Synthesis,characterization of new carboxylic acid‐containing benzoxazine and its cocuring behaviors with bisoxazoline

A new benzoxazine‐benzoic acid (BBA) was synthesized and the structure was conformed by ¹H‐NMR, ¹³C‐NMR, FTIR, etc. The cure behavior of BBA and cocure behavior of BBA with phenylene bisoxazoline (1,3‐PBO) were investigated by differential scanning calorimetry (DSC). It was found that BBA showed a single curing exothermic peak at about 217°C. However, all BBA/1,3‐PBO systems exhibited two exothermic peak. One may be attributed to the reaction between carboxyl groups of BBA and 1,3‐PBO. And the other was attributed to the ring‐opening polymerization of oxazine rings and the reaction between phenolic hydroxyl groups generated by the ring opening of benzoxazine ring and 1,3‐PBO. The curing temperature of benzoxazine containing carboxyl groups could be lowered by the copolymerization of 1,3‐PBO. Thermogravimetric analysis showed that the incorporation of ester–amide groups had a significant effect on decreasing thermal stability and char yield of the cured resin. SEM results indicated that 1,3‐PBO could toughen BBA benzoxazine resin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011