Supercritical carbon dioxide impregnation of LLDPE films with eugenol. Influence of process conditions and film characterization

GOÑI M.L.; GAÑAN N.A.; VICENTE A.; QUIROGA N.; ANDREATTA A.; MARTINI R.E.

Viña del Mar

Congreso; IV Iberoamerican Conference of SuperCritical Fluids (ProSCiba 2016); 2016

ProSCiba

The use of supercritical carbon dioxide (scCO2) in polymeric matrices impregnation with biologically active substances has gained attention in the last years due to several advantages: the solute penetration and internal diffusion is improved by polymer swelling and plastification; solvent-free products are obtained; thermolabile compounds are preserved by low temperature operation. In this work, linear low density polyethylene (LLDPE) films were impregnated with eugenol using scCO2 as solvent, as a strategy for the obtention of a loaded material to be applied in active packaging or other controlled release devices. Eugenol ?the main component of clove oil? is well known as a natural antifungal, antiseptic and antioxidant agent. Impregnation tests were performed in a lab-scale high pressure stirred cell at 45°C, three pressure levels (10, 12 and 15 MPa) and three depressurization rate levels (0.5, 1 and 5 MPa/min) during 4 hs. The impregnation yield was determined gravimetrically and spectrophotometrically. Yields of 1-6% (w/w) were achieved, with higher values at low depressurization rate. Results suggest that pressure has a minor influence on impregnation yield, allowing operation at milder conditions. Film samples were characterized by differential scanning calorimetry (DSC), infra-red spectroscopy (FT-IR) and optical microscopy. DSC revealed a decrease in the crystallinity degree in the impregnated samples as well as films subjected to pressurization with scCO2 but not impregnated with eugenol. FT-IR analysis suggested that the distribution of eugenol in the films is not homogeneous. Changes in mechanical properties were also investigated in a universal dynamometer. A decrease of LLDPE tensile strength and Young modulus was observed after high pressure impregnation.