Correlation of miscibility and mechanical properties of polypropylene/olefin block copolymers: Effect of chain composition

This study examines the miscibility and mechanical properties of isotactic polypropylene (iPP) and olefin block copolymer (OBC) blends (70/30 wt %). The blends exhibit phase‐separated morphology. The OBC domain size decreases with increasing the 1‐octene content in the soft segment. The crystallization, melting behavior, and the long spacing of the iPP component in the blends are nearly the same as those of neat iPP, while the Tg of the iPP component shifts slightly to lower temperature. “Blocky” OBC is immiscible with iPP, while the soft segment rich polymers in OBC could be partially miscible with iPP. The impact strength of the blends is greatly increased with increasing the 1‐octene content in the OBC soft segment.