Compatibilization of Polyethylene and Polypropylene via Lignin-Cluster-Induced Dynamic Cross-Linking

Polyethylene (PE) and polypropylene (PP) are thermodynamically immiscible, posing significant challenges for their recycling. Consequently, enhancing the compatibility of PE/PP blends has garnered increasing research interest in recent years. In this study, we transformed the physical mixture of PE and PP into a dynamically cross-linked single network of the two immiscible polymers by utilizing a lignin-based cluster as the interfacial compatibilizer and dynamic cross-linker. Through precise morphology control at the PE–PP interface, the originally brittle PE/PP blend was converted into a tough hybrid plastic with excellent photothermal conversion and ultraviolet (UV) shielding properties. At the optimal formulation, (PE60/PP40)-g-(L2-Zr-GMMA) achieved a tensile strength of 24.35 MPa, an elongation at break of 675.48%, and a Young’s modulus of 279.11 MPa. The lignin-cluster-induced compatibilization process we report here may shed some light on addressing the major obstacle in sustainable PE and PP recycling.