AbstractThis paper reports on the gas sorption and transport properties of poly(vinylidene fluoride) (PVF2) and on the effects uniaxial drawing and processing temperature have on these properties. Sorption and transport were first examined for “as‐received” commercial Kynar PVF2film at 35°C. This film was 54 crystalline by weight. Solubility, diffusion, and permeability coefficients were measured for He, H2, Ar, O2, N2, CH4, and CO2. The solubility coefficient and the diffusion coefficientDwere correlated with the Lennard–Jones potential and mean molecular diameter of the gas, respectively. Uniaxial drawing of PVF2films was performed up to a draw ratio of 3.7 and over the temperature range 75–140°C. Transport properties were correlated with the extent of draw and drawing temperature. The permeabilityPandDwere found to significantly decline with uniaxial drawing; the magnitude of this effect was dependent on both the drawing temperature and the molecular size of the penetrant considered. Roduetions inPandDbecame progressively more pronounced with increasing molecular diameter and with decreasing drawing temperature (down to a limit of about 75°C), which reflects an increase in effectiveness of drawing at low temperatures. PVF2films annealed above 75°C showed an increase inPandDas opposed to the effect of drawing. The solubility of various gases in PVF2was not found to be sensitive to processing treatments such as drawing and annealing, in agreement with the relatively small changes observed in free volume. PVF2films subjected to various treatments were characterized by DSC, density, birefringence, and dynamic mechanical measurements. Gas transport measurements appear to provide a more sensitive and hence more viable measure of the effectiveness of drawing than these other techniques. Drawing PVF2in the melt state was found to increasePandD, in contrast with the effects observed for solid‐state drawing. The results have been interpreted in terms of existing theories on morphology and microstructure in semicryst
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