Adhesion of olefin block copolymers to polypropylene and high density polyethylene and their effectiveness as compatibilizers in blends

Adhesion of four ethylene-octene block copolymers (OBCs) to polypropylene (PP) and high density polyethylene (HDPE) was studied by peeling PP/OBC/HDPE microlayered tapes. The four OBCs had different comonomer composition, mechanical properties and phase morphology. Through the Irwin damage zone analysis, it was found that the stress-strain behavior of OBC was the primary factor that determined the adhesion strength. Effectiveness of these OBCs as compatibilizers in PP/HDPE blends was also investigated. Toughness of all OBC-compatibilized blends was effectively improved. The OBCs having higher adhesion strength also resulted in better mechanical performance for the compatibilized blends. A quantitative correlation was established between the adhesion strength and mechanical performance of the blends.