Flammability and Thermomechanical Properties of Dianhydride-modified Polybenzoxazine Composites Reinforced With Carbon Fiber

Composites based on carbon fiber (CF) and benzoxazine (BA-a) modified with PMDA were investigated. The flammability of the carbon fiber composites was examined by limiting oxygen index (LOI) and UL-94 vertical tests. The LOI values increased from 26.0 for the CF/poly(BA-a) composite to 49.5 for the CF-reinforced BA-a/PMDA composites as thin as 1.0 mm and the CF-reinforced BA-a/PMDA composites were also achieved the maximum V-0 fire resistant classification. Moreover, the incorporation of the PMDA into poly(BA-a) matrix significantly enhanced the T-g and the storage modulus (E') values of the CF-reinforced BA-a/PMDA composites rather than those of the CF/poly(BA-a). The T-g values and storage moduli of the obtained CF-reinforced BA-a/PMDA composites were found to have relatively high value up to 237 degrees C and 46 GPa, respectively. The CF-reinforced BA-a/PMDA composites exhibited relatively high degradation temperature up to 498 degrees C and substantial enhancement in char yield with a value of up to 82%, which are somewhat higher compared to those of the CF/poly(BA-a) composite, i.e., 405 degrees C and 75.7%, respectively. Therefore, due to the improvement in flame retardant, mechanical and thermal properties, the obtained CF-reinforced BA-a/PMDA composites exhibited high potential applications in advanced composite materials that required mechanical integrity and self-extinguishing property. POLYM. COMPOS., 34:2067-2075, 2013. (c) 2013 Society of Plastics Engineers