TGA與FTIR分析腐朽木材之化學結構變化

TGA and FTIR Analyses of the Chemical Structure Changes of Decayed Wood

吳季玲(Chi-Lin Wu) ； 張上鎮(Shang-Tzen Chang)

《中華林學季刊》 43卷1期 (2010/03) Pp. 147-155

https://doi.org/10.30064/QJCF.201003.0010

摘要

本研究利用熱重分析(TGA)及傅立葉轉換紅外線光譜(FTIR)微量分析的方法，進行腐朽木材之固態分析，探討木材經真菌腐朽後的化學結構的變化。由在氮氣下熱重分析結果得知，台灣杉心材經L. sulphureus褐腐菌腐朽後，纖維素受到破壞，最大熱解溫度降低了9.2℃；經過T. versicolor白腐菌腐朽後，雖然試材的重量損失率僅有3.5%，但由導數熱重分析(DTG)得知最大熱解溫度產生明顯的變化，降低了14.7℃。在空氣下，經過L. sulphureus褐腐菌腐朽後，木材二階段之最大熱解溫度分別降低了7.8℃與10.9℃；而經T. versicolor白腐菌腐朽後，最大熱解溫度則分別降低了10.9℃與17.2℃。顯示木材被真菌腐朽後，主成分降解而使其熱穩定性降低，而導致木質素或纖維素等的熱解溫度降低，且TGA分析白腐菌對木材的降解作用較為靈敏。至於木材腐朽後化學結構的變化，FTIR分析結果顯示，木材腐朽的降解反應形成各種不同化學結構之衍生物，可知褐腐菌與白腐菌不同的降解方式。台灣杉經L. sulphureus褐腐菌腐朽後，纖維素中β-葡萄醣苷的鍵結減少，使纖維素的聚合度降低，碳水化合物的含量減少，使木質素於木材中的相對含量增加，木質素僅產生輕微的氧化作用。此外，台灣杉經T. versicolor白腐菌腐朽後，木質素結構中共軛羰基含量增加，半纖維素亦有輕微的降解。

關鍵字

化學結構 ； 耐腐朽性 ； 傅立葉轉換紅外線光譜分析 ； 熱重分析

並列摘要

The variations in the chemical structures of decayed wood were evaluated by using solid state analyses including thermogravimetry analysis (TGA) and Fourier transform infrared spectroscope (FTIR) in this study. Result from TGA revealed that the decrement in the maximum temperature of pyrolysis in N2 was 9.2℃ due to the destruction of cellulose by brown-rot fungus L. sulphureus compared to the control. Although the weight loss of white-rot fungus decayed wood was only 3.5%, the distinguished change was observed from- Derivative TG (DTG) result. There was an obvious decrease (14.7℃) in maximum pyrolysis temperature of wood decayed by white-rot fungus T. versicolor compared to the control. Furthermore, the decrement in the two-step maximum temperature of pyrolysis in air was 7.8℃ and 10.9℃, respectively after the wood was decayed by brown-rot fungus L. sulphureus. Also, after the wood was decayed by white-rot fungus T. versicolor the decrement in the two-step maximum temperature of pyrolysis in air was 10.9℃ and 17.2℃, respectively. Based on the results obtained, the thermal stability and maximum pyrolysis temperature were influenced by the decomposition of wood. Furthermore, TGA was a more sensitive method for the degradation analysis of wood decayed by white-rot fungi. Results from FTIR analysis demonstrated decomposition of wood and composition of the products were influenced by the different decay mechanisms caused by brown-rot fungus and white-rot fungi. The amount of β-D-glucoside linkage of wood decreased after the decay test with L. sulphureus, revealing that the polymerization degree of cellulose and the content of carbohydrate of brown-rot decayed wood were reduced. Besides the minor degradation of hemicelluloses were also observed, the lignin of wood decayed by T. versicolor was also deteriorated, consequently leading to the formation of small amounts of derivatives with conjugated carbonyl and carboxyl groups.

並列關鍵字

Chemical structure ； Decay resistance ； Fourier transform infrared spectroscope ； Thermogravimetry analysis