Evaluation of the hardness properties of the thermally modified tree-of-heaven (Ailanthus altissima) for parquet production

Developing wood-based industries such as structure, pallet, parquet etc., expanded the usage area of the wood. However, the development increased rivalry between these industries and naturally pressure to the forests for serving raw material. Therefore, many industries and scientist studied obtaining fast-growing tree species and increasing its properties to meet the related industry requirements. Many modification techniques with using heat, chemical treatments etc. were tried. In this study, tree-of-heaven (Ailanthus altissima) as a fast-growing species was investigated to evaluate in the solid-based (solid and upper layer of the laminate) parquet production. Thermal modification method was applied with 205oC temperature and 2 hours duration to increase its stability and darkening the colors. In the same samples, Brinell hardness were measured before and after the treatment. They were both classified related to characteristic values for evaluating the species to meet the parquet production requirements according to a standard. Results showed that hardness values of the 90% of the all thermally-treated samples were found higher than untreated samples. It’s thought that the decrement of the equilibrium moisture content (11-13% to 3-4%) after the treatment could increase the hardness values. Additionally, both values of the untreated and treated tree-of-heaven samples was at the highest level with the many species which were shown as a reference in the related standard. Consequently, if the invasive characteristic of this species can be controlled, unmodified and modified wood can be a good alternative for solid-based parquet production.