Leandro Calegari

Qualidade das chapas de partículas aglomeradas fabricadas com resíduos do processamento mecânico da madeira de Pinus elliottii (Engelm.).

This work was undertaken with the objective of evaluating the mechanical properties of particleboard manufactured with slash pine residues, resulting from woodxa0 mechanical processing. The boards were produced with two types of residues: chips and shaves, used pure or mixed. The adhesive employed was ureia-formaldehyde in proportions of 4, 8 and 12% based on ovendry weight of particles, and densities of 0.6 and 0.7 g/cm 3 . There were evaluated the bending properties, internal bond and screw withdraw. The bending properties values increased with increasing shaves in the mixture, with board density and proportion of adhesive. It was possible to conclude that boards made of shaves, with larger proportions of adhesive and higher board densities present satisfactory quality.

Monitoramento do teor de umidade de madeiras de Pinus elliottii Engelm. e Eucalyptus grandis W. Hill ex Maiden, sob diferentes temperaturas de secagem, através do ultra-som.

With the purpose of evaluating the viability of use of ultrasonic technique to estimate the wood moisture content during the drying process, samples of Pinus elliottii Engelm. and Eucalyptus grandis W. Hill ex Maiden with dimensions of 3.5 cm thick, 10 cm width and 25 cm long were submitted to drying temperatures of 20, 40 and 70oC. A PUNDIT ultrasonic equipment with plane face transducers by 50 KHz was used to measure sound velocity in the longitudinal direction of the wood. Results indicated increase of estimated ultrasonic speed with reduction of moisture content.xa0 This relationship showed to be valid for the wood from green to the end of the drying process, and the best determination coefficients were found in the eucalypt wood (R² = 81%). Although no influence of the species in the ultrasonic speed has been observed, this one was influenced by the wood specific gravity and by the drying temperature. The effect of the specific mass was directly proportional for the pinus wood.xa0 Opposite effect was observed in eucalypt wood. The ultrasonic speed tended to decrease as drying temperature increased for both species. Results suggest that this method presents good potential for the control of the drying process.

Fabricação de chapas de partículas aglomeradas usando gesso como material cimentante.

In this work, gypsum bonded particleboards were manufactured using recycled paper (newspaper and offset) and pine wood particles. In all treatments the ratio wood/gypsum was kept in 0.25 (ovendry base) and two water content (w) were employed: 0.4 and 0.8, corresponding to the water/gypsum ratio. The boards were cold pressed in laboratory in a process similar to the conventional particleboard fabrication. Then, they were tested in static bending, hardness, screw withdrawal and thickness swelling. In general, the addition of fibers improved the board properties. Significant differences were found for some of the treatments for static bending strength, hardness and screw withdrawal, while the inclusion of paper recycled fibers with w = 0,4 did not show differences for water absorption and thickness swelling, when compared to conventional gypsum boards. The best results were obtained when newspaper type recyclable fibers were introduced, with w = 0,4.

Propriedades físicas de chapas de partículas aglomeradas fabricadas com resíduos de processamento mecânico da madeira de Pinus elliotii Engelm.

The objective of this research was the investigation of dimensional stability of particleboard made with slash pine wood residues. The boards were manufactured with chips and shaves, resulting from sawmill and planermill industries, respectively, used pure or mixed. The adhesive used was urea-formaldehyde in proportions of 4, 8 and 12%, based on the ovendry weight of the particles. Board density investigated were 0.6 and 0.7 g/cm 3 . The properties evaluated were water absorption and thickness swelling. The best boards were those made of shaves glued with 8 and 12% adhesive content.

Resistência mecânica e à umidade de painéis aglomerados com partículas de madeira de diferentes dimensões.

Neste trabalho, foram confeccionadas e testadas chapas aglomeradas estruturais utilizando particulas de Pinus elliottii Engelm com dimensoes nominais de 110, 75 e 40 mm de comprimento, 0,5 e 1,0 mm de espessura e 20 mm de largura. As particulas foram orientadas ao acaso em moldes sem-fundo com dimensoes de 50 x 50 x 20 cm. Os colchoes foram prensados a 180 0 C por 10 minutos ate atingir espessura de 9,5 mm e densidade de, aproximadamente, 0,7 g/cm 3 . O adesivo utilizado foi 8% (em relacao ao peso seco das particulas) de tanino-formaldeido.xa0 Foram analisadas as propriedades de flexao estatica, ligacao interna, resistencia ao arrancamento de parafusos, dureza Janka, inchamento em espessura e absorcao d’agua para 2 e 24 horas de imersao. Todos os testes foram realizados segundo a norma americana ASTM D 1037 (1995). As propriedades de flexao estatica (MOR e MOE) aumentaram com o aumento do comprimento e diminuicao da espessura das particulas. Ja o inchamento em espessura e a resistencia ao arrancamento de parafusos aumentaram com o aumento da espessura das particulas.

Adição de aparas de papel reciclável na fabricação de chapas de madeira aglomerada.

In this work, there were analyzed the properties of particleboards produced with two types of recycled paper (newspaper and offset) and slash pine wood particles ( Pinus elliottii Engelm.). The paper was introduced into the mattress in two forms: strands and after hammer milling, in different proportions: 0, 20, 40, 60 and 100% of ovendry weight of the particles. The adhesive used was 10% tannin-formaldehyde (100:10 parts by weight). The experiment was set according to a factorial model, with three replications. The tests were conducted following ASTM D1037 (1995). Boards produced both with offset and newspaper strand inclusions showed tendency to blow at press opening. The inclusion of paper caused decrease in the properties, in such degree that boards did not meet commerce standards DIN 68761 (1)-1961, (3)-1971 and ANSI A 208.1 (1987). Water absorption after 24 hours, internal bond and screw whitdraw were the properties most affected. In general, the use of newspaper was more encouraging than offset paper.

