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Flow-induced β-crystal of iPP in microinjection molding: effects of addition of UHMWPE and the processing parameters

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Abstract

The flow-induced β-crystal of isotactic polypropylene (iPP) with addition of ultrahigh molecular weight polyethylene (UHMWPE) molded by microinjection and influences of processing parameters on the formation of β-crystal in iPP/UHMWPE microparts were investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM). It was found that the contents and the dispersion of UHMWE affect the formation of β-crystal in iPP/UHMWPE blend. With the addition of UHMWPE, Kβ values of the blends increased significantly compared with that of the pure iPP and reached the maximum at the content of 2 wt% UHMWPE. In addition, a better dispersion of UHMWPE can facilitate the formation of the β-crystal in the iPP/UHMWPE. The results showed that the thermal stability of the β-crystal was enhanced with increasing the mold temperature. When the mold temperature was increased from 60 to 120 °C, the β-crystal become more perfect. High injection speeds can promote the formation of the β-crystal, but the value of the injection speed must be within a certain range.

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Acknowledgments

This paper was financially supported by State Key Laboratory of Polymer Materials Engineering (Grant No.sklpme2014-2-08), the National Science of China (51121001), Sichuan Youth Science and Technology Foundation (2015JQ0012).

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Authors and Affiliations

  1. College of Polymer Science and Engineering, the State Key Laboratory for Polymer Material Engineering, Sichuan University, Chengdu, 610065, People’s Republic of China

    Qianying Chen, Zhang Xiang, Qi Yang, Miqiu Kong, Yajiang Huang, Xia Liao, Yanhua Niu & Zhongguo Zhao

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  1. Qianying Chen
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Correspondence to Qi Yang.

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Chen, Q., Xiang, Z., Yang, Q. et al. Flow-induced β-crystal of iPP in microinjection molding: effects of addition of UHMWPE and the processing parameters. J Polym Res 23, 16 (2016). https://doi.org/10.1007/s10965-015-0910-4

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