MEASUREMENT OF SOLUTE DIFFUSION IN POLYMERS BY INVERSE GAS-CHROMATOGRAPHY USING FUSED-SILICA OPEN-TUBULAR COLUMNS

Inverse gas chromatography (i.g.c.) using a fused-silica open tubular column has been developed and evaluated for measuring diffusion coeffi cients of small molecules in polymers; this diffusivity data can be us ed, for example, to model reactive extrusion processes. We have shown the applicability of this technique by measuring the diffusion and par tition coefficients of various small molecules in polystyrene, poly(me thyl methacrylate) (PMMA), and poly(methyl methacrylimide). The result s for polystyrene and PMMA were in good agreement with existing data b y gravimetric sorption/desorption, packed column and glass capillary c olumn i.g.c. techniques. The diffusion data for the polyimide were gen erated for the first time.