The effect of nano-SiO2 particles and film thickness on physical properties of transparent wood coatings

In this study, the effect of different levels of nano-SiO2 particles and film thickness on physical properties of acid catalyzed and nitrocellulose transparent coatings applied to beech and spruce wood was investigated. Nano-SiO2 particles were added to coatings in order to improve adhesion characteristics and wettability behavior. For this purpose, specimens were prepared to dimensions of 220 ×80 ×20 mm. Nano-SiO2 particles were prepared at concentrations of 0, 0.5, 1 and 2 wt% and added to the acid catalyzed and nitrocellulose transparent coatings. To study the effect of different levels of film thickness on adhesion characteristics of nano coatings, specimens were coated at two levels of thickness of 60 µm and 120µm using film applicator. According to ASTM D 4541 standard, the adhesion strength of specimens was determined. Scratch resistance was determined according to ASTM D 3359. According to ASTM D 5946 standard, contact angle was measured. Results revealed that the highest adhesion strength was obtained in beech species coated with acid catalyzed containing 1% nano-SiO2 particles with thickness of 60 µm. Increasing the nano particles up to 2% had negative effect on adhesion characteristics.The increase of the film thickness decreased adhesion characteristics significantly. The increase of nano-SiO2 particles, up to 2%, increased the contact angle of the surfaces of specimens significantly. Thus the incorporation of nano-SiO2 particles into coatings, up to 1%, improved adhesion characteristics and the incorporation of nano-SiO2 particles into coatings, up to 2%, improved the wettability behavior of coatings. Furthermore applying films with lesser thickness led to increase of adhesion characteristics.