RESUMO As flores tas de pinus vêm sendo implantadas no sul do Brasil desde a década de 1960 em diferentes espaçamentos e colhidas em prazos mais curtos para aumentar a produção de madeira. A redução do período de rotação e a alteração do espaçamento das plantações florestais podem influenciar nas propriedades físicas e mecânicas da madeira, por tratar-se de árvores mais jovens que ainda não possuem uma quantidade significativa de madeira adulta em sua composição. Nesse contexto, o objetivo desta pesquisa foi estudar a influência de três espaçamentos de plantio (3,0 × 2,0 m, 4,0 × 2,0 m e 2,0 × 2,0 m) e duas idades (13 e 15 anos) nas características de crescimento e nas propriedades físico-mecânicas da madeira, bem como a relação entre elas. Foi avaliada a densidade aparente, a porcentagem de lenho tardio, o número de anéis por polegada, a resistência e a rigidez em flexão estática e em compressão paralela, e a resistência ao cisalhamento. Os espaçamentos de plantio avaliados não causaram alterações estatisticamente significativas nas propriedades mecânicas da madeira juvenil de Pinus taeda L. As idades estudadas não influenciaram na densidade aparente da madeira, mas o aumento da idade de corte de 13 para 15 anos aumentou significativamente a resistência e a rigidez da madeira. Houve correlação significativa entre as características de crescimento das árvores e a resistência e rigidez, em flexão estática e em compressão paralela, com R2 próximo de 0,500, o que sugere que as características de crescimento podem ser utilizadas para auxiliar na estimativa destas propriedades. A madeira de Pinus taeda L. utilizada neste estudo pode ser classificada como madeira estrutural, classe C20 para 13 anos de idade e classes C25 e C30 para 15 anos de idade, de acordo com a norma NBR 7190/97.

ABSTRACT Pinus forests have been implanted in the South of Brazil since the 1960s in different spacing and harvested in shorter terms to increase wood yield. Reducing the rotation period and changing the spacing of forest plantations can influence the wood’s physical and mechanical properties, as they are younger trees that do not yet have a significant amount of mature wood in their composition. In this context, this research aimed to study the influence of three levels of planting spacing (3.0 × 2.0 m, 4.0 × 2.0 m, and 2.0 × 2.0 m) and two ages (13 and 15 years old) on growth characteristics and physical-mechanical properties of wood, as well as the relationship between them. Apparent density, latewood percentage, rings per inch, strength and stiffness in static bending as well as compression parallel to the grain, and shear strength were evaluated. The evaluated planting spacings did not cause statistically significant changes in the mechanical properties of juvenile Pinus taeda L. wood. The studied ages did not influence the wood’s apparent density. However, changing the cutting age from 13 to 15 years significantly increased the strength and stiffness of the wood. There was a statistically significant correlation between tree growth characteristics and strength, and stiffness in bending and parallel compression, around 0.500 R2, which suggests that this parameter can be used to assist in estimating those properties. The wood of Pinus taeda L used in this study can be classified as structural wood, class C20 for 13 years-old trees and classes C25 and C30 for 15 years-old trees, according to NBR 7190/97 requirements.

Abstract This study aimed to verify technical potential of using waste from wood veneers and plywood as a raw material for the production of MDP. The variance analysis of the panels density was carried out. Physical-mechanical properties were evaluated by comparing them with the international standards and by analysis of variance. The averages were subjected to the analysis of covariance, at the level of 5% probability. Finally, Pearson’s correlation analysis between properties was performed. The panels produced with “log core” and “veneer clippings” residues showed equivalent averages for physical properties and higher for mechanical properties of internal bond and surface screw withdrawal, when compared the averages of panels produced with commercial particles. Panels produced with “plywood cutting” showed unsatisfactory mechanical properties. It’s concluded that the “log core” and “veneer clippings” residues show potential for use as a raw material in the composition of MDP.

Abstract The aimed to evaluate the properties of MDP and HDP panels, produced with pure Populus deltoides or in a mixture with Pinus taeda, together with urea-formaldehyde resin. The density and chemical properties of this wood with 8 and 12 years of age were determined, which were used for the production of panels with nominal density of 0.65 and 0.90 g.cm-3. Water absorption and thickness swelling tests were performed after 2 and 24 hours of immersion, as well as static bending and perpendicular tensile. Populus deltoides wood was classified as low-density in both ages and presented chemical properties similar to Pinus taeda. Mechanical properties obtained for the panels produced reached the minimum requirements values established by the standards NBR 14810-2 and ANSI A208.1, demonstrating the potential use of wood species for the production of MDP and HDP panels, at both ages studied and used pure or mixed with Pinus taeda wood.

ABSTRACT Wood scarcity, attacks by primates and insects, and fungal damage in forest plantations make the introduction of new species necessary. Given this, it is important to understand the potential uses of wood in the production chain. Pinus patula Schltdl & Cham presents good adaptation to Brazilian conditions and is a candidate for wood supply. Its juvenile wood density however, is lower than that of other pine species. This study aimed to evaluate the properties of veneer on panels produced with twelve-year old P. patula wood compared with panels produced with P. taeda wood of the same age, which is commonly used for panel production. Panels were bonded with urea-formaldehyde and phenol-formaldehyde adhesives using veneers applied on two types of plywood panel. The P. patula panels showed lower strength, stiffness and density when bonded with urea-formaldehyde, and higher strength, density and stiffness when bonded with phenol-formaldehyde in comparison with P. taeda. P. patula panels can be used for multilayer panel production.

