Processo Kraft de polpação de Eucalyptus grandis para a obtenção de madeira transparente

Abstract

The present study deals with the use of the kraft pulping process in the production and evaluation of transparent wood of the Eucalyptus grandis species with a 4:1 ratio (liquor / wood) with conditions of active alkali of 18% and sulfidity of 20% with the use of hydroxide sodium (NaOH) and sodium sulfide (Na2S). The extraction took place in a water bath at 90 °C and 4 times were tested from 15 to 60 min. Subsequently, the samples in the form of slides were subjected to a treatment with hydrogen peroxide (H2O2) with 35% concentration until the elimination of the yellowish color. After bleaching treatment, the slides were dehydrated by immersion in pure ethanol in order to preserve their structure and carry out the impregnation/polymerization process in situ of the methyl methacrylate monomer. Chemical, thermal, surface, hygroscopic and mechanical characteristics were evaluated. The production of Eucalyptus grandis transparent wood through the kraft process and methyl methacrylate impregnation is possible from a delignification process longer than 30 min of kraft cooking. Samples prepared under these conditions showed the best indices of thermal stability, roughness and anti-swelling efficiency. In addition, the water repellency exceeded 80% in relation to the control in all cases, showing that the transparent wood produced is a material with water repellency and with properties that can reach a modulus of rupture of 554.82 MPa and a modulus of elasticity. of 7.44 GPa.