Relating scratch resistance to injection molding-induced morphology of polypropylene

Authors

  • Yutaka Kobayashi,

    Corresponding author
    1. Research & Development Division, Prime Polymer Company, Limited, 580-30 Nagaura, Sodegaura-City, Chiba 299-0265, Japan
    2. Division of Material Sciences, Graduate School of Natural Science & Technology, Kanazawa University, Kakuma-Machi, Kanazawa-City, Ishikawa 920-1192, Japan
    • Research & Development Division, Prime Polymer Company, Limited, 580-30 Nagaura, Sodegaura-City, Chiba 299-0265, Japan
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  • Yasuhiko Otsuki,

    1. Research & Development Division, Prime Polymer Company, Limited, 580-30 Nagaura, Sodegaura-City, Chiba 299-0265, Japan
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  • Hiroaki Kanno,

    1. Analysis Research Laboratories, Mitsui Chemical Analysis & Consulting Service Incorporated, 580-30 Nagaura, Sodegaura-City, Chiba 299-0265, Japan
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  • Yasuhiro Hanamoto,

    1. Analysis Research Laboratories, Mitsui Chemical Analysis & Consulting Service Incorporated, 580-30 Nagaura, Sodegaura-City, Chiba 299-0265, Japan
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  • Toshitaka Kanai

    1. Division of Material Sciences, Graduate School of Natural Science & Technology, Kanazawa University, Kakuma-Machi, Kanazawa-City, Ishikawa 920-1192, Japan
    2. Research & Development Laboratory, Idemitsu Kosan Company, Limited, Anasaki-Kaigan, Ichihara-City, Chiba 299-0193, Japan
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Abstract

The relationship between the scratch resistance and the injection molding-induced morphology of polypropylene (PP) was investigated. The crystal structure near the surface was controlled by the mold temperature and the doping of a nucleating agent (NA). Although α- and β-NA were used to improve the scratch resistance of PP that was molded at a mold temperature of 40°C, both of the NAs only slightly affected the scratch resistance due to low crystallinity at the surface. When the mold temperature was increased, the skin layer became thin and a β-form crystal formed. Plastic deformation under the scratch was limited in the frozen layer. Consequently, the thickness of the frozen layer (which had low crystallinity) had the predominant effect on the scratch resistance in comparison to the polymorphism differences. The crystal morphology was analyzed with synchrotron micro-beam wide angle X-ray diffraction and Fourier transform infrared spectroscopy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

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