Static and dynamic mechanical properties and fracture morphology of EPDM composites containing silicate nanofibers and short PA-66 microfibers

Ethylene propylene diene monomer rubber composites reinforced with micro- and nano-sized short fibers were made by mechanically blending of silanized fibrillar silicate (FS) nanofibers and polyamide 66 (PA-66) microfibers. A synergistic reinforcement on static and dynamic mechanical properties was revealed. When FS nanofibers and PA-66 microfibers were used together in an appropriate volume ratio, static and dynamic mechanical properties (such as tensile stress, mechanical anisotropy, compression modulus, dynamic storage modulus and tensile fatigue property) of the resulting composites were substantially improved. The co-reinforcement mechanism of nano- and micro-sized fibers was discussed in terms of composite fracture morphology. The synergetic reinforcement effect on the dynamic fatigue properties is attributed to the result of competitive factors including stress transfer, crack initiation and propagation, and matrix reinforcement, whereas the synergetic reinforcement effect on the static tensile properties is achieved due to the strong interfacial adhesion between FS nanofibers and rubber.