Modification of three-component bismaleimide resin by poly(phthaloyl diphenyl ether) and related copolymers

A three-component bismaleimide resin, composed of 4,4 ' -bismaleimido-diphe nyl methane (BDM), o,o ' -diallyl,bisphenol A (DBA), and o,o ' -dimethallyl bisphenol A (1.0/0.3/0.7 eq ratio) was used as a parent bismaleimide resin . Modification of the three-component bismaleimide resin was examined by bl ending it with poly(ether ketone ketone)s. Poly(ether ketone ketone)s inclu de poly(phthaloyl diphenyl ether) (PPDE), poly(phthaloyl diphenyl ether-co- isophthaloyl diphenyl ether) (PPIDE), and poly(phthaloyl diphenyl ether-co- terephthaloyl diphenyl ether) (PPTDE). The PPIDE (51 mol % isophthaloyl) an d PPTDE (44 mol % terephthaloyl) were more effective as modifiers for the b ismaleimide resin than was PPDE. For example, the fracture toughness (K-IC) for the modified resin increased 30% with no deterioration in the flexural strength and modulus with a 15 wt % inclusion of PPTDE (MW 23,400) compare d to the parent three-component bismaleimide resin: the K,, increased 95% c ompared to the value for the Matrimid 5292 resin composed of BDM and DBA. T he morphologies of the modified resins changed from particulate to cocontin uous phase structures, depending on the modifier structure and concentratio n. Toughening of the cured bismaleimide resin could be achieved because of the cocontinuous phase structure. (C) 2001 John Wiley & Sons, Inc.