from oxydiphthalic anhydride (ODPA) and 3,4-oxydianiline (ODA) in diglyme. In order to obtain optimal flow properties, which improves wetting, the molecular weight of the polymer was controlled by use of a monofunctional anhydride, phthalic anhydride (PA). Adhesively bonded lap shear specimens, using Ti-6AI-4V adherends, were prepared and tested to assess its adhesive potential. Specimens were exposed to water boil and thermal aging to determine the adhesive system's durability. Flatwise tensile strength and critical fracture energy were also determined. Results were compared to data for LARC-TPI. Preliminary flexural strength and modulus results were also obtained for composites fabricated from LARC-IA (5% PA) and graphite fibers (AS4, 12K). Initial results of this study indicate considerable promise for this material as a structural adhesive for applications for temperatures up to 200°C.