| Summary: In this study, it is aimed to increase the service life of pre-protected (heat treatment-impregnated) wood material used in outdoor conditions of waterborne acrylic coatings containing bark extract as UV absorbing agent. For this purpose, waterborne acrylic coatings, which are widely used in our country and which extracts from the bark of 10 tree species with high antioxidant properties, are used as additives. These coatings were applied to two different wood surfaces, scots pine and oriental beech. Test coatings containing bark extract, control coatings containing commercial UV absorber and no commercial UV absorber or bark extracts were compared to the performance of wood surface protection against natural and artificial weathering conditions. The change in color, surface roughness, chemical structure, layer thickness, adhesion resistance and macroscopic appearance of the test and control varnishes subjected to the weathering test were evaluated. For chemical analysis, ATR-FTIR and UV-VIS spectroscopy were performed.
After the natural and artificial weathering test, the color, roughness, varnish layer thickness and adhesion resistance change values of acrylic coatings containing bark extract on the heat treated scots pine and beech surfaces was applied (Z group) were found close to control coatings. The macroscopic evaluation of test and control coatings on the Z group scots and beech surfaces is quite good. The change in color and roughness values of test coatings applied to the impregnated scots surface (Y) was the lowest. After the natural and artificial weathering test, the change in color change and adhesion resistance values of test coatings on the (Z) scots pine surfaces were determined close to the control coatings. ATR-FTIR and UV-VIS spectroscopy analysis also supported the results of the weathering test analysis. Based on the results, it has been found that acrylic coatings containing bark extract on scots surfaces treated with impregnation under outdoor conditions have higher protection performance than commercial UV absorbers. However, the increase in antioxidant effect in bark extract has a positive effect on scots pine wood in order to increase the resistance in outdoor conditions, while it has a low effect on beech wood.
Keywords: Tree bark extract, acrylic varnish, outdoor condition, heat-treatment, impregnation, UV absorber |
