Structural and Thermal Properties of Starch Plasticized with Glycerol/Urea Mixture

Abstract

AbstractThe paper presents the results of research on the influence of used plasticizing system on the structural and thermal properties of thermoplastic starch (TPS). The thermoplastic starch granulate was obtained by extrusion of native starch in the presence of a plasticizing system using a twin-screw extruder. Glycerol and urea were used as plasticizers in various proportions. In order to evaluate the effectiveness of the starch plasticization process, changes in its chemical structure were analyzed by infrared spectroscopy (FTIR), gel permeation chromatography (GPC) and X-ray diffraction (XRD). TPS thermal stability was determined by thermogravimetric analysis (TGA). An improvement in the efficiency of the plasticization process has been found for a urea-containing plasticizing system compared to the composition of starch plasticized only with glycerol. In addition, the XRD analysis confirms the beneficial effect of urea on the inhibition of starch retrogradation process.