The effect of polyvinyl chloride and polyethylene terephthalate on the mechanical properties of butyl rubber (IIR)-based thermoplastic elastomer using semi-efficient vulcanisation system and a nano zinc oxide as activator

Abstract

Thermoplastic elastomers (TPEs), a class of materials bridging the gap between rubber and thermoplastics, have revolutionised diverse fields with their unique properties and applications. This study highlights the critical importance of compatibility between plastics, polyvinyl chloride (PVC), polyethylene terephthalate (PET), and butyl rubber (isobutylene-isoprene rubber, IIR) components in TPEs for optimal performance. Several TPEs were prepared with different amounts of plastics. Subsequently, the TPEs were cured, and curing and mechanical properties, and correspondent thermal stability and solvent resistance were measured. It revealed that the thermal stability of TPEs, containing PVC, PET and IIR, was influenced by the type and quantity of each plastic, affecting degradation temperatures. PVC and PET exhibited distinct effects on the curing behaviour of IIR-based TPEs, impacting scorch time and optimum cure time differently. The incorporation of PVC and PET enhanced the organic solvent resistance of the TPEs, attributed to physical barrier effects, enhanced crosslinking, increased crystallinity, and specific interfacial interactions. Tensile strength and elongation at break generally decreased with the addition of plastics, reflecting incompatible interactions and increased crystallinity. Meanwhile, hardness increased due to the rigid structure and filler effects of plastics. Achieving an optimal TPE formulation involves balancing these competing effects.