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

Abstract

In this work, low density polyethylene (LDPE) films were loaded by scCO2-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 °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 scCO2-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.