Efeito da acetilação nas propriedades tecnológicas da madeira de Jacarandacopaia

Abstract

Based on the assumption that the chemical modification, specifically the acetylation method, results in an improvement in the wood properties due to the alteration of the basic molecular structure of the cell wall components, this work had as objective to prove this efficiency. For this, were obtained infrared spectra with Fourier transform for qualitative analysis of the chemical modifications provided by the acetylation. In addition, the alterations provided in the Jacaranda copaia wood were evaluated in relation to the following quantitative parameters: mass gain, colorimetric properties (L*, a*, b*, C and h*), physical properties (apparent and basic density, absorption in water and volumetric swelling), mechanical resistance (Rockwell hardness) and resistance to biodeterioration (durability to attack of rotting fungi and termites).The acetylation of Jacaranda copaia wood was carried out by immersion of samples in acetic anhydride, being evaluated 5 treatments: a) control (non-acetylated); b) acetylation for 2 hours; c) acetylation for 4 hours; d) acetylation for 6 hours; e) acetylation for 8 hours; all with a constant reaction temperature of 90°C. The acetylated wood presented a mass gain between 18 and 21%, in order to provide an increase in its density, compared to non-acetylated wood. It was evidenced the chemical modification in the structural components of the acetylated wood, through the increase of the peaks in the bands 1735, 1375 and 1250 cm-1 referring to the addition of acetates groups. Regarding the colorimetry, the darkening of acetylated wood was verified in all the treatments. Acetylation improved the dimensional stability of the Jacaranda copaia wood, with reduction in absorption and volumetric swelling for 2h, 24h and even total saturation in water. Regarding the Rockwell hardness, the acetylation provided an increase in the resistance to the wood superficial penetration. Acetylated wood showed a decrease in mass loss when submitted to laboratory accelerated rotting tests for fungi of white rot (Trametes versicolor) and brown rot (Gloeophyllum trabeum) in all treatments, but it was more expressive for 8 hours acetylation. There was no loss of mass for the attack of termites Nasutitermes sp in all treatments for acetylated wood.