One-Step Deposition of Polyester/TiO2 Coatings by Atmospheric Pressure Plasma Jet on Wood Surfaces for UV and Moisture Protection

In this work, polyester/TiO2 coatings on wood surfaces were prepared in one step via two deposition methods by using an atmospheric pressure plasma jet technique with the aim to further enhance the stabilization of the wood surfaces against UV-radiation and moisture. The first method, based on the combination of plasma spray powder (PSP) coating and liquid precursor plasma spraying (LPPS) coating techniques, used polyester powder and titanium tetraisopropoxide (TTIP) liquid precursor as feedstock. In the second method, the polyester/TiO2 coatings were prepared by using a mixed powder of polyester micro-particles and TiO2 nano-particles as feedstock and applied via plasma spray powder coating technique. The surface topology and morphology of the wood samples were observed by scanning electron microscopy (SEM). The SEM results showed the presence of a rough structure after coating with polyester/TiO2. The surface chemical compositions of the samples were characterized by X-ray photoelectron spectroscopy and by Fourier transform infrared spectroscopy. The wetting behaviour of the coated wood surfaces was studied by measuring the water contact angle. After coating a hydrophilic wood surface with polyester/TiO2 prepared via (PSP + LPPS), it showed excellent water repellency; the wood surfaces were transformed from hydrophilic to superhydrophobic, while the polyester/TiO2 coating prepared via (PSP) was hydrophilic. Protection against UV radiation-induced colour changes was determined by UV tests and photo-assisted analysis using the CIELab colour system. The abrasion test results indicated that the polyester-containing films had good abrasion resistance and good adhesion to the wood substrates.