Virgin-like High-Density Polyethylene from Recycled Mixed Polyolefins

Reported herein is the compatibilization of mixed polyolefins containing a rheology modifier (M-PORM) derived from municipal solid waste (MSW) by using different types of compatibilizers. One compatibilizer was produced “in situ” during reactive extrusion (REX), and the other compatibilizers were commercial styrenic block copolymer and maleated polymer-based compatibilizers. Both “in situ” and commercial compatibilizers were first used in laboratory-controlled polyolefins containing a rheology modifier (denoted as L-PORM) and were investigated for their mechanical properties. The study was then extended to a rheology modifier containing recycled mixed polyolefins (M-PORM), where the effects of both compatibilizers were evaluated. Compared to the in situ and other commercial compatibilizers, the styrenic block copolymer offered superior performance, as it enabled the synthesis of virgin-like high-density polyethylene (HDPE) from the M-PORM. The findings suggest that M-PORM can be transformed into blends with virgin HDPE-like properties, thus offering an industrially relevant approach for the re- and upcycling of mixed polyolefins. The M-PORM pellets with uniform MFI and good mechanical properties can be used as injection mold feedstocks for different applications such as in the construction and automotive sectors.