The influence of blend composition and filler on the microstructure, crystallization, and mechanical behavior of polymer blends with multilayered structures

Abstract

The preparation of multilayered structures has been thought as a complicated process until our recent study illustrating an effective method through high speed thin wall injection molding (HSTWIM) of polypropylene (PP) and polyethylene (PE) based blends. Current study investigates the effect of blends composition as well as the addition of carbon nanotubes (CNT) on the structure and properties of these blends. It is observed that a close ratio of high density polyethylene (HDPE) and impact copolymer polypropylene (ICP) triggers the formation of a multilayered structure. Meanwhile, PE is migrated into the rubber phase in ICP, leading to the distribution of some rubber phase on the interface between PP and PE, which is thought as beneficial for the interfacial interaction. Meanwhile, epitaxial growth of PE crystals on PP substrate is also observed. The presence of rubber phase on the interface, multilayered structure and epitaxial growth of PE crystals on PP are thought to be responsible for the observed mechanical enhancement in tensile strength as well as strain at break. Furthermore, the addition of CNTs leads to enhanced strength, reduced strain at break and anisotropic conductive network.