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Öğe Determination of color-changing effects of bleaching chemicals on some heat-treated woods(Springer Japan Kk, 2020) Akkus, Memis; Budakci, MehmetThe aim of this study was to use bleaching chemicals to remove the discoloration occurring on the surface of wood after heat treatment in order to restore the natural color of the wood. For this purpose, samples prepared from Scots pine (Pinus sylvestrisL.), sessile oak (Quercus petraeaL.), Eastern beech (Fagus orientalisL.), and Uludag fir (Abies bornmuellerianaMattf.) were exposed to heat treatment at temperatures of 140 and 160 degrees C for time periods of 3, 5, and 7 h. Bleaching solutions S1 (NaOH + H2O2), S2 (NaSiO3 + H2O2), and S3 (H2C2O4) at a concentration of 18% were then applied to the surface of the materials and the color change was determined according to ASTM D 2244 standard. Depending on the heat treatment temperature and duration, an increase in total color change values was detected on the surfaces of the materials and the color of the samples became darker. The total color change values decreased after bleaching with the S2 solution in the heat-treated Scots pine and fir samples, with the S3 solution in the beech samples, and with the S1, S2, and S3 solutions in the oak samples. The findings showed that by using bleaching chemicals to lighten wood materials darkened after heat treatment, it is possible to obtain results close to the natural color values.Öğe Formaldehyde emission, combustion behavior, and artificial weathering characteristics of electrostatic powder coated wood composite panels(Taylor & Francis Ltd, 2021) Akkus, Memis; Akbulut, Turgay; Candan, ZekiRecently, research and development works have expanded to include the application of electrostatic powder coatings on non-conductive materials such as plastic, wood, and wood-based composite panels. Within the scope of this research, low temperature curing (120-130 degrees C) was applied to wood-based composite panels of medium-density fiberboard (MDF), particleboard, and plywood panels to facilitate conductivity. Epoxy, polyester, and hybrid (epoxy-polyester) types of powder coating and waterborne acrylic liquid coating were applied to the surface of the materials. The panels coated with the powder coatings were compared to the panels coated with the waterborne acrylic resin coating (control group). Combustion behaviors was determined according to ISO 13927 standard, formaldehyde emission according to TS EN 717-2, and color and gloss changes after accelerated weathering according to ASTM G151 and ASTM G154. The best results for combustion behavior were obtained with the plywood panels and MDF panels coated with waterborne acrylic coating, for formaldehyde emission with plywood panels coated with epoxy powder coating and waterborne acrylic coating and plywood panels, MDF panels, and particleboard coated with polyester powder coating. The least color change and gloss loss were detected in the plywood panels, particleboard, and MDF panels groups with polyester-based powder coating.