Influence of complexing treatment and epoxy resin coating on the properties of aramid fiber reinforced natural rubber

In this work, natural rubber/aramid fiber (NR/AF) composites were prepared with master batch method. AF was modified by using epoxy resin (EP) and accelerator 2‐ethyl‐4‐methylimidazole (2E4MZ) through surface coating on the basis of the complexing treatment with CaCl₂ solution. Hydroxyl‐terminated liquid isoprene rubber (LIR) was regarded as a compatibilizer between EP and NR. It is found that the crystallinity on AF surface is decreased by complexing reaction with CaCl₂ solution. Swelling and mechanical properties of the vulcanized composites, such as swelling degree, tensile and tear strength, tensile modulus at 300% elongation, are measured, and the tensile fracture morphology and dynamic mechanical analysis of the composites are investigated. The results show that the mechanical properties of composites with modified fibers are improved obviously and interfacial adhesion between matrix and the fiber is enhanced, especially for the AF coated with EP and imidazole. The best comprehensive mechanical properties of the composites are obtained with using CaCl₂‐EP/2E4MZ system when the ratio of m(EP)/m(AF) is 3%. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42122.