Desenvolvimento de filme polimérico à base de hemicelulose extraída de serragem de Mezilaurus itauba e Pinus eliottii

Abstract

Aiming to link sustainability to economic development, the use of raw materials from renewable sources as an alternative to the production of biofilms is growing. The residues generated in the wood processing correspond to about 50 % of its initial volume and being generally destined to incineration for energy generation, they are no longer explored as a source of polysaccharides that are promising for the development of new materials. Representing about 20 % of the composition of Mezilaurus itauba (ITA), a North Brazilian native species largely used in the timber industry, and 24 % of Pinus elliottii (PIE), a species widely cultivated in the South of Brazil used in pulp and construction industries, hemicellulose is an amorphous polysaccharide studied for application since the fuel production until the development of films and gels. In this study, hemicellulose was removed from the extractive-free wood sawdust and was characterized by FTIR and thermogravimetry, where its presence was confirmed through the IR bands and degradation peaks characteristic of the polyoses. The extraction method tested was not efficient to remove hemicellulose from ITA, therefore only the hemicellulosic content extracted from Pinus at concentrations of 2 %, 3 % and 4 % (w/v) was used to the development of films by casting placed on polytetrafluoroethylene surface, which had their morphological, physical, thermogravimetric and mechanical properties subsequently analyzed. The films exhibited a dense and pore-free structure with average thicknesses ranging from 0.1034 to 0.1451 mm, but with the presence of contaminants seen in the microscopies and identified as sodium chloride in the EDS analysis. The films' FTIR spectra were similar for all hemicellulose concentrations, but thermogravimetry showed higher thermal stability and higher ash content for the 4 % (w/v) film. Mechanically, the films presented elongations ranging from 0.86 % to 2.25 %, and low tensile strength possibly due to the salt crystals, since the most resistant hemicellulose film (4 % (w/v)) supported a tensile strength of 0.64 ± 0.02 MPa. Despite the fragility of the films, they exhibited a tendency of increasing thickness, thermal stability and tensile strength with increasing hemicellulose content, which can be improved by further purification of the extracted hemicellulose. The study indicated the possibility of utilizing hemicellulose extracted from ITA and PIE woods for the development of polymeric films. [resumo fornecido pelo autor]