Chitosan-based films with alternative eco-friendly plasticizers: Preparation, physicochemical properties and stability

Chitosan-based films modified with synthesized (propylene glycol monoacetate, propylene glycol esters of fatty acids, and epoxidized propylene glycol esters) and commercial eco-friendly plasticizers (epoxidized soybean oil and epoxidized palm oil) were prepared by a casting technique, with the aim to obtain environmentally friendly materials for packaging applications. To assess the applicability of alternative plasticizers, their properties were compared to the two most common plasticizers, i.e. glycerol and sorbitol. The chemical structure of newly synthesized plasticizers was verified by gas chromatography with mass detector, infrared spectroscopy and ¹H NMR; and their acid, epoxy, iodine, and saponification values were determined. Plasticized chitosan-based films were characterized in terms of hydrophilic, barrier, thermal, mechanical properties, zeta potential and morphology, confirming their flexibility and homogeneity. The research confirmed that the alternative plasticizers introduced by us are more effective than commercially available ones, exhibiting lower hydrophilicity and superior mechanical properties compared to samples plasticized with traditional plasticizers. Moreover, these properties were found to be even better after ageing for 10 months.