The perfluorinated copolymer of tetrafluoroethylene and perfluoromethoxydioxole, Hyflon® AD80x, is investigated by inverse gas chromatography. C5C13 n alkanes are used as sorbates, for which the specific retention volume, the solubility coefficient at infinite dilution, and the excess thermodynamic functions are calculated in the temperature range 30115°C. The solubility coefficients of the hydrocarbons in the studied polymer are shown to be lower than those in amorphous Teflons AF1600 and AF2400, a finding that is consistent with the difference between the glass transition temperatures of these polymers. The correlation between excess partial molar enthalpies and critical volumes of n alkanes testifies that the upper limit for the size of the free volume element in this polymer is 613 Å3. Mixing of n alkanes with Hyflon AD80 is thermodynamically disadvantageous ( > 0) and becomes even less advantageous with an increase in the size of hydrocarbon molecules. Excess entropy mainly contributes to the high values of excess free energy, thus indicating a higher order in the system containing the glassy polymer than that in systems in which the polymer occurs in the rubberlike state.
Study of perfluorinated polymer hyflon 80AS using inverse gas chromatography
Jansen;J C
2010
Abstract
The perfluorinated copolymer of tetrafluoroethylene and perfluoromethoxydioxole, Hyflon® AD80x, is investigated by inverse gas chromatography. C5C13 n alkanes are used as sorbates, for which the specific retention volume, the solubility coefficient at infinite dilution, and the excess thermodynamic functions are calculated in the temperature range 30115°C. The solubility coefficients of the hydrocarbons in the studied polymer are shown to be lower than those in amorphous Teflons AF1600 and AF2400, a finding that is consistent with the difference between the glass transition temperatures of these polymers. The correlation between excess partial molar enthalpies and critical volumes of n alkanes testifies that the upper limit for the size of the free volume element in this polymer is 613 Å3. Mixing of n alkanes with Hyflon AD80 is thermodynamically disadvantageous ( > 0) and becomes even less advantageous with an increase in the size of hydrocarbon molecules. Excess entropy mainly contributes to the high values of excess free energy, thus indicating a higher order in the system containing the glassy polymer than that in systems in which the polymer occurs in the rubberlike state.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
