Obtenção e aplicação de celulose de resíduos agroindustriais em filmes compósitos

Abstract

Cellulose is of interest in several applications because it has high crystallinity, besides conferring stability and structural resistance to the cell wall of the fibers. Because of its attributes, it is considered as a material with different uses, being widely applied in composites, materials used in the preparation of food packaging, such as films, paper and plastics. With the increasing production of urban solid waste impacting the environment, the possibility has arisen of developing efficient systems for food packaging through biodegradable and renewable packaging of raw materials originating from agricultural waste. Like this, the objective was to study the use of corn starch and cellulose extracted from raw materials derived from agricultural residues of corn such as straw, plant and cob for the preparation of composite films. The cellulose fibers were isolated by alkaline treatment and characterized by microscopic, morphological characteristics, determination of lignocellulosic material and Fourier transform infrared spectroscopy (FTIR-ATR). The composite films were made by casting with cornstarch and adding 5g 100g-1, 10g 100g-1, 15g 100g-1 and 20g 100g-1 of the straw, plant and corn cob celluloses. These composites were evaluated for macroscopic, microscopic, morphological characteristics, thickness, moisture, water solubility, water vapor permeability (WVP), FTIR-ATR, mechanical properties and sorption isotherms. Composite films with plant cellulose and corn cob showed increased water solubility and reduced water vapor permeability when compared to the control film. Composite films with plant cellulose and corn cob showed increased water solubility and reduced water vapor permeability when compared to the control film. Tensile strength and Young’s modulus increased only with the addition of maize straw cellulose fiber to a concentration of 15 g 100 g-1 starch. Fiber-added starch films, regardless of fiber residue concentration and source, showed less elongation when compared to films without fiber addition. Moisture in the monolayer was reduced with fiber incorporation, except for the addition of 5 g 100g-1 corn husk pulp. Thus, the desired properties of a composite vary according to its application. For use as food packaging it is feasible to consider, in addition to the properties of the composite, the physical and chemical properties of the food to be stored.