Bisphenol A based benzoxazine was prepared from bisphenol A, formaline, and aniline. This benzoxazine was used as a hardener of the epoxy resin. Curing behavior of the epoxy resin and the properties of the cured resin were investigated. Consequently, curing reaction proceeded without a curing accelerator. The molding compound showed good thermal stability under 150ЊC, which corresponded to the temperature in the cylinder of injection molding. Above 150ЊC, the curing reaction proceeded rapidly. The cured epoxy resin showed good heat resistance, water resistance, electrical insulation, and mechanical properties compared with the epoxy resin cured by the bisphenol A type novolac.
Abstract. Curing reaction of bisphenol-A based benzoxazine with cyanate ester resin and the properties of the cured thermosetting resin were investigated. The cure behavior of benzoxazine with cyanate ester resin was monitored by model reaction using nuclear magnetic resonance (NMR). As a result of the model reaction, the ring opening reaction of benzoxazine ring and thermal self-cyclotrimerization of cyanate ester group occurred, and then the phenolic hydoroxyl group generated by the ring opening reaction of benzoxazine ring co-reacted with cyanate ester group. The properties of the cured thermosetting resin were estimated by mechanical properties, electrical resistivity, water resistance and heat resistance. The cured thermosetting resin from benzoxazine and cyanate ester resin showed good heat resistance, high electrical resistivity and high water resistance, compared with the cured thermosetting resin from benzoxazine and epoxy resin.
Terpenediphenol-based benzoxazine was prepared from terpenediphenol, formaline, and aniline. Curing behavior of the benzoxazine with epoxy resin and the properties of the cured resin were investigated. Consequently, the curing reaction did not proceed at low temperatures, but it proceeded rapidly at higher temperatures without a curing accelerator. The properties of the cured resin both from neat resins and from reinforced resins with fused silica were evaluated, respectively. The cured resins showed good heat resistance, mechanical properties, electrical insulation, and especially water resistance, compared with the cured resin from bisphenol A type novolac and epoxy resin.
Curing reaction of bisphenol-A-based benzoxazine (Ba) with epoxy resin (Ep) using latent curing agent, and the properties of the cured resin were investigated. Consequently, by using latent curing agent, the ring opening reaction of benzoxazine ring occurred more rapidly, and then also the phenolic hydoroxyl group generated by the ring opening reaction of benzoxazine ring reacted with epoxy ring more rapidly. And it was found that the cure time of the molten resins from Ba and Ep with latent curing agent could be reduced and also the cure temperature could be lowered, compared with those from Ba and Ep without latent curing agent. The melt viscosity of the molten resins from Ba and Ep with latent curing agent was kept about 50 [Pa s] at 1008C even after 30 min, the molten resins from Ba and Ep with latent curing agent showed good thermal stability below 1008C. However, above 1708C the curing reaction of Ba with Ep with latent curing agent proceeded rapidly. The cured resin from Ba and Ep with latent curing agent showed good heat resistance, flame resistance, mechanical properties, and electrical insulation, compared with the cured resin from Ba and Ep without latent curing agent.
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