Clovis Roberto Haselein

Efeito do espaçamento e da adubação no crescimento de um clone de Eucalyptus saligna Smith.

In this research, the spacing (3 x 2, 3 x 3 and 3 x 4 m) and fertilization (400 and 800 kg/ha) effects on growth of Eucalyptus saligna clone were studied. The growth in diameter at breast height (Dbh), height (h) and volume per tree were studied from ages between three and ten years, using the Backman’s function. By covariance analysis it was possible to verify that the treatments with the same spacing showed same growth pattern, for all variables. During all observed period, the fertilization treatment had no effect on mostly of the studied characteristics. The factor spacing had outstanding influence in the growth in diameter and commercial volume without bark per tree. Only the trees under the smallest spacing showed a trend of growing slowly in height over time. The volume yield per ha without bark was smaller for the treatments with larger spacing. No differences in volumetric production were found between the two smaller spacings.

Propriedades físico-mecânicas de painéis aglomerados produzidos com diferentes proporções de madeira e casca de arroz

This work aimed at evaluating the quality of particleboard manufactured with different wood proportions ( Eucalyptus grandis ) and rice husk. The composites were produced in the proportions 0, 20, 40, 60, 80, and 100% of rice husk with the use of urea-formaldehyde and tannin-formaldehyde adhesives. In order to characterize the quality of the particleboards, physical properties (density; moisture content; water absorption and thickness swelling after 2 and 24 hours of immersion in water) and mechanical properties (static bending; internal bonding and screw withdrawal) were considered. Results showed that increasing rice husk proportion caused larger instability and a decrease in the resistance of particleboards. Particleboards manufactured with tannin-formaldehyde resins presented higher quality when compared to urea-formaldehyde.

Efeito da intensidade de desbaste nas características dendrométricas e tecnológicas da madeira de Eucalyptus grandis

This study aimed at evaluating the effect of different thinning intensities in the dendrometric and technological characteristics of 14 years-old Eucalyptus grandis W. Hill ex Maiden wood sited in the northern coast of Rio Grande do Sul. Randomized blocks experiment, with four treatments (T1 = 1638 trees/ha; T2 = 1150 trees/ha; T4 = 589 trees/ha and T8 = 192 trees/ha) and four repetitions was analyzed. The trees were selected on the basis of the dominant and average diameter of each treatment. After cutting down, trees were measured and the volume was determined by the Smalian method, disks were taken at the base 0, 25, 50, 75 and 100% of the commercial height, and at the DBH (diameter at breast height), for basic density, dry mass and radial shrinkage determination. In relation to the dendrometric characteristics, results indicate that the application of more severe thinning caused significant gain in diameter at breast height, height and volume in average trees, not influencing the dominant ones. Concerning the technological characteristics, results indicate that the basic density of the average trees was influenced by thinning; however, without presenting clear trend regarding the intensity of the intervention. The production of dry mass of the average trees increased with the thinning intensity and did not affect the production of the dominant trees. The radial shrinkage of the dominant and average trees grew up in the pith-to-bark direction, not being modified by thinning intensity. Results allow concluding that the silvicultural interventions applied in the forest influence wood quality.

Modeling the physical processes relevant during hot pressing of wood-based composites. Part II. Rheology

A rheological model to describe the development of the vertical density profile and of internal stresses within wood-furnish mats during hot pressing is presented in this paper. The rheological model is part of a comprehensive three-dimensional simulation model that accounts for those mechanisms most important during the pressing process, including heat and mass transfer inside the mat and adhesive cure. To model the rheological behavior of the mat, the four-element Burgers model commonly used to describe visco-elastic material behavior has been expanded with the addition of a fifth element that represents plastic and micro-fracture related deformation. The coefficients of the non-linear model are highly dependent on the material conditions. Equations of the coefficients as a function of temperature, moisture content and density, as well as a mathematical formulation of the five-element model is presented in this paper. Furthermore, model predictions for both a batch and a continuous press are given. A comparison with experimental results shows that the expanded Burgers model is suitable to predict typical features of the vertical density profile, such as the development of density maxima near the surfaces, shoulders or side maxima as a consequence of intermediate or final densification steps, and differences in the density profile between the mat center and the edges in the horizontal plane. Such agreement provides the basis for a wide range of industrial and research applications.ZusammenfassungIm vorliegenden Artikel wird ein rheologisches Modell zur Beschreibung der Entwicklung des Dichteprofils senkrecht zur Plattenebene sowie der Spannungen innerhalb des Holzwerkstoffvlieses während des Heisspressens vorgestellt. Das rheologische Modell ist Bestandteil eines umfassenden drei-dimensionalen Simulationsmodells, welches weitere für den Pressvorgang wichtige Vorgänge wie Wärme- und Stofftransport und Klebharzaushärtung beinhaltet.Zur Modellierung des rheologischen Vliesverhaltens wurde das aus vier Elementen bestehende Burgers-Modell, das sich zur Beschreibung von visko-elastischen Verformungen eignet, um ein fünftes Element für plastische und microbruchinduzierte Verformungen ergänzt. Die Koeffizienten des nicht-linearen Modells hängen in starkem Masse vom Vlieszustand ab. Gleichungen zur Beschreibung der Koeffizienten als Funktion von Temperatur, Feuchte und Dichte werden zusammen mit der mathematischen Formulierung des Fünf-Elemente-Modells präsentiert. Darüber hinaus werden Modellrechnungen sowohl für Takt- als auch für Doppelbandpressen dargestellt. Ein Vergleich mit experimentellen Ergebnissen zeigt, dass das erweiterte Burgers-Modell für die Vorhersage der charakteristischen Merkmale eines Dichteprofils geeignet ist; charakteristisch sind die Entwicklung von oberflächennahen Dichtemaxima, von Schultern oder Zwischenmaxima als Folge von Zwischen- oder Nachverdichtungsschritten sowie Unterschiede im Dichteprofil zwischen der horizontalen Mattenmitte und den Kanten. Die gute Übereinstimmung zwischen Simulation und Experiment bietet die Grundlage für den Einsatz des Simulationsmodells für eine Reihe von Anwendungen in Industrie und Forschung.

