The silica-filled natural rubber in presence of epoxidized natural rubbers: curing, swelling and tensile properties

Abstract

The two types of epoxidized natural rubbers (ENR-25 and ENR-50), having 25 and 50 moles of epoxidation, were used to study the influences of their incorporations on optimum curing time, swelling and tensile properties of silica-filled natural rubber (NR) compounds. The NR vulcanizates were filled by silica filler at a fixed loading at 30.0 phr and the ENRs were incorporated separately into the filled NR compounds with varied concentration i.e 5, 10, 15, 20 and 25 phr. The filled-NR compounds were prepared based on a semi-efficient cure formulation and cured at 150 °C. From the results, it was revealed that both the ENRs acted as curatives and compatibilizers. They increased the optimum curing time and crosslinks level of the silica-filled NR compounds. The higher the ENRs loadings; the higher was the optimum curing time and crosslinks level. It was also revealed that the tensile moduli and tensile strength were raised; the elongations at break were reduced as the ENRs incorporations were raised to 25 phr of concentration. At a similar concentration, the ENR-25 exhibited a less pronounced curative and compatibilization affections than ENR-50.