Effect of silane coupling agent on the curing, tensile, thermal, and swelling properties of ethylene-propylene-diene monomer rubber (EPDM)/mica composites

Abstract

The influence of silane (bis[3-triethoxysilylpropyl] tetrasulfide) coupling agent on the properties of ethylene-propylene-diene monomer rubber (EPDM)/mica composites was studied. Both EPDM/mica composites with silane and those without silane were compounded by using a two-roll mill at various filler loadings (i.e., 100/0, 100/10, 100/30, 100/50, 100/70). The tensile and thermal properties as well as the fracture surfaces of the composites were investigated by using an Instron Universal Testing Machine, a thermal gravimetric analyzer, and a field emission scanning electron microscope. The results indicated that the optimum cure time (t90) and scorch time (ts2) values were shorter, whereas the maximum torque (MH) value was slightly higher, for EPDM/mica composites with silane compared to those without silane. The tensile properties, modulus at 100% elongation, and modulus at 300% elongation increased for the composites made with silane, and the optimum filler loading for those properties was 50 parts by weight per hundred parts of rubber. In addition, thermal stability and swelling ratio for both composites improved with increased filler loading. However, the composites with silane showed better thermal stability and swelling ratio because of stronger linkage at the rubber-filler boundary, which promoted filler dispersion. J. VINYL ADDIT. TECHNOL., 20:116-121, 2014. © 2014 Society of Plastics Engineers.