Abstract
Wood–plastic composites (WPC) are widely used for many purposes due to their interesting properties, but they have poor surface adhesion due to the chemical inertness of the matrix. Thus, in this work, the effect of plasma treatment on the WPC was investigated regarding its influence in the aluminum oxide (Al2O3) nanoparticles attachment to the surface. WPC were prepared in a polypropylene (PP) matrix, plasma-treated at 100 W for 600 s, and then covered with Al2O3 nanoparticles dispersion. The WPC/Al2O3 surfaces have been investigated by means of morphology, surface roughness, chemical structure, wettability, and nanohardness. Plasma treatment improved the attachment of Al2O3 onto WPC, which was confirmed by the higher presence of aluminum and oxygen-containing functional groups and the reduction of the intensity of peaks of methylene (CH2) and methyl (CH3) groups on the WPC surface. The higher surface reactivity of plasma-treated WPC resulted in a better distribution of the nanoparticles over the entire surface. In addition, plasma treatment avoided the formation of coffee-ring phenomenon but it was able to create cone-like structures on the WPC, increasing the surface roughness due to the etching effect and the attachment of Al2O3 nanoparticles. Plasma treatment followed by Al2O3 nanoparticles attachment increased the wettability, hardness, and elastic modulus of WPC at nanometric scale.
ACKNOWLEDGMENTS
This work was partially supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Embrapa Forestry, Electron Microscopic Center (CME-UFPR), and Senai Institute of Innovation in Electrochemistry (ISI). The authors express their gratitude to Ms Bia Carneiro for the English language support.