Processing, structure, and property relationships in reactively compatibilized heterogeneous multicomponent polyolefin blends

This study investigates the relationships between processing conditions, structural evolution, and macroscopic properties in highly heterogeneous multicomponent polyolefin blends subjected to reactive extrusion. Unwashed post-consumer multilayer plastic films were employed as a complex polyolefin-rich model system to examine reactive compatibilization under realistic compositional heterogeneity. Maleic anhydride–grafted polypropylene (PP-g-MA) was introduced to promote in situ interfacial modification and morphological stabilization, while virgin PP/LDPE blends were used as reference systems to distinguish immiscibility-driven effects from impurity-related contributions.,Blends were processed under two distinct thermomechanical histories to elucidate the competition between reactive interfacial graft formation and thermally induced degradation. Morphological and spectroscopic analyses reveal that moderate processing conditions (<245 °C, medium shear) favor refined phase dispersion, reduced domain size, enhanced interfacial adhesion, and attenuation of carbonyl absorption bands, consistent with controlled compatibilization. Under optimized conditions, incorporation of 5 phr PP-g-MA yielded simultaneous stiffness enhancement and substantial ductility improvement, achieving mechanical performance comparable to, or exceeding, that of selected virgin immiscible blends.,In contrast, severe processing conditions (~260 °C, low shear) promoted volatile formation, interfacial over-stiffening, and embrittlement, indicating that excessive thermal exposure shifts the balance toward degradation-dominated structural evolution. Overall, the results demonstrate that thermomechanical history governs the interplay between reactive compatibilization and degradation processes, ultimately dictating morphology stabilization and mechanical performance in complex immiscible multicomponent polyolefin systems.