The Possible Scalability of Mesophase Separation on Macrophase Separation and Crystallization of iPP/OBC Blends

Abstract

This work focuses on the effect of the unique molecular structure of OBC (olefin block copolymer) constituted by soft blocks and hard blocks on the compatibility of OBC/iPP (isotactic polypropylene) blends. Two OBCs with high and low octene content were selected to blend with iPP. The thermal behavior, morphology, and kinetics of crystallization of the binary blends were studied systematically. The variation in octene content of the OBCs caused a dramatic difference in their own mesophase separation as well as their compatibility with iPP in blends. As the octene content increased, mesophase separation of OBC became more and more dominant, with the strong repulsive interaction between the hard and soft blocks of OBC and the coupled fact that the majority of the soft blocks are more compatible with iPP, resulting in its better compatibility with iPP. This was proved by smaller dispersed domain size, better interfacial adhesion, and faster crystallization kinetics. On the other hand, we also found that annealing time was important in controlling the superstructure in blends. There is a possible scalability of the mesophase separation of OBC on the compatibility and superstructure of the OBC/iPP binary blends. According to our results, it is reasonable to obtain a systematic profile to adjust the compatibility as well as the superstructure to satisfy different mechanical requirement by regulating octene content in the OBC and the annealing condition of the blends.

A physical strategy for the preparation of isotactic polypropylene spheres with microsphere and bead–string spherulite morphologies

“…When comparing Figure (a) with Figure (b), it is confusing to find out that the domain size in 4–70 was almost the same or a little larger than that in 1–70, which is again seemingly contradictory to our previous results . To explain this somewhat surprising result, spinodal decomposition kinetics were considered.…”

“…To explain the difference between these two blends, it is necessary to recall the conclusion of our previous study on iPP/OBC . According to the results of our previous studies, it is known that the compatibility of iPP with OBC4 is much better than that with OBC1.…”

“…As for the iPP/OBC blends, the effect of OBCs' distinct molecular structure on the compatibility of iPP/OBC blends was also investigated systematically earlier . The repulsion effect between the hard blocks and the soft blocks enhances mixing between iPP and OBC comparatively.…”

Properties and preparation of olefin block copolymer/thermoplastic polyurethane blends

“…Several recent works have investigated the relationships between structure and properties of novel OBCs . However, only a few OBC blends available in the literature includes OBC/PP (polypropylene), OBC/SEBS (styene‐ethylene‐butylene‐styrene copolymer), and OBC/ethylene‐octene (EO) copolymer …”

Mechanical and optical effects of elastomer interaction in polypropylene modification: Ethylene-propylene rubber, poly-(ethylene-co-octene) and styrene-butadiene elastomers

“…The main reason for the comparably poor impact performance is the relatively high glass transition temperature of these polymers at ~-30°C. Only limited experience exists so far for the use of olefin block copolymers produced with a chain-shuttling catalyst concept [18,21,22], but no particularly advantageous optical performance has been reported. Finally, styrene-based elastomers of the di-or triblock type have found uses in special areas despite their comparatively higher price [23,24].…”