Swelling behavior of polyester in supercritical carbon dioxide

The present study aimed to investigate the effects of different supercritical CO2 conditions on the swelling of polyester. We employed a Box-Behnken design to discuss three variables governing the polymer swelling: system temperature, system pressure and treatment time. The obtained results showed that the system temperature and pressure played significant influence on the swelling of polyester samples. The second-order polynomial formula developed provided accurate predictions for the experimental data, with coefficient of determination R2 0.9938. The theoretical maximum for the swelling of polyester was 0.725 mm under the optimum treatment condition with a system temperature of 140 °C, a system pressure of 26 MPa and a treatment time of 60 min. In addition, it is proposed that the swellability of polyester was dependent upon the polymer plasticization in supercritical CO2 and the intermolecular interactions between the CO2 and the carbonyl groups in polyester.