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Foaming of polystyrene particles

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The understanding of the polymer foaming process is important for controlling the foam morphology and reducing the amount of blowing agent. The choice of the suitable blowing agent is very important not only for technical properties of the resulting foam but also because of the environmental influence of blowing agent. Many of industrial blowing agents have negative impact on the environment, e.g., on the ozone layer and many of blowing agents are greenhouse gases. Thus it is desirable to decrease the content of the blowing agent escaping to the atmosphere during the foaming process, during the storage of impregnated particles and even during the use of the final foam. It is necessary to understand the partial processes of the foam manufacturing and also to evaluate the factors affecting the foaming processes:

  • concentration distribution of the blowing agent in the particle,
  • foaming temperature and pressure,
  • rate of pressure release,
  • initial size of foaming particle,
  • etc.

The foaming experiments consist of impregnation and foaming period. We usually impregnate the polystyrene (PS) particles by pentane which is widely used in the industrial foaming. Impregnation process is closely related to the sorption and diffusion phenomena that are studied in the gravimetric apparatus. The diffusion front (so called Case II diffusion) is also observed by video microscopy (Fig. 1).

 

The concentration of blowing agent is given by its partial pressure and by the length of impregnation period. The effect of the impregnation period is shown in Figure 2.

 

Published results:

Salejová G., Kosek J.: Dynamics of foaming of polystyrene particles. Macromolecular Symposia, 2006, 243, 233-246.

 

Contact

Juraj Kosek
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+420 220 443 296

University of Chemistry and Technology Prague
Department of Chemical Engineering
Technicka 5
166 28 Prague 6
Czech Republic

University of West Bohemia
New Technologies Research Centre (NTC)
Univerzitní 8
306 14 Pilsen
Czech Republic