Benzoxazine/Bisphenol A Novolac Epoxy Resin Curing Kinetics And Performance Testing

Epoxy resin, which was the most widely used thermosetting material in theworldwide, has excellent adhesion properties, electrical insulation and corrosionresistance. Nevertheless, epoxy resin has some shortcomings such as mechanicalproperties, heat resistance and wet performance.In addition to the high temperatureresistance, flame retardant, electrical insulation as well as low cost, benzoxazine alsohas a low water absorption. Composite materials mixed the epoxy resin and threedifferent benzoxazine respectively to improve the performance of the epoxy resin,which has the advantages of epoxy and benzoxazine at the same time.In this paper, the benzoxazine monomers containing rigid maleimide can improvethe heat resistance of the epoxy resin, and at the same time, the carboxylgroup-containing benzoxazine monomers can reduce the curing temperature of thecomposite materials. Bisphenol A formaldehyde novolac epoxy resin was the epoxy thatwas chose. The brief contents are shown as follows:Firstly, three different benzoxazine were synthesized, wherein M1contains onlythe benzoxazine ring and a benzene ring structure, M2containing a carboxyl groupmore than M1, M3containing a rigid ring more than M2. DSC method was used tocharacterize the curing behavior of the three benzoxazine monomer.Secondly, thermal performances of three benzoxazine/bis-ANER compositematerial were studied by DSC and TG method. With the composite system benzoxazinecontent increases, the heat resistance of the material is also increased. With the thebenzoxazine monomer molecular weight increases, the char yield is increased, too. InM3series composite, the10%weight loss temperature was about400°C and char yieldwas44.1%at800°C.Thirdly, the curing reaction were also investigated under non-isothermal DSCmethod at different heating rates. The average activation energy of the curing reactionwere calculated by three methods can maintain a good consistency. The autocatalytickinetic model was found to be the best description of the investigated curing reactionsaccording to Friedman method. Non-isothermal DSC curves obtained from theexperimental data showed a good agreement with that theoretically calculated.