Alexandre Monteiro de Carvalho

Surface roughness of heat treated Eucalyptus grandis wood

This study aimed to evaluate surface roughness of heat treated Eucalyptus grandis wood after peripheral planning and sanding performed in directions to the grain and against the grain. For machining tests, workpieces were collected from two different regions in the radial direction, as follows: internal, nearby the pit; external, nearby the bark. Heat treatment was carried out by heating samples at a maximum temperature of 190oC, with total treatment duration of 390 minutes. Heat treated and control samples underwent peripheral planning and sanding tests. The quality of machined surfaces was assessed by means of roughness average (Ra) measurements across and along the grain orientation. Results indicated significant differences in surface roughness as a function of machining feed direction, sandpaper grit size, and heat treatment. Surface roughness has not shown any difference in the radial direction.

Correlações da altura e diâmetro com tensões de crescimento em árvores de Corymbia citriodora e Eucalyptus urophylla

The multiple-use of planted forests by the forest products industrial sector has been increased gradually. Today, eucalyptus wood is used for nobler applications. However, some limitations, such as the presence of growth stresses, are responsible for great losses in the sector. Growth stresses generate cracks in the tops of logs and boards followed by warping. In this context, the objectives of the present work were to evaluate the growth stresses in individual Corymbia citriodora and Eucalyptus urophylla with different diameter and height classes, by the longitudinal residual strain (LRS) nondestructive method, around the trees circumference. The average longitudinal residual strain, associated to the Corymbia citriodora and Eucalyptus urophylla growth stresses, were 0.106 and 0.092 mm, respectively. For Corymbia citriodora, the diameter at breast height (DBH) had a negative significant correlation with the LRS, while the height did not show a significant correlation. For Eucalyptus urophylla, a negative significant correlation between LRS and both variables, DBH and height, was observed. Indeed, growth stresses were lower for greater DBH and heights.

Estudo de Caso de uma Planta de Carbonização: Avaliação de Características e Qualidade do Carvão Vegetal Visando Uso Siderúrgico

Charcoal is a product of great importance in the Brazilian economy, a fact linked to its use as a renewable energy source and reducing the steel industry. Efforts have been made aiming at improving the production process of charcoal, which can be obtained in different furnace types with varying yield and quality. Taking these factors into consideration, the aim of this study was to survey the characteristics relating to the carbonization plant belonging to the Saint Gobain Ltda. company, in the city of Seropedica/Rio de Janeiro-Brazil and chemically analyze the coal produced. The data were obtained through a questionnaire and compared to the other two companies in the same industrial segment. The analysis of charcoal samples was conducted in the laboratory through chemical analysis. The furnaces used in charcoal production in existing carbonization plant analyzed company are characterized as surface furnaces with chimney. The average output of the conversion of wood charcoal was 50%. Compared to other carbonization systems, the company analyzed showed intermediate values ​​in terms of process yield and charcoal produced is considered good quality, with high fixed carbon content (82.70%) and low ash content (1,30%).

Correlações dendroclimatológicas do Eucalyptus grandis Hill ex Maiden na região de Rio Claro, RJ

The commercial forests plantation contributes decisively to generate socio-economic and environmental benefits, providing sustainability at the forest-based industries. The Eucalyptus grandis Hill ex Maiden stand out as one of the most cultivated species for reforestation in Brazil. The objective of this study was to determine the relationship between precipitation and wood production for 23-year old Eucalyptus grandis from a commercial plantation in Rio Claro, Rio de Janeiro state, Brazil. The annual increment of wood was determined by the X-ray densitometry, which provides a detailed wood density profile in radial direction for each sample. One year of the tree life was considered because this the period for the formation of two consecutive latewood rings formation, which corresponds to two high density peaks. The results showed a positive correlation between precipitation data and annual increment of wood, revealing the dendroclimatology potential of this species in this region.

Copaifera langsdorffii Bark as a Source of Chemicals: Structural and Chemical Characterization

The chemical composition and the anatomy of Copaifera langsdorffii bark are reported here for the first time by studying trees grown in a native forest area in the Amazon region, Brazil. The bark is thin, dark reddish brown, and exfoliates in irregular flakes. It is very dense, showing highly lignified cells and abundant sclereids, and cellular fillings of phenolic nature. It includes a poorly developed rhytidome and a periderm with thin- and thick-walled phellem cells. The mean chemical composition was: ash 3.7%, total extractives 21.3%, mainly corresponding to polar compounds soluble in ethanol and water, suberin 0.8%, and lignin 36.6%. The polysaccharides showed a predominance of glucose and xylose (66.4% and 23.5% of total monosaccharides, respectively). The ethanol-water bark extract had a high content in phenolics: total phenolics 589.2 mg gallic acid/g extract, flavonoids 441.9 mg catechin/g extract, and tannins 54.8 mg catechin/g extract. The antioxidant activity was high, comparable to known antioxidant reference compounds: 720.3 mg Trolox per g of extract or 92.1 mg Trolox per g of bark. After bark grinding, the finest fraction was enriched in polar extractives (40.6%). C. langsdorffii bark is a potential source of functional extractives, therefore representing a valorization of the residual bark obtained during the industrial tree processing for timber.

