Effect of surface modification of Kevlar stitch threads on mechanical interfacial properties of carbon fiber/bismaleimide stitched composites

To improve the properties of durability towards combined moisture and temperature attack of stitched composites with Kevlar thread, the surface of Kevlar stitch thread was modified using the metalation and grafting Allyl group. The modified thread was characterized with tensile measurement, SEM and XPS. The results show that the surface of the chemical treated Kevlar stitch thread is rougher than that of the untreated thread. The oxygen content increases by 23% and the tensile strength decreases little under the proper condition. The interfacial properties of the stitched carbon fibre reinforced bismaleimide (BMI) resin composites T300 /QY9512 with Kevlar stitched threads were studied by interlaminar shear strength (ILSS). The result shows that the moisture uptake of carbon fibre/stitched BMI composites with chemical treated Kevlar threads decreases by 52% and the residue ratio of ILSS in the wet state improves by 15%.