关键词：
竹;结晶度;热处理;化学处理;X射线衍射;热重分析
摘 要：
为探明不同热处理条件下毛竹的结构变化特性,提高毛竹热处理加工及竹基复合材料的开发利用技术,以四年生毛竹为研究对象,分别研究其在不同的热处理温度和酸碱、甘油处理介质下的结构变化规律。研究主要应用X射线衍射法(X-ray diffraction,XRD)测定和计算处理前后毛竹结晶区长度、晶面间距、衍射峰晶面峰强位置、结晶度指数及结晶区宽度等参数,并用扫描电镜(Scanning Electron Microscopy,SEM)进行结晶区变化的结果验证,利用热重分析(thermo gravimetric Analysis,TGA)完成处理前后毛竹热降解性研究。结果表明:经过化学热处理后,002峰位向大角度方向偏移明显,结晶区晶粒尺寸减小,结晶区半峰宽变小,结晶区层间距尺度变小,各参数集中变化程度,碱处理强于酸处理。此外,经过不同介质和不同加热温度进行化学热处理后,其峰形变高且尖锐,结晶强度明显增加。相对结晶度在117℃时,出现下降趋势,当温度升至135℃时,逐步恢复增加趋势。SEM和TGA进一步验证了处理后纤维结构变细及化学成分热解温度的倾向性差异,综合研究结果显示处理后纤维素含量增大,木质素去除效果明显,几种不同处理过程的化学成分差异变化较大。研究结果为竹材的再生加工及竹基复合材料的开发利用提供理论参考依据。
译 名：
Structural performance analysis of bamboo under different chemical and heat treatments
作 者：
Chu Jie;Zhang Junhua;Lu Haidong;College of Forestry,Northwest A&F University;
关键词：
bamboo;;crystalline;;heat treatment;;chemical treatment;;X-ray diffraction;;thermo gravimetric analysis
摘 要：
In order to make clear of the crystallinity change characteristics of moso bamboo in different heat pretreatments,improve the treatment processing and the development and utilization technology of bamboo base composite material, the changing rule of the crystallinity of four-year raw bamboo was studied under the 117 and 135 ℃ with different concentration of acid, alkali and glycerol. The pretreated bamboo samples were filtered through a Buchner funnel and washed with deionized water until the effluent was p H-neutral, and then dried in the oven for 1 h at(103±5) ℃. Extractives in the samples were removed by Soxhlet extractor for 12 h with 80 m L ethanol and 40 m L benzene. The extracted residue was air-dried overnight prior to characterization. Holocellulose was isolated from extractive-free biomass using a modified procedure from the literature. Extractive-free pretreated samples(2 g), deionized water(150 m L), sodium chlorite(1.0 g) and glacial acetic acid(0.2 g) were added into a kapak sealing pouch, and the sealing pouch was in a shaking water bath for 1 h at 75 ℃. After 1 h,another batch of sodium chlorite and glacial acetic acid were added and the mixture was heated in the water bath for 1 h again. This process was repeated 4 times until the holocellulose turned white. Then, the pretreated bamboo samples were cooled, filtered through a Buchner funnel, washed several times with deionized water and air-dried in a fume hood. Cellulose was isolated from holocellulose sample by an acid treatment following a procedure from the literature that holocellulose was treated with 17.5% Na OH(50 m L) at 98-100 ℃ for 4 h, cooled to 0 ℃, filtered in a Buchner funnel, washed several times with deionized water and air-dried in a fume-hood. The methods included using crystal X-ray diffraction to measure the area length, spacing, crystal plane diffraction peak position, crystalline index and parameters, using scanning electron microscopy( SEM) to verify the change of crystalline region, and using thermo gravimetric analysis( TGA) to complete the thermal degradation studies for moso bamboo. Results showed that the 002 peak position in the direction of large angle was obviously offset, the 002 crystal width and the grain size in crystalline region were decreased, and the half peak width in crystalline region was becoming smaller. In addition, its high peak deformation was sharp, and the crystalline intensity increased significantly after different chemical heat treatment; the trend of relative crystallinity declined at 117 ℃, and when the temperature rose to 135 ℃, it recovered gradually. SEM and TGA further validated that the fibrous structure became thinner and there was the tendency difference for pyrolysis temperature of chemical compositions after processing; a comprehensive study showed that after treatment the cellulose content was increased, the lignin removal effect was obvious, and the chemical composition of several different processes had a relatively large difference. Research results will provide the theoretical reference basis for the regeneration and processing of bamboo and the development and utilization of bamboo base composite.
