Sorption and transport of CO2 above and below the glass transition of poly(ethylene terephthalate)

摘要: At temperatures at least 30°C above the glass transition (Tg) sorption and transport of carbon dioxide in poly(ethylene terephthalate) (PET) can be described conveniently using Henry's law Fick's with a constant diffusion coefficient. Below Tg concentration- dependent coefficient, coupled isotherm which is concave toward pressure axis adequately describes observed data. Physical interpretations quantitative deviations from form concentration dependence coefficient provided by model hypothesizes dual modes separate non zero mobilities two populations sorbed species local equilibrium. The implications temperature variations phenomenological parameters are discussed. Dilatometric for PET, polycarbonate, poly(acrylonitrile) (PAN) shown to correlate well simple. relationship developed explain existence “extra” mode responsible CO glassy polymers. In range + 20°C, Fickian behavior also apparent. These effects consistent nature polymer an elastic solid below viscous liquid narrow slightly T time scale chain rearrangements apparently approaches that process. polymer's viscoelastic response probing molecule, therefore, causes classical lag predictions. disappear Tg.