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Temperature is one of the key parameters to determine the structures and properties of polymers during processing, but the effect of processing temperature on similar-structured polymer blends has rarely been reported. In this work, a linear low-density polyethylene (LLDPE)/ethylene-octene copolymer (EOC) blend with similar-structured components was chosen as a model system to study the effect of processing temperature (including compounding temperature and molding temperature) on its crystallization, phase morphology, and tensile behavior. It was found that the blends presented evenly distributed rubbery domains at lower processing temperatures, whereas a special, EOC-rich phase domain consisting of a less stable crystalline phase and a rubbery phase was observed at higher processing temperatures. The phase morphology was mainly determined by the final processing temperature, which had a major effect on the yield stress of the material. This work not only reports novel results on processing-structure-performance relations of similar-structured blends but can also guide the design and production of LLDPE-based products with tailored properties. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]