Research On High Char Yield Benzoxazine Resin

In this study,benzoxazine was took as high char yield resin.By taking advantage of the molecular design flexibility of benzoxazine chemistry,many benzoxazines of different molecular structure were synthesized,and they were expected to achieve high char yield and good processibility.First,BOZ1 was synthesized.The best reaction condition was determined by varing the reaction temperature and reaction time.Both 1HNMR and FTIR confirmed the structure of BOZ1 and BOZ2,indicating the presence of the oxazine.The gel-activation enegy ,viscosity,thermal-curing activation enegy and char yield at 800℃under nitrogen environment of BOZ1 and BOZ2 were researched.The results were as follows:the gel-activation enegy and thermal-curing activation enegy of BOZ1 were 69.06 KJ/mol and 192.3 KJ/mol,respectly.The lest viscosity of BOZ1 at 110℃,120℃and 130℃was 50.6Pa·S,13.1 Pa·S,and 7.44 PaS.The char yield of BOZ1 at 800℃under nitrogen environment was 31%. The gel-activation enegy and thermal-curing activation enegy of BOZ2 were 75.509 KJ/mol and 346.2 KJ/mol,respectly.The lest viscosity of BOZ2 at 80℃and 90℃was 0.273Pa·S and 0.120 Pa·S.The char yield of BOZ2 at 800℃under nitrogen environment was 36%.In view of the above results,BOZ2 were desirably modified by changing molecular structure and by mixing a benzoxazine compound and a furan compound,which resulted in higher amounts of char.In the study,we used two methods to form high char yield benzoxazine. First,BOZ3,BOZ4,and BOZ5 were synthesized by altering the functional group on the amine and/or phenol.The molecular structure of them were confirmed by both HNMR and FTIR.Thermal-curing behavior and thermal stability were also studied by DSC and TGA. The results of TGA indicated that the char yield of BOZ3,BOZ4,and BOZ5 at 800℃under nitrogen environment was 58.5%,52%,and 62.5%,respectly.The second method,a char yield benzoxazine compounds was formed by mixing BOZ2 and furfural,wherein the mixture has a benzoxazine ring to furan ring ritio from 0.5 to 2.The results of TGA showed :when benzoxazine ring:furan ring = 1:1,the mixture had the highest char yield,and the char yield of the mixture at 800℃under nitrogen environment was 45.8%,which was 10% higher than the char yield of BOZ2.