The Research On The Property Of Hydrophobic And Light Aging Resistance Film At Wood Surface Built Via Nano TiO₂and Hydrophobic Agent

In recent years, the research on wood as a natural organic material combining with inorganic nanoparticles to form wood-inorganic nanocomposites has made a considerable progress. In this thesis, in order to enhance the hydrophobicity and UV-shielding property of wood, the wood surface was modified by TiO2sol coating via sol-gel process, and followed by the low surface energy treatment with stearic acid or hexadecyltrimethoxysilane(HDTMS) to make the wood surface change from hydrophilic to hydroponic, while using the excellent UV-shielding property of TiO2nanoparticles to improve the wood photostability. In addition, the morphology, structure and chemical composition of the treated wood were analyzed by field emission scanning electron microscopy(FESEM), energy dispersive X-ray analysis(EDX), and Fourier transform infrared spectroscopy(FTIR). At the same time, the hydrophobicity and anti-photodiscoloration performance of the treated wood were investigated. The major results obtained in this dissertation are described as follows:1) The SEM images and EDX analysis showed that the wood surface was successfully coated with TiO2nanoparticles of which the diameter was about60-150nm, facilitating the generation of a dual-size micro/nano roughness on wood substrate with introducing TiO2nanoparticles. The FTIR indicated that the hydrophobic agent(stearic acid or HDTMS) and-OH on the TIO2surface reacted, with the long-chain alkyl groups being successfully grafted on the wood surface, giving the wood good hydrophobic performance. Moreover, the absorption peak intensity of HDTMS modified with TiO2nanoparticles increased obviously.2) The wood surface changed from hydrophilic to hydroponic by being treated with hydrophobic agent and TiO2nanoparticles. With the TiO2concentration increasing, the hydrophobicity of wood sample only treated with TiO2rose linearly. When the TiO2concentration was more than1%, the contact angle was stable at about110°.By being modified with low surface energy materials (stearic acid and HDTMS), the CA(contact angle) of wood surface was improved. The CA of wood sample only treated with stearic acid remained at127°; The CA of wood sample treated with TiO2and stearic acid kept at133°; The CA of wood sample only treated with HDTMS was stable at135°. The CA of wood sample treated with TiO2and HDTMS maintained at140°.The data analysis suggested that compared with the wood only coated with TiO2, the hydrophobic performance of the wood sample coated with TiO2and hydrophobic agents increased by40%; HDTMS was more hydrophobic than stearic acid, resulting from the covalent bonding between HDTMS and inorganic nanoparticles.3) The WPG of untreated wood soaked in water increased to60%rapidly, and the WPG gradually ascended with the soaking time increasing. Before50h, the wood sample only treated with TiO2sol had a similar water absorption rate with the wood treated with stearic acid. However, after50h, it rose rapidly up to150%. The wood sample treated with TiO2and stearic acid or HDTMS always exhibited the low water absorption capacity, while not meeting the superhydrophobic requirement. The data analysis indicated that the water absorption capacity of composite materials treated with HDTMS ethanol solution was relatively lower than composite materials treated with stearic acid acetone solution. The contact angle experiments showed the same result.4) The introduction of TiO2nanoparticles on the wood surface improved the anti-photodiscoloration performance. With the TiO2increasing, the wood surface loaded more nanoparticles, and the UV-shielding ability was much stronger, leading to a better color stability. The anti-photodiscoloration performance of the wood treated with TiO2sol (5wt%), and the chroma difference (ΔE*) of the wood samples was only45%of the control samples after120h artificial accelerated photoaging.