Utilização da fibra poda do cajueiro como fonte de lignina e nanocristais de celulose para incorporação em filmes de celulose bacteriana

Abstract

The accumulation of nonbiodegradable plastic packaging in nature has caused environmental problems. One of the solutions found, particularly in the area of ​​food packaging, is the development of films from renewable and biodegradable sources that can replace petroleum-based materials. Bacterial cellulose (BC) is a promising polysaccharide, however, its low temperature resistance and high water vapor permeability are among the main deficiencies that make the use of pure BC unfeasible. The introduction of natural fibers and lignin into polymeric composites has great applicability because they have renewable origins and have great capacity to bond to the matrix phase, giving the composite high mechanical and thermal resistance, in addition to improvements in barrier properties. The objective of this work was to evaluate the effect of the addition of different concentrations of lignin (LIG) and cellulose nanocrystals (CNC), both extracted from cashew wood fiber (CWF), on the properties of the films nanofibrilada BC (NFBC) produced from cashew juice. Nine films with different proportions of LIG and CNC were formulated and characterized chemically, physically and morphologically. In all treatments, water vapor permeability (WVP), tensile properties, solubility, contact angle and opacity were determined. Some treatments were selected to be submitted to the following analyses: Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD), antioxidant and antimicrobial activity. The films were homogeneous with color tending to brown (due to the presence of LIG), and good thermal stability. The addition of lignin altered the hydrophilic character of the films, making them more hydrophobic, incorporated phenolic compounds and antioxidant activity, however did not show antimicrobial action. As for opacity, it was possible to obtain films with a high index, indicating protection from UV light. The combination (LIG/CNC) provided significant improvements properties of (WVP), tensile strength and modulus of elasticity. It can be concluded that BC films added with LIG and CNC showed favorable characteristics for application as active packaging.