Supercritical CO2-assisted impregnation kinetics of polyamide fibers with eugenol: experimental data and modeling

MOSQUERA RUIZ, JOSÉ E.; GOÑI, MARÍA L.; MARTINI, RAQUEL E.; GAÑAN, NICOLÁS A.

Campinas

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

Supercritical fluid technology has been widely used to incorporate active substances into polymeric matrices with different potential applications, principally due to the advantage of obtaining solvent-free products and the enhanced mass transfer rates that can be obtained in CO2-swollen polymers. The present work was aimed to investigate the supercritical CO2-assisted impregnation kinetics of eugenol into polyamide 6 fibers in order to obtain a material potentially applicable as an active dental floss, based on the well known antimicrobial activity of eugenol. Impregnation essays were performed in a high-pressure cell at two temperature levels (40 and 60°C), two pressures levels (10 and 12 MPa) and two depressurization rates (0.5 and 5 MPa min−1), at different contact times (from 15 min to 6 h). Experimental results of eugenol uptake vs. time suggested that the impregnation process follows a ?two-stage? sorption behavior, with sigmoidal uptake curves. The sorption process was modeled by developing an analytical solution of the second Fick?s law of diffusion for cylindrical fibers with a time-dependent surface concentration of eugenol. This kind of behavior has been reported for sorption in glassy polymers when the diffusion and relaxation rates are comparable. The resulting three-parameter model was fitted to reproduce the experimental data with a good agreement.