Abstract
The objectives of this study were to improve the dimensional stability of medium-density fibreboard (MDF) by heat treatment and to determine the effects of the treatment on the mechanical properties and vertical density profile of the panels. MDF panels were produced from untreated fibres and fibres treated at two different temperatures (150 and 180°C) for 15, 30 and 60 min. Panels produced from heat-treated fibres showed an important reduction in thickness swelling and water absorption after water soaking. Linear expansion and contraction were not improved by the treatment. Thickness swelling after repeated cycles of adsorption and desorption increased, while thickness shrinkage under the same conditions was not changed by the treatment. The springback of panels after repeated cycles of adsorption and desorption was not improved, either. Statistical analyses did not show significant differences in the modulus of rupture, modulus of elasticity and internal bond strength of panels following heat treatment. No significant effect was found for the vertical density profile of panels following heat treatment, although the profiles for panels produced from heat-treated fibres were flatter than those produced from untreated fibres.
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