Rafael Rodolfo de Melo

Physical and mechanical properties of particleboard manufactured from wood, bamboo and rice husk

In this work, the physical-mechanical properties of particleboards manufactured with wood (Eucalyptus grandis), bamboo (Bambusa vulgaris) and/or rice husk (Oryza sativa) particles, combined or not, were assessed. They were produced in the following proportions: 100% wood; 100% bamboo; 100% rice; 50% wood and 50% bamboo; 50% wood and 50% rice husk. In order to characterize the manufactured particleboards, their physical (density; moisture content; water absorption and thickness swelling) and mechanical properties (static bending; internal bonding and screw withdrawal) were assessed. The results indicated that the use of rice husk caused reduction in particleboard quality. Particleboards manufactured with bamboo showed better quality than those using rice husk as raw material. For most parameters, the particleboards manufactured exclusively with wood particles showed similar performance to bamboo and wood-bamboo particleboards.

Rotary peeling yield of Schizolobium amazonicum (Leguminosae - Caesalpinioideae)

The tropical tree Schizolobium amazonicum is native from the Amazonian forest, naturally occurring in Brazil, Peru and Colombia. This work aimed to study the veneer yield made from this species. For this purpose, 50 logs from S. amazonicum were rotary peeled in a plywood industry installed in Brazilian Amazon region. The results indicated that S. amazonicum had a peeling yield similar or even higher than those usually obtained for species traditionally used for this purpose in Brazil, like those of Pinus and Eucalyptus. It was also observed that the dendrometric parameters of the log can be used to estimate the peeling yield in this species.

Influência de diferentes combinações de lâminas de Eucalyptus saligna e Pinus taeda em painéis LVL

This research aimed to investigate the influence of the positioning of Eucalyptus saligna and Pinus taeda wood veneers on layers of laminated veneer lumber (LVL) panels. The compositions were manufactured in six different combinations of five veneers of 3.2 mm thickness, glued with phenol-formaldehyde, resulting in treatments composed of wood of the same species or with a combination of two wood types. The evaluation of the proposed arrangements was performed under the characterization of physical properties (moisture content and density) and mechanical properties (modulus of elasticity - MOE and modulus of rupture - MOR) verified in flatwise and edgewise static bending tests. The results obtained indicated that, in most situations, the different positions of the veneers with higher density (in the outer, intermediate and inner layers) influenced the mechanical properties of the panels. The influence detected was varied for MOE and MOR, especially when comparing the flatwise and edgewise test values. In certain positions, on the layers of the LVL compositions, the presence of eucalypt veneers resulted in stiffness and strength increases. However, the treatments formed by interposed veneers of eucalypt and pine demonstrated interesting performances for structural use, in either flatwise or edgewise position, once they present values of MOE and MOR that allow to distinguish them as 1st class, according to the North American standard APA/EWS PRL-501 (2001).

ESTIMATIVAS DAS PROPRIEDADES FÍSICO-MECÂNICAS DE COMPOSTOS LVL CONFECCIONADOS COM PARICÁ POR MEIO DE ULTRASSOM

This study aimed at evaluating the utilization of ultrasound nondestructive method to estimate physical and mechanical properties of laminated veneer lumber (LVL) manufactured with Schizolobium amazonicum Huber ex. Ducke by ultrasound. For this, LVL boards were manufactured in laboratory. After manufacturing, the boards were nondestructively tested using ultrasound and afterwards the following physical and mechanical properties were assessed: water absorption; thickness swelling residual swelling, flatwise static bending; edgewise static bending; compression strength parallel to grain; shear strength parallel to glue-line; shear strength perpendicular to glue-line. Data about speed of sound and dynamic modulus of elasticity were used in different equations to estimate the properties evaluated. The results showed the use of ultrasound as an effective tool for prediction of most of the properties. Among the independent variables, the dynamic modulus of elasticity obtained the best results when compared to the speed of sound.

Production and Properties of a New Wood Laminated Veneer/High-Density Polyethylene Composite Board

The paper aimed at evaluating the feasibility and the properties of a new product which combines wood veneer and high-density polyethylene (HDPE) from post-consuming plastic bags. Three HDPE amounts were evaluated: 150g/m2, 250 g/m2 e 350 g/m2. The boards were manufactured using a single-opening hot-press under such conditions: 140oC, for 20 minutes and pressure of 1 N/mm2. It was found that the production of this kind of composite board is technically possible and relatively simple and they did not present any veneer delamination. The properties of the composite boards were quite similar or even higher to those found in LVL made using thermosetting resin. The higher the HDPE amount the higher the density of the composite board, which imparted significantly in mechanical properties. However, when the composite boards were evaluated under same density the effect of the HDPE amount affected only Janka hardness.

