Filmes compósitos de celulose bacteriana e goma de cajueiro para aplicação em alimentos

Abstract

The wide use of plastic products derived from petroleum in the world has had a great impact on the environment, since these materials take a lot of time to decompose, so an alternative for the substitution of these materials is the use of biodegradable polymers. Cashew gum (GC) has already been suggested as a filmmaking material, but its use is limited by its very low viscosity and poor mechanical properties. The objective of this work was to evaluate the effect of the addition of different concentrations of nanofibrillated bacterial cellulose (CBNF) and cashew gum on the properties of composite films. Eight films with different proportions of GC and CBNF were formulated, and then their chemical characteristics were verified, both physically and morphologically. In all formulations water vapor permeability (PVA), mechanical tests, solubility, opacity, color and humidity were performed. From the results obtained, the treatments T1, T5 and T8 were selected to be submitted to the following analyzes: Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR) and Lightning Diffraction X (XRD). The films were homogeneous with color tending to yellow (due to the presence of GC), and good thermal stability. The increase in the concentrations of CBNF provided significant improvements in the properties of tensile strength and modulus of elasticity. The same behavior was observed for the resistance to moisture, since the content of insoluble matter increased gradually with higher concentrations of CBNF. The permeability to water vapor significantly decreased with the 25% increase in the concentration of CBNF. In the diffractograms of the films, it was observed that the addition of CBNF was determinant for the increase in crystallinity. Considering these results, it can be concluded that the film formulated with 25% CBNF and 75% GC presented promising physical characteristics presenting potential for the elaboration of alimentary packages, besides being attractive, economically, since greater amount GC in the formulation makes this kind of film more accessible.