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DENSIFICATION EFFECT OF ASH (Fraxinus americana) WOOD INTO ITS MICROSTRUCTURE AND CHEMICAL COMPOSITION
Many studies shows that through a hot press, the wood could increases its density, mechanical properties, hardness, dimensional stability, moisture content equilibrium, permeability and surface quality.
The objective of the study was to evaluate the effect of densification by hot press on cell wall structure, chemical components and resistance to fungal attack.
The raw material was American ash (Fraxinus americana). Wood specimens, radial orientation, were cut, 50 x 100 x 400 mm. Further they were conditioned to either 12 and 30% moisture content, and then exposed to a thermo-mechanical process, 120, 140 and 160ºC temperatures and 20, 30 and 40% compression rates. Wood specimens, 10 x 10 x 5 mm were used for the chemical characterization. The microstructure evaluation was performed using a scanning electron microscope (SEM) and chemical characterization an infrared spectroscopy study by Fourier Transforms (FTIR).
The results showed that wood densification occurs mainly in the early wooden vessels. Also, it was observed a collapse of the cell wall and in some cases ruptures. The analytical analysis showed the reduction of hydroxyl groups and formation of cross-links. According the results it could be expected that resistance to fungal attack will be improved due to the increase in the hydrophobicity of the compressed wood.