Added-value for wood bark as a coating layer for flooring tiles

Worldwide more than 50% of the bark amount is used for energy generation. In this research, physicomechanical and surface properties of flooring tiles coated with thin layers made of larch bark are presented for the first time. Two types of adhesives were involved to bond the bark particles, namely polyurethane and a formaldehyde-free tannin-hexamine resin. Larch (Larix decidua Mill) bark was used to produce layers with 3 mm thickness at three levels of density, from 0.6 to 0.8 g/cm(3), to coat standard high density fiberboard (HDF) as core material. Mechanical and physical properties of the specimens including surface soundness, Brinell hardness, dimensional stability, abrasion resistance, cross-cut test, resistance to chemicals and fire resistance of the bark coated panels were determined and compared with the properties of industrial multilayered boards with granulated cork as wear layer. Overall, excepting the Brinell hardness, all the properties of the boards produced with wear layer made of larch bark were lower compared to cork-based coated control. Surface soundness of panels with larch wear layer was 30% or 60% lower compared to control. Both thickness swelling and water absorption after 24 h of the panels were too high. Neither polyurethane nor formaldehyde-free tannin adhesive influenced better the panel's properties. Surface properties were similar to control. Although mechanical properties of the samples considered in this work were inferior to those of typical flooring material coated with cork layer, it can be stated that such a little used material like bark may have a useful potential as a value-added product for such application. (C) 2017 Elsevier Ltd. All rights reserved.