Resistance properties of water-based varnishes modified with nanoparticles against the aging effect of uv on surface of some thermo-wood materials

The aim of this study is to determine the resistance properties of water-based varnishes modified with nanoparticles against accelerated UV aging effect in some ThermoWood materials. For this purpose, American ash (Fraxinus americana) and scotch pine (Pinus sylvestris Lipsky) wood were heat treated at a temperature of 190 °C for 1,5 hours and 212 °C for 2 hours. Later two-component water-based varnishes, with D70 - D99 commercial codes, modified with 1%, 3% and 5% ZnO and ceramic spherical nanoparticles were applied to the sample surfaces. And then the samples were then subjected to accelerated aging for 240 hours according to ASTM G154. The FTIR and SEM analyses were conducted to the specimens. The hardness of varnish layers was determined by ASTM D4366, surface roughness by TS 6956 EN ISO 4287/A1, scratch resistance by TS EN 15186, surface adhesion resistance by ASTM D4541, thermal conductivity coefficients by ASTM C1113/C1113M and total color change by ASTM D2244 principles. The results of the study indicated that ZnO and ceramic spherical nanoparticles used for modifying water-based varnishes increased the hardness and scratch resistance in D99 and decreased them in D70. The adhesion resistance decreased because of the nanoparticles used in D99 whereas it increased in D70 applied with 5% ZnO and 1% ceramic spherical additives. It was found that the nanoparticles used in water based varnishes generally decreased the surface roughness while only 5% ceramic spheres increased it in D99 and 1% ZnO increased it in D70. In this study, the effect of nanoparticles used in the modification of varnishes on the thermal conductivity coefficient in general was found not to be significant, but 5% ceramic spherical additive in D99 was found to be significant. It was also determined that the nanoparticle additives in this study generally reduced the total color change values, except 1% and 3% ZnO additives which caused an increase in D70 varnish.