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Relationship between the crystallization behavior and the warpage of film-insert-molded parts

Authors

  • Jin Young Kim,

    1. Petrochemicals and Polymers R&D, LG Chem, Limited, Moonji-Dong, Yuseong-Gu, Daejeon 305-380, Korea
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  • Seong Yun Kim,

    1. Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University, Sillim-Dong, Gwanak-Gu, Seoul 151-742, Korea
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  • Young Seok Song,

    1. Fiber System Engineering, Dankook University, Jukjeon-Dong, Suji-Gu, Yongin-Si, Gyeonggi-Do 448-701, Korea
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  • Jae Ryoun Youn

    Corresponding author
    1. Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University, Sillim-Dong, Gwanak-Gu, Seoul 151-742, Korea
    • Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University, Sillim-Dong, Gwanak-Gu, Seoul 151-742, Korea
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Abstract

The dimensional variation of an injection-molded, semicrystalline polymer part is larger than the variation of an amorphous polymer part because the shrinkage of a crystalline polymer is generally greater than the shrinkage of an amorphous one. We investigated the warpage of film-insert-molded (FIM) specimens to determine the effect of the crystallization behavior on the deformation of FIM parts. More perfect crystalline structures and higher crystallinity developed in the core region of the FIM specimens versus other regions. Relatively imperfect crystalline structures and low crystallinity developed in the adjacent regions of the inserted films, whereas a thin, amorphous skin layer developed in the adjacent regions of the metallic mold wall. The crystallizable substrate in the FIM specimens caused very large warpage because nonuniform shrinkage occurred in the thickness direction of the specimens. Therefore, the warpage of an experimentally prepared FIM poly(butylene terephthalate) specimen was greater than that predicted numerically because of its complex crystallization behavior. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

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