Morphological development in water assisted injection molded polyethylene/polyamide-6 blends

Shih Jung Liu*, Wei Ru Lin, Kun Yeh Lin

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

12 Scopus citations


Water assisted injection molding (WAIM) has gradually become one of the most important polymer processing methods for making hollowed parts. This study examined the morphological development in water assisted injection molded high density polyethylene (HDPE)/polyamide-6 (PA-6) blends. Samples for microscopic observation were prepared by an 80-ton injection-molding machine equipped with a tube cavity and with a water injection unit. A distinct skin layer, core region, and channel layer were observed across the thickness. The shape and size of the dispersed phase depended on the position both across the part thickness and along the flow direction. Small and large particles coexisted in the skin and channel layers, indicating that both coalescence and disintegration of the dispersed phase occurred in these layers. High water pressures were found to mold parts with smaller polyamide particle distributions. Additionally, the morphology of water assisted injection molded parts was compared to that of gas assisted injection molded products. It was found that water molded parts exhibit a smaller polyamide particle distribution than their gas counterparts.

Original languageEnglish
Pages (from-to)2062-2068
Number of pages7
JournalPolymers for Advanced Technologies
Issue number12
StatePublished - 12 2011


  • Gas assisted injection molding
  • Morphology
  • Polyethylene/polyamide blends
  • Water assisted injection molding


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