Modeling and simulation of a supercritical CO2-assisted polymer impregnation process

GAÑAN, NICOLÁS A.; MARTINELLI, FRANCO; STOFFEL, FLORENCIA; GOÑI, MARÍA L.

Campinas

Congreso; V Iberoamerican Conference on Supercritical Fluids (PROSCIBA 2019); 2019

The impregnation of polymeric matrices with active compounds using supercritical CO2 (scCO2) as solvent and diffusion enhancer is a promising alternative for the development of active materials with applications in food packaging, controlled drug delivery, pesticide release, etc. The efficiency and costs of this process strongly depend on the mass transfer kinetics as well as the thermodynamic behavior of the fluid-polymer system under different process conditions. In this work, the mathematical model of a scCO2-assisted impregnation of a polymeric film with a selected compound (eugenol) is presented. The model involves the calculation of the equilibrium partition coefficient of the compound at the fluid-polymer interphase and the description of its diffusion into the polymeric matrix. Equilibrium calculations are performed using the Sanchez-Lacombe equation of state (SL-EOS), while diffusion is modeled according to a Fickian behavior. The influence of different process parameters, such as temperature, pressure, fluid phase composition and exposure time, is investigated by simulations and validated by comparison with experimental data concerning the impregnation of low density polyethylene (LDPE) with eugenol, as a model system. Diffusion coefficients for this compound in LDPE films under high-pressure treatment were estimated at 10e-10 to 10e-9 m2/s, being temperature and pressure the process variables that showed the most important effects on this parameter. On the other hand, polymer/CO2 partition coefficients for eugenol mostly varied with the composition of the fluid phase, ranging approx. from 1 to 10. Finally, the experimental data were successfully reproduced by the mathematical model, obtaining a useful tool for process simulation. With this model, it was possible to simulate the penetration curves of eugenol into LDPE films for different times and process conditions.