Gravimetric and volumetric study of the sorption of gases and vapors in poly(vinyl chloride) powders

The sorption of a variety of gases and organic vapors in poly(vinyl chloride) (PVC) powders has been studied gravimetrically with a recording microbalance and volumetrically with a gas pycnometer and an automatic surface area analyzer. For nitrogen, carbondioxide, vinyl chloride, methanol, acetone, n‐butane, and benzene at low penetrant activities and temperatures below T g , sorption isotherms exhibit the downward curvature characteristic of dual‐mode sorption. The solubility of each of these penetrants is lower in heat‐treated PVC samples than in samples recovered from the polymerization without additional heating. It has been possible to estimate the parameters of the dual‐mode sorption model for carbondioxide, vinyl chloride, and methanol. The results indicate that the history‐dependence of gas or vapor solubility is associated only with the “hole‐filling” term of the dual‐mode model; the normal dissolution or Henry's Law term is essentially unaffected by the prior heat treatment of the PVC.