Effect of thermoplastic toughening agent on phase separation and physicochemical properties of bismaleimide resin

The modified resin system of 4, 4'bismaleimidodiphenylmethane ((BDM)/ ortho-diallyl bisphenol A(DBA)(BMI)/ reactive groups-terminated polyethersulfone (rPESU) (BMI/P)was prepared by melting pre-polymerization. Typical properties (The gelation time, mechanism, phase structure and thermal stability) of the BMI/P resin were systematically investigated, and their origins were discussed. The results show that the addition of rPESU into BMI resin not only significantly improves the impact toughness and the strength, but also effectively improves the thermal stability although the glass transition temperature is reduced slightly. However the reaction rate of BMI/P resin is accelerated and the gelation time is shortened because of the presence of reactive groups. And then, the cured BMI/P resin has a more complex multi-stage phase structure. Those are the difference with the polyethersulfone (PES) without terminated by reactive groups.