Síntese de resinas ligno-fenol-formaldeído para aplicação em painéis de média densidade

Abstract

Sugarcane bagasse is a source of lignocellulosic biomass, consisting mainly of cellulose, hemicellulose and lignin. Lignin has an aromatic character, making it suitable for nobler use such as phenol substitute in phenol-formaldehyde resins. This work aimed to evaluate the lignin extracted from sugarcane bagasse as a substitute for phenol in phenol-formaldehyde resins in different proportions (0%, 40%, 50%, 70% and 100%), using phenolation for modify the lignin, making it more reactive and apply these resins to medium density panels (MDF). The experimental procedure consisted of the treatment of sugarcane bagasse by means of a steam explosion followed by the extraction of lignin through the organosolv process, using ethanol as a solvent and sulfuric acid as a catalyst. Lignin was characterized by Infrared Absorption Spectroscopy (FT-IR), Gel Permeation Chromatography (GPC), Nuclear Magnetic Resonance (HSQC 1H-13C and 31P NMR) and elementary analysis. The synthesized resins had a low content of free formaldehyde (up to 0.81%) and were characterized by FT-IR, HSQC 1H-13C and Differential Scanning Calorimetry (DSC). The MDF panels produced were analyzed for water absorption, swelling and their morphology analyzed by Scanning Electron Microscopy (SEM). From the results it was possible to conclude that the lignin obtained from sugarcane bagasse can be used as a partial substitute for phenol in the development of resins and in the development of MDF panels.