Toughness improvement of carbon-fibre/polybenzoxazine composites by rubber modification

Abstract

Carbon-®bre/polybenzoxazine composites were fabricated in order to examine the toughening e ect of amine-terminated buta- diene acrylonitrile rubber (ATBN) and carboxyl-terminated butadiene acrylonitrile rubber (CTBN) modi®cations of poly- benzoxazine. The mode II delamination toughness of carbon-®bre/polybenzoxazine composites was measured as a function of rubber content. Transmission optical microscopy (TOM) and scanning electron microscopy (SEM) were used to investigate the fracture mechanism and toughening e ect in the carbon-®bre/polybenzoxazine composites. Delamination toughness of the carbon- ®bre/polybenzoxazine composites increased by ATBN modi®cation as a result of the enhancement of the toughness of poly- benzoxazine and interfacial bonding in the composites with increasing ATBN content. The better interfacial bonding in the ATBN- modi®ed system induced the growth of some cracks allowing the intrinsic resin toughness to be fully extracted during composite delamination. In the case of CTBN modi®cation, the delamination toughness of the composite was hardly increased because of the weak interfacial bonding. # 2000 Elsevier Science Ltd. All rights reserved.