溶剂抽提对柚木材色及光诱导变色的影响

【目的】柚木在阳光照射下由浅棕色转变成金黄色从而变得更加珍贵,对柚木光变色机理的研究可以增加柚木的商品价值,也是建立木材材色调控技术方法的基础,本文旨在探讨溶剂抽提对柚木光变色的影响。【方法】采用溶剂水、乙醇、乙酸乙酯、氯仿、苯、石油醚、苯-乙醇混合物(1:1、2:1、4:1、9:1)对柚木试样进行抽提,探究溶剂极性对柚木试样的色差的影响,然后再对抽提完的试样进行氙光光照处理,通过色差的分析探究不同溶剂抽提对柚木光诱导变色的影响。【结果】1)混合溶剂苯-乙醇抽提后抽提物溶液的颜色最深,极性溶剂抽提出的显色物质含量较多。2)柚木试样经抽提后可以增加柚木的明度色品指数L^*,尤其是2:1的混合溶剂苯-乙醇抽提后L^*增大最为显著,抽提的更完全。3)光照苯-乙醇抽提后的柚木试样,其红绿色品指数a^*增加较少,说明苯-乙醇抽提物是主要柚木试样呈现红色的物质基础。4)苯-乙醇抽提后b^*值减小较多抽提试样光照后b^*值反而增加较多,这表明苯-乙醇抽提掉的物质有可能就是木质素,木质素部分被苯-乙醇混合溶剂抽提出来,抽提后光照作用下木质素更容易降解呈现出更多的黄色。【结论】溶剂抽提处理和光照处理,对柚木材色都有显著的影响。不仅苯-乙醇混合溶剂抽提处理对柚木材色影响较多,而且苯-乙醇混合溶剂抽提试样在进一步光照处理后材色变化也很大,其中2:1的苯-乙醇溶剂是最为合适的用于研究柚木光变色成分变化的溶剂。

Effects of solvent extractionon the color changes and light-induced discoloration of teak

【Objective】Teak becomes more precious by changing from brown to golden after irradiation.Studying the mechanism of photo-discoloration of teak was the basis to establishwood color control technology.The purpose of this paper was to explore the effect of solvent extraction on the color changes and light-induced.【Method】Different polar solventsof water,ethanol,ethyl acetate,chloroform,benzene,petroleum ether,benzene-ethanol(1:1,2:1,4:1,9:1)were used to extract teak samples to explore the influence of solvent polarity on the color difference of teak samples.Then xenon light was applied to the extracted samples,and the effects of different solvent extraction on the photo-discoloration of teak were analyzed by CIE Lab.【Result】1)The color of the solution is the darkest after benzene-ethanol extraction,which indicates that the content of chromogenic substance extracted by benzene-ethanol is the highest.2)The L^* of teak can be increased after extraction,especially after 2:1 benzene-ethanol solvent extraction.3)The a^* of teak samples increased slightly when extracted by benzene-ethanol after irradiation,which indicates that benzene-ethanol extract is the main material basis for the red appearance of teak samples.4)After benzene-ethanol extraction,the b^* value of teak samples decreases more,but increases more after irradiation.It indicates that the component extracted by benzene-ethanol may be lignin.A small amount of lignin can be extracted by benzene-ethanol solvent,and lignin is easier to degrade under irradiation after extraction,which results in more yellow color of teak samples.【Conclusion】Solvent extraction and irradiation had significant effects on the color of teak.Not only the color of teak is more influenced by extraction of benzene-ethanol mixed solvent,but also the color of the extracted sample changes greatly after further irradiation.2:1 benzene-ethanol mixed solvent is the most suitable solvent for studying the changes of the photo-discoloration composition of teak.