Thermal Degradation Study of Sodium Alginate-Zeolite 4A Composites

Natural biodegradable materials have now received ever-increasing attention in the food industries as they provide an alternative as green packaging materials to conventional non-degradable plastic films, and their utilizations once commercialized will extremely reduce the dependence and consumption of nonrenewable fossil resources. Thus, there is imminent need to develop highly-performed biodegradable materials for food packaging applications. In this work, a few zeolite 4A modified sodium alginate films have been fabricated using the solution casting method. The aqueous dope with different zeolite loadings was cast on clean glasses, followed by ambient drying treatment before obtaining final hybrid films. Then the membrane thermal properties have been characterized in detail to investigate the pyrolysis characteristics and kinetics in the course of heating process. The experiments were performed at the air flow rate of 30 ml/min with temperature from ambient up to 1050 K. From experimental results, thermal degradation of the sodium alginate composites could be clearly separated into several stages based on the weight loss and the weight loss rate. The kinetic parameters for the main degradation phase thus were estimated by using the pseudo first-order assumption. The heating rates used for sodium alginate hybrid membranes ranges from 5 to 30 K/min so as to evaluate its influences on the thermal degradation. The results have also shown that the introduced zeolite as well as its content has obviously affected the thermal properties of the sodium alginate composites. These pyrolysis investigations will be useful for better understanding the thermal stability of these sodium alginate biocomposites and provide necessary information for thermally processing packaging wastes from these biodegradable materials.