Produção madeireira na região da Quarta Colônia de Imigração Italiana do Rio Grande do Sul.

This study was conducted with the objective of quantifying the production of wood in the Area of the Fourth Colony of Italian Immigration in Rio Grande do Sul. Firstly, using a questionnaire, a census of the consuming companies of wood in that area was made, investigating mainly the amount, type, origin of the consumed raw material, and the amount, type and end use of wood products. As principal results, it was verified that such area presents 77 consuming companies and wood processing units. These were classified into micro and small companies, with familiar features and capital, and low industrialization. In the visits made to the industries, it was evident that many technological aspects are not known or are neglected, thus causing loss of the raw material and/or in low quality of the final products. A great amount of raw material (96,8% of the boards and 98,9% of the timber) comes from other areas of the State or the country. In the same way the main products are sold abroad (wood frames 86,3%, panelings 99,7%, sawed wood 53%).

CARACTERÍSTICAS ENERGÉTICAS DO CARVÃO VEGETAL DE AROEIRA ( Myracrodruon urundeuva Allemão) E LEUCENA ( Leucaena leucocephala (Lam.) R. de Wit)

The exploitation of wood energy purposes (firewood and charcoal) has caused reduction in native vegetation, added to this, problems are generated for fauna, flora and soil. The objective of the research was to evaluate the energy characteristics of charcoal Aroeira ( Myracrodruon urundeuva Allemao ) and Leucaena ( Leucaena leucocephala (Lam.) R. de Wit ). Suppression of five specimens of urundeuva Myracrodruon and Leucaena leucocephala was performed, following quality, phenological and health criteria. Carbonization was performed in duplicate, using anhydrous wood. Also, it was carried out the coal chemical analysis and the determination of true and bulk densities. The gross calorific value was determined by adiabatic calorimeter. The experiment was arranged in a completely randomized design (DIC) and the values were submitted to analysis of variance by the test F at 5% of probability level. The Myracrodruon urundeuva wood and Leucaena leucocephala showed no statistical differences, with 41.22% and 40.59% of charcoal. The apparent density of charcoal Myracrodruon urundeuva (0.59 g / cm 3 ) was higher than that of Leucaena leucocephala (0.39 g / cm 3 ), but the species were similar to the true density of charcoal, with 1.21 g / cm 3 and 1.11 g / cm 3 , respectively. Similarly, the gross calorific value of charcoal showed no difference between species the wood, Myracrodruon urundeuva (6869 kcal / kg) and Leucaena leucocephala (6977 kcal / kg). The amount of released volatiles and ash produced was higher on the wood Myracrodruon urundeuva with 33.87% and 3.79%. The fixed carbon content was higher in Leucaena leucocephala (67.15%). The species showed similar energy characteristics so the wood of Leucaena leucocephala can be used for the production and the use of charcoal when compared to the native species which are already known and are used for the same purposes.

Determinação do módulo de elasticidade em madeiras por meio de métodos destrutivo e não-destrutivo - DOI: 10.5039/agraria.v3i2a284

Realizou-se o presente estudo em funcao de se correlacionar os modulos de elasticidade obtidos por metodos destrutivo e nao-destrutivo, das madeiras de Eucalyptus grandis W. Hill ex Maiden e Pinus elliottii Engelm., provenientes de regioes proximas a medula e a casca, razao pela qual se utilizou equipamento emissor de ondas ultra-sonicas, com transdutores de faces planas de 50 kHz. A velocidade ultra-sonica foi determinada ao se considerar a transmissao da onda ao longo do comprimento de corpos-de-prova com dimensoes nominais de 5 x 5 x 20 cm (espessura x largura x comprimento). Para avaliar a sensibilidade do metodo ultra-sonoro, corpos-de-prova foram ensaiados destrutivamente a compressao paralela as fibras, com determinacao do modulo de elasticidade (metodos destrutivo e nao-destrutivo). Os resultados indicaram que os valores da constante elastica obtida pelo metodo ultra-sonoro, para as madeiras de Eucalyptus grandis e Pinus elliottii , foram mais elevados que os dos modulos de elasticidade a compressao paralela as fibras. Apesar da diferenca de valores absolutos entre os dois metodos em funcao da natureza viscoelastica da madeira, o metodo ultra-sonoro foi eficiente em virtude de avaliar, de forma rapida e eficaz, as diferencas relativas a qualidade da madeira.

Monitoramento da temperatura no interior de chapas aglomeradas durante o processo de prensagem.

The objective of the present work was to investigate the behaviour of core and face temperatures of particleboard glued with 8% tannin-formaldehyde adhesive. The boards were manufactured with three replication per treatment, with density of 0,7 g/cm³ and 27 kgf/cm² of pressing specific pressure. Pine flakes (40, 75 and 110 mm long and 0,5 and 1,0 mm thick) and eucalypt particles were used and two pressing temperatures (140 and 180oC) along with two mat moisture content (17 and 21%) were employed. The curves of temperature rise with pressing time indicated a fast temperature rise during the first 100 seconds of pressing, remaining at a plateau possible after reaching water boiling temperature. The temperature increased again, but on a more gradual form, after the lost mat moisture. It was possible to observe that mat formed by flakes of larger thicknesses showed faster initial temperature rise. The main factor that influenced the temperature behaviour at the board core was the mat moisture content. The higher the mat moisture content, the faster the temperature rise.