Solubility And Diffusivity Of Carbon Dioxide In Polyols

The apparent solubility and diffusivity of CO2in polyols were measured by magnetic suspension balance at temperatures of308.15K,333.15K and353.15K, and CO2pressures ranging from2to10MPa. Meanwhile, the swelling volume of the polyols/CO2solutions was experimentally measured under the same conditions by using a high-pressure view cell with direct visual observation, and it was then used to correct the gas buoyancy acting on the polyols in the MSB measurement so that the real solubility of CO2in the polyols was determined. The effects of the temperature, CO2pressure, and functionality, molecular weight and hydroxyl value of the polyols on the solubility and diffusion coefficient of CO2in the polyols were investigated. It was found that the solubility of CO2in the polyols increased with increasing CO2pressure and molecular weight of the polyols as well as decreasing temperature and functionality of the polyols. The diffusivity became larger with increasing both CO2pressure, temperature and molecular weight of the polyols, and decreasing functionality of the polyols. Three polyols with higher CO2solubility were selected and mixed together. The influence of additives including PVAc, zeolite and EH-14on the solubility of CO2in the mixed polyols was further studied. It was found that the addition of EH-14could significantly improve the solubility. However, the addition of PVAc and zeolite affected the solubility little. Henry’s law, Langmuir equation and dual-mode sorption model were applied to correlate the solubility of CO2in the polyols, respectively. Langmuir equation and dual-mode sorption model correlated the experimental results better than Henry’s law. The results provided basic data for polyurethane foaming process using CO2as foaming agent.