Production of polystyrene microcellular foam plastics and a comparison of late- and quick-heating

• Published in: Journal of applied polymer science Vol. 77; no. 11; pp. 2383 - 2395
• Main Authors: Sumarno, Sato, Yoshiyuki, Takishima, Shigeki, Masuoka, Hirokatsu
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 12.09.2000; Wiley
• Subjects: Applied sciences; Cellular; Exact sciences and technology; Forms of application and semi-finished materials; late-heating; microcellular; nucleation; Polymer industry, paints, wood; polystyrene; quick-heating; quick‐heating, nucleation; Technology of polymers; Structure processing relationship; Cell structure; Foaming process; Saturation pressure; Foam(plastics); Styrene polymer; Nitrogen; Experimental study
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/1097-4628(20000912)77:11<2383::AID-APP6>3.0.CO;2-U

A batchwise process for the production of microcellular plastics was studied in the polystyrene–nitrogen system. The effects of saturation temperature, saturation pressure, and late‐ and quick‐heating on the microcellular structure were investigated by considering the solubility of the gas in the polymer. It was found that the mean cell diameter was reduced and the cell number density increased with increase in the gas solubility. Variation in the saturation temperature showed that the cell number density had a minimum and the mean cell diameter had a maximum at about 350 K, which was related to the minimum solubility of nitrogen in polystyrene. The long heating time at 393 K of a solution saturated under 25 MPa increased the cell diameter, reduced the cell number density, and gave a maximum volume expansion ratio at about 300 s. Further heating caused the cell size and volume expansion ratio to be decreased, which might be caused by diffusion of the gas out of the polymer sample. The effect of the saturation temperature under high saturation pressure on the cell number density was qualitatively well predicted by the nucleation theory. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2383–2395, 2000