Impact of Commercial Polyolefin Architecture and Composition on Its Ability to Compatibilize High‐Density Polyethylene/Isotactic Polypropylene Blends

ABSTRACT Recycling polyolefins is a growing concern as these materials make up approximately 50% of plastic waste. This research focuses on elucidating the relationship between monomer sequence distribution of commercially available ethylene–propylene random copolymers and an ethylene/1‐olefin copolymer and its effect on compatibilizer efficiency in high‐density polyethylene (HDPE)/isotactic polypropylene ( i‐ PP) blends. The compatibilization of both HDPE‐rich and i‐ PP‐rich blends was examined to determine the impact of matrix composition on the ability of these compatibilizers to enhance the mechanical properties of the phase‐separated blend. Overall, the results show that increasing the concentration of the semicrystalline ethylene content and ethylene–ethylene–ethylene triad components in the copolymer compatibilizer improved the tensile toughness of both blends. The toughness of the HDPE‐rich blend was improved by a maximum factor of 20, while the toughness of the i‐ PP‐rich blend doubled in the presence of 5 wt% compatibilizer loading. These findings indicate that the compatibilization of these blends with random copolymers is entanglement‐dependent; however, the presence of semicrystalline segments can greatly increase the compatibilizer efficiency. Additionally, ethylene‐1‐olefin copolymers appear to improve the toughness of the compatibilized blends the most in the HDPE‐rich blends, whereas the ethylene–propylene copolymers are the most effective compatibilizer in the i‐ PP‐rich blends.