Investigation of thermodynamic properties of the binary system polyethylene glycol/CO2 using new methods

The solubility and diffusivity of CO2 in polyethylene glycols (PEGs) of different molecular weight measured by two different methods are discussed in the present work. Before solubility measurements, the melting temperatures of PEG with different molecular weights were determined by means of differential scanning calorimetry. For the purpose of the present study a temperature of 343 K was chosen as the working temperature for both employed methods since all studied polymers are in liquid state at this temperature. All samples were analyzed at isothermal conditions and in the pressure range from 0 MPa up to 30.0 MPa. A set of absorption experiments on the PEG/CO2 systems was performed using an external balance method. In order to validate results obtained by the new method they were compared to the data obtained at the same process conditions by a method using magnetic suspension balance (MSB).