Effects of palmitamide on cure and tensile properties of styrene butadiene rubber

Abstract

A semi EV curing system was applied for studying the effects of palmitamide on cure and tensile properties of silica-filled styrene-butadiene rubber (SBR) compounds. The palmitamide was prepared from palmitic acid and urea. As an additive material, the palmitamide was added into the silica-filled SBR at 0.0, 1.0, 3.0, 5.0 and 7.0 parts per hundred rubber (phr.). It was found that the palmitamide acted as a curative additive material which decreased the scorch and cure times but increased the difference in torque of the silica-filled SBR compounds. The higher the palmitamide loading, the shorter the scorch and cure times were. It was also found that the palmitamide acted as an internal plasticizer material which decreased the minimum torque. The tensile moduli and tensile strength were increased but the elongation at break was decreased up to a 3.0 phr. of palmitamide loading. From the swelling test, the improvements in tensile properties were attributed to the improvements in crosslink density as well as the cure state of the silica-filled SBR compounds.