A novel approach to prepare self-healing vulcanized natural rubber using tetramethylthiuram disulfide

A novel and simple approach was developed in the present work to prepare vulcanized natural rubber with high tensile strength and self-healing capability. Solid rubber from high ammonia natural rubber (HANR) was vulcanized using various contents (1.0, 1.5, 2.0, 2.5, and 3.0 phr) of tetramethylthiuram disulfide (TMTD). The vulcanized HANR samples were characterized with Raman spectroscopy, swelling tests, and tensile tests to determine their disulfide/polysulfide ratio, crosslinking density, and tensile stress and strain recoveries, respectively. The optimum TMTD content for rubber vulcanization was from 1.5 to 2.0 phr, and the temperature to achieve the best self-healing performance was 150 °C, during which the tensile strength obtained was approximately 4–6 MPa, with 50–60% stress recovery and 80–95% strain recovery. High tensile strength and good self-healing performance were observed for vulcanized HANR samples with high amounts of disulfide bonds and low crosslinking densities.