Valorização da lignina kraft: uso na preparação de filmes compósitos de lignina e quitosana

Abstract

The agro-industry and the fishing industry generate tons of waste and by-products that harm the environment but can be transformed into new materials with aggregated value. Aiming at the need to reuse waste, this study seeks to use the by-products of the paper and cellulose industry and the waste from the fishing industry, in the preparation of films composed of chitosan (Q) and kraft lignin microparticles (MLK). The MKLs were prepared from the sonification of a kraft lignin suspension. Dynamic light scattering (DLS) analysis was used to verify the average size of the MKLs, which was between 100 and 700 nm. The chitosan films were prepared by the solvent evaporation method (casting). Nine films with different concentrations of Q and MLK were prepared. The films were characterized by different techniques: scanning electron microscopy (MEV), thermogravimetry (TGA), spectroscopy in the infrared region (FTIR), mechanical tests, humidity, thickness, water vapor permeability (PVA), and optical properties (UV-vis). The MEV results showed films with good microstructure, this feature is a positive point in the mechanical properties and barrier properties of the film. Adding MLK to the films increases the value of tensile strength and modulus of elasticity. The transparency of the film drops considerably with the increase in MLK concentration. The polymeric films have an excellent UV light barrier property that increases as the concentration of MLK increases. The physical properties (humidity and water vapor permeability) are directly linked to the MLK concentration. Humidity and PVA are higher in films with lower concentrations of MLK. The constitution of the films was analyzed using TGA and FTIR analysis.