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

Neng Li,Chengjian Huang,Minzhen Bao,Chengming Xiu,Rencong Guo,Fei Rao,Yuhe Chen,Zhonghua Huang,Yongjie Bao,Yi Shu

doi:10.1186/s10086-019-1789-1

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.

Highlights

The favourable properties of bamboo scrimber products in terms of dimensional stability, natural colour, elegant texture, and ease of processing has led to its widespread application
Colour changes The colour changes are related to chemical changes such as the degradation of outdoor bamboo scrimber (OBS) lignin and coatings, which degrades the aesthetics of the material surface [1]
The ΔL* values of samples A and B after 312 h exposure were obviously larger than that of samples C and D, indicating that the addition of BTZ-1 was effective in enhancing the stability of the L* value upon UV irradiation

Summary

Introduction

The favourable properties of bamboo scrimber products in terms of dimensional stability, natural colour, elegant texture, and ease of processing has led to its widespread application. Bamboo scrimber is considered to be a good biological material for outdoor application [1]. When it is exposed to outdoor conditions, such as solar radiation, moisture, oxygen, high temperature, and bacteria and fungi, its exterior tends to undergo discolouration, decreasing the glossiness and increasing the roughness. It loses its strength and adhesiveness and becomes sensitive to decay [2,3,4,5,6]. The investigation of how to reduce the effect of UV radiation on bamboo scrimber and other biological materials is essential to improve the durability of bamboo products

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Results

Conclusion