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Effect of polytetrafluoroethylene on the foaming behaviors of linear polypropylene in continuous extrusion

Authors

  • Kun Wang,

    1. Ningbo Key Lab of Polymer Materials, Division of Polymers and Composites, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, China
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  • Fei Wu,

    1. Ningbo Key Lab of Polymer Materials, Division of Polymers and Composites, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, China
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  • Wentao Zhai,

    1. Ningbo Key Lab of Polymer Materials, Division of Polymers and Composites, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, China
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  • Wenge Zheng

    Corresponding author
    1. Ningbo Key Lab of Polymer Materials, Division of Polymers and Composites, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, China
    • Ningbo Key Lab of Polymer Materials, Division of Polymers and Composites, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, China
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Abstract

Linear polypropylene (PP) foams, blown in the continuous extrusion process using supercritical CO2 as the blowing agent, exhibited poor cell morphology and narrow foaming window, because of their low melt strength. In this study, polytetrafluoroethylene (PTFE) was blended with PP resin with the aim of improving the foaming behavior of PP. It was found that the PTFE particles were deformed into fine fibers under shear or extensional flows during the extrusion process, which significantly increased the melt strength of PP from 0.005 N to 0.03 N (PP/PTFE with PTFE content of 4.0 wt %) at 230°C. The experimental results indicated that the presence of PTFE improved the cell morphology of PP foams and broadened the foaming window of PP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

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