Effect of heat treatment on some technological properties of ash (Fraxinus angustifolia Vahl.) wood grown in natural and plantation forests

In this study, the effect of heat treatment on some technological properties of ash (Fraxinus angustifolia Vahl.) woods, obtained from natural and plantation (3x2,5 m ve 4x4 m) forests of Adapazarı, were examined. By cutting down 4 pieces sample trees from three stand (12 trees in total) which are crack-free and do not show any abnormal head shape, physical, mechanical and technological tests were made. Disks were taken from the longitudinal direction of the trees to determine the chemical analyzes and width of the annual ring. The samples suitable for related standards were prepared for each experiment that will be applied to test and control samples. Heat treatment were performed with water wapour at four different temperature (120,160, 190 and 210°C) and three different time (3, 6 and 9 hour). There is no difference statistically between main wood compounds of each stand?s control samples. The most damaged cell wall due to heat treatment became xylan. It was determined from the physical tests that the properties other than weight loss and density were improved as a result of heat treatment. Especially, the dimensional stabilization has been increased about 62% (3x2,5 m). The most adversely affected mechanical property of ash wood was determined as bending strength. The modulus of elasticity and Janka hardness value was not affected significantly with treated under at 210°C. However, decrease rates belonging to compression strength parallel to grain, bending strength, modulus of elasticity and Janka hardness values show significant increases in all applications at 210°C (3, 6 and 9 hours). Therefore, ash wood samples processed by heat treatment with high temperatures and for a long time should not be used load-bearing structure element in the buildings. Generally, the best results were determined from ash tree samples supplied from 3x2,5 m spacing. The most suitable heat treatment combination of temperature and time was decided as 3 hours at 190°C.