Facile strategy and mechanism of greatly toughening epoxy resin using polyethersulfone through controlling phase separation with microwave-assisted thermal curing technique

Toughening has been the essential issue for developing high-performance thermosetting resins. Herein, starting from polyethersulfone (PES) and bisphenol A epoxy resin (EP), a facile strategy is developed to prepare tough resins through controlling phase structure with microwave-assisted thermal curing. PES/EP resins cured with the assistance of microwave curing (m-PES/EP) have two major differences compared with those using traditional heat curing (t-PES/EP), one is high degree of phase separation, and the other is phase separation mechanism. Initial phase separation of all t-PES/EP resins follows spinodal decomposition mechanism, while those of m-PES/EP systems with 8 wt% and 18 wt% of PES follow nucleation and growth mechanism. These differences are derived from the fact that microwave curing has much faster phase separation rate and curing reaction rate than thermal curing owing to the higher thermal effect. Differences in phase structure bring different macro performances, and m-PES/EP systems have higher impact strengths, fracture toughnesses, and flexural strengths than t-PES/EP resins. This investigation provides a facial and effective way of developing higher performance thermoplastic/thermosetting resin system through controlling phase structure. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48394.