Dilation of polyethylene by sorption of carbon dioxide

The dilation of low‐density polyethylene accompanied by the sorption of CO 2 was measured by microscopy under pressures up to 50 atm at temperatures from 25 to 55°C. The dilatometry measurement, which is also applied to the determination of the thermal expansion coefficient, is directly performed by a cathetometer. The dilation of LDPE by sorbed CO 2 is linear with concentration. The buoyancy correction is described for the CO 2 sorption isotherms in LDPE. The partial molar volume of CO 2 in LDPE, calculated from the dilation and the sorption isotherms, is almost independent of temperature.