Utilization of chloroprene rubber waste as blending component with natural rubber: aspect on metal oxide contents

Recently, reutilization of rubber waste and finding an alternative way to extend its use are a keen interest. This has come to an idea to blend it with virgin rubber to gain synergistic properties from its own advantages. In this study, natural rubber (NR) and recycled chloroprene rubber (R-CR) were blended as a way to combine the mechanical properties and solvent resistance given by NR and R-CR, respectively. Detailed investigations on the role of metal oxide contents in NR/R-CR blends were thoroughly focused. This was mainly to improve the final properties of the blends. Three main functions of metal oxides were promoted, namely activator, curing agent and reinforcing filler. The vulcanization process was found to be accelerated where the mechanical properties and thermal properties are obviously enhanced. Higher amount of metal oxides resulted in excessive crosslink networks and agglomeration formation which detrimental the properties of NR/R-CR blend. Based on the obtained result, the amount of metal oxides required for optimal properties was 4 phr of MgO and 10 phr of ZnO. The glass transition temperature (Tg) of the blends can be increased with increasing the amount of metal oxide due to the presence of molecular restriction arising from its cross-link density.