Enhancing Polypropylene/Polyethylene Blend Performance Through Compatibilization for A Sustainable Future: A Mini Review Focusing on Establishing Bio‐Derived Filler Based Hybrid Compatibilizer System

Polypropylene (PP) and polyethylene (PE) are widely used polymers but significantly contribute to plastic waste. Effective recycling of PP and PE is essential for reducing plastic pollution and enhancing sustainability. Collection of post-consumer PP and PE wastes forming comingled mixtures is routinely done due to the difficulty of sorting. While polymer blending offers a cost-effective way to recycle these mixtures, their inherent immiscibility limits the development of high-performance blends. This review provides an overview of recent advances in compatibilization strategies aimed at enhancing the PP/PE blend performance, with a focus on using bio-derived fillers as sustainable compatibilizers. Mechanical properties of the PP/PE blends compatibilized by various approaches, including non-reactive, reactive, and bio-derived filler compatibilizations are summarized and discussed in terms of their advantages and weaknesses. Simultaneous incorporation of bio-derived fillers and commercial compatibilizers potentially provides PP/PE blends with more desirable mechanical performance. Furthermore, the review summarizes the rheological and crystallization behaviors of compatibilized blends, emphasizing the significant impact of compatibilization on the processing-structure-property relationships within the blends. Current challenges and future directions in using bio-derived fillers to enhance PP/HDPE compatibilization are discussed. This review provides insight into a sustainable future by endowing plastic waste with desirable properties for broader applications.