Sunlight, oxygen, changes of atmospheric moisture and temperature influence the colour of the natural wood surfaces. Due to this, wood surfaces should be protected with different coating systems, which should reduce the influence of the outdoor effects. It is known, that the clear water-based wood coatings are susceptible to the harmful ultraviolet (UV) rays and cannot preserve the surfaces of wood from the colour changes. In order to improve the resistance against UV, a small amount (up to 5 %) of inorganic nanoparticles can be used.
For this research, radial/tangential planed defect free kiln-dried pine (Pinus sylvestris L.) and ash (Fraxinus excelsior L.) wood samples with dimensions of 45×45×24 mm were chosen. Two formulations of clear water-based acrylic wood coatings containing inorganic nanoparticles of CeO2 (5 %) and ZnO (5 %) were mixed. Coated wood samples were exposed to the artificial UV rays for 20 cycles (1 cycle – 2 hours). In comparison of the wood species, the performance of colour and gloss changes of coated wood samples was different. After 40 h of UV exposure, the higher retention of colour and lower loss of the wood surface gloss were observed in a group of ash wood samples. It was determined that both types of inorganic nanoparticles significantly influenced the coating performance during the initial stage of UV ageing. The higher resistance of surface gloss was observed in a group of ZnO nanoparticles. Meanwhile, the coating containing CeO2 nanoparticles showed the different performance of surface gloss as well as resistance of the wood surface colour.
Keywords: wood coatings, inorganic nanoparticles, UV resistance
Authors
Vitosytė J.
Department of Materials Engineering, Kaunas University of Technology, Kaunas
Krystofiak T.
Department of Wood Based Materials, Poznan University of Life Sciences, Poznan
Lis B.
Department of Wood Based Materials, Poznan University of Life Sciences, Poznan
Ukvalbergienė K.
Department of Materials Engineering, Kaunas University of Technology, Kaunas
Login to download the PDF