Crystallization, Phase and Mechanical Behaviors of Linear Low Density Polyethylene/Thermoplastic Polyolefin Elastomer Blends

Blending polyethylene with thermoplastic polyolefin elastomers (TPOs) is a promising way to manipulate its structures and tailor its properties. Herein, three TPOs, i.e., two ethylene-octene copolymers (EOCs) and an olefin block copolymer (OBC) with different structures, were used to comparatively investigate the miscibility, crystallization, and phase behavior of their blends with a linear low-density polyethylene (LLDPE). It was found that large differences occurred in the crystallization and phase behaviors of the blends due to the different extent of similarity in the molecular structure between the TPO and the LLDPE matrix. In particular, a unique segregated phase morphology comprised a less stable crystalline phase and a rubbery phase was found in an LLDPE/EOC blend. The tensile performance and elasticity of the blends were also studied and correlated with the structures of the blends. This work not only provides novel results on the miscibility and phase behavior of the similar-structured LLDPE/TPO blends, but can also guide the design of LLDPE-based products with tailored performances.