Journal of Materials Science

, Volume 46, Issue 24, pp 7830–7838 | Cite as

Morphological comparison of isotactic polypropylene molded by water-assisted and conventional injection molding

  • Xianhu Liu
  • Guoqiang ZhengEmail author
  • Kun Dai
  • Zhenhua Jia
  • Songwei Li
  • Chuntai LiuEmail author
  • Jingbo Chen
  • Changyu Shen
  • Qian Li


It is well known that water-assisted injection molding (WAIM) process can be fulfilled based on the melt filling stage of conventional injection molding (CIM) process. However, due to the different physical fields involved during WAIM and CIM processes, WAIM part should exhibit unique morphological features compared with the CIM one. In this study, isotactic polypropylene (iPP) parts were prepared by WAIM and CIM, respectively, and their comparative study on morphology were therefore carried out by means of polarized optical microscopy (POM) and two-dimensional (2D) wide-angle X-ray diffraction (WAXD). POM observations illustrated that the WAIM part exhibits a “skin–core–water channel” structure, while the CIM part shows a typical “skin–core” structure. 2D-WAXD results showed obvious arclike reflections in each position along thickness direction of the WAIM part, indicating a pronounced molecular orientation. Furthermore, a parent–daughter model (or branched shish-kebab structure) appears at 0 and 100 μm for both the parts, and the fraction of daughter lamellae for WAIM part is lower than that of CIM part. As for the 1D-WAXD curves, it is noticed that there is a very tiny (300) reflection of β-form in the CIM part, while it is invisible in all positions of the WAIM part. In addition, the crystallinity and crystalline size L of CIM part are found to be higher than that of WAIM part. Those results demonstrate that water penetration and rapid cooling rate have a significant effect on the morphological features of WAIM part.


Water Injection Water Penetration Core Zone Isotactic Polypropylene Crystalline Morphology 



The authors thank National Natural Science Foundation of China for financial support (Grant No. 50803060, 10872185, and 10872186) and the authors also thank Prof. Guoqiang Pan and Liangbin Li from National Synchrotron Radiation Laboratory (NSRL) in University of Science and Technology of China for their help in synchrotron 2D-WAXD experiment.

Supplementary material

10853_2011_5764_MOESM1_ESM.docx (158 kb)
Supplementary material 1 (DOCX 157 kb)


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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Xianhu Liu
    • 1
  • Guoqiang Zheng
    • 1
    Email author
  • Kun Dai
    • 1
  • Zhenhua Jia
    • 1
  • Songwei Li
    • 1
  • Chuntai Liu
    • 1
    Email author
  • Jingbo Chen
    • 1
  • Changyu Shen
    • 1
  • Qian Li
    • 1
  1. 1.College of Materials Science and Engineering, The Key Laboratory of Advanced Materials Processing & Mold of Ministry of EducationZhengzhou UniversityZhengzhouPeople’s Republic of China

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