Enhancing mechanical properties of prevulcanized natural rubber latex via hybrid radiation and peroxidation vulcanizations at various irradiation doses

Abstract

At present, there are three popular vulcanization processes being used in natural rubber latex industries, which are sulfur, radiation and peroxide vulcanization. Sulfur vulcanization produced products with superior mechanical properties compared to radiation and peroxide vulcanization. This paper discussed the effect of gamma irradiation dose on hybrid radiation and peroxidation vulcanizations in improving the mechanical properties of radiation vulcanized natural rubber latex (RVNRL). Latex compounding formulations are developed based on 2.5 parts per hundred rubber (phr) of hexanediol diacrylate (HDDA) as the sensitizer, 0.1 phr of tert-butyl hydroperoxide (t-BHPO) as the co-sensitizer and 2.5 phr of Aquanox LP antioxidant. The RVNRL was prepared and irradiated at various gamma radiation doses of 2, 4, 6, 8, 10 and 12 kiloGray (kGy). The rubber film obtained from irradiation at 6 kGy had tensile strength, modulus @ 500% and modulus @ 700% of 27.0, 3.0 and 11.0 MPa, respectively, which is more than 37% increment compared to the control film. Besides, the crosslink percentage of the rubber film showed 4% increment from 90% to 94%.