Carvone-loaded LDPE films for active packaging: Effect of supercritical CO2-assisted impregnation on loading, mechanical and transport properties of the films

In this work, low density polyethylene (LDPE) films were loaded by scCO(2)-assisted impregnation with R(-)-carvone, the main component of M. spicata and A. polystachya essential oils with antimicrobial and insecticidal activity. Impregnation runs were performed in a lab-scale high-pressure cell, and the effect of CO2 density (240-700 kg m(-3)) and temperature (35-60 degrees C) on impregnation yield was evaluated. Impregnation yields of 2.0-4.8% (w/w) were obtained, achieving higher values at low CO2 density. Thermal and mechanical properties of the films, before and after impregnation, were also investigated. The diffusion coefficient of carvone in scCO(2)-swollen films was estimated by impregnating film rolls and modeling the concentration profile through the roll thickness using an analytical solution of second Fick's law. Release profiles into air were determined, allowing to estimate diffusivity values in non-swollen films at ambient conditions.