Solubilities of sub‐ and supercritical carbon dioxide in polyester resins

In supercritical carbon dioxide (CO₂) assisted polymer processes the solubility of CO₂ in a polymer plays a vital role. The higher the amount of CO₂ dissolved in a polymer the higher is the viscosity reduction of the polymer. Solubilities of CO₂ in polyester resins based on propoxylated bisphenol (PPB) and ethoxylated bisphenol (PEB) have been measured using a magnetic suspension balance at temperatures ranging from 333 to 420 K and pressures up to 30 MPa. An optical cell has been used to independently determine the swelling of the polymers, which has been incorporated in the buoyancy correction. In both polyester resins, the solubility of CO₂ increases with increasing pressure and decreasing temperature as a result of variations in CO₂ density. The experimental solubility has been correlated to the Sanchez–Lacombe equation of state. POLYM. ENG. SCI. 46:643–649, 2006. © 2006 Society of Plastics Engineers