Effect of Silane Concentrations on Mode I Interlaminar Fracture of Woven Silk/Epoxy Composites

The aim of the project is to study the effect of silane concentrations on the interlaminar fracture toughness, G(Ic) of silk/epoxy composites. Woven silk fibre has been treated with five different silane concentrations and fabricated into a panel with two layers of silk fibre. The processing technique used to prepare the sample is by a vacuum bag in an autoclave. Six sets of panels were fabricated based on different 3-aminopropyl triethoxysilane silane concentrations which include one sets of specimens without treatment for comparison. Mode I test based on double cantilever beam specimens (DCB) method has been used over all the specimens. The results of the G(IC) were plotted and compared with the untreated composites panel. G(IC) of the composite has been found to increase when the silane concentrations exceeded certain minimum silane contents of 15 ml. During the test, crack propagation is stable and no fibre bridging occurred between both sides of fracture surfaces. All the failure that occurred were at the fibre-matrix interface. The G(IC) of woven silk/epoxy composites can be enhanced by surface treatment using coupling agent. Surface treatment has affected the properties of the composite panel by increasing the interlaminar fracture toughness by a maximum of 53% at a 5.8vol% silane concentrations.