Resin transfer molding (RTM) with toughened cyanate ester resin systems

Abstract This investigation explored the feasibility of recently developed toughened cyanate ester networks as candidate materials for high performance composite matrix applications. The resin investigated was a bisphenol‐A cyanate ester toughened with hydroxy functionalized phenolphthalein based amorphous poly(arylene ether sulfone). A series of four toughened cyanate ester resins were generated by varying the concentration and the molecular weight of the toughener. The thermoplastic modified toughened networks exhibited improvement in the fracture toughness over the base cyanate ester networks without significant reductions in mechanical properties or glass transition temperature. Carbon fabric composite panels were manufactured by liquid molding processes (resin transfer molding and resin film infusion) with the untoughened and toughened cyanate ester resin systems. The panels were subjected to physical, impact damage, and fracture toughness tests. The results of physical testing indicate consistently uniform quality, and the maximum void content was found to be less than 2%. The toughened cyanate ester composites exhibited significantly improved impact damage resistance and tolerance compared with hot‐melt epoxy systems. A marked increase in the mode II composite fracture toughness was observed with an increase in the concentration and the molecular weight of the toughener.