Get access

Effects of the properties of blowing agents on the processing and performance of extruded starch acetate

Authors

  • Jiahua Zhou,

    1. Industrial Agricultural Products Center and Department of Biological Systems Engineering, University of Nebraska, Lincoln, Nebraska 68583-0730
    Search for more papers by this author
  • Milford A. Hanna

    Corresponding author
    1. Industrial Agricultural Products Center and Department of Biological Systems Engineering, University of Nebraska, Lincoln, Nebraska 68583-0730
    • Industrial Agricultural Products Center and Department of Biological Systems Engineering, University of Nebraska, Lincoln, Nebraska 68583-0730
    Search for more papers by this author

  • This is Journal Series No. 14375 of the Agricultural Research Division, Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln. This study was conducted at the Industrial Agricultural Products Center, University of Nebraska-Lincoln.

Abstract

The extrusion of polysaccharide-based polymers, such as starch acetate, is quite different from that of ordinary synthetic polymers. To understand how the physiochemical properties of blowing agents affect plasticization and expansion processes, starch acetate was extruded with water, ethanol, and ethyl acetate. The studied properties and factors were the evaporation rate, surface tension, boiling point, solubility index, latent heat of vaporization of blowing agents, extrusion temperature, and nucleating- and blowing-agent concentrations. The properties of the blowing agents and operating conditions affected the solubility of the matrix polymer, the nucleation process, and cell growth, which affected the foam density and specific volume. A high temperature increased the cell density and specific volume when water and ethanol were used because a high temperature increased the solubility of starch acetate in water and ethanol and promoted nucleation. Ethyl acetate already had high solvency to starch acetate and a high evaporation rate. A high temperature reduced the melting strength, thereby reducing the cell density and specific volume. Water evaporation was greater, despite a high latent heat of evaporation (hr) and boiling point, than the average volumes of ethanol and ethyl acetate that evaporated. The blowing-agent efficiency was a function of the solvency, blowing-agent evaporation rate, and operating conditions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1880–1890, 2005

Get access to the full text of this article

Ancillary