Abstract
The Single fiber fragmentation test is carried out to examine the microscopic degradation process of the inner fiber surrounded by matrix resin and the interface under acid stress environment. The single fiber model composite specimen of C-glass fiber/Vinylester resin system is immersed in environmental solution under constant loading before the fragmentation test. Average strength of the fiber and maximum interfacial shear strength are obtained by the Weibull scale parameter and the Cox's interfacial stress transfer model, respectively. It is noted that the diffsion phenomenon in polymer materials is generally accelerated by the applied stress, the present results indicate the influence of water diffusion. The fiber strength lowered with the immersion time, at the same time also lowered with the applied stress. It is considered that the dterioration of the fiber strength is due to the exist of the inherent flaw on the fiber surface originally covered with the surface treatment agent. These hydrophilic coupling agent is affected by the diffusive water. Thus, it is considered that these phenomenon make the apparent strength of the fiber. On the other hand, the interfacial shear strength are affected by the immersion time, however, it is independent of the applied stress. The experimental data indicates the affect of water diffusion into the interface through the matrix as the fiber strength. Some factors to govern the deterioration in the interfacial shear strength can be estimated. According to the Cox's model, the deterioration of the interfacial strength is explained by the variation of the matrix elastic properties.
