Biocomposites of thermoplastic starch with surfactant

Thermoplastic starch films were prepared by a casting technique. Microfibrillated fibers from husks of corncobs were added as reinforcing agents and glyceryl monostearate (GMS) as surfactant. The films were characterized using X-ray diffraction studies, thermal and mechanical analysis and water uptake experiments. Differential scanning calorimetry (DSC) and X-ray diffraction showed the formation of amylose-GMS complexes. Compared to films without GMS the films with GMS showed significant reductions in water uptake and an increase in tensile strength. Important differences in the DSC measurements in the 160-200 °C range of films with and without GMS were also exhibited. These effects can be related to the reinforcement of the polymer matrix by the web-like network of the microfibrillated fibers, the formation of amylose-GMS complexes and the interactions of the polar groups of the GMS with the hydroxyl groups of the cellulose. Retrogradation tendencies of the TPS films were also changed by these phenomena.