| Cardanol is a kind of phenolic compound, it not only is natural but also has variety excellent properties. It can be used in place of traditional phenol. In this paper, cardanol was used to synthesize cardanol-based aromatic diamine benzoxazine resin(PCBOZ), then studied and improved its properties.Using unsaturated cardanolã€4,4’-diaminodiphenyl methane and formaldehyde to synthesize cardanol-based aromatic diamine benzoxazine(CBOZ) by solvent method. And the monomer CBOZ was characterized by FTIR and 1HNMR. The synthesis procrss of CBOZ was optimized by single factor experiments, got the optimum conditions: reaction temperature is 100 ℃, reaction time is 4h, the amount of solvent(toluene) is 30ml/0.2mol cardanol, n(4,4’–diaminodiphenyl methane): n(cardanol): n(formaldehyde) is 1:2:4.5. On this reaction condition, the yield of CBOZ is 91.3%.Studied the monomer CBOZ’s curing behavior and kinetics by non-isothermal DSC test method. The curing kinetics factors were calculated: activation energy E =93.71 k J/mol, the pre-exponential factor A =6.51×108, the reaction order n =0.91. The curing process temperature of CBOZ was determined by(T-β) extrapolation method: initial curing temperature(Ti) is 221℃, thermostatic curing temperature(Tp) is 234℃, after-treatment temperature(Tf) is 248℃.Curing the monomer CBOZ and epoxy resin E-44/CBOZ by temperatureprogrammed method respectively to synthesize benzoxazine resin PCBOZ and blending resin PCBOZ-E. Comparing the FTIR spectras of the monomer CBOZ and the cured resin determined that the monomer CBOZ had been successful on ringopening polymerization. Studied the curing exothermic peak enthalpy of PCBOZ and PCBOZ-E were by DSC test method, the degree of curing about PCBOZ is 100%, and the degree of curing about PCBOZ-E is 100% when the content of epoxy resin E-44 was no more than 50%. The cross-sections of PCBOZ and PCBOZ-E were investigated by SEM. The cross-sections didn’t exist bubbles, PCBOZ was brittle fracture, PCBOZ-E was ductile fracture.The thermal stabilities of PCBOZ and PCBOZ-E were studied by TG test. The initial decomposition temperature(T0%) of cardanol-based benzoxazine resin PCBOZ was 260.1℃, which was 30 ℃higher than that of phenol-based benzoxazine resin PBOZ(T0%=233.2℃). Then blending resin PCBOZ-E was superior in heat tolerance compared to neat benzoxazine resin PCBOZ, and the thermal stabilitiy of the copolymerization system PCBOZ-E was best(T0%=304.9℃) when the content of epoxy resin E-44 was 50%, which was 44.8 higher than that of PCBOZ.℃Studied the resin PCBOZ’s thermal decomposition kinetics by TG test. The thermal decomposition activation energy kE of PCBOZ was calculated by Kissinger method, Flynn-Wall-Ozawa method, and Starink method. The thermal decomposition reaction order n was calculated by Crane equation, it was 0.95. |
