Interfacial shear strength of microwave processed carbon fiber/epoxy composites characterized by an improved fiber-bundle pull-out test

Quantitative assessments of the fiber-matrix interface are crucial steps in tailored design of fiber reinforced polymer composites. Nevertheless, most of the common test methods seem to be inapplicable to measure the interfacial parameters of carbon fiber based composites processed by microwave, due to the severe arcing caused by exposed carbon fibers. In this paper, an improved fiber-bundle pull-out test was developed to solve this problem. It was demonstrated to be a feasible plan through the observation of fracture surfaces with optical microscopes and further comparison of resulting data between this and several single-fiber tests. Statistical analysis shows that the interfacial interaction of carbon fiber/epoxy composites could be significantly reinforced with MW heating which brought an increase of about 52.8% in interfacial shear strength. Meanwhile, a cycle time reduction of 54.2% was obtained compared with thermal curing. The interfacial reinforcing mechanism was explored by analyzing the selective heating effect of microwaves, and the chemical mechanism of the fiber-matrix interface using Fourier-Transform infrared spectrometers.