Efeito da modificação térmica nas propriedades físicas de seis madeiras Amazônicas

Abstract

Thermal modification is a process that promotes improvements in wood properties, such as reduced hygroscopicity, greater dimensional stability, increased biological resistance and color change, making it more attractive and with greater added value. This work aimed to evaluate the effect of different thermal modification temperatures on the physical properties of Amazonian woods. Samples with dimensions of 12.5 x 10 x 5 cm (length x width x thickness, respectively) were used for the application of heat treatment in an oven, with the following temperatures being adopted: 150°, 170° and 190°C with two hours and thirty minutes treatment. For the physical tests, the samples were resized with dimensions of 2 x 3 x 5 cm (thickness x width x length, respectively), according to the NBR 7190 standard (ABNT, 1997). Colorimetric analysis was performed using the Munsell chart. The results showed that there was mass loss for all treated woods and a more accentuated darkening at higher temperatures. The hygroscopicity of the treated woods makes it evident that the dimensional stability has been improved. The basic density showed slight variations with increasing temperature. The rate of water absorption between species reduced slightly in the first 24 hours, except for the species Licaria aritu which increased until the end of the test. The heat treatment proved to be effective in increasing the dimensional stability of the woods, despite not having significantly reduced all contractions (tangential, radial and volumetric) between treatments for the six treated species, in addition to the anisotropic factor.