Copolymerizing Behavior and Processability of Benzoxazine/Epoxy Systems and Their Applications for Glass Fiber Composite Laminates

Copolymerizing behavior and processability of epoxy/benzoxazine containing cyano groups (EP/BA-ph) systems were investigated by differential scanning calorimetry and dynamic rheological analysis. The results showed that EP/BA-ph systems exhibited two characteristic peaks corresponding to ring-opening of benzoxazine and ring-formation of cyano groups, respectively. Compared with BA-ph, EP/BA-ph copolymer processability was improved and can be controlled by varying EP contents, processing temperature, and time. Then EP/BA-ph copolymers were employed to prepare EP/BA-ph/glass fiber (GF) composite laminates and their mechanical, morphological, and thermal properties were investigated. Compared with those of BA-ph/GF composites, the flexural strength, and modulus of EP/BA-ph/GF composites with 50 wt % EP content were increased by 13.5 and 20%, respectively. The enhancements in mechanical properties are mainly due to the strong interfacial adhesions between GF and matrices, which was confirmed by SEM observations. All EP/BA-ph/GF composite laminates are stable up to 510 degrees C in air. EP/BA-ph/GF laminates will have potential applications in the areas where require of excellent mechanical properties and high temperature resistance. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 1176-1184, 2013