APPLICATION OF INVERSE GAS-CHROMATOGRAPHY TO MOLECULAR-DIFFUSION IN POLYMERS

Changes in the carrier gas flow rate have been used to separate bulk d iffusion and surface adsorption contributions from total retention dat a in inverse gas chromatographic experiments. The polymer was a styren e/4-vinylpyridine diblock copolymer, and experiments were carried out at temperatures both below and above its T-g. It has been found that b oth contributions coexist and neither one is negligible at normal flow rates of the carrier gas. The diffusion coefficients at infinite dilu tion, or zero concentration, of n-alkane vapors in the polymer phase h ave been estimated from the separated bulk diffusion data and from the retention times for the adsorption of the probes on the polymer surfa ce.