Effect of silane coupling agent modification on shape memory behavior and mechanical properties of knitting fabric reinforced composites

Continuous glass fiber fabrics can improve the shortcomings of shape memory polymers in terms of mechanical properties. However, the mechanical properties of shape memory composites will not be optimal if the interface between the glass fibers and the matrix is poorly bonded. The purpose of this study is to explore the thermomechanical properties and shape memory behavior of shape memory epoxy resin and composites before and after the chemical modification of glass fiber. The effects of the ratios of epoxy to curing agent and whether the knitting fabrics are modified with silane coupling agent on the properties of the composites are investigated. The results show that the thermal decomposition temperature and glass transition temperature of the shape memory epoxy polymers increase with the increasing mass ratio of diaminodiphenylmethane. The shape fixing ratios and shape recovery ratios of the knitting fabric reinforced composites with different mass contents and silane coupling agent modification are above 98.0% at 18.0% tensile strain. After 10 cycles, the shape memory performance of the composites modified with KH560 is still good. Besides, the addition of silane coupling agent to the composites can reduce the shape recovery time by 17.9% and increase the recovery force with 30.0% subjected to 18.0% tensile strain. The tensile strength of the shape memory composites modified with silane coupling agent can increase 32.8% as compared with that of the composites without modification.