The Effects of Shellac and Glycerol on the Physicochemical Properties of Chitosan Films

Chitosan has been investigated for applications in biomaterials, pharmaceuticals, food, biodegradable packaging, and adsorbents. Various natural substances have been incorporated to modify chitosan properties and fabricate functionalized materials. Shellac, a lac-based biopolymer, is a biodegradable, edible, and biocompatible compound used in the food and pharmaceutical industry. Several materials combining chitosan and shellac were studied for packaging, food preservation, or drug delivery systems. In the present study, chitosan films enriched with shellac and glycerol were prepared. The physicochemical characterization of biopolymeric materials was performed (atomic force microscopy, scanning electron microscopy, contact angle and surface free energy, attenuated total reflectance Fourier-transform infrared spectroscopy, thermogravimetric analysis, mechanical testing, and swelling analysis). The effect of shellac and glycerol on chitosan materials was investigated. As a result, modified chitosan films were homogeneous and were characterized by increased elongation at break, surface free energy, and surface hydrophilicity (samples containing higher concentration of shellac), as well as decreased tensile strength, swelling degree determined at a pH of 7.4, and surface roughness in comparison to pure chitosan films. No significant differences in the thermal properties of modified chitosan-based materials were observed. The incorporation of shellac and glycerol influenced the physicochemical properties of chitosan films, which may act as a matrix for incorporating active substances for use in biomaterials, food packaging, cosmetics, or pharmaceuticals.