Effect of Rubber-to-Plastic Ratio on POE/HDPE Thermoplastic Vulcanizates Prepared by Dynamic Vulcanization

Thermoplastic vulcanizates (TPVs) are attracting growing interest for their recyclability, low cost, and ease of processing. While polypropylene-based TPVs are well studied and partly commercialized, polyethylene-based systems remain underexplored. Polypropylene tends to degrade during dynamic vulcanization due to its tertiary carbon atoms, requiring stabilizers and complicating processing. In contrast, polyethylene offers better thermal stability and simpler processing, making it a promising alternative for developing cost-effective and high-performance TPVs. In this study, a series of TPVs based on polyolefin elastomer (POE) and high-density polyethylene (HDPE) were prepared via dynamic vulcanization using 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (DBPH) as a crosslinking agent under optimized conditions. The effects of varying rubber-to-plastic ratios on the mechanical, rheological, and thermal properties were systematically investigated. As the POE content increased, torque and gel content rose, while melting/crystallization temperatures and crystallinity decreased. At a rubber-to-plastic ratio of 80:20, the TPV exhibited the best overall performance, with a tensile strength of 4.8 MPa, elongation at break of 282%, and hysteresis loss of 55%. Rheological measurements revealed strong crosslinked networks and good processability under shear. This study demonstrates the significant influence of rubber-to-plastic ratio on TPV properties and offers a practical route to developing high-performance, polyethylene-based thermoplastic elastomers.