Regulation of crystalline morphologies and mechanical properties of olefin multiblock copolymers by blending polymer with similar architecture of constituent blocks

- OBC is blended with polymers possessing architecture similar to constituent blocks.
- The crystalline morphologies and mechanical properties are regulated by blending approach.
- PE chains and OBC hard blocks are inclined to cocrystallize.
- The strength of OBC samples is improved without great depression of tenacity.

In this work, the crystalline morphologies and mechanical properties of olefin multiblock copolymer (OBC) were regulated by blending with polymers possessing architecture similar to the constituent blocks. In order to understand the influence of multiblock architecture on the interaction between OBC and blended substances, ethylene-octene random copolymer (ORC) with similar crystallinity was blended with corresponding substances for comparison. We found that polyethylene (PE) chains, which possessed architecture resembling hard blocks, were inclined to cocrystallize with OBC and form remarkable lamellar structure in their blends. On the contrary, they aggregated together in ORC matrix and developed crystals similar to pure PE. The distinct crystalline properties were closely correlated to their state in the melt as revealed by Time-Temperature superposition examinations. The results of tensile tests exhibited that the strength of OBC samples could be improved without great depression of tenacity when appropriate amount of PE was blended. This might be ascribed to the good compatibility between added PE and OBC hard blocks considering their similar chain architecture. The findings contribute to understanding the relationship between morphologies and apparent properties of multi-block copolymer-based blends, which can be significant to achieve target mechanical properties for multiblock copolymers by a simply blending approach.