USE OF ARTIFICIAL NEURAL NETWORKS IN PREDICTING PARTICLEBOARD QUALITY PARAMETERS

This study aims to assess Artificial Neural Networks (ANN) in predicting particleboard quality based on its physical and mechanical properties. Particleboards were manufactured using eucalyptus (Eucalyptus grandis) and bonded with urea-formaldehyde and phenol-formaldehyde resins. To characterize quality, physical (density and water absorption and thickness swelling after 24-hour immersion) and mechanical (static bending strength and internal bond) properties were assessed. For predictions, adhesive type and particleboard density were adopted as ANN input variables. Networks of multilayer Perceptron (MLP) were adopted, training 100 networks for each assessed parameter. The results pointed out ANN as effective in predicting quality parameters of particleboards. With this technique, all the assessed properties presented models with adjustments higher than 0.90.

The influence of different combinations of Eucalyptus saligna and Pinus taeda veneers in LVL panels

This research aimed to investigate the influence of the positioning of Eucalyptus saligna and Pinus taeda wood veneers on layers of laminated veneer lumber (LVL) panels. The compositions were manufactured in six different combinations of five veneers of 3.2 mm thickness, glued with phenol-formaldehyde, resulting in treatments composed of wood of the same species or with a combination of two wood types. The evaluation of the proposed arrangements was performed under the characterization of physical properties (moisture content and density) and mechanical properties (modulus of elasticity – MOE and modulus of rupture – MOR) verified in flatwise and edgewise static bending tests. The results obtained indicated that, in most situations, the different positions of the veneers with higher density (in the outer, intermediate

Estimativas das propriedades de compostos LVL produzidos com paricá (Schizolobium amazonicum Huber ex Ducke) por meio de stress wave

Foram avaliadas as propriedades fisicas e mecânicas de compositos LVL produzidos com a madeira de parica (Schizolobium amazonicum Huber ex. Ducke), por meio de Stress Wave Timer. Os compositos foram confeccionados em laboratorio, dos quais foram retiradas amostras, que foram inicialmente destinadas a realizacao dos ensaios nao destrutivos. Todas as amostras, com dimensoes de 2,2 × 2,2 × 40 cm, foram ensaiadas, nao destrutivamente, com a propagacao de ondas nos sentidos flatwise e edgewise. Em sequencia, as mesmas amostras foram destinadas a confeccao de subamostras, para realizacao dos ensaios destrutivos, fisicos (absorcao de agua, inchamento em espessura e inchamento residual) e mecânicos (resistencia e rigidez a flexao estatica flatwise; resistencia e rigidez a flexao estatica edgewise; resistencia a compressao paralela e resistencia ao cisalhamento paralelo e perpendicular). A velocidade de propagacao das ondas (V0) e o modulo de elasticidade dinâmico (Emd), obtidos com o auxilio do Stress Wave, foram utilizados para elaboracao de modelos de predicao das propriedades avaliadas. Os resultados indicaram que o Stress Wave Timer apresenta resultados satisfatorios para predicao das propriedades mecânicas de compositos LVL. Com relacao as propriedades fisicas, embora tenham sido verificados modelos com ajustes significativos, constatou-se limitacao dessa ferramenta para predicao desses parâmetros. Contudo, considerando ambas as propriedades, fisicas e mecânicas, os melhores ajustes foram observados em amostras ensaiadas com a propagacao de ondas no sentido edgewise e com o uso da variavel independente Emd.

Efeito da inversão no tratamento de moirões submetidos ao método de substituição da seiva

This work aimed to evaluate the effect of inversion of Prosopis juliflora and Leucaena leucocephala fence posts, in distribution, penetration and retention of copper chrome borate (CCB) solution applied by sap displacement method. The Prosopis juliflora was collected in Brazilian Agricultural Research Company (EMBRAPA) and the Leucaena leucocephala at the Federal University of Campina Grande in Patos, Paraiba state, Brazil. Trees with DAP from 5.0 to 10.0 cm were employed. Disks of 2.0 cm of thickness were retired on the top and on the base of pieces. The external disks were then discarded and the intern ones were employed to determine the wood characteristics, being the round pieces with 2.0 m. A solution of 2% of active ingredients of CCB was used to treated woods. A total of 10 pieces of each species were treated, and five of them remained in the solution for 8 days and the five ones had their tops inverted after the sixth day of treatment. The pieces were seasoned; disks of 2.0 cm of thickness were taken in 5 positions along of pieces and the analyses for determination of copper and boron penetration took place. The values of wood characteristics indicated that the pieces were homogeneous. The absorption of the solution was of 19.9 liters (Prosopis juliflora) and of 17.0 liters (Leucaena leucocephala). The nominal retentions of CCB were 7.72 and 5.34 kg active ingredients (a.i.)/m3, respectively. In general, the inversion of the pieces in the preservative solution is recommended, by providing a better distribution, penetration and retention of CCB on treated pieces.