Abstract: [Objective] Wood as well as wooden decorative materials produced by dyeing or/and color modulation are easy to be discoloration and degradation when exposed to light radiation. These will decrease its decorative effect and shorten the service life. The objective of this study was to investigate the effect of acetylation treatment on light fastness and thermal stability of plantation wood, and provide a theoretical basis for wood color regulation technology and the development of high light stability dyed wood. [Method] The Pinus sylvestris var. mongolica wood powder was reacted with acetic anhydride and xylene solution under the temperature of 120 ℃ for 5, 10, 20, 40 and 60 min, respectively. The effect of acetylating time on weight gain rate of wood powder was tested. One gram untreated wood powder and wood powder treated by different acetylating time, respectively, were irradiated in a UV light source accelerated aging tester for 100 h. Then, the changes of chemical functional groups, thermal stability and morphology for the acetylated wood powder before and after UV radiation were characterized by FTIR, TGA and SEM.[Result] The weight gain rate of Pinus sylvestris var. mongolica wood powder was increased firstly and then reduced as the time of acetylation reaction prolonged and reached the maximum at acetylating 40 min. The characteristic absorption peak intensity of acetylated wood powder at 1 741 cm^-1 and 1 385 cm^-1, respectively, standing for C O and C—H was greater than those of the control, and reached the maximum at acetylating 40 min. After UV irradiation, the characteristic absorption peak intensity at 1 508 cm^-1 for lignin benzene ring of acetylated wood powder was significantly higher than that of the control, and also reached the maximum at 40 min acetylation, indicating that acetylation treatment effectively enhanced the light fastness of wood powder. TGA result showed that the thermal stability of acetylated wood powder was improved due to the temperature of thermal decomposition increased significantly. SEM images showed that acetylation treatment can enhance the ability of wood powder's microscopic structure to resist photo-degradation.[Conclusion] Acetylation treatment is an effective method to inhibit the photo-degradation of Pinus sylvestris var. mongolica wood and increases its thermal stability.

Key words: Pinus sylvestris var.mongolica, acetylation, UV radiation, functional groups, light fastness, thermal stability