Abstract

This paper preliminarily presented two principles on interface design including the principle of interface bonding and the principle of smooth transition on interfacial residual stress. According to these principles, the designed glass fiber/epoxy resin composite materials using CCVC (Copolymer of Controllable Volume-change on Curing) as interfacial layer, in which the volume-change can be arbitrarily controlled from shrinkage to expansion on curing, were experimentally studied. When the interfacial layer of CCVC shrank slightly, the impact fracture energy of the thermal treatment glass fiber reinforced composite increased 63% more than that without CCVC layer, and no decreasing on the strengths. For the coupling agent KH-560 treating glass fiber reinforced composite, the impact fracture energy increased 11% when CCVC layer had zero shrinkage. The experiments revealed that interfacial residual stress could be regarded as biaxial stresses which included the shear internal stress along the direction of interface and the internal pressure perpendicular to interface. The former one reduced the performances of composites since the interfacial shear residual stress led to stress concentration, defects and debonding, and the latter one, however, would contribute the friction bonding strength which had important significance to the work of fracture when the broken fibers were pulled out.

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