Novel hydrophobic, tough, and high temperature matrix resins for polymer composites

The improved thermal, mechanical, and environmental properties of a number of matrix resins are described. Chlorinated epoxy resins were found to adso rb much less water than their non-chlorinated analogues, and showed improve d hot-wet properties. Custom synthesised thermoplastic toughening agents we re used to improve the fracture toughness of a tetrafunctional epoxy resin system. Substantial increases in K-IC and G(IC) were achieved, with minimal loss of temperature performance. A number of highly functionalised epoxy monomers, with up to eight epoxy gr oups each, were prepared. The resulting cured matrixes were found to have g lass transition temperatures in excess of 300 degrees C. Blends of cyanate ester and bismaleimide were investigated as tough, high t emperature performance matrixes. Addition of bismaleimide to cyanate ester resulted in an increase in fracture toughness. Dynamic mechanical analysis showed two distinct glass transitions, suggesting that the material has a t wo phase morphology such as an interpenetrating network. PRC/1582. (C) 1999 British Crown Copyright.