Formation of double skin-core orientated structure in injection-molded Polyethylene parts: Effects of ultra-high molecular weight Polyethylene and temperature field

In the current work, the effect of ultra-high molecular weight polyethylene (UHMWPE) and temperature field on the unique double skin-core orientated structure and mechanical properties of high-density polyethylene (HDPE) parts molded by multi-melt multi-injection molding (MMMIM) were investigated us...

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Bibliographic Details
Published in:Journal of polymer research 2014-05, Vol.21 (5), p.1-14, Article 432
Main Authors: Feng, Jian, Wang, Long, Zhang, Rui-Yan, Wu, Jing-Jing, Wang, Chun-Yan, Yang, Ming-Bo, Fu, Xiao-Rong
Format: Article
Language:English
Subjects:
Characterization and Evaluation of Materials
Chemistry
Chemistry and Materials Science
Industrial Chemistry/Chemical Engineering
Lamellar structure
Melts
Molecular structure
Molecular weight
Original Paper
Polyethylenes
Polymer Sciences
SAXS
Scanning electron microscopy
Temperature distribution
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Summary:In the current work, the effect of ultra-high molecular weight polyethylene (UHMWPE) and temperature field on the unique double skin-core orientated structure and mechanical properties of high-density polyethylene (HDPE) parts molded by multi-melt multi-injection molding (MMMIM) were investigated using a variety of characterization techniques including rheological experiments, scanning electron microscopy (SEM), synchrotron small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC) and tensile testing. The SEM results revealed that a distinct double skin-core orientated structure was formed in samples molded via MMMIM. That is, compact lamellar together with typical shish-kebab structures was formed from the skin to the sub-skin, and large area of oriented lamellar was formed again near the core layer due to the significantly improved relaxation time of the UHMWPE/HDPE blend and intensive shear flow resulted from the secondary melt penetration process. Additionally, with increase temperature of the second melt, the oriented lamellar near the core layer tended to develop into irregularly-arranged lamellar and the double skin-core orientated structure weakened gradually. These results were further authenticated by SAXS. Results of tensile testing indicated that with reduced temperature of second melt, samples with higher tensile strength and modulus were obtained.
ISSN:1022-9760
1572-8935
DOI:10.1007/s10965-014-0432-5