A Study On The Synthesis And Self-catalyzed Cure Mechanism Of Copolymer Of Novolac/benzoxazine

In this paper, the copolymer of phenolic/benzoxazine is prepared by the reaction of the novolac, primary amines and formaldehyde. Considering the low curing temperature of navolac, the aim of this paper is to reduce the curing temperature of polybenzoxazine resin and study the rule of the curing behavior of the copolymer. The research on the curing of this copolymer has not been reported before to our best knowledgeThe synthesis condition of copolymer of phenolic/benzoxazine resin has been studied and the influence of reaction time and rate of phenol/ formaldehyde have been reviewed in this paper. The result showed that the visicocity of the system is the important factor to the successful process of synthesis and a best synthesis condition has been made.The behaviors of ring-opening copolymerization, which play very role in the properties of the thermoset resin, have been studies in the detail by isothermal and dynamic differential scanning calorimetry (DSC) and torsional braid analysis (TBA).In the dynamic DSC analysis, the activation energy and the order of the reaction are determined by using the difference-differentiation computational method. Kissinger equation, Ozawa equation and Freeman-Carroll equation has been introduced to deal with the data of DSC analysis. The result show that Kissinger and Freeman-Carroll equation suit to the copolymer system while Ozawa equation isadverse.By using the torsioal braid analysis (TBA), the isothermal and dynamic curing behaviors of the copolymer have been studies intensively. During the cure, the phase of the copolymer changes from liquid to glass, which is accompanied by two phenomena, gelation and vitrification. Compared with benzoxazine, the cure temperature of copolymer has been reduced and the secondary transition is more complicated.Benzoxazine resin has a wide molecular structure designment and a new kind of benzoxazine has been synthesized and characterized by 'H-NMR, RT-IR and DSC. In addition, two different synthesis processes and three solvent have been adopted to study the best condition of synthesis.