Carbon dioxide in polycarbonate

In Section I we introduce the gas-polymer-matrix model for gas sorption and transport in polymers (10, LI), which is based on the experimental evidence that even permanent gases interact with the polymeric chains, resulting in changes in the solubility and diffusion coefficients. Just as the dynamic properties of the matrix depend on gas-polymer-matrix composition, the matrix model predicts that the solubility and diffusion coefficients depend on gas concentration in the polymer. We present a mathematical description of the sorption and transport of gases in polymers (10, 11) that is based on the thermodynamic analysis of solubility (12), on the statistical mechanical model of diffusion (13), and on the theory of corresponding states (14). In Section II we use the matrix model to analyze the sorption, permeability and time-lag data for carbon dioxide in polycarbonate, and compare this analysis with the dual-mode model analysis (15). In Section III we comment on the physical implication of the gas-polymer-matrix model. 

The solid line in Fig. 1 represents the sorption isotherm of carbon dioxide in polycarbonate calculated by fitting the solubility expression, eq. (11), to experimental data of Wonders and Paul (15). The best fit to the experimental data was achieved with the parameters ao=7.33cm3(STP)/cm3(polymer)-atm and a = 0.161 cm3(polymer)/cm3(STP). As can be seen in Fig. 1, eq. (11) describes the experimental data over the entire pressure range. The algorithm used to fit eq. (11) to the experimental data is described elsewhere (FI). 

TAN Tang, M., Du, T.-B., and Chen, Y.-P., Sorption and diffusion of supercritical carbon dioxide in polycarbonate, J. Supercrit. Fluids, 28, 207, 2004. 

ZHA Zhao, J.J., Zhao, Y.P., and Yang, B., Investigation of sorption and diffusion of supercritical carbon dioxide in polycarbonate, 7. Appl. Polym. Sci., 109, 1661, 2008. 

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See also in sourсe #XX -- [ ]

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