故宫长春宫木构件材质劣化研究
|
摘要
为了探讨故宫长春宫承重木构件的老化及其机理,从长春宫主殿明间(C1)及主殿外南侧立柱(C2)外观开裂、变色严重部位分别取样,在木构件材种鉴定的基础上,分析了木构件的化学组分;并通过X射线衍射分析(XRD)、热重分析(DTG)以及红外光谱分析(IR),测定了木构件的相对结晶度以及组分中化学基团的变化。研究结果表明,受试木构件中的纤维素、木质素以及半纤维素含量均不同程度下降;由于长期暴露在自然环境中,C2木构件降解程度比较严重,其纤维素含量下降较C1木构件更快;DTG分析结果表明,在纤维素快速下降的同时,C2木构件半纤维素含量也发生了明显的降解,进而导致C2中的相对结晶度远远低于C1木构件;红外光谱对木构件化学基团变化分析结果表明,与同种现代材相比,C1、C2木构件在波数分别为1 732,1 635,1 510和1 460 cm~(-1)处吸收峰减弱和消失,这表明受试木构件化学组分的降解非常明显,尤以C2木构件木材化学组分降解更加严重。另外,C2木构件在波数1 510 cm~(-1)处的吸收峰完全消失,而该处应为芳香族的木质素苯环骨架振动特征吸收峰。这一现象表明光降解是C2木构件老化的主要原因之一。
In this study, we evaluated the age-induced degradation of wood structural components of the Changchun Palace in the Forbidden City. The wooden structural component(stand column) samples were taken from the interior of the main shrine(C1) and the exterior of the shrine on the south side(C2). Because of the location of C2 in an area where it has long been exposed to natural environmental conditions such as ultraviolet rays in sunlight, it could be seen to be severely degraded by visual evaluation. The columns were determined to have been made of larch wood(Larix gmelinii(Rupr.) Kuzen.). A variety of scientific methods, including X-ray diffraction(XRD), derivative thermogravimetry(DTG) and infrared spectroscopy(IR) were used for further analyses. The results show that the cellulose, lignin and hemicellulose of both C1 and C2 samples have degraded over the years, but the degree of degradation of the cellulose of C2 is more remarkable than that of C1, due to the long-term exposure to ultraviolet light in sunlight. DTG analysis also shows the hemicellulose in C2 had similarly degraded, with the result that the relative crystallinity of C2 is much lower than that of the larch wood used inside the shrine. Furthermore, analyses of chemical group changes by IR spectroscopy show that absorption peaks of C1 and C2 samples have weakened or disappeared at 1 732 cm~(-1), 1 635 cm~(-1), 1 510 cm~(-1) and 1 460 cm~(-1), indicating that chemical compositions of these larch wood samples have changed markedly, especially for C2. It is also noted that the absorption peak of C2 at the wave number of 1510 cm~(-1) which represents skeleton vibration of benzene ring originating mainly from lignin has disappeared. This suggests that photodegradation(degradation of lignin primarily due to irradiation of ultraviolet light) would be the main reason for the aging of C2.
In this study, we evaluated the age-induced degradation of wood structural components of the Changchun Palace in the Forbidden City. The wooden structural component(stand column) samples were taken from the interior of the main shrine(C1) and the exterior of the shrine on the south side(C2). Because of the location of C2 in an area where it has long been exposed to natural environmental conditions such as ultraviolet rays in sunlight, it could be seen to be severely degraded by visual evaluation. The columns were determined to have been made of larch wood(Larix gmelinii(Rupr.) Kuzen.). A variety of scientific methods, including X-ray diffraction(XRD), derivative thermogravimetry(DTG) and infrared spectroscopy(IR) were used for further analyses. The results show that the cellulose, lignin and hemicellulose of both C1 and C2 samples have degraded over the years, but the degree of degradation of the cellulose of C2 is more remarkable than that of C1, due to the long-term exposure to ultraviolet light in sunlight. DTG analysis also shows the hemicellulose in C2 had similarly degraded, with the result that the relative crystallinity of C2 is much lower than that of the larch wood used inside the shrine. Furthermore, analyses of chemical group changes by IR spectroscopy show that absorption peaks of C1 and C2 samples have weakened or disappeared at 1 732 cm~(-1), 1 635 cm~(-1), 1 510 cm~(-1) and 1 460 cm~(-1), indicating that chemical compositions of these larch wood samples have changed markedly, especially for C2. It is also noted that the absorption peak of C2 at the wave number of 1510 cm~(-1) which represents skeleton vibration of benzene ring originating mainly from lignin has disappeared. This suggests that photodegradation(degradation of lignin primarily due to irradiation of ultraviolet light) would be the main reason for the aging of C2.
