Diego Martins Stangerlin

Estimativa da idade de segregação do lenho juvenil e adulto por meio de parâmetros anatômicos para madeira de Luehea divaricata Mart.

This study aimed at determining the age of demarcation of juvenile and mature wood of Luehea divaricata Mart., using anatomical characteristics. Three adult trees, in good trunk, with diameter at DBH larger than 30 cm, from Encosta Superior do Nordeste do Estado do Rio Grande do Sul, were selected. Discs with thickness of 2 cm at 0.1 m of height from the base of the trunk were used. From each disc a radial ribbon 2 cm wide including the pith was removed. The initial wood of each growth ring was separated for maceration (method of Jeffrey). There were measured length and diameter of thirty fibers from each growth ring. Demarcation of the two types of wood was defined by the radial variation (pith-bark) of the anatomical characteristics (length, diameter, width of the lumen and wall thickness of fibers), using simple linear regression. Results indicate that fiber length is the best characteristic, while fiber diameter, lumen width and wall thickness were considered inadequate for demarcation. The age of demarcation of juvenile and mature wood of Luehea divaricata was defined as 21 years-old, approximately.

Características tecnológicas das madeiras de Luehea divaricata, Carya illinoinensis e Platanus x acerifolia quando submetidas ao vergamento.

This work was conducted with the purpose of investigating bending characteristics of the wood of Platanus x acerifolia (Ait.) Willd., Luehea divaricata Mart. et Zucc and Carya illinoinensis (Wangenh) K. Koch. Such species were collected from non-managed forests located in Depressao Central and Encosta Superior do Nordeste, Rio Grande do Sul, Brazil. Five representative adult trees from each species per studied area were cut down, corresponding to a total of thirty trees. From the trunk, a 2.5 m long log was taken and, afterwards, transported to a sawmill for processing. A central 8 cm thick plank was sawn, from which samples for bending were manufactured. The samples were conditioned in standard room to a moisture content of approximately 14%. Then, the samples were placed in boiling water during 35 minutes and bended in rays of 16 and 21cm. For the qualification of the bending defects, the methodology presented by Vorreiter (1958) was used. Results showed that the wood of Carya illinoinensis (Wangenh) K. Koch had the best bending characteristics when compared to the other two species, independently of the ray bending tested. It seems that the ring porosity, characteristic of the Carya illinoinensis wood, contributed to the result. On the other hand, the wood of Platanus x acerifolia (Ait.) Willd. and Luehea divaricata Mart. et Zucc, with diffuse porosity and larger parenchyma proportion, presented more defective pieces.

Decay and termite resistance of particleboard manufactured from wood, bamboo and rice husk

The resistance of particleboards, made from wood, bamboo and rice husk, to fungi and termites was evaluated. Panels were composed of 100% wood (Eucalyptus grandis), 100% bamboo (Bambusa vulgaris), 100% rice husk (Oryza sativa), 50% wood and 50% bamboo; and 50% wood and 50% rice husk. Panels exposed to the decay the brown-rot fungus (Gloeophyllum trabeum and the white-rot fungus (Trametes versicolor), and, in a choice feeding trial, to termites (Nasutitermes corniger). The rice husk particleboards had the highest resistance of all samples and the bamboo particleboards had the lowest resistance. T. versicolor fungi produced a larger mass loss in the particleboards than did G. trabeum.

USO DE HERBICIDA NA REDUÇÃO DAS TENSÕES DE CRESCIMENTO NA MADEIRA SERRADA DE Eucalyptus grandis

This work aimed to evaluate the efficiency of herbicide in reduction of growth stress effects on the incidence of splits and warps on boards originated from Ecalyptus grandis trees. For this, 40 trees were selected at random, subdivided into four chemical treatments with application of herbicide (“Imazapyr” active principle) and one treatment without herbicide application, with eight repetitions each. After the action of herbicide, the trees were harvested and the first log of each tree was cut. The logs were sawn to make the analyses before and after air drying operation. The results indicated higher efficiency of herbicide in treatments 4 and 5 on the effect of growth stresses in the form of splits in the boards. For the crook, the treatments 2 and 4 showed lowest levels of defects. The bow had influence of air drying operation, while the cup was not observed significantly in the pieces of sawn timber from five treatments.

