Blending Behavior of High-Degree Long-Chain-Branched Polypropylene Prepared by Ziegler–Natta Catalysis with Common Polypropylene
Kang Li, Yawei Qin, Songmei Zhao, Jin‐Yong Dong
Abstract
Two high-degree long-chain-branched polypropylenes (LCB-PPs), one being homopolymer and the other random copolymer (with a minor composition of ethylene), were prepared in industrial trials by Ziegler–Natta catalysis with the ω-alkenylmethyldichlorosilane-mediated successive polymerization-hydrolysis chemistry. They were then melt-blended with a common PP homopolymer and random copolymer resins, respectively. The compositional ratios (weight percentage ratio, LCB-PP/common PP) in the blends were controlled in a broad range, from 20/80 to 80/20, each increased/decreased by 10%. The results indicate that the LCB-PP is well miscible with the common PP. From the perspective of LCB-PP, the blends diversify their properties, extending the product range to higher melt flow rates. On the other hand, the blends bring the best-fit LCB structure to common PP, boosting their melt strength and melt processability involving extensional flow in a highly controlled manner. However, exceptions exist to defy the composition dependency. For the homopolymer blends, their Young’s moduli are noticeably higher than the individual LCB-PP and common PP constituents. Moreover, both the homopolymer and random copolymer blends were measured at higher crystallization temperatures (Tc) than their individual components. The nucleation effect of the LCB structure is deemed to play an exceptional role in the LCB-PP/common PP blends.