Controlling the evolution of polypropylene microstructure during melt free radical modification using zinc dithiocarbamate with different N-substituted groups |
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Authors: | Zhenjiang Zhang Dong Wan Yanjie An Feng Liu Haiping Xing Lu Wang Zhiwei Jiang Tao Tang |
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Affiliation: | a State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China b Graduate School of the Chinese Academy of Sciences, Beijing 100039, PR China |
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Abstract: | The effects of zinc dithiocarbamates on degradation and branching of polypropylene (PP) were studied during melt radical modification using a tri-functional monomer (trimethylol propane triacrylate (TMPTA)). High-temperature size-exclusion chromatography (HT-SEC) coupled with differential refractive index detector (DRI), light scattering detector (LSD) and viscometer detector (VD) and rotational rheometry were used to analyse the microstructure of modified PP samples. The chemical structure of the N-substituted group showed an important influence in controlling the evolution of PP microstructure during melt radical reaction. The chain cleavage of PP was controlled in the presence of zinc N, N-dimethyldithiocarbamate (ZDMC), and a substantial long chain branched (LCB) fraction was formed. Without co-agent, the molecular weight of PP decreased measurably, and only a minor LCB fraction was formed. Importantly, considerable amounts of highly branched (microgel and hyperbranched) structures were formed in this case. |
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Keywords: | Degradation Long chain branched Microstructure Polypropylene |
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