Controlling melt reactions during preparing long chain branched polypropylene using copper N,N-dimethyldithiocarbamate |
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Authors: | Zhenjiang Zhang Haiping Xing Jian Qiu Haiou Yu Xiaohua Du Yanhui Wang 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, China |
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Abstract: | Effect of copper N,N-dimethyldithiocarbamate (CDD) on melt reactions during preparing long chain branched polypropylenes (LCB-PP) via free radical grafting was studied. The structure and rheological properties of the modified PPs were characterized. The results showed that CDD could efficiently control two side reactions, i.e. degradation of PP backbone and homopolymerization of multifunctional monomer (trimethylol propane triacrylate (TMPTA)) in the presence of peroxide. Meanwhile the addition of CDD also increased the efficiency of forming LCB structure. The reaction between CDD and active free radicals (carbon centered and alkoxy species) led to forming in situ dithiocarbamate radicals, which cannot attack PP backbone and are weaker initiator for TMPTA. The resultant dithiocarbamate radicals could react with the PP macroradicals and the acrylic radicals reversibly, which prolong the life time of PP macroradical and increase the reaction probability between macroradicals. The obtained LCB-PP showed high melt strength. |
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Keywords: | Long chain branch Melt reaction Polypropylene |
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