Strategies to Improve the Compatibility of Polyethylene Terephthalate and Polyethylene Blends

Polyethylene terephthalate (PET) and polyethylene (PE) exhibit complementary properties, offering great potential for applications in recycling and multifunctional material development. However, due to significant differences in polarity, crystallinity, and interfacial tension, PET/PE blends typically suffer from poor compatibility, which affects their mechanical properties, thermal stability, and processability. This review summarizes recent advances in improving the compatibility of PET/PE blends, with a particular focus on the design principles and mechanisms of various compatibilizers, including graft copolymers, functionalized polymers, nanomaterials, and reactive compatibilization agents. In addition, the effects of processing optimization, particle size control, and flowability adjustment on blend performance are discussed. Application such as food packaging, construction engineering, automotive components, and recycling are critically evaluated. Finally, this review identifies key challenges and outlines future strategies: developing eco‐friendly compatibilizers, enhancing multifunctionality, and advancing sustainable recycling. These approaches offer both theoretical insight and practical guidance for PET/PE composite innovation.