The Study On Surface Modification Of Aramid Fiber And Aramid/Rubber Adhesive Properties

Aramid fiber has excellent performance such as high strength, high modulus, high temperature resistance, good dimensional stability. It is the ideal rubber skeleton material, but the adhesion performance of aramid fiber and rubber matrix is poor which limits the application of aramid fibers in rubber composites. Therefore, it is very necessary to improve interfacial bonding performance of the aramid fiber and rubber by surface modification of aramid fiber.This paper investigated two modification methods of aramid fiber and adhesive properties of aramid fiber/rubber composites. The modification methods are Silane coupling agent KH560grafting and UV-irradiation induced grafting.Firstly, the aramid fibers were functionalized with polydopamine (PDA) coating, Silane coupling agent KH560grafting reaction was then carried out on the surface of the polydopamine-coated fiber. The surface changes and properties of modified aramid fiber were characterized by XPS, FTIR, SEM and TGA. The results show that the active functional groups like epoxy and hydroxy are introduced onto aramid fiber surface successfully. The interfacial properties of aramid/rubber composites were investigated by the fiber pull-out test and the interfacial shear strength increased by about62%. After RFL dippling, the adhesion strength was further improved because the active groups on fiber surface react with RFL. Adhesion strength test results of aramid fibers/rubber after air aging show that boding interface has good aging resistant performance.Furtherly, the surface modification of aramid fiber by ultraviolet irradiation induced GMA grafting was also studied. The surface changes and properties of modified aramid fiber were characterized by XPS and SEM, the influence of reaction conditions to adhesive force and grafting ratio was also investigated, the grafting reaction conditions were optimized by comparing experiment. GMA was grafted on aramid fiber surface by ultraviolet irradiation induced reaction and reactive groups like epoxy and ester were introduced. Adhesion strength was increased significantly after ultraviolet induced grafting modification. After RFL dippling the adhesion strength was34%higher than that of traditional isocyanate impregnation method and bonding interface has good aging resistance performance.