Compatibilization of iPP/HDPE Blends with PE‑g‑iPP Graft Copolymers

• Published in: ACS macro letters Vol. 9; no. 8; pp. 1161 - 1166
• Main Authors: Klimovica, Kristine, Pan, Sanshui, Lin, Ting-Wei, Peng, Xiayu, Ellison, Christopher J, LaPointe, Anne M, Bates, Frank S, Coates, Geoffrey W
• Format: Journal Article
• Language: English
• Published: American Chemical Society 18.08.2020
• ISSN: 2161-1653; 2161-1653
• DOI: 10.1021/acsmacrolett.0c00339

The compatibilization of polyethylene (PE) and isotactic polypropylene (iPP) blends is of particular interest due to the challenges associated with recycling these plastics from mixed waste streams. Polyethylene-graft-iPP copolymers (PE-g-iPP) were prepared using a grafting-through strategy by copolymerization of ethylene with allyl-terminated iPP macromonomers in the presence of a hafnium pyridylamido catalyst. Graft copolymers with a variety of graft lengths (M n = 6–28 kg/mol), graft numbers, and graft spacings were prepared. These graft copolymers were melt-blended with high-density polyethylene (HDPE) and iPP (iPP/HDPE = 30/70 w/w), and the blend properties were evaluated by tensile testing. The blends showed enhanced tensile strength at 5 and 1 wt % loading, with higher tensile strength observed for larger block numbers and graft lengths. These results indicate that graft copolymers are efficient compatibilizers for blends of HDPE and iPP.