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Capillary column inverse gas chromatography (CCIGC) for the study of diffusion in polymer-solvent systems
Abstract
Capillary Column Inverse Gas Chromatography (CCIGC) has been developed for accurate measurement of diffusion coefficients in polymer-solvent systems at conditions approaching infinite dilution of the volatile component. Measurements of diffusion coefficients have been made for a wide range of solvents in poly(methyl methacrylate) (PMMA), poly(vinyl acetate) (PVAc), and poly(p-methyl styrene) (PPMS). These data are analyzed using a free-volume theory of diffusion to investigate the effects of the solvent and the glass transition on the diffusion process. Experimental data for PPMA-solvent and PVAc-solvent systems clearly demonstrate that certain solvent molecules are able to move segmentally in these polymers. Some of the parameters that influence the size of the solvent jumping unit have been identified experimentally. These are: the size of the entire solvent molecule, the flexibility and geometry of the solvent molecule, and the amount of free-volume present in the polymer. The results suggest that the current free-volume theory of diffusion does not provide a complete description of the diffusion process of solvent molecules that move segmentally. Finally, diffusivity data measured above and below the glass transition temperature of PMMA and PPMS are used to test a free-volume theory of diffusion in glassy polymers. The data appear to be well correlated by the theory, but some of the theoretical predictions were not confirmed experimentally.
Subject Area
Polymers
Recommended Citation
Arnould, Dominique Daniel, "Capillary column inverse gas chromatography (CCIGC) for the study of diffusion in polymer-solvent systems" (1989). Doctoral Dissertations Available from Proquest. AAI9001477.
https://scholarworks.umass.edu/dissertations/AAI9001477