Qualidade das toras e da madeira serrada de Eucalyptus dunnii Maiden

Abstract

Wood is a material that has intrinsic characteristics and has been gaining ground in the market due to its wide application. However, with a growing, demanding and competitive market, it is of significant importance to understand the behavior of technological properties to highlight the quality of the wood, ensuring adequate characteristics for each procedure that it will be subjected to. Therefore, the present work aims to evaluate the quality of Eucalyptus dunnii logs and sawn wood. To develop the study, samples of 23-year-old Eucalyptus dunnii were used from a village located in the municipality of Rio Pardo-RS, in an area belonging to the Brazilian Tobacco Growers Association (AFUBRA). From the forest inventory, the plot was classified into 4 diameter classes (1: 30-40 cm; 2: 40-50 cm; 3: 50-60 cm; 4: 60-70 cm), from which 5 were selected. individuals by class. Subsequently, the trees were felled, cubed and sectioned into samples to determine the apparent saturated and basic specific masses, in accordance with NBR 7190-1. The first and second logs measuring 3 m in length were removed from each tree, which were transported to the Wood Processing and Drying Laboratory at UFSM - Frederico Westphalen campus, to evaluate log defects and be unfolded following radial orientation. and tangential. When the boards were made, 320 samples were evaluated based on sawn wood defects pre- and post-air drying, as well as the presence of knots. Based on the results, it was observed that the largest diameter classes resulted in trees with smaller heights and larger volumes. As for log defects, the cracking rates were lower in the first log and its base; As for flattening and conicity, the best results came from the second log. From the characterization of the specific masses in the base-to-top direction, the basic one resulted in a growing trend and showed interference from the classes, while the apparent saturated one demonstrated an opposite pattern without their influence. Using the weighted basic specific mass, the wood was classified as medium density. There was no difference in pre- and post-drying board cracking rates, but a reduction was identified with increasing diameters. When analyzing the warping in relation to the classes, the one with the largest diameter obtained the best results and, for the orientations, the tangential boards demonstrated greater intensities of buckling and bending, while the radial ones, showed higher rates of cracks, knots and greater intensity. of arching. It was also observed the influence of the classes on the outdoor drying curves, the transition and stabilization of drying occurred in sequence for classes 2, 1, 3, and 4 and, regarding the orientations, the tangential boards dried more quickly. In general, it is concluded that Eucalyptus dunnii wood has the potential to be used in the wood industry, however, it requires care to obtain a higher quality product, such as choosing the class, orientation of the pieces and drying depending on the destination. of this raw material.