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.