引文
[1] 斉藤幸恵,信田聡,太田正光,等.古材の劣化調査——福勝寺本堂(重要文化財)垂木用材の食害と材質[J].木材学会誌,2008,54(5):255-262.Saito Yukiea Wakako, Makihara Hiroshi, Nohjo Shuichi, et al. Degradation survey of old materials: Fukatsukiji Temple hall (important cultural property) Eating damage and material of rafter timber materials[J]. Journal of Wood Society,2008,54(5):255-262.
[2] 成俊卿,杨家驹,刘鹏.中国木材志[M].北京:中国林业出版社,1992:48-50.CHENG Jun-qing, YANG Jia-ju, LIU Peng. Identification of China Wood[M]. Beijing: China Forestry Press,1992:48-50.
[3] INAGAKI T, SIESLER H W, MITSUI K, et al. Difference of the crystal structure of cellulose in wood after hydrothermal and aging degradation: a NIR spectroscopy and XRD study[J]. Biomacromolecules,2010,11(9):2300-2305.
[4] AKGüL M, GüMü?KAYA E, KORKUT S. Crystalline structure of heat-treated Scots pine[Pinus sylvestris L.] and Uludag fir[Abies nordmanniana (Stev.) subsp. bornmuelleriana (Mattf.)] wood[J]. Wood Sciences and Technology,2007,41(3):281.
[5] 李贤军,刘元,高建民,等.高温热处理木材的FTIR和XRD分析[J].北京林业大学学报,2009,31(1):104-107.LI Xian-Jun, LIU Yuan, GAO Jian-Ming, et al. Characteristics of FTIR and XRD for wood with high-temperature heating treatment[J]. Journal of Beijing Forest University,2009,31(1):104-107.
[6] 沈德魁,余春江,方梦祥,等.热辐射下常用木材热解的动力学与燃烧特性[J].燃烧科学与技术,2008,14(5):446-452.SHEN De-kui, YU Chun-Jiang, FANG Meng-Xiang, et al. Kinetic study of thermal decomposition and combustion characteristics of wood under thermal radiation[J]. Journal of Combust Sciences and Technology,2008,14(5):446-452.
[7] 李宇宇,李瑞,田启魁,等.热重法研究落叶松热解动力学特性[J].东北林业大学学报,2011,39(7):63-66.LI Yu-yu, LI Rui, TIAN Qi-kui, et al. Pyrolysis kinetics of larch wood by thermogravimetric analysis[J]. Journal of Northeast Forest University,2011,39(7):63-66.
[8] 杜洪双,常建民,李瑞,等.落叶松木材的热解特性[J].东北林业大学学报,2009,37(12):25-29.DU Hong-shuang, CHANG Jian-min, LI Rui, et al. Pyrolysis characteristics of larch wood[J]. Journal of Northeast Forest University,2009,37(12):25-29.
[9] ZHU P, SUI S, WANG B, et al. A study of pyrolysis and pyrolysis products of flame-retardant cotton fabrics by DSC, TGA, and PY-GC-MS[J]. Journal of Applied Pyrolysis,2004,71(2):645-655.
[10] ORF?O J J M, ANTUNES F J A, FIGUEIREDO J L. Pyrolysis kinetics of lignocellulosic materials: three independent reactions model[J]. Fuel,1999,78(3):349-358.
[11] BILBAO R, MASTRAL J F, ALDEA M E, et al. Kinetic study for the thermal decomposition of cellulose and pine sawdust in an air atmosphere[J]. Journal of Applied Pyrolysis,1997,39(1):53-64.
[12] GRIOUI N, HALOUANI K, ZOULALIAN A, et al. Thermogravimetric analysis and kinetics modeling of isothermal carbonization of olive wood in inert atmosphere[J]. Thermochimica Acta,2006,440(1):23-30.
[13] UWE M, MANFRED R, MANFRED S, et al. Yellowing and IR-changes of spruce wood as result of UV-irradiation[J]. Journal of Photochemistry and Photobiology B:Biology,2003,69(2):97.
[14] TEAC? C A, DAN R, BOD?RL?U R, et al. Structural changes in wood under artificial UV light irradiation determined by FTIR spectroscopy and color measurements: a brief review[J]. Bioresources,2013,8(1):1478-1507.
[15] 武井利之,濱島正士,神庭信幸.FT-IRによる法隆寺古材の劣化の解析[J].木材学会誌,1997,43(3):285-294.Takei Toshiyuki, Masashi Hamajima, Nobuyuki Kaniya. Analysis of deterioration of Horyuji old material by FT-IR[J]. Journal of Wood Society,1997,43(3):285-294.
[16] COLOM X, CARRILLO F, NOGUES F, et al. Structure analysis of photodegraded wood by means of FTIR spectroscopy[J]. Polymer Degradation Stability,2003,80:543-549.
[17] COGULET A, BLANCHET P, lANDRY V. Wood degradation under UV irradiation: A lignin characterization[J]. Journal of Photochemistry and Photobiology B:Biology,2016,158:184-191.
