Preparation of long-chain branching polypropylene and investigation on its foamability

Authors

  • Wen Zhang,

    Corresponding author
    1. College of Materials Science and Engineering, Fujian Normal University, Fuzhou 350007, People's Republic of China
    2. Fujian Key Laboratory of Polymer Materials, Fuzhou 350007, People's Republic of China
    • College of Materials Science and Engineering, Fujian Normal University, Fuzhou 350007, People's Republic of China
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  • Lili Yang,

    1. College of Materials Science and Engineering, Fujian Normal University, Fuzhou 350007, People's Republic of China
    2. Fujian Key Laboratory of Polymer Materials, Fuzhou 350007, People's Republic of China
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  • Peng Chen,

    1. College of Materials Science and Engineering, Fujian Normal University, Fuzhou 350007, People's Republic of China
    2. Fujian Key Laboratory of Polymer Materials, Fuzhou 350007, People's Republic of China
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  • Huaji Zhang,

    1. College of Materials Science and Engineering, Fujian Normal University, Fuzhou 350007, People's Republic of China
    2. Fujian Key Laboratory of Polymer Materials, Fuzhou 350007, People's Republic of China
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  • Wei Lin,

    1. Quanzhou Sansheng Rubber & Plastic Foamed Shoes Materials Co., Ltd., Quanzhou 362000, People's Republic of China
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  • Yuexiang Wang

    1. Quanzhou Sansheng Rubber & Plastic Foamed Shoes Materials Co., Ltd., Quanzhou 362000, People's Republic of China
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Abstract

In this work, zinc N,N-dimethyldithiocarbamate (ZDMC) was used to mediate the melt modification of polypropylene (PP) with 1,6-hexanediol diacrylate (HDDA) in an internal mixer in the presence of dicumyl peroxide (DCP). Fourier transformed infrared spectroscopy analysis revealed that HDDA was directly grafted onto PP backbone. The dependence of torque on processing time indicated that the presence of ZDMC restrained the degradation of PP, and the end-torque value increased with the addition of ZDMC. Dynamic rheological measurement indicated that the modified PP possessed higher G′ and lower tan δ at low frequency, displaying an increase in η* and disappearance of Newtonian plateau in η*–ω plot, as well as larger radius of semicircle in Cole–Cole plot. All the rheological characterizations, together with the decreased gel content with the increase of ZDMC, confirmed the formation of long-chain branching. Subsequently, the foamability of the modified samples was investigated by one-step compression–molding process. The cellular structure and morphology of the obtained foams were observed by scanning electron microscopy, and the results showed that the addition of ZDMC decreased the cell size, increased the cell density, and brought about well-defined closed cell structure. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

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