Dynamic Modificationof Polyolefin Elastomer UsingBenzoyl Peroxide for Enhanced Compatibility in Immiscible PolymerBlends

Developing effective compatibilizers is essential for improving the performance of immiscible polymer blends and enabling the upcycling of mixed plastic waste. In this work, a dynamically modified polyolefin elastomer (POE) compatibilizer was prepared, and its compatibilization effect was evaluated in polyethylene (PE)/polystyrene (PS) blends. Through dynamic melt-mixing POE with 2 phr benzoyl peroxide (BPO) at 160 °C for 30 min, a modified POE compatibilizer (designated as POEBPO) with a grafting level of 2.9 benzoate groups per 1000 carbon atoms was successfully obtained. Upon incorporating 10 wt % POEBPO into a PE/PS blend (80/20, w/w), the dispersed-domain size was decreased from 4.08 ± 1.8 μm to 3.24 ± 0.9 μm, while the elongation at break and notched impact strength were significantly improved compared to those of the blend containing 10 wt % unmodified POE. Spectroscopic analyses revealed increased gauche conformations of PS chains in the presence of POEBPO, which, together with other characterization results, indicate the existence of enhanced intermolecular interactions, likely involving π–π interactions between the grafted benzoate groups and the aromatic rings of PS. Together with the intrinsic structural similarity between the POE backbone and the PE matrix, the long-chain branched architecture of POEBPO and the possible π–π interactions synergistically contribute to the enhanced compatibilization efficiency for PE/PS blends. These findings demonstrate that dynamic modification of POE offers a practical strategy for preparing efficient compatibilizers for immiscible polymer blends, thereby providing a viable route toward the upcycling of mixed plastic waste.