Evaluation of weathering resistance of cross-laminated timber blocks surface-treated with TiO₂ nanoparticles by liquid-precursor flame spray pyrolysis

Abstract

Wood is a versatile and renewable resource utilized in a wide range of applications, including tools, furniture, construction, and advanced engineering structures. However, certain inherent properties of wood, such as moisture and ultraviolet (UV) degradation, impose limitations on its long-term durability and dimensional stability for outdoor applications. This research investigates the weathering durability of cross-laminated timber (CLT) blocks surface-treated with titanium dioxide (TiO₂) nanoparticles synthesized via liquid-precursor flame spray pyrolysis (FSP), directly deposited onto the surface of CLT blocks, and thereby resulting in a porous TiO₂ coating. This coating endows the CLT surface with superhydrophobic properties evidenced by a water contact angle of ≥150°. Results from scanning electron microscopy and X-ray diffraction show the coating to be comprised of crystalline, sub-100 nm individual and aggregated TiO₂ particles with significant porosity. Even after an 8-week accelerated weathering test, a portion of the crystalline TiO₂ particles remains on the CLT surface. The TiO₂-treated CLT demonstrates enhanced resistance to discoloration and gloss change over 8-weeks of accelerated weathering conditions, which are evidenced by a total color difference (ΔE) that is 3–4 times lower than that of the untreated CLT in the initial two weeks, and 58% lower after 8 weeks of weathering. Furthermore, the TiO₂-treated CLT exhibits fewer weathering defects, such as splits and cracks, than the untreated CLT. The enhanced weathering durability of the TiO₂-treated CLT is attributed to reduced lignin degradation, which is supported by the Fourier-transform infrared spectroscopy analysis. The findings of this study suggest that the TiO₂ coating by FSP offers a viable and cost-effective method for modifying engineered wood products for improving hydrophobicity and protecting against the deteriorating effects of UV irradiation and moisture exposure.

Citation

Sedhain, Ganesh; Kim, Yunsang; Mubarak, Shuaib A.; Eberhardt, Thomas L. 2024. Evaluation of weathering resistance of cross-laminated timber blocks surface-treated with TiO₂ nanoparticles by liquid-precursor flame spray pyrolysis. Construction and Building Materials. 419(12): 135481. https://doi.org/10.1016/j.conbuildmat.2024.135481.