GAS-SOLID CHROMATOGRAPHIC STUDY OF POLYMER SURFACES - ADSORPTION ON POLYSTYRENE

Inverse gas chromatography (IGC) has been used to construct the adsorp tion isotherms for a series of n-alkanes on polystyrene in the finite concentration region at 30-degrees. Isotherms for n-heptane were also constructed at 30, 40, 50 and 60-degrees. All isotherms were of type I I with a very weak knee, according to the BET classification. Uptake i ncreased with increasing hydrocarbon chain length. Integration of the isotherms gave the spreading pressure (35.5 mN/m) from which the Londo n force component of the polystyrene surface free energy was estimated (55.0 mN/m). N on-dispersive (acid/base) interactions were estimated by exposing the polystyrene surface to acidic and alkaline vapours res pectively and calculating the OMEGA interaction parameter. OMEGA value s indicated a weakly alkaline polystyrene surface. Adsorption data ref lect a relatively high non-specific adsorption potential of the polyst yrene surface for the hydrocarbons studied. Calculated, thermodynamic parameters support this finding.