基于近红外光谱技术的紫外光老化落叶松木材表面材色变化的定性和定量研究  

A Qualitative and Quantitative NIRs Study on Larch Wood Surface Color Change by UV Light Irradiation

作　　者：符瑞云 符小慧[1] 张文博[1,4] 黎冬青 管成[3,4] 张厚江[3,4] FU Rui-yun;FU Xiao-hui;ZHANG Wen-bo;LI Dong-qing;GUAN Cheng;ZHANG Hou-jiang(College of Material Science and Technology,Beijing Forestry University,Beijing 100083,China;Beijing Research Institute of Historic Architecture Conservation&Design,Beijing 100050,China;College of Technology,Beijing Forestry University,Beijing 100083,China;Joint International Research Institute of Wood Nondestructive Testing and Evaluation,Beijing Forestry University,Beijing 100083,China)

机构地区：[1]北京林业大学材料科学与技术学院,北京100083 [2]北京市文物建筑保护设计所,北京100050 [3]北京林业大学工学院,北京100083 [4]北京林业大学木材无损检测国际联合研究所,北京100083

出　　处：《光谱学与光谱分析》2022年第1期56-61,共6页Spectroscopy and Spectral Analysis

基　　金：国家科技支撑计划项目(2015BAD14B0302)资助。

摘　　要：自然光中的紫外光在木材表面产生复杂的光化学反应,是木材在自然环境中老化降解速度最快,反应最强的化学过程。基于近红外光谱(NIRs)技术探讨了落叶松表面材色在340 nm波长紫外光照射条件下的老化状况。不同时间(180,540,900,1080 h)试材弦切面经紫外光人工老化后,测量木材表面材色色度学指数,并采集NIRs信息。由NIRs二阶导数及其差谱图反映的信息,定性分析和讨论了木材表面化学组分基团的变化;定量建立基于偏最小二乘法(PLS)结合留一交叉验证的木材表面材色预测模型。结果表明:(1)随着人工老化时间延长,木材表面明度值L^(*)降低,红绿指数a^(*)与黄蓝指数b*出现先增加后缓慢降低的趋势,表明发色基团的形成随着紫外光照射时间的延长而减少,在辐射时间540 h达到最大值,此外,色差值ΔE^(*)与紫外光照射时间成正相关。(2)NIRs二阶导数在6996,6773以及6287 cm^(-1)等分别反映木材中纤维素非结晶区、半结晶区和结晶区的光谱吸光度随着老化时间的延长而增加,而5986 cm^(-1)反映木质素特征性谱带吸收峰随着紫外光老化时间的延长而降低,表明木质素出现降解。通过紫外光照射1080 h与对照材的差谱分析发现,纤维素和半纤维素基团的特征峰差谱值为正,表明紫外光辐射后木材表面的纤维素和半纤维素相对含量增加,而木质素基团特征峰差谱值为负,表明经紫外光辐射后,木质素的降解导致其相对含量减少。这些结果与色度值测量结果相一致。(3)基于NIRs建立的紫外光照射落叶松表面材色预测模型中,L^(*)交叉验证模型决定系数(R^(2))为0.949,相对分析误差(RPD)为4.42;a^(*)交叉验证模型R^(2)是0.928,RPD是3.73;b^(*)的交叉验证模型R^(2)是0.831,RPD为2.43,建立的材色预测模型满足预测要求。Among environmental degradation of wood,photodegradation originated mainly by ultraviolet light is the fastest and the strongest chemical reaction process.This work on the base of near-infrared spectroscopy(NIRs)technology studied color changes of Larch wood surface irradiated by UV light with 340 nm wavelength.At different times(180,540,900,1080 h),the wood surface colorimetric index was measured and NIRs information was collected after ultraviolet light.Qualitatively chemical group changes of the wood surface were discussed according to collecting NIRs 2nd derivative spectra and their difference spectra.Quantitatively,the prediction of color the UV-irradiated wood surface were constructed using partial least squares regression method combined with leave-one-out cross-validation process.The results can be drawn as follows:(1)The color changes for UV light irradiated larix wood surface showed that lightness(ΔL^(*))decreases,whereas a^(*)and b^(*)showed increasing then decreased slowly,indicating chromatic groups formed and then decreased with prolonged irradiation time.ΔE^(*)increase with increasing irradiation time.(2)The amorphous,semi-crystalline and crystalline wood surface occurred at the wavenumbers of 6996,6773 and 6287 cm^(-1),respectively increased with prolonged UV-irradiation time.The wavenumber at 5986 cm^(-1) assigned to lignin,however,decreased with increasing UV light irradiation time to some degree.Furthermore,the difference spectra between 1080 h UV light irradiation and control found that the positive values representing cellulose and hemicellulose showed quantitative increment,the negative value representing lignin showed a quantitative decrement in relative content,respectively.(3)The color prediction models established by NIRs information in combination with measuring the L^(*),a^(*),b^(*)showed that the determined coefficient(R^(2))and Ratio of performance to deviation(RPD)were 0.949 and 4.42,0.928 and 3.73,0.831 and 2.43 for L^(*),a^(*)and b^(*),respectively.These results confirmed that t

关 键 词：近红外光谱 差谱 落叶松 表面材色变化 紫外光照射 

分 类 号：O657.3[理学—分析化学]