| Wood is a special composite with micro-nano structure, the application of nano science and technology to the functional improvement of wood surface can not only improve the wood property of its own, but also endow the wood with the characteristics of nanoparticles which makes wood have some new properties. Hydrothermal method is a kind of surface functional improvement of wood that can be functionally controlled. The combination property is obviously improved through hydrothermal grown of micro-nano particles on wood or bamboo surface. In this paper, hydrothermal method is used to synthesize Al(OH)3coatings on wood surface to improve the thermodynamic and flammable properties of wood. X-ray photoelectron spectroscopy is used to analyze the change of element content and chemical combination state of wood surface before and after treatment. The influence of hydrothermal temperature, hydrothermal time, hydrothermal solvent, aluminum source and concentration of the precursor on the morphology, particle size and the amount of growth of Al(OH)3particles grown on wood surface is studied by Field Emission Scanning Electron Microscopy. In addition, Ultraviolet Aging Instrument, Dynamic Mechanical Analyzer, Thermogravimetric Analyzer, Cone Calorimeter and Oxygen Index Apparatus are applied to selective analysis the light discoloration resistance property, dynamic thermal mechanical property, thermal weight loss and combustion performance of wood before and after treatment. By exploring various factors on the properties of wood, better technological conditions are finally confirmed. The main conclusions are as follows:(1) Al(OH)3coatings were grown on wood surface by using hydrothermal method, in the analysis of the elements on the surface of wood through X-ray photoelectron spectroscopy, it can be understood that compounds containing Al elements were grown on wood surface, in combination with the absorption spectroscopy of O elements, the compounds grown on wood surface were composed of Al elements and O elements, thus we can conclude that the compounds grown on wood surface were Al(OH)3.(2) By changing the conditions of the experiment, for example, changing the hydrothermal time and temperature, reaction solvent, aluminum source and the concentration of the precursor, there will be some corresponding change of the morphology, structure and amount of Al(OH)3on wood surface. Considering the influence of various factors, the best process conditions were at100℃,8h or120℃,6h. Under this condition, there was no obvious difference between the treated and untreated wood from a macro view, the Al(OH)3were mainly composed of sub-micro balls, and it will be transform into the flake structure of boehmite after further grown.boehmite after further grown. (3) The result of woods after ultraviolet aging test explained that after a ultraviolet aging time of480h, The quality of the coating on wood surface was uniformly in a better density when hydrothermal grown at100℃for8h, while the whole change of the red to green index and yellow to blue index is similar with the example; in the other side, there is a obvious change lightness when hydrothermal grown at120℃for6h, besides the red to green index and yellow to blue index is similar with last example which has a smaller range ability. In the whole, the ability of handling the anti-lightness and anti-color on the example increased triple times, then we can see that the lightness stability become forcer than before.(4) After the research of dynamic thermal mechanical analysis (DMA) and thermal degradation performance analysis (TG) on the woods with a Al(0H)3surface, conclusion shows that:the storage modulus of wood increased by30%and the loss tangent increased slightly when the hydrothermal treated wood at100℃for8h, in the meantime, the storage modulus of wood and the loss tangent do not change obviously at120℃for6h. Thus the above-mentioned conditions are the best choice for the grown of Al(OH)3coating, so we can know that the wood with Al(OH)3coating can improve the elasticity modulus on woods.(5) With the LOA analysis of woods, we can learn that the index of wood with Al(OH)3coating has increased in some way. Besides, the best choice of hydrothermal conditions is at100℃for8h and120℃for6h, this can draw form the result of SEM and other lab text.(6) The CONE calorimeter was used to analysis the flame retardant properties of wood, from the result, at the hydrothermal conditions of100℃,8h and120℃,6h compare with the untreated one, its heat release rate was decreased51.75%and47.41%respectively, the total heat quantity decreased66.71%、45.61%and the total smoke release quantity was79.61%、67.96%, while the mass loss was36.36%、45.45%, what’s more, its effective heat of combustion was also reduced. Therefore, the Al(OH)3thin film can improve the flame retardant performance of wood, it can also improve the safety of wood using.In conclusion, with the hydrothermal condition of100℃for8h and120℃for6h, the Al(OH)3coating on wood surface can improve the thermodynamics properties, the light discoloration resistance and flame retardant of wood in all aspects. |
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