Get access
Advertisement

The effects of gas counter pressure and mold temperature variation on the surface quality and morphology of the microcellular polystyrene foams

Authors

  • Shia-Chung Chen,

    Corresponding author
    1. Department of Mechanical Engineering, Chung Yuan Christian University, Taiwan
    2. R&D Center for Mold and Molding Technology, Chung Yuan Christian University, Taiwan
    3. R&D Center for Membrane Technology, Chung Yuan Christian University, Chung-Li, Taiwan
    • Department of Mechanical Engineering, Chung Yuan Christian University, Taiwan
    Search for more papers by this author
  • Ping-Shun Hsu,

    1. Department of Mechanical Engineering, Chung Yuan Christian University, Taiwan
    2. R&D Center for Mold and Molding Technology, Chung Yuan Christian University, Taiwan
    3. R&D Center for Membrane Technology, Chung Yuan Christian University, Chung-Li, Taiwan
    Search for more papers by this author
  • Shyh-Shin Hwang

    1. Department of Mechanical Engineering, Ching-Yun University, Taiwan
    Search for more papers by this author

Abstract

In this study, we developed a foaming control system using the Gas Counter Pressure (GCP) combined with mold temperature control during the microcellular injection molding (MuCell) process and investigated its influence on the parts' surface quality and foams structures. The results revealed that under GCP control alone when GCP is greater than 10 MPa, part surface roughness for transparent polystyrene (PS) improved by 90%. When GCP increased, the skin thickness also increased, the weight reduction decreased and the average cell size reduced to about 30 μm. For black PS parts, when GCP is greater than 10 MPa, the part gloss reaches the same value as that molded by conventional injection molding. By increasing gas holding time, the cell density decreased and the cell size distribution became more uniform. The increase in amount of supercritical fluid foaming agent also increased the cell density. Applying mold temperature control alone with temperature in the range of 90–120°C (near Tg), the surface roughness improved by 65%. Increasing mold temperature decreased the skin thickness; however, the cell size distribution became significantly nonuniform. It was found that thin skin, small and uniform cell size as well as good surface quality can be achieved efficiently by simultaneous combining of GCP and mold temperature control. The proposed innovative approach may lead to a significant improvement and a more broad application for MuCell process. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Get access to the full text of this article

Ancillary