Influência da incorporação de nanopartículas de argila e de celulose microfibrilada nas propriedades de materiais biodegradáveis a base de fécula de mandioca

Abstract

The purpose of this study was to analyze the incorporation effect of clay nanoparticles (in three concentrations: A1 - 0.05 g/100g; A2 - 0.10 g/100g; A3 - 0.15 g/100g) and cellulose microfibrils (in three concentrations: C1 - 0.20 g/100g; C2 - 0.30 g/100g; C3 - 0.40 g/100g) as structural reinforcements of biodegradable materials based on cassava starch, aiming to improve their properties for future application in food packaging to replace oil-derived polymers. Control films (FM) were elaborated without structural reinforcements, containing only cassava starch as filmogenic matrix, glycerol and water as plasticizing agents. All materials were characterized concerning their mechanical (tensile strength and elongation at break), barrier (water vapor permeability and oxygen permeability coefficient), morphological (moisture content, solubility and degree of swelling) and visual properties (thickness and opacity) and degradation. The materials showed uniform thickness, good appearance and homogeneous surface. Regarding the opacity, cellulose microfibrils caused a decrease in films transparency, being this effect highlighted with the increase of the incorporated amount. The incorporation of both reinforcements significantly decreased the water vapor permeability and the oxygen permeability coefficient, suggesting a greater difficulty in the exchange of water vapor and oxygen gas between the packaged product and the environment outside the packaging. In addition, they contributed to the decrease of films moisture content and solubility. Another finding was that the incorporation of the reinforcements did not cause a significant change in the values of the degree of swelling, due to the amount maintenance of cassava starch, glycerol and water in all formulations. Mechanical properties of biodegradable materials based on cassava starch were not improved with the addition of reinforcement particles. Finally, in relation to degradation, there was a significant loss of mass of the system over time, concluding that films elaborated with cassava starch and incorporated with clay nanoparticles or cellulose microfibrils can be considered as biodegradable.