[18] PANDEY K K. Study of the effect of photo-irradiation on the surface chemistry of wood[J]. Polymer Degradation & Stability,2005,90(1):9-20.
[2] 成俊卿,杨家驹,刘鹏.中国木材志[M].北京:中国林业出版社,1992:48-50.CHENG Jun-qing, YANG Jia-ju, LIU Peng. Identification of China Wood[M]. Beijing: China Forestry Press,1992:48-50.
[3] INAGAKI T, SIESLER H W, MITSUI K, et al. Difference of the crystal structure of cellulose in wood after hydrothermal and aging degradation: a NIR spectroscopy and XRD study[J]. Biomacromolecules,2010,11(9):2300-2305.
[4] AKGüL M, GüMü?KAYA E, KORKUT S. Crystalline structure of heat-treated Scots pine[Pinus sylvestris L.] and Uludag fir[Abies nordmanniana (Stev.) subsp. bornmuelleriana (Mattf.)] wood[J]. Wood Sciences and Technology,2007,41(3):281.
[5] 李贤军,刘元,高建民,等.高温热处理木材的FTIR和XRD分析[J].北京林业大学学报,2009,31(1):104-107.LI Xian-Jun, LIU Yuan, GAO Jian-Ming, et al. Characteristics of FTIR and XRD for wood with high-temperature heating treatment[J]. Journal of Beijing Forest University,2009,31(1):104-107.
[6] 沈德魁,余春江,方梦祥,等.热辐射下常用木材热解的动力学与燃烧特性[J].燃烧科学与技术,2008,14(5):446-452.SHEN De-kui, YU Chun-Jiang, FANG Meng-Xiang, et al. Kinetic study of thermal decomposition and combustion characteristics of wood under thermal radiation[J]. Journal of Combust Sciences and Technology,2008,14(5):446-452.
[7] 李宇宇,李瑞,田启魁,等.热重法研究落叶松热解动力学特性[J].东北林业大学学报,2011,39(7):63-66.LI Yu-yu, LI Rui, TIAN Qi-kui, et al. Pyrolysis kinetics of larch wood by thermogravimetric analysis[J]. Journal of Northeast Forest University,2011,39(7):63-66.
[8] 杜洪双,常建民,李瑞,等.落叶松木材的热解特性[J].东北林业大学学报,2009,37(12):25-29.DU Hong-shuang, CHANG Jian-min, LI Rui, et al. Pyrolysis characteristics of larch wood[J]. Journal of Northeast Forest University,2009,37(12):25-29.
[9] ZHU P, SUI S, WANG B, et al. A study of pyrolysis and pyrolysis products of flame-retardant cotton fabrics by DSC, TGA, and PY-GC-MS[J]. Journal of Applied Pyrolysis,2004,71(2):645-655.
[10] ORF?O J J M, ANTUNES F J A, FIGUEIREDO J L. Pyrolysis kinetics of lignocellulosic materials: three independent reactions model[J]. Fuel,1999,78(3):349-358.
[11] BILBAO R, MASTRAL J F, ALDEA M E, et al. Kinetic study for the thermal decomposition of cellulose and pine sawdust in an air atmosphere[J]. Journal of Applied Pyrolysis,1997,39(1):53-64.
[12] GRIOUI N, HALOUANI K, ZOULALIAN A, et al. Thermogravimetric analysis and kinetics modeling of isothermal carbonization of olive wood in inert atmosphere[J]. Thermochimica Acta,2006,440(1):23-30.
[13] UWE M, MANFRED R, MANFRED S, et al. Yellowing and IR-changes of spruce wood as result of UV-irradiation[J]. Journal of Photochemistry and Photobiology B:Biology,2003,69(2):97.
[14] TEAC? C A, DAN R, BOD?RL?U R, et al. Structural changes in wood under artificial UV light irradiation determined by FTIR spectroscopy and color measurements: a brief review[J]. Bioresources,2013,8(1):1478-1507.
[15] 武井利之,濱島正士,神庭信幸.FT-IRによる法隆寺古材の劣化の解析[J].木材学会誌,1997,43(3):285-294.Takei Toshiyuki, Masashi Hamajima, Nobuyuki Kaniya. Analysis of deterioration of Horyuji old material by FT-IR[J]. Journal of Wood Society,1997,43(3):285-294.
[16] COLOM X, CARRILLO F, NOGUES F, et al. Structure analysis of photodegraded wood by means of FTIR spectroscopy[J]. Polymer Degradation Stability,2003,80:543-549.
[17] COGULET A, BLANCHET P, lANDRY V. Wood degradation under UV irradiation: A lignin characterization[J]. Journal of Photochemistry and Photobiology B:Biology,2016,158:184-191.
[18] PANDEY K K. Study of the effect of photo-irradiation on the surface chemistry of wood[J]. Polymer Degradation & Stability,2005,90(1):9-20.