| Nowadays,along with the decrease of precious wood and the improvement of human's living standard,cheap wood that imitates the expensive one has raised more and more concern.That makes it meaningful to find a way of processing simulated valuable wood to improve people's life,of course in the premise of making most of wood.In this study,correspondingly low-cost heat-treated Larch plantation were used to imitate precious wood and to improve the dimensional stability and crystallinity,aiming at finding the best conditions of heat-treated so that wood with best color and with the best film performance can be made.The conclusions are as follows:(1)By controlling the heat treatment temperature and the time to change the values of ?C*,?E*and ?H*,the change of the color from artificial forest larch to precious wood can be realized.It was observed that the best temperature is 210? and the best time is 6h,under which the color of Larch is similar with Cochin Dalbergia.The maximum effects of heat treatment temperature on ?C*,?E*and ?H*were 22.7 times,17.2 times and 3.7 times of that of time,respectively.The effects of heat treatment temperature on plantation of Larch were much higher than that of heat treatment time.(2)In pace of the increase of the treatment temperature and the prolongation of the time,the carbonyl group decreased first and then increased along with the conjugated aryl ketone increasing,which accounts for color changing and finally turning into the color of precious wood.What's more,color changing can also be attributed to the addition of polyhydric phenols such as tannins and flavonoids in dioxane extracts,or the increase of functional groups such as conjugated double bonds and carbonyl groups.(3)High temperature heat treatment can effectively reduce the chord(wet)shrinkage rate and shrinkage rate of larch wood,and then reduce the ASE value of wood,and finally make the wood to improve the dimensional stability.Wherein the width dimension change of chord direction is much larger than radial.The heat treatment temperature has a greater effect on the dimensional stability than the heat treatment time.With the increase of treatment temperature and the extension of time,hydroxyl content in larch wood declined and crystallinity increased,which is the main reason for the increased dimensional stability.(4)Jet plasma treatment to heat-treated wood can effectively reduce the loss rate of its film after painting,and can enhance the film adhesion.When the plasma was used to treat at the height of 15mm over the surface,the film quality loss rate decreased to 89.78%(60s).Researches found that the loss rate of the film gradually decreased by time.The optimum plasma treatment process is as follows:the treatment height is 15mm,while the processing time is 20s.(5)In the process of plasma treatment,a large amount of amino,hydroxyl,carbonyl and carboxyl groups were introduced,resulting in the decrease of C element content and so do O element and N element,in different degree.Since amino,hydroxyl,carbonyl,carboxyl and so on are all hydrophilic groups,the surface of the tested material presented reducing contact angle and increasing free energy.Ultimately,surface wettability improved and hence its film performance improved. |
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