RESUMO O objetivo foi analisar a qualidade de painéis compensados produzidos com lâminas de Eucalyptus saligna, Eucalyptus dunnii e o híbrido Eucalyptus urophylla x Eucalyptus grandis, em diferentes composições de misturas. Foram produzidos painéis com 500 × 500 × 14 mm e sete camadas de lâminas, coladas com fenol-formaldeído (FF), na gramatura de 360 g. m-2 em linha dupla e teores de sólidos de 28% e 32%. A prensagem dos painéis foi realizada a 130 °C, 12 kgf. cm-2 e 15 minutos. Analisaram-se as propriedades massa específica, umidade, absorção d’água, inchamento em espessura, cisalhamento na linha de cola e flexão estática. Os resultados foram comparados aos requisitos do catálogo técnico da ABIMCI e das normas EN 314-2 e DIN 68792. Os painéis de Eucalyptus dunnii apresentaram menores valores de propriedades mecânicas, com tendência de aumento quando em misturas. Os painéis de Eucalyptus saligna e do híbrido Eucalyptus urophylla x Eucalyptus grandis apresentaram bons resultados, tanto puros como em mistura com as outras espécies.

ABSTRACT The quality of plywood produced with wood veneer of Eucalyptus saligna, Eucalyptus dunnii and Eucalyptus urophylla x Eucalyptus grandis hybrid in different compositions was analyzed. Seven-layer veneer panels measuring 500 × 500 × 14 mm, glued with phenol-formaldehyde (PF), weighing 360 g. m-2 in double line and with 28 or 32% of solid content were produced. Panels were pressed under 130 °C and 12 kgf. cm-2, during 15 minutes. We analyzed the properties of specific gravity, moisture content, water absorption, thickness swelling, glue line shear and static bending. The results were compared to the requirements of the ABIMCI technical catalog and EN 314-2 and DIN 68 792 standards. Eucalyptus dunnii panels presented lower values of mechanical properties, with an upward trend when in mixtures. The panels produced with Eucalyptus saligna and the Eucalyptus urophylla x Eucalyptus grandis hybrid showed good results, either pure or mixed with the other species.

O conhecimento da estabilidade térmica da madeira e materiais celulósicos é um importante fator na utilização destes materiais de fontes naturais como carga de reforço em matrizes poliméricas. Entretanto, estes materiais possuem baixa resistência à degradação térmica causado principalmente pela presença de espécies voláteis que entram em ignição em baixas temperaturas. Características dessa natureza contribuem significativamente na limitação do uso de tais materiais como cargas de reforços em situações que exigem temperaturas mais elevadas. Neste trabalho é avaliada a degradação térmica de duas espécies de madeira, em atmosfera de nitrogênio, por meio de medidas termogravimétricas. Os parâmetros cinéticos de decomposição térmica foram estimados com o método proposto por Flynn-Wall-Ozawa (FWO). A Garapeira apresentou energia de ativação menor nas frações reação até 0,4. Na fração de reação de 0,9 foi observada a maior diferença de energia de ativação entre as espécies de madeira. O mecanismo de reação para duas espécies é basicamente controlado por difusão (Dn) até a fração de reação de 0,8, sendo que após segue cinética de terceira ordem (F3).

The thermal stability of wood and cellulosic materials is an important factor for applications of these natural renewable materials as fillers for reinforcing polymeric matrices. However, these materials have low thermal stability caused mainly by species that ignite at low temperatures. These characteristics contribute significantly to limit their use in situations where higher temperatures are required. In this work, the thermal degradation of two kinds of wood (Pinus and Garapeira) was evaluated using thermogravimetric measurements under nitrogen atmosphere. The parameters of thermal decomposition kinetics were estimated using the Flynn-Wall-Ozawa (FWO) method. The Garapeira wood showed lower activation energy at reaction degrees below 0.5, probably due to the presence of volatiles compounds, such as oil and wax. The Pinus wood had different characteristics in the initial reaction degree (up to 0.4). After this point, however, Garapeira becomes more stable than Pinus due to the formation of more thermally stable species and because of the higher amount of lignin. Besides, the thermal degradation processes of both woods were found to be mainly controlled by diffusion (Dn) of volatile species at reaction degrees up to 0.8, achieving a third order (F3) mechanism afterwards.

RESUMO Neste trabalho, foram analisadas as propriedades físico-mecânicas de chapas aglomeradas produzidas com dois tipos de papel reciclável (papel jornal e offset) e partículas de madeira de Pinus elliottii Engelm. As aparas de papel foram usadas no colchão em dois diferentes formatos (tiras ou moídas) e em diferentes proporções: 0, 20, 40, 60 e 100% do peso seco das partículas. Utilizoaram-se 10% de adesivo à base de tanino-formaldeído na proporção 100:10. O experimento foi estabelecido segundo modelo fatorial, com três repetições. Os testes físico-mecânicos das chapas foram realizados segundo a norma ASTM D1037 (1995). Chapas aglomeradas produzidas tanto pela inclusão de papel jornal quanto offset no formato de tiras apresentaram tendência ao estouro durante a abertura dos pratos da prensa, causado pelo alto teor de umidade do colchão. A inclusão de aparas de papel prejudicaram a maioria das propriedades analisadas, fazendo com que não atendessem aos valores estabelecidos pelas normas DIN 68761 (1)-1961, (3)-1971 e ANSI A 208.1 (1987). A absorção d’água após 24 horas de imersão, a ligação interna e a resistência ao arrancamento de parafusos foram as propriedades mais prejudicadas. De modo geral, o uso de papel jornal se mostrou mais promissor do que o papel offset.

ABSTRACT 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.