Freeze-purged-desorption method for quantitative evaluation of CO2-solubility in polymeric films

A new experimental method, named as freeze-purged-desorption (FPD) method, to evaluate quantitatively the amount of gases sorbed in polymeric films, h as been developed by using carbon dioxide gas and five different films (low density polyethylene: LDPE, polypropylene: PP, polystyrene: PS, polyacrylo nitrile copolymer: PAN, polycarbonate: PC). The FPD method consisted of thr ee operational periods of time based on the stepwise change in the system t emperatures, the freeze periods of sorbed CO2 at -196 degreesC, the purging period of atmospheric CO2 at -78 degreesC and the desorption period of the freezed CO2 in the film at -9 degreesC. The evaluated values for LDPE, PP, PS, PAN and PC were 0.310, 0.65, 3.90, 0.098 and 6.90 (cm(3)(STP)/cm(3) at m), respectively, which were about 20-40% higher than the reference values. The validity of the method was reconfirmed by a good reproducibility of th e desorption curves of sorbed gases referring to a blank curve obtained fro m the non-porous glass beads. (C) 2001 Elsevier Science B.V. All rights res erved.