EFFECT OF THE HEAT TREATMENT OF Hovenia dulcis Thunb. WOOD ON THE PRODUCTION OF EGP PANELS WITH DIFFERENT ADHESIVES

The objective of this work was to analyze the shear strength of edge-glued panels (EGP) made from the H. dulcis Thunb. wood thermally modified by the VAP HolzSysteme® process. Initially, the Hovenia dulcis samples were heat-annealed by the VAP HolzSysteme® process, and then bonded with Resorcinol-formaldehyde (RF), Melamine-urea-formaldehyde (MUF), Isocyanate Polymer Emulsion (EPI) and Polyvinylacetate (PVAc) and submited to pre-treatments for dry, humid and external environment and without pre-treatment to evaluate the shear strength, 5th percentile and failure in the wood. It was observed a decrease in the shear strength of the thermorrectified H. dulcis wood for all adhesives. All adhesives obtained results superior to the minimum required by the standard EN13354 (2009) for the wood without pre-treatment as for the wood without thermoregulation as well as for the heat treated wood, and may be used for non-structural purposes. However, for the external environment (three cycles) only the MUF adhesive obtained value that meets the minimum standards of the standard, in this way, it is suggested to glue the EGP of H. dulcis without thermortification and with thermorrectification using the MUF adhesive, which has achieved better performance offering greater resistance in dry, wet and external environments

Determination of the chemical composition of Eucalyptus spp. For cellulosic pulp production

Funding Information: Funding: This research was partially supported by CAPES (Coordination for the Development of Higher Level Personnel). This work was also partially supported by Base Funding—UIDB/EQU/ 50020/2020 and Programmatic-UIDP/50020/2020 Funding of the Associate Laboratory LSRE-LCM— and UIDB/00511/2020 of the Laboratory for Process Engineering, Environment, Biotechnology and Energy, LEPABE—funded by national funds through FCT/MCTES (PIDDAC). This work was also supported by national funds through FCT, under the Scientific Employment Stimulus Institutional Call (CEECINST/00102/2018) and partially supported by the Associate Laboratory for Green Chemistry—LAQV, financed by national funds from FCT/MCTES (UIDB/50006/2020 and UIDP/50006/2020) and IF/01381/2013/CP1160/CT0007, Investigador FCT program, with financing from the European Social Fund and the Human Potential Operational Program. T.A.S.V. is grateful to the Erasmus Mundus program.The chemical composition of wood is important to assess the quality of this raw material for the industry of cellulosic pulp production. The purpose of this work was to determine the chemical composition of Eucalyptus spp. grown for cellulosic pulp production. Ten Eucalyptus spp. clones with six years of age, located in the municipality of Itamarandiba, Minas Gerais, Brazil, were used. Quantification was obtained for extractives, monosaccharides, uronic acids, acetates, lignin, ash and the phenolic composition of the extracts. In average, clones showed around 2.7% extractives, with a predominance of polar compounds soluble in ethanol and water; 27.7% lignin and 0.3% ash. Glucose was the main sugar detected (64.2%), followed by xylose (19.3%). The main components of the extractives were steroids, fatty acids and aromatic acids, followed by smaller amounts of substituted alkanoic acids, fatty alcohols, glycerol derivatives and triterpenes. The ethanol–water extracts presented total phenol contents ranging from 321.4 to 586.6 mg EAG/g of extract, tannins from 28.1 to 65.1 mg catechin/g of extract and flavonoids from 73.6 to 256.9 mg catechin/g of extract. Clones with a higher holocellulose amount and a lower lignin content showed a higher potential for cellulosic pulp production. These findings are important for the development of high-quality wood based on important traits for the pulp and paper sector.publishersversionpublishe

