Research Of Reaction Induced Phase Separation In Epoxy Systems Modified By Thermoplastic Acrylic Resin

Epoxy/thermoplastic acrylic resin blends was respectively cured by three differentcuring systems. They were DETA, HHPA and HHPA contained initiator BDMA. Thereaction induced phase separation in blends was studied. This paper had analyzed the finalphase structure of blends cured at setting temperature, investigated the viscoelastic model incuring blends, and characterized mechanical properties of cured blends.Reaction induced phase separation of blends started at the micro-phase separationdisplayed in OM. Only D systems cured at30℃had micro-continuous phase structure. Thephase structure of other systems showed monodisperse, co-continuous and phase-invertedstructure, changed with the content of acrylic resin. Studies shown that monodisperse andphase-inverted structure followed Nucleation and Growth mechanism, co-continuousstructure followed spinodal decomposition mechanism. The change of temperature and theintroduction of the accelerator didn’t alter the original blends critical range, but promoted asecondary phase separation.TRLS experiment identified the onset and evolution time of phase separation in curingblends. The results showed that the evolution of scattering vector qmcorresponding to epoxydroplets followed Maxwell-type relaxation equation. Therelaxation time and periodic length was obtained. As the curing temperature rised, gradually reduced but periodic length firstly increased and then decreased.The relaxation time corresponding to curing temperature T followedWilliams-Landel-Ferry equation. The reference temperature Tswas obtained, which isapproximately50℃higher than the Tgof epoxy-curing agent mixture. It displayed that theepoxy-rich phase was the fast dynamic phase in the process of phase separation, coarsenedand grew up, eventually break through the mesh acrylic resin-rich phase and integrated. Asa result, co-continuous phase structure formed. The viscoelastic model in curing blends hadbeen verified, which didn’t impact by the type of curing agent.The mechanical properties displayed that the epoxy blends achieved toughening effectmodified by thermoplastic acrylic resin when the blends had monodisperse or co-continuousphase structure. This paper determined the optimal content of the acrylic resin toughenedepoxy curing system.