Sorption and diffusion in polystyrene


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Polystyrene (PS) foams are widely used as heat and sound insulators or shock absorbers. In the past, fluorinated hydrocarbons were employed as blowing agents in PS foam production. As these compounds are harmful to the environment, they are being replaced by alternative agents, such as chlorofluorohydrocarbons, alkanes or CO2. However, for many of the alternative agents, inadequate sorption data are available in the literature. In our laboratory, we study the sorption of various alternative blowing agents in PS. In recent years, we mainly focused on the sorption of pentane, but CO2 is now receiving significant attention. This is because supercritical CO2 can be used to produce nano- and micro-cellular foams [odkaz], which have superior material properties.


Sorption and diffusion of blowing agents in PS are studied experimentally on the gravimetric apparatus. Apart from the sorption of pure species in PS, we also study co-sorption, i.e., the sorption of binary gas mixtures in PS, which is both theoretically interesting and industrially important. Supplementary data are also provided by video-microscopy, which enables to observe diffusion fronts in glassy PS. Sorption equilibrium data are correlated using the PC-SAFT equation of state and the Flory-Huggins theory, while diffusion data are evaluated by the Ficks and Case II diffusion models. We also analyze the dominant diffusion mechanisms at various conditions.




Figure 2: Comparison of various diffusion mechanisms: experimental data and models. Anomalous diffusion refers to a situation when none of the two basic diffusion models (Ficks and Case II diffusion) describes the experimental data.


Published Results:

Hajova H., Chmelar J., Nistor A., Gregor T., Kosek J.: Experimental study of sorption and diffusion of n-pentane in polystyrene. Journal of Chemical Engineering Data, 2013, 58(4), 851–865.

Chmelař, J.; Gregor, T.; Hajová, H.; Nistor, A.; Kosek, J. Experimental study and PC-SAFT simulations of sorption equilibria in polystyrene. Polymer, 2011, 52, 3082–3091. 



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