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Unexpected molecular weight dependence of shish kebab in water‐assisted injection molded HDPE
Author(s) -
Liu Xianhu,
Zhang Changyan,
Dai Kun,
Zheng Guoqiang,
Liu Chuntai,
Shen Changyu
Publication year - 2013
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.3071
Subject(s) - materials science , high density polyethylene , composite material , polymer science , chemical engineering , polyethylene , engineering
As a part of continuous efforts to systematically understand the morphological development in water‐assisted injection molding, high density polyethylene with different molecular weights was molded in this study. Unexpectedly, it was found that shish kebab with high lamellar and molecular orientations was formed in the sample with a lower molecular weight (LMW) rather than in the higher one, especially in the water channel layer. Present finding is obviously inconsistent with the general consensus, that is, higher molecular weight (HMW) polymer is much easier to form preferential orientation in flow field than LMW one. Such anomalous phenomenon is explained by the fact that even though melts experienced the same processing, lower shear rate is practically achieved in HMW sample due to its high viscosity. The result indicates that the flow history in industrial processing method is far from that in laboratory one. Copyright © 2012 John Wiley & Sons, Ltd.