GAS-PERMEABILITY IN THE POLYSTYRENE FILMS UNIAXIALLY DRAWN UNDER CO2 PLASTICIZING

Gas permeability coefficients, Ps, of CO2, O-2, and N-2 have been meas ured in four kinds of polystyrene (PS) films: an unconditioned film wi th no orientation (1), a high pressure CO2-conditioned film with no or ientation (2), an uniaxially hot-drawn film with some orientation (3), and a film uniaxially drawn under CO2 plasticizing with some orientat ion (4). Wide angle X-ray diffraction (WAXD) scans for each sample hav e also been made. High-pressure CO2-conditioning effect was confirmed from the result that P values for any permeation gas in sample 2 were larger than those in sample 1. Values of P for any gas in sample 3 wer e almost close to those in sample 1 and decreased slightly with Herman s orientation function, f. Gas permeability coefficients in sample 4 a re larger than those in sample 3 over the whole range of f studied in this work and increased with f. These results were discussed from a vi ewpoint of inter-segmental distances for PS films.