Bamboo scrimber refers to a lignocellulosic structural material, which is usually attacked by water, ultraviolet radiation and fungus. Surface coating is an effective way to protect it, and its coating properties depend on surface wettability. In this study, the surface wettability of bamboo scrimbers with varying resin content was investigated via the comprehensive analysis of surface roughness, surface contact angle, surface free energy, surface chemical composition and coating properties. The resultant scrimbers had a similar profile with low roughness. Their surface was hydrophilic, but the hydrophilicity decreased with the increase in resin content. High resin content gave rise to low total free energy, in which the Lifshitz–van der Waals component was dominant and it decreased with the increasing resin content. Meanwhile, the ratio of the electron-accepting component to the electron-donating component becomes higher. This was due to the decreasing hydrophilic groups (e.g., -OH and -COOH groups) and the increasing oxygen-free groups (e.g., C-H and -CH2groups) on the scrimber surface. The resin content affected the adhesion by decreasing the surface wettability, but the coating adhesion still reached the level of 2 for all bamboo scrimbers. The results will provide a theoretical reference for the surface coating of bamboo scrimbers in the structural application for good coating durability.Keywords:bamboo scrimber;resin content;surface free energy;chemical composition;coating adhesion
Bamboo scrimber (BS) as an engineering material has been widely used in outdoor areas, in order to improve the protective properties of bamboo scrimber, this study prepared a new composite coating. Wood wax oil (WO) and Zeolitic Imidazolate Framework-8 (ZIF-8) nanoparticles were prepared separately, and ZIF-8 nanoparticles were modified with low surface energy perfluorooctyltriethoxysilane (POTS). ZIF-8/POTS nanoparticles were constructed on the surface of bamboo scrimber to form ZIF-8/POTS/WO/BS composite coatings via the mediating effect of wood wax oil. The composite coatings were superhydrophobic, with a water contact angle of 161.4°. After aging tests, the contact angle of the composite coatings decreased by only 6.51 %, indicating that they remained superhydrophobic. Compared with uncoated substrates, after anti-mildew and preservative treatment tests, the bamboo scrimber coated with ZIF-8/POTS/WO/BS showed an improvement in its discoloration level from grade 4 to grade 1 and an infection level improvement from grade 3 to grade 0. The composite coatings had a nanoscale surface roughness with a surface energy of 2.94 mJ/m 2 . The coatings also exhibited self-cleaning performance, with a dust removal efficiency of 90.91 %. The air layer created on the surface of the composite coating made it difficult for water and microorganisms to directly contact the surface of the coatings. Furthermore, The Zn 2+ ions and 2-methylimidazole released by ZIF-8 disrupted the ionic balance in the surrounding environment, achieving a dual synergistic antifungal effect, which inhibited microbial growth and reproduction on the surface of the coatings, thus providing greater outdoor protection. This work pioneered the use of MOFs and wood wax oil to construct superhydrophobic, self-cleaning, and weather-resistant composite coatings on bamboo scrimber. This coating may enable bamboo scrimber to be used in outdoor building structures, highway guardrails, and bridge components, especially in harsh and wet outdoor environments.
危险品化学品经营许可证（带存储）