Investigation of some surface properties of varnishes modified with nanoparticles (TiO₂ ve SiO₂) on wooden materials

This thesis investigates the effects of varnishes modified with nanoparticles (TiO₂ and SiO₂) on some surface properties of wood. Two wood species representing different specific gravities were selected for the study: local, low-density Pinus brutia (red pine) and imported, high-density Chlorophora excelsa (iroko). Test samples were prepared in accordance with the TS 3129 standard. Titanium oxide (TiO₂) and silica (SiO₂) were used as nanoadditives at 1% and 2% ratios. Two-component epoxy resin with hardener and acrylic-based two-component hardener varnish were chosen as coating materials. A total of eight different combinations were obtained: 2 wood species × 2 varnish types × 2 nanoparticle types × 2 additive ratios. Test samples were varnished according to ASTM D 3023. Color values were determined based on ASTM D 2244, gloss values were determined based on ASTM D 523, and surface roughness was determined based on TS 2495 EN ISO 3274 and TS 6212 EN ISO 4288 standards. Varnish applications were performed using a brush method, and surface properties were then evaluated using standardized tests. Color measurements included CIE L*, a*, b*, C*, and h° values. For gloss measurements, gloss values were measured at 60° angles in directions parallel and perpendicular to the fibers; for roughness measurements, Ra, Rz, and Rq parameters were examined. The obtained data were subjected to analysis of variance (ANOVA) and Duncan's multiple comparison test using the SPSS software package. In the color change of the surface treatment materials, the L* value showed the highest increase of 138.34 in the iroko wood acrylic varnish + 2% TiO2 application and the lowest decrease of 0.65 in the iroko wood epoxy resin + 2% SiO2 application. The a* value showed the highest increase of 58.77 in the red pine wood epoxy resin + 2% SiO2 application and the lowest decrease of 103.41 in the iroko wood acrylic varnish + 2% TiO2 application. b* value increased by 16.85 μm the most in red pine wood epoxy resin + 2% SiO2 application, and decreased by 124.12 μm the least in red pine wood acrylic varnish + 2% TiO2 application. In the gloss change perpendicular to the fibers, the most gloss increase was 5.11 gloss in red pine wood epoxy resin + 1% SiO2 application, and decreased by 18.29 gloss in red pine wood acrylic varnish + 2% TiO2 application, while in the gloss change parallel to the fibers, the most gloss increase was 6.85 gloss in red pine wood epoxy resin + 1% SiO2 application, and decreased by 4.38 gloss in red pine wood acrylic varnish + 2% SiO2 application. Ra roughness values increased by 190.17 μm the most in red pine wood acrylic varnish + 1% SiO2 application, and decreased by 190.17 μm the least in red pine wood epoxy resin control group. Rq roughness values increased by 161.09 μm in the red pine wood acrylic varnish + 1% SiO2 application, and the lowest in the red pine wood epoxy resin control group. Rz roughness values were highest in the red pine wood acrylic varnish control group application, while the lowest were 42.40 μm in the red pine wood epoxy resin + 2% SiO2 application. The study revealed that nanoparticle additives have significant effects on the aesthetic and physical properties of wood surfaces. In particular, nano TiO₂ and SiO₂ additives improved the gloss and roughness of wood surfaces, while color values varied depending on the wood species, varnish type, and additive ratio. These results demonstrate that adding nanoadditives to high-end surface treatment materials used in the industry can yield more durable and aesthetically enhanced wood veneer surfaces.