Growth Stress in Peltophorum dubium and its Correlation with the Growth Variables

The exploitation of valuable native timber species in forest restoration projects has emerged as a promising strategy to make restoration financially viable. There are few studies regarding the quality of timber from restoration plantations. The aim of this study was to analyze growth stresses by determining the longitudinal residual strain (LRS) and evaluate their correlation with the growth variables in the species Peltophorum dubium (Spreng.) Taub in a 14-year old restoration plantation. Eighteen individuals were evaluated, determining the following variables: diameter at breast height (DBH), bark thickness, average annual growth in diameter (IMA) and annual periodic growth in diameter (IPA 2012-2015). The LRS was determined by the extensometer (CIRAD-Forêt), on DBH height and in the north-south direction of each tree. The LRS average was 0.072 mm, within the range of expected wood values for sawmilling. There was a significant positive correlation between the LRS, DBH and IMA.

DENSITOMETRIA DE RAIOS X NA AVALIAÇÃO DA DENSIDADE EM PAINÉIS DE PARTÍCULAS

This study aimed to determine the apparent density, by gravimetric technique and X-ray microdensitometry of particleboard produced with Acacia mangium wood and search existence of correlation between both methods. It was used urea formaldehyde adhesive and commercial tannin Acacia mearnsii applied in powder form directly to the previously glued particles. The panels manufactured using four compression ratios (1.39, 1.55, 1.73, and 2.00) combined four levels of powdered tannin (0, 10, 20 and 30%), making up 16 treatments (4 panels by treatment). The particleboard apparent density parameters (mean, maximum and minimum) and gravimetric density were determined, analyzed and compared. The density profile presented graphically and interpreted by analysis of variance and multiple linear regression. The apparent density, medium, maximum and minimum for particleboard obtained by microdensitometry X-ray ranged 357-697 kg/m 3 , 386-824 kg/m 3 , and 334-634 kg/m 3 , respectively, and gravimetric method 369-742 kg/m 3 . The technique was effective in determining variations in the density profile in the thickness of the particleboards in all treatments, as well as direct obtain the apparent density. These variations could be reduced if the tannin used was previously hydrated in water. Was found strong correlation (R 2 = 0.99) between the mean apparent density obtained by X-ray microdensitometer and gravimetric method.

Production and evaluation of charcoal fines briquettes compressed with cellulosic waste from paper and pulp industry.

Este trabalho teve por objetivo avaliar briquetes produzidos a partir de finos de carvao vegetal compactados com residuo celulosico gerado na decantacao dos efluentes da industria de papel e celulose. Foram realizados os seguintes tratamentos: briquetes produzidos com fino de carvao vegetal e residuo celulosico nas proporcoes de 25% (T1), 30% (T2), 35% (T3), 40% (T4) e 45% (T5) e briquetes produzidos com finos de carvao vegetal com 10% de amido e residuo celulosico nas proporcoes de 0% (T6), 5% (T7), 10% (T8), 15% (T9), 20% (T10) e 25% (T11). A caracterizacao dos briquetes foi realizada por meio de ensaios de analise quimica imediata, determinacao do poder calorifico superior, densidade aparente e avaliacao da resistencia mecânica apos a secagem dos briquetes em estufa ou ao ar livre. Observou-se que os briquetes com residuo celulosico e amido em sua composicao apresentaram maior densidade e resistencia mecânica a compressao, concluindo-se, assim, que a presenca do amido favoreceu a compactacao e estabilidade dos briquetes. Observou-se, tambem, que o processo de secagem em estufa prejudicou a qualidade dos briquetes, de modo que a secagem ao ar livre forneceu briquetes mais resistentes e estaveis.

Surface evaluation of the heat treated wood of Eucalyptus grandis Hill ex Maiden

The objective of this study was to study the machined surface quality of Eucalyptus grandis wood submitted to heat treatment. The machining operations realized on the boards obtained from the processing of six trees were: planing, thicknessing, tear in horizontal drilling, drilling, drilling hinge and sanding. 208 boards of 125 x 25 x 500 mm were selected, with 104 untreated and 104 heat-treated boards at maximum temperature of 190oC. The evaluation of the surface was performed according to ASTM D-1666/87 standard. The result showed that the Eucalyptus grandis wood presents a good behavior during the machining tests, obtaining notes 1 and 2 (excellent and good), except for drilling hinge test in the bolt hole and drilling with 12, 8, 6 mm, reaching notes between 2 and 4 (good, regular and bad). The heat treatment reduced the number of defects on the machined samples, except for torn grain in some machining operations.

AVALIAÇÃO DA SUPERFÍCIE DA MADEIRA DE Eucalyptus grandis Hill ex Maiden TRATADA TERMICAMENTE

O objetivo deste estudo foi estudar a qualidade da superficie usinada da madeira de Eucalyptus grandis, submetida ao processo de tratamento termico. As operacoes de usinagens realizadas nas tabuas obtidas a partir do processamento de mecânico de seis arvores foram: desempeno, desengrosso, rasgo na furadeira horizontal, furacao, furacao para dobradica e lixamento. Foram selecionadas 208 tabuas de 125 x 25 x 500 mm, sendo 104 nao tratadas e 104 tratadas termicamente a uma temperatura final de 190oC. A avaliacao da superficie foi feita de acordo com a norma ASTM D-1666/87. O resultado mostrou que a madeira de Eucalyptus grandis apresenta um bom comportamento durante os testes de usinagem, obtendo notas 1 e 2 (excelente e bom), exceto para os testes de furacao para a dobradica no furo passante e furacao com broca de 12, 8 e 6 mm, pois alcancaram notas entre 2 e 4 (bom, regular e ruim). O tratamento termico diminuiu a quantidade de defeitos nas amostras usinadas, com excecao para o defeito gra arrancada, em algumas operacoes de usinagem.