Experimental Design and Modeling for Propylene Oxide - CO2 - Poly (Propylene Carbonate) Solutions

Abstract

In this research, experimental design was used to formulate the empirical models of viscosity and density of poly(propylene carbonate) (PPC), propylene oxide (PO), and carbon dioxide (CO2) solutions by designing experiments at key values of the process variables; concentration of PPC between 0 to 34% (% w/w), temperature in the reactor between 50 to 75°C, and gas phase manometric CO2 pressure between 20 to 40 bar. A bench scale reactor (2000 ml) comprising an external circulation loop equipped with in-line viscosity and density measurement devices was used to carry out the tests. The results show that the equilibrium viscosity and density of the solution increased with the concentration of PPC and decreased with the pressure and temperature in the reactor. The density model has Radjusted 2 value close to unity indicating that the model can predict the variation in the density with very high accuracy. In comparison, the viscosity model has a lower Radjusted 2 value indicating a need for additional experiments to improve the model. However, both empirical models predict the general trends of the density and viscosity characteristics in the selected range and can be used as a viable alternative to thermodynamic models.