Flexural and Hydrothermal Aging Behavior of Silk Fabric/Glass Mat Reinforced Hybrid Composites

Recycled natural materials such as silk fabric have attracted more and more public attention over the past few years. In this research, unsaturated polyester resin was used as matrix, glass mat and silk fabric were employed as reinforcement to fabricate the laminated hybrid composites by hand lay-up method. Three-point flexural quasi-static and load-controlled low cycle bending fatigue (LCBF) tests at 55 %, 70 % and 85 % pre-set load levels were performed. The composite specimens were also subjected to hot water immersion treatment at 80 degrees C for different durations. The effects of the immersion treatment on the bending and impact fracture. characteristics were investigated. The results showed that higher flexural modulus and strength were obtained when silk fabric layer was stacked at the middle layer. It seems that the anti-fatigue property was improved by the inclusion of silk fabric reinforced in glass mat hybrid composites. In the water immersion experiments, both the flexural properties and impact properties were improved initially until reaching the maximum and then decreased continuously with further increase in exposure time. These seemingly contradictory behaviors are due to relaxation of the internal stress, swelling of the silk fibers and the weakening of fiber/matrix interface.