Feasibility of Utilizing Waste Natural Rubber Gloves as a Primary Rubber Matrix: Aspect of Vulcanization Systems

In this study, the potential for re-mixing and re-vulcanizing waste natural rubber glove (WNRG) material by using it as the primary matrix was investigated. Alternative types of vulcanization systems, namely, sulfur, phenolic resin, and peroxide, were employed. The results unequivocally demonstrated that residual vulcanizing agents contained in the WNRG were not sufficient to cause crosslinking reactions without re-mixing with vulcanizing agents. Among the various vulcanization approaches, sulfur produced the greatest properties, whereas phenolic resin gave moderate performance. The WNRG vulcanized with sulfur demonstrated the highest crosslink density, tear strength, tensile strength, hardness, and strain-induced crystallization ability among the tested alternatives. The tensile strength of WNRG vulcanized with sulfur was approximately 16.23 MPa, which was 31.7% and 51.1% greater than the WNRG vulcanizates made with phenolic resin and peroxide, respectively. Because of its highest crosslink density, the WNRG vulcanizate with sulfur also offers the greatest storage modulus among the tested cases. The results clearly suggest that the WNRG can potentially be re-compounded, re-vulcanized, and used as the primary matrix. WNRG could be used as a matrix at an industrial scale, to minimize the environmental issues and increase the added value from waste gloves. The findings provide practical guidance for recycling waste rubber gloves in industrial applications, which would be a more sustainable solution for solving the problems associated with WNRG.