Properties of Epoxy Resins Modified by the Polyimide-urethane Elastomers with the Pyromellitic Imide Bond

Abstract

Polyimide-urethane elastomers（PIUEs）were polymerized by reaction isocyanate-terminated prepolymerwith pyromellitic dianhydride and 1,4-butanediol in epoxy resin（in-situ polymerization）.It was investigated that the relationship between pyromellitic imide bond contents and the physicalproperties of epoxy resin modified by PIUEs. The adhesive properties and the fracture toughness of cured epoxides have improved with the amounts of PIUEs. Micro phase separation structure of the sea and island type were observed by scanning electron microscope（SEM）. Fracture toughness of the epoxy resins with PIUEs which consist of various pyromellitic imide bond contents correlated to the individual particle diameter. Generally, the bending modulus and T_g of epoxy resins were decreasedby adding polyurethanes. On the other hand, by incorporation of the rigid pyromellitic imide bondinto the hard segment of PIUE, the restraint about lowering of physical properties even though theamounts of PIUEs hugely increased were indicated.