Thermal Degradation of Sodium Alginate- Incorporated Soy Protein Isolate/Glycerol Composite Membranes

摘要

Soy proteins are one of the most important natural biopolymers used to produce biodegradable materials,and thus have received ever-increasing attention in the food packaging materials, for compromisingpackaging materials and environmental protection so as to satisfy the requirements of the green packaging. Inthis work, a few new glycerol-plasticized soy protein isolate (SPI) composite membranes, modified by the incorporationof sodium alginate, were fabricated by using the solution casting method. The obtained films wereexamined with a thermogravimetric analyzer for thermal treatment consideration. The thermal characterizationwas conducted in detail to investigate the pyrolysis characteristics and kinetics of obtained SPI composites.The experiments were performed at the air flow rate of 30 ml/min, under different heating rates of 5, 10,15, 20 and 30 K/min and from ambient temperature up to 1050 K. Thus the influences of heating rate andmembrane composition on the thermal degradation of SPI composite have been evaluated, respectively. Basedon TGA and DTG results, thermal behaviour of the SPI composites could be clearly separated into severaldegradation stages. The pseudo first-order kinetic parameters for the main degradation phase thus were estimatedby means of certain conventional methods. These thermal investigations will be useful for better understandingthe thermal stability of these SPI bio-composites and provide necessary information for thermallyprocessing packaging wastes from these composite materials.