PROPRIEDADES DE PAINÉIS AGLOMERADOS SUBMETIDOS AO TRATAMENTO TÉRMICO

The particleboards are the most consumed in the world, where much of the demand is associated to furniture sector. This study aims to assess the heat treatment effect on particleboard panels. The experiment consisted of four treatments and the control sample, evaluating temperatures of 160°C and 180°C for six and twelve minutes. Commercial particleboard panels were produced with particles of Eucalyptus sp. and urea-formaldehyde synthetic resin. Samples for physical testing (water absorption, and thickness swelling) and mechanical (static bending strength and screw withdrawal strength) were taken from these panels. For physical properties, the assessed heat treatments influenced significantly the water absorption of the panels after 24 hours of immersion. The treatment that utilized temperature of 180°C for six minutes provided the best performance. Concerning to the mechanical properties, the evaluated treatments had non-significantly influence in the panels strength.

EFFICIENCY OF BURNT OIL AS WOOD PRESERVATIVE SUBMITTED TO FIELD DETERIORATION TESTS

EFICIENCIA DO OLEO QUEIMADO COMO PRESERVATIVO DE MADEIRAS SUBMETIDAS A ENSAIOS DE DETERIORACAO DE CAMPO O objetivo desse estudo foi avaliar a eficiencia do oleo queimado como preservativo de madeiras de Trattinnickia rhoifolia Willd. submetidas a ensaios de deterioracao de campo. Os tratamentos preservativos com oleo queimado foram realizados pelo metodo de imersao simples considerando dois fatores de variacao: viscosidade do oleo (SAE 10 e SAE 15) e tempo de imersao (3 min, 3 h e 24 h). A eficiencia dos tratamentos preservativos foi avaliada por meio da taxa de retencao do produto oleoso, quantificacao da lixiviacao apos exposicao em campo e perda de massa causada pela deterioracao biologica. Adicionalmente, foi empregada a tecnica de colorimetria para avaliacao do escurecimento causado pelo tratamento preservativo e no monitoramento da alteracao da cor superficial da madeira devido a lixiviacao pela exposicao a campo. Com base nos resultados pode-se concluir que o tratamento preservativo com oleo queimado foi eficiente, de modo a proporcionar as madeiras uma maior resistencia biologica, com destaque para o uso do oleo de menor viscosidade (SAE 10). As maiores taxas de retencao e menores perdas de massa devido a deterioracao biologica foram obtidas ao empregar o oleo queimado SAE 10, por outro lado tambem apresentaram as maiores taxas de lixiviacao. Palavras-chave: preservacao da madeira, imersao simples, preservativo oleoso, madeira tropical. ABSTRACT The objective of this study was to evaluate the efficiency of oil burned as a wood preservative of Trattinnickia rhoifolia Willd submitted to field deterioration tests. The preservatives treatments with burnt oil were performed by the simple immersion method considering two variation factors: oil viscosity (SAE 10 and SAE 15) and immersion time (3 min, 3 h and 24 h). The effectiveness of the preservative treatments was evaluated through oily product retention rate, quantification of leaching after exposure in the field and mass loss caused by biological deterioration. Additionally, the colorimetric technique was used to assess the darkening caused by preservative treatment and monitoring of the change of surface color of the wood due to leaching by exposure to the field. Based on the results, it can be concluded that the preservative treatment with burnt oil was efficient, to provide the woods a greater biological resistance, especially the use of the oil with lower viscosity (SAE 10). The higher retention rates and low mass loss due to biological deterioration were obtained when employing the burnt oil SAE 10, and on the other hand also showed the highest rates of leaching. Keywords: wood preservation, simple immersion, oily preservative, tropical wood. DOI: http://dx.doi.org/10.14583/2318-7670.v04n03a04

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.