Peel Adhesive Properties of Polymer Laminates Composed of Polyethylenes and Polypropylenes

Abstract

Peel adhesive strengths of multi-layered laminates composed of two polypropylene (PP) sheets and an inserted polyethylene (PE) layer (the middle layer) between the PP layers were evaluated. PE-glycidyl methacrylate (GMA) copolymers and a maleic-anhydride grafted PP (MAPP) were compared to the PE homopolymer and the PP homopolymer. The peel adhesive strength of PE-GMA/MAPP laminates was much higher than that of PE homopolymer/PP homopolymer laminates. Meanwhile, the blends composed of the PE-GMA and three types of PE homopolymer (PE-GMA+LDPE, PE-GMA+MDPE, PE-GMA+HDPE) were formulated as the PE middle layer of the multi-layered laminates. The PE blends had the same amount of glycidyl groups, and the deformation capacity was different in each. Namely, the PE blend of LDPE had higher elongation to break than the PE blend of HDPE. The peel adhesive strength of the multi-layered laminates with the middle layer of the LDPE blend was highest among the three types of laminates with the middle layer of the PE blends. Scanning electron microscopy on the fractured surfaces revealed that the large plastic deformation of the LDPE blended middle layer was responsible for the high energy absorption, and resulted in the high peel strength.