Thermal modification can improve the dimensional stability of wood without the use of biocides, but the process also changes the colour. Changes in relative amounts of chromophores and auxochromes of poplar extracts during thermal modification were investigated by pre-extraction of ground wood in increasingly polar solvents followed by thermal modification. Changes in wood colour and FTIR spectra were used to assess the effects of extraction/thermal modification, while selected extracts were analysed by GC–MS. Colour of non-modified poplar was mainly affected by ethanol extraction, while thermally modified poplar was most affected by 1,4-dioxane and acetone extraction. GC–MS analysis to characterize the main chromophores and auxochromes in the 1,4-dioxane and acetone extracts from non-modified or thermally modified poplar suggested that chromophores and/or auxochromes in extracts including carbonyl, vinyl, benzene ring and hydroxyl groups tended to be much more abundant in thermally modified poplar which accounts for the darkening of the wood.

热改性可以在不使用杀菌剂的情况下提高木材的尺寸稳定性，但该过程也会改变颜色。通过在极性增加的溶剂中预提取磨碎的木材，然后进行热改性，研究了热改性过程中杨树提取物发色团和辅助色素相对量的变化。木材颜色和 FTIR 光谱的变化用于评估提取/热改性的影响，同时通过 GC-MS 分析选定的提取物。未改性杨树的颜色主要受乙醇提取的影响，而热改性杨树的颜色受1,4-二氧六环和丙酮提取的影响最大。GC-MS 分析以表征 1 中的主要发色团和辅助色素，