Interfacial improvement and mechanical properties of epoxy resin/ultra-high molecular weight polyethylene fibre composites compatibilized with glycidyl methacrylate

In this paper, interfacial adhesion of epoxy resin/ultra-high molecular weight polyethylene fibre composites by polymerization grafting of glycidyl methacrylate onto fibre surface was investigated. To optimize the grafting process, experiment design method was applied using the time and monomer concentration as grafting variables. In order to confirm the formation of glycidyl methacrylate bonds onto the polyethylene chains, attenuated total reflectance-infra red test was performed. Besides, Pull-out test was utilized to measure the interfacial shear strength of fibres with the matrix for both modified and unmodified ultra-high molecular weight polyethylene fibre composites. Tensile test was carried out. Three amounts, 11%, 25%, and 40%, of polymerized glycidyl methacrylate grafted onto the fibre surface was obtained. The grafting percent of glycidyl methacrylate onto the fibre showed enhancement by increasing the amount of glycidyl methacrylate monomer and the reaction time which was bigger by monomer increment. The interfacial shear strength of 11%, 25%, and 40% glycidyl methacrylate grafted fibres with epoxy matrix showed 126%, 195%, and 220% enhancements, respectively, in comparison with untreated fibre. The tensile strength of 11% glycidyl methacrylate grafted polyethylene fibre-epoxy composite showed about 10% enhancement; however, the tensile strengths of 25% and 40% glycidyl methacrylate grated polyethylene fibre-epoxy composites showed decrement. Toughness results showed improvement for 11% glycidyl methacrylate grafted composite due to appearing of energy absorbing mechanisms while fracturing.