Surface protection of wood using cerium oxide nanoparticles dispersed paraffin wax nanoemulsion

Abstract

Exposure to solar UV radiation and other environmental factors promotes the degradation and reduces the serviceability of the wood material under outdoor use. Oils and waxes have been found to be promising solutions for wood protection. This study elucidates the use of paraffin wax based emulsions incorporated with cerium oxide nanoparticles to improve weathering performance of wood. For this purpose, paraffin wax nanoemulsions were prepared by ultrasonication method using tween 80 as surfactant. Cerium oxide nanoparticles (conc. 0.5- to 2%) were added to provide protection against degradation caused by solar UV radiation. The storage stability of nano emulsion was assessed over a period of 30 days by measuring effective particle size and zeta potential. The microstructure of nanoemulsions was observed by optical microscopy and distribution of CeO2 nanoparticles on coated wood was observed through scanning electron microscopy (SEM). The chemical changes were analyzed by Fourier Transform Infrared spectroscopy (FTIR). Wood specimens of Pinus radiata coated with nanoemulsions were subjected to the accelerated weathering tests for 500h. The time dependent changes in surface color of uncoated and coated wood samples were examined. Moreover, the chemical changes on exposed wood surfaces were analyzed by ATR-FTIR spectroscopy. Stable and homogenous nanoemulsions with particle diameter between 200 and 400 nm were formed and exhibited excellent storage stability. Results of color changes showed that maximum degradation was observed in uncoated wood whereas wood coated with paraffin wax nanoemulsion alone could not improve the UV resistance. However, the addition of cerium oxide nanoparticles proved to be efficient in controlling the color changes on wood surfaces. The degradation of wood components reduced significantly in cerium oxide coated wood which was confirmed by FTIR results.