Desenvolvimento de programas de secagem para madeiras de Eucalyptus de meia rotação

Abstract

Due to its desirable characteristics to the timber sector, there is currently a wide availability of species of the genus Eucalyptus on the market, mainly in middle rotation ages, making it essential to engage in research related to drying and quality of young wood for its better use. Thus, the main objective that guided the realization of this study was to elaborate drying programs for Eucalyptus woods of half rotation. Were selected4 individuals from clone 58 (E. urophylla x E. camaldulensis) and 4 individuals from clone GG100 (E.urophylla x E. grandis) from a plantation in the city of Luminárias-MG, with age11 and 10 years old, respectively, were selected . The proof bodies were selected from three heights of the tree stem, named as base, middle and total commercial height of the tree. Subsequently, part of the specimens was used for drying tests at temperatures of 100°C, 80°C and 60°C and the rest were used to determine the basic density and initial moisture content, carried out by the immersion method and gravimetric, respectively. To define the drying programs, calculations were performed using samples in the dimensions of 100 x 50 x 10 mm, considering its surface area as 130 cm² (value found from the specific formula for surface area). The moisture content data of the samples were interpolated to obtain the exact times when each sample reached 30% and 5% moisture content. To obtain the sample masses with 30% and 5% moisture content, the wet mass was isolated from the moisture content formula. The parameters of the drying programs found from all these calculations, were called “Updated Equation”. The calculations mentioned above were reproduced for the definition of drying programs according to what is recommended by the literature, for the level of comparison, which were called “Standard Equation”. It was observed that clone 58 had a lower initial moisture content compared to clone GG100, as well as a longer drying time in each test and a higher average density. It was found that there was a significant difference between the "Standard" and "Updated" equations in all tests, for all drying program parameters, except for the drying potential in the test at 100°C. It was possible to define three drying programs for each clone. The comparison between the three drying tests revealed that the test at 80 ° C generated appropriate drying program parameters for both clones.