A two‐component bismaleimide resin composed of 4,4′‐bismaleimidediphenyl methane (BDM) and o,o′‐diallyl bisphenol A (DBA) (Matrimid 5292 resin) was used as a parent bismaleimide resin. Modification of the parent bismaleimide resin was examined using several kinds of (meth)allyl compounds as the third component. The (meth)allyl compounds include triallyl isocyanurate (TAIC), o,o′‐dimethallyl bisphenol A (DMBA) and trimethallyl isocyanurate (TMAIC). In the ternary BDM/DBA/TAIC blends, the fracture toughness KIC and flexural strength for the cured resins decreased with increasing TAIC content; thermal properties of the cured resins were not deteriorated. In the ternary BDM/DBA/DMBA blends, KIC and flexural modulus for the cured resins increased and their glass transition temperatures decreased with an increase in DMBA content. Flexural strength increased up to DMBA 70 eq% blend and then decreased. In the ternary blend of BDM/DBA/TMAIC (1.0/0.5/0.5), KIC for the blend increased 15%, with retention of flexural property and Tg. In the ternary BDM/DMBA/TMAIC (1.0/0.5/0.5) blend, the cured resin had balanced properties and its KIC increased 50% compared to the cured Matrimid resin. © 1999 Society of Chemical Industry

A three-component bismaleimide resin, composed of 4,4Ј-bismaleimidodiphenyl methane (BDM), o,oЈ-diallyl bisphenol A (DBA), and o,oЈ-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 blending it with poly(ether ketone ketone)s. Poly(ether ketone ketone)s include 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) and PPTDE (44 mol % terephthaloyl) were more effective as modifiers for the bismaleimide 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) compared to the parent three-component bismaleimide resin: the K IC increased 95% compared to the value for the Matrimid 5292 resin composed of BDM and DBA. The morphologies of the modified resins changed from particulate to cocontinuous phase structures, depending on the modifier structure and concentration. Toughening of the cured bismaleimide resin could be achieved because of the cocontinuous phase structure.