Reinforcement of tire tread and radiator hose rubbers with short aramid fibers

Short fiber reinforced rubber composites have gained great importance due to their advantages in processing and low cost, coupled with high strength. Reinforcement with short fibers offers attractive features such as design flexibility, high modulus, tear strength, etc. The degree of reinforcement depends upon many parameters, such as: the nature of the rubber matrix, the type of fiber, the concentration and orientation of the fibers, fiber to rubber adhesion to generate a strong interface, fiber length distribution and aspect ratio of the fibers. In the present research polyaramid fibers are investigated because of their significantly higher modulus and strength, compared to other commercial fibers. Compounds based on different types of rubbers: NR and EPDM have been made to investigate the use of these fibers in different applications, in particular in tire treads for an improved balance in properties. Fibers with different kinds of surface treatments are investigated. The reinforcing effect of these short polyaramid fibers has been studied by mechanical and viscoelastic experiments, and by studying the fracture surfaces with microscopic techniques.