Sorption and Swelling Measurements of CO₂ and N₂ on Polyol for Their Use As Blowing Agents in a New PU Foaming Process Device

From an industrial point of view, polymeric foams are of great importance because of their good mechanical and thermal properties and their low weight. Among them, polyurethane foams are the most versatile and, thus, the most consumed. Traditional methods for polyurethane foaming have the disadvantages of negative spin-offs due to chemical foaming reactions or use of flammable gases. A new foaming process device has been developed to overcome these drawbacks by performing physical foaming with safe blowing gases. In relation to this setup, the sorption of a polyol provided by Bayer MaterialScience, in the presence of pure N₂ and pure CO₂, was examined at three isotherms at 293, 303, and 313 K and at pressures up to 6 MPa. Swelling measurements for CO₂ were also performed at 293 K at pressures up to 5.6 MPa. Both sorption and swelling measuring methods were based on the magnetic suspension balance. Sorption data were obtained by means of a very accurate gravimetric method, whereas swelling data were acquired visually by using an optical pressurized cell. Results for N₂ sorption on polyol showed that no appreciable sorption occurred for this gas. However, CO₂ sorption was observed to be significant, and thus, the swelling of the polyol sample was measured to correct the CO₂ sorption values. Corrected sorption results for CO₂ on the polyol yielded a maximum uptake of 617 mg/g at 293 K and 5.4 MPa with an increase in the sample volume of about 47%. Measuring data showed that CO₂ sorption increased with pressure and decreased with temperature.