Get access

Investigation on the morphology and tensile behavior of β-nucleated isotactic polypropylene with different stereo-defect distribution

Authors

  • Hongmei Peng,

    1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan, People's Republic of China
    Search for more papers by this author
  • Bin Wang,

    1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan, People's Republic of China
    Search for more papers by this author
  • Jinggang Gai,

    1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan, People's Republic of China
    Search for more papers by this author
  • Jinyao Chen,

    1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan, People's Republic of China
    Search for more papers by this author
  • Feng Yang,

    1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan, People's Republic of China
    Search for more papers by this author
  • Ya Cao,

    1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan, People's Republic of China
    Search for more papers by this author
  • Huilin Li,

    1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan, People's Republic of China
    Search for more papers by this author
  • Jian Kang,

    Corresponding author
    1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan, People's Republic of China
    Search for more papers by this author
  • Ming Xiang

    1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan, People's Republic of China
    Search for more papers by this author

ABSTRACT

Large amount of work has been published on the tacticity-properties relationship of isotactic polypropylene (iPP). However, the stereo-defect distribution dependence of morphology and mechanical properties of β-nucleated iPP (β-iPP) is still not clear. In this study, two different iPP resins (PP-A and PP-B) with similar average isotacticity but different uniformities of stereo-defect distribution were selected, their β-iPP injection molding specimens were prepared, and the morphology evolution and tensile behaviors were studied by means of differential scanning calorimetry (DSC), 2D wide-angle X-ray diffraction (2D-WAXD) and scanning electron microscope (SEM). DSC results showed that with the same concentration of β-nucleating agent (0.3 wt % WBG-II), PP-B with more uniform stereo-defect distribution exhibited more amount of β-phase than that of PP-A with less uniform stereo-defect distribution, indicating that PP-B is more favorable for the formation of β-phase. SEM results showed that PP-B formed more amount of β-crystals with relatively high structural perfection, while in PP-A a mixed morphology of α- and β-phase with obviously higher amount of structural imperfection emerges. The results of room-temperature tensile test indicated that the yield peak width of PP-B was obviously wider, and the elongation at break of PP-B was higher than that of PP-A, showing a better ductile of PP-B. The morphology evolution results of SEM, 2D-WAXD and DSC suggest that, a combination of lamellar deformation and amorphous deformation occurred in PP-A, while only amorphous deformation mainly took place in PP-B, which was thought to be the reason for the different tensile behaviors of the samples. In the production of β-PP products via injection molding, the uniformity of stereo-defect distribution was found to be an important factor. PP with more uniform distribution of stereo-defect favors the formation of large amount of β-phase with high perfection, which exhibit superior ductile property. The related mechanism was discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40027.

Ancillary