Dissertação
Influência dos tratamentos termomecânicos na madeira
Date
2015-02-25Registration in:
PERTUZZATTI, Anderson. INFLUENCE OF THERMOMECHANICAL TREATMENTS ON WOOD. 2015. 98 f. Dissertação (Mestrado em Recursos Florestais e Engenharia Florestal) - Universidade Federal de Santa Maria, Santa Maria, 2015.
Author
Pertuzzatti, Anderson
Institutions
Abstract
Thermomechanical treatments seek to increase the wood density, throught of the temperature
and pressure combination, which results in a material with improved physical and mechanical
properties. Thus, the study aimed to evaluate the influence of thermomechanical treatments in
Pinus elliottii Engelm and Eucalyptus grandis W. Hill ex Maiden wood. So, were prepared
from five trees of each species, wood pieces that have been submitted to six different
thermomechanical treatments. For this purpose, we used a laboratory oil bath to perform
preheating of wood and a hydraulic press with the temperatures of the dishes ranging from 150
to 190°C. Compression time used was between 30 and 60 min. After, physical (compression
rate, weight loss, equilibrium moisture content, density, dimensional stability and
hygroscopicity), mechanical (static bending, dynamic bending and Janka hardness), surface
(colorimetry and roughness) and infrared spectroscopy (ATR-IR) tests were performed. For
statistical analysis, we used qualitative factorial 3 x 2, with three temperature levels and two
compression time and Tukey test. Furthermore, it was performed to compare the treatments
with the control. The main results for the technological properties showed that the degree of
compression and mass loss increased with the temperature increase. The equilibrium moisture
content decreased and the density obtained increases. For the dimensional stability was
observed that there was a reduction of the effect of the return densified wood, and
hygroscopicity was increased in both wood species. The mechanical properties showed
increases with the densification, except for the Janka hardness and dynamic flexion in E.
grandis wood treated with high temperatures. Infrared spectroscopy showed degradation of the
amorphous cellulose and hemicellulose, providing a proportional increase of crystalline
cellulose and lignin. The color of the densified wood was changed presenting surface browning,
measured by decrease in brightness L* parameter. Roughness was reduced, making the surface
softer wood. Before the alterations, it is indicated using thermomechanical treatment with
temperature of 150°C and the compression time of 60 min. In this respect, it is recommended
the use of densified wood floors and coatings, even for softwoods (conifers).
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