Structure and Properties of Isotactic Polypropylene/Polybutene-1 In-reactor Alloys
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ARTICLE
POLYMER SCIENCE
https://doi.org/10.1007/s10118-020-2468-9 Chinese J. Polym. Sci.
Structure and Properties of Isotactic Polypropylene/Polybutene-1 In-reactor Alloys Ya-Ping Ma, Ning Zhang, Wei-Ping Zheng, Ai-Hua He*, and Chen-Guang Liu* Shandong Provincial Key Laboratory of Olefin Catalysis and Polymerization, Key Laboratory of Rubber-Plastics (Ministry of Education), School of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
Abstract The composition and structure of polymer largely determine the properties of its final products. As a novel polymer material, the composition, structure, and properties of the isotactic polypropylene/polybutene-1 in-reactor alloy (iPP/iPB alloy) synthesized by sequential twostage polymerization with Ziegler-Natta catalyst were correlated for the first time in this work. The iPP/iPB alloy was fractionated by temperature rising elution fractionation (TREF) in a broad temperature ranged from –30 °C to 140 °C, and the chain microstructures and sequence distributions of isolated fractions were analyzed by DSC, GPC, 13C-NMR, and FTIR. The iPP/iPB alloy was composed of five components, namely high isotactic PB (iPB, 85.8 wt%), medium isotactic PB (mPB, 5.1 wt%), poly((butene-1)-block-propylene) copolymers (PB-b-PP, 4.1 wt%) which contained PB and PP blocks with different lengths according to the isolation temperature, isotactic PP (iPP, 2.7 wt%), and atactic PB (aPB, 2.3 wt%). Compared to other commercial pipe materials, the iPP/iPB alloy presented outstanding thermal creep resistance and gas permeability resistance, high strength and low deformation at high temperature, and appropriate flexural strength. The roles of PP and PB-b-PP components in the alloy were interpreted. This work is expected to elucidate the potential application of iPP/iPB alloy as pipe materials and provide solutions for the design and synthesis of high performance pipe materials. Keywords Polybutene-1; Alloy; Block copolymer; Structure; Property Citation: Ma, Y. P.; Zhang, N.; Zheng, W. P.; He, A. H.; Liu, C. G. Structure and properties of isotactic polypropylene/polybutene-1 in-reactor alloys. Chinese J. Polym. Sci. https://doi.org/10.1007/s10118-020-2468-9
INTRODUCTION Isotactic polybutene-1 (iPB) possessing excellent creep resistance, high toughness, and high thermal deformation temperature is widely used in hot-water pipe fields.[1] iPB exhibits complex polymorphic behavior and can crystallize into hexagonal form I/I′, tetragonal form II, or orthorhombic form III according to the crystallization situations.[2−4] The kinetically favored metastable form II crystallized from molten state can transform into thermodynamically stable form I spontaneously and irreversibly, and finally iPB with significantly enhanced mechanical properties is obtained.[5−11] However, this transformation usually takes more than one week and the long transition period inevitably increases the production cost of the iPB pipes. It was reported that mixing iPB with isot
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