PACKING DENSITY AND PHYSICAL STATE OF CAR BON-DIOXIDE IN POLY(METHYL METHACRYLATE)

Measurements of the volume and density of PMMA saturated with gaseous carbon dioxide showed that polymer swelling was accompanied by a decre ase in the molar volume of a solid polymer. The nonlinear character of changes in the packing coefficient calculated from experimental data suggested that the gas-polymer solution involved not only the molecula r dispersion of carbon dioxide but also the structurally dispersed pha se of this component. This conclusion was proved by the fact that, at high saturation pressures, the volumes of the polymer matrix and sorbe d gas were additive and the value of density of the dissolved carbon d ioxide was characteristic of a condensed state. Irreversible changes i n the PMMA matrix during intensive gas saturation were observed.