Effect of the properties of polyether polyol on sorption behaviour and interfacial tension of polyol/CO2 solutions under high pressure condition

Abstract

The interaction between CO2 and polyol plays crucial role in the preparation of rigid polyurethane foams using CO2 as blowing agent directly. The solubility and diffusivity of CO2 in polyether polyols with different molar mass and functionality were measured using magnetic suspension balance in pressure range of 2–6 MPa, and the interfacial tension of these polyol/CO2 systems were determined by pendant drop method. The solubility of CO2 in polyols became larger when their molar mass rose up to 1000 g·mol−1, and had the highest values when the functionality of polyether polyols was 3. The dual-mode sorption model can fit the solubility of CO2 in different polyols well. Both the diffusivity of CO2 in polyol and specific volume of polyol/CO2 solution increased with higher molar mass, but changed indistinctly with different functionality. The diffusivity of CO2 in polyols was (10−9–10−8) m2 s−1 order of magnitude, and the specific volume has a non-monotonic change with pressure. Higher solubility of CO2 in polyols resulted in lower interfacial tension of polyol/CO2 solutions, so that the interfacial tension of polyol/CO2 solution has lowest values for polyether polyol with molar mass of 1000 g·mol−1 and functionality of 3, which decreased with the increasing of pressure. All interfacial tension data of polyol/CO2 solutions can be correlated by a unified Macleod’s equation.