Composição química da madeira de eucalipto com diferentes níveis de desbaste

http://dx.doi.org/10.5902/1980509812359The objective of this study was to evaluate different thinning regimes in forest plantations of eucalypt(Eucalyptus grandis x Eucalyptus urophylla) clones to produce timber for cellulose and charcoal to verifywhether this effect could affect the proportion of the chemical components of wood. The average initialspacing between plants was 3x3 m and the treatments were: T1= control, T2, T3and T4 with thinning 20%,35% and 50% of the basal area, respectively. The results were analyzed by Tukey test at 5% probability.According to the results found the lignin content from treatment T4 was higher than that of the others; thegroups of uronic acids of the T1 was similar to all other treatments, but the levels of T2 and T4 differedbetween them. The extractives content of T1was similar to the T2 and T3 and lower than that of theT4; thecarbohydrates of T1 were similar to that of T3 and higher than the others. It was concluded that thinningincreases the quality of the wood to be used as energy purposes, such as charcoal production, but it did notincrease productivity for wood pulp and paper production.http://dx.doi.org/10.5902/1980509812359O objetivo deste estudo foi avaliar diferentes regimes de desbaste em plantios silviculturais de clones de eucalipto (Eucalyptus urophylla x Eucalyptus grandis) para produção de madeira visando à obtenção de celulose e carvão com a finalidade de verificar se este efeito poderia afetar quantitativamente a proporção dos componentes químicos da madeira. O espaçamento inicial médio entre plantas foi de 3 x 3 m e os tratamentos foram: T1= testemunha, T2, T3 e T4 com desbaste de 20%, 35% e 50% da área basal presente, respectivamente. Os resultados foram submetidos ao teste de Tukey com 5% de probabilidade. De acordo com os resultados, constatou-se que o teor de lignina resultante do tratamento T4 foi maior que o dos demais; o de grupos urônicos do T1 foi semelhante ao dos demais tratamentos, mas os teores dos T2 e T4 diferiram entre si. O teor de extrativos do T1 foi semelhante ao dos T2 e T3 e menor que o do T4; o de carboidratos do T1 foi semelhante ao do T3 e superior aos demais. Concluiu-se que o desbaste aumenta a qualidade da madeira para ser utilizada como fins energéticos, como produção de carvão, mas não aumenta a produtividade de madeira destinada à confecção de celulose e papel

Predicting moisture content from basic density and diameter during air drying of Eucalyptus and Corymbia logs

In air drying of Eucalyptus urophylla and Corymbia citriodora logs for the production of charcoal it is necessary to be able to predict when logs have reached the required moisture content of ≤ 35%. This study is aimed to produce models using basic density and diameter to predict the moisture content of Eucalyptus urophylla and Corymbia citriodora logs after 30, 60 and 90 days drying. 1,2 m long logs were taken at three different heights from three C. citriodora trees and three trees each from two E. urophylla clones (VM4 and Mn463). The 27 debarked, end sealed logs were air dried under cover for 90 days during which the change in moisture content was monitored. The relationship between density and drying was analyzed by Pearson’s correlation coefficient and the models for predicting the moisture content based on the basic density and diameter were produced. The density and the drying showed a high correlation coefficient. The coefficient of determination of the models was above 0,89 with a standard error lower than 6%. The use of the density and diameter to estimate the wood moisture content simplifies the production of the models, which can be used for Eucalyptus and Corymbia genetic materials

Effect of extractives on wood color of heat treated Pinus radiata and Eucalyptus pellita

Heat treatment can change wood color without any use of environmentally harmful chemicals, and the efficiency of this process depends on the raw material to be treated. The objective of this study was to evaluate the influence of extractives on the color change of Eucalyptus pellita and Pinus radiata wood during heat treatment. The extractives were extracted in cold water and in dichloromethane as well as totally removed and the wood was treated at 170°C and 200°C for three hours under atmospheric pressure and in presence of air for evaluating the lightness (L*), green-red coordinate (a*), blue-yellow coordinate (b*), color saturation (C) and tonality angle (H) values. Pinus radiata wood was more resistantto discoloration by heat treatment. The removal of total and cold water-soluble extractives before heat treatment changed the L* value of Pinus radiata, a* value of Eucalyptus pellita, and b*, C, and H valuesof both species. Removal of extractives soluble in dichloromethane did not affect the color of heat treated wood. Thus, understanding the influence of extractives on heat treated wood can allow adapting the raw material to the process for enhancing the applicability of heat treatment for changing wood color