Massa específica básica e massa seca de madeira de Eucalyptus grandis sob o efeito do espaçamento de plantio e da posição axial no tronco.

The basic density and dry mass of wood and bark of Eucalyptus grandis W Hill ex-Maiden of growing under twelve tree spacing were investigated. Thirty six trees (three per unit), with age of approximately ten years, coming from experimental units of AFUBRA, were used. Disks at base, DBH, 25, 50, 75 and 100% of trunk commercial height were taken from each tree for determination of wood and bark basic densities. Except for the smaller tree spacing, there was a decrease in basic density and dry mass of wood and bark with increasing planting spacing. The between lines tree spacing that produced the larger values of the studied variables were from 1,5 to 2 m.

Qualidade de chapas de partículas de madeira aglomerada fabricadas com resíduos de uma indústria de celulose.

The objective of this work was to investigate the quality of particleboards made with Eucalyptus saligna wood residues, resulting from the chiping of logs for pulp production. The boards were producted with two types of residues, sticks and sawdust, used pure. The adhesive used was urea-formaldehyde resin in proportions of 4, 8 and 12% (based on ovendry weight of wood particles) and the nominal densities were 0.55, 0.65 and 0.75 g/cm 3 . Bending properties, internal bond, screw withdrawal, water absorption and thickness swelling ware evaluated. The results indicated that the bending properties, internal bond and screw withdrawal were slightly higher with the sawdust type residue than boards made with sticktype residue. For water absorption, the values increased with the reduction of the density, for both type of particles. Thickness swelling increased with the reduction of resin proportion, independent of the type of residue used. Results showed that using both particles type with larger resin proportion and larger densities, boards with acceptable quality can be made.

Durabilidade natural da madeira de três espécies florestais em ensaios de campo.

This work aimed to evaluate the natural durability of heartwood and sapwood of Luhea divaricata , Carya illinoinensis and Platanus x acerifolia . Test samples measuring 2.5 x 2.5 x 30.0 cm (radial x tangential x longitudinal) were placed in a pine forest stand and an open field. During a year, the samples were repeatedly weighed and evaluated by a rating system to determine mass loss and decay index, respectively. The results showed that regardless of species and type of wood, the forest environment is more favourable to decay than that of the open field. Despite the high correlation between mass loss and decay index, variations in the durability of wood were found between these parameters. The wood from the internal section of the log (sapwood) was the more affected. For mass loss, no significant variation was observed for the species analyzed, however, for the decay index Platanus x acerifolia was shown to be the most affected.

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.

Desempenho silvicultural e seleção precoce de clones de híbridos de eucalipto

The objective of this work was to evaluate the genetic variability and silvicultural performance of clones from interspecific hybrids of Eucalyptus urophylla, E. globulus, E. maidenii, E. saligna, E. grandis, E. pellita, E. resinifera, E. kirtoniana and E. dunnii, and to determine the feasibility of early selection in selecting superior clones. The stem diameter at breast height at three (DAP3) and seven years (DAP7) and the total tree height at seven years were evaluated. A randomized complete block design, with138 clones, ten replicates and six plants per plot was used. Data were subjected to analysis of variance and clustered by the k-means method; the means were compared, and the Pearson correlation (r) was determined between variables. Clustering validation was performed using analysis of variance and Tukeys test. Clones of interspecific Eucalyptus hybrids showed genetic variability. Five groups of clones were established based on their silvicultural performance (DAP3, DAP7 and height). The DAP3 is highly correlated to DAP7 and height at seven years. The selection based on DAP3 can be used to identify superior clones of Eucalyptus with good growth vigor.

Qualidade da madeira serrada na região da Quarta Colônia de Imigração Italiana do Rio Grande do Sul.

This study was undertaken with the objective of evaluating the quality of the sawed wood produced in the Area of the Fourth Colony of Italian Immigration in Rio Grande do Sul. Three plants processing pine wood were investigated with respect to sawing and drying methods and moisture content of the industrial wood. The main method used was air seasoning and the resulting defects observed influenced the quality of the sawed wood negatively, suggesting the need of improving the process. However, the average moisture content was in agreement with the standards recommended for air seasoned wood. About 75% of the sawed wood of the area was classed as first when green. After drying, only 45% were first while 45% were of third grade. The remaining 10% were classed as super, extra or of second quality.