Improvement of surface photostability of bamboo scrimber by application of organic UV absorber coatings

Abstract

Improving the durability of biological materials is essential for expanding their application areas. In this study, an organic ultraviolet (UV) shielding layer (coating) composed of a UV-curable paint, ethyl acetate, anhydrous alcohol, and an organic UV absorber is constructed on the surface of outdoor bamboo scrimber (OBS). The behaviour of OBS with or without this coating was investigated under accelerated weathering. The physical properties photostability of the samples before and during exposure were evaluated by characterizing the colour and glossiness. Contact angle (CA) measurements and surface free energy (SFE) calculations were performed to investigate the wettability of the coatings. Attenuated total reflectance Fourier transform infrared spectroscopy was used to characterize the changes in the functional groups of the coatings during weathering. The experimental results have shown that the colour, glossiness, CA, SFE, and functional groups photostability of the sample with the UV shielding coating increased significantly compared to those of the control sample. The coating with 5% organic UV absorber was considered as the best UV shielding layer in this study, as it successfully protected the OBS and reduced the surface photodegradation of the substrate and the coating itself. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Photostabilizing Efficiency of Acrylic-based Bamboo Exterior Coatings Combining Benzotriazole and Zinc Oxide Nanoparticles

“…Two reasons can explain this change: (1) Polyacrylate photo-oxidized during the photodegradation of the clear coatings, which may have been due to abstraction of CO 2 [14], and (2) UV-induced crosslinking of acrylates reduced the number of carbonyl groups present [14]. A related study found that adding BTZ to coatings may induce the decomposition of ester groups [11]. Consistent with a previous study [13], films containing only BTZ were very efficient at inhibiting the photo-oxidation of the acrylic binder.…”

“…Benzotriazole (BTZ) is the most important organic UV absorber for many transparent coatings because of its high UV but low visible-light absorbance [9,10]. A UV-curable coating containing 5% BTZ successfully protected outdoor bamboo scrimber and hindered the photodegradation of the substrate and the coating itself [11]. Another study determined that the critical loading of BTZ for a high degree of UV shielding was 1.82 ± 0.05 g/m 2 [12].…”

The Properties of an Aluminum/UV-Curable, Infrared, Low-Emissivity Coating Modified by Nano-Silica Slurry

“…When the UV-curing time increased from 30 to 360 s, the glossiness of the UV-curable coating slowly decreased from 11.1% to 9.0%, a decrease of only 2.1%. This is because with increasing the time, the nano-silica slurry begins to act slowly, reducing the coating's glossiness [25]. During UV curing, the solvent in the nano-silica slurry will volatilize slowly, which will weaken the visible light reflection of the particles and reduce the glossiness [26].…”

A Note on the Surface Deterioration of Scrimber Composites Exposed to Artificial Ageing

“…Photodegradation resulted in the formation of novel lignin chromophores that were primarily comprised of quinone-type structures and caused discoloration [14]. In addition, the condensation of water induced the washing out of the degradation products on the material surface, and, consequently, the underlying fresh surface was further exposed [22]. This process affected the surface smoothness, which reduced the gloss and further affected the light reflection and hydrophobicity.…”