Development of a Hybrid Solid-Microcellular Co-injection Molding Process

L. S. Turng*, H. Kharbas

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

64 Scopus citations

Abstract

This paper presents the development of a hybrid solid-microcellular co-injection molding process that combines aesthetic and processing advantages of injection molding with benefits and property attributes of microcellular plastics (MCPs). A two-color injection molding machine has been modified and equipped with an interfacial platen and a supercritical fluid (SCF) unit for co-injection molding with regular resins and MCPs. Co-injection molded polystyrene (PS) parts with a microcellular core encapsulated by the solid skin layer have been successfully produced. Systematic experiments were carried out with solid-microcellular co-injection molding, conventional solid-solid co-injection molding, and regular microcellular injection molding processes to study the effects of process conditions and core/skin volume ratios on the penetration and morphology of the microcellular core. Light microscopy and scanning electron microscopy (SEM) of the solid-microcellular co-injection molded specimens reveal a microcellular core with fairly fine and uniform cell size of 8 to 12 microns and a cell density of up to 3 × 108 cells/cm3. Under similar process conditions, microcellular cores were found to penetrate longer and generate a more uniform and thicker skin layer than do solid cores. While improving the surface finish with solid skin layers, this process is capable of producing parts with reduced sink marks, lighter part weights, and shorter cycle times.

Original languageEnglish
Pages (from-to)77-86
Number of pages10
JournalInternational Polymer Processing
Volume19
Issue number1
DOIs
StatePublished - 03 2004
Externally publishedYes

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