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Yi Min Wei Bunichiro Tomita Yasushi Hiramatsu Atsushi Miyatake Tsuyoshi Fujii 《Journal of Wood Science》2002,48(5):365-373
To provide information on the feasibility of using exploded wood fiber strand (WFS) obtained by the water-vapor explosion process in wood-cement mixtures, the compatibility between cement and exploded WFS and its improvement with various additive chemicals were investigated by observation and analysis on hydration behaviors in terms of hydration characteristics: maximum hydration temperature (T
max) and required time (t
max). The three types of cement, six additive chemicals, and exploded WFS (sugi, air-dried and water-soaked) were employed as raw materials in this study. The hydration behaviors of mixtures demonstrated that exploded WFS had strong retarding effects on cement hydration and completely prevented mixtures from setting. The analysis of sugar revealed that the sugar contents of exploded WFS were much higher than those in unexploded wood and increased to about 20-fold (air-dried) and 10-fold (water-soaked), respectively. The degraded polysaccharides became a major factor and played an important role in inhibiting the setting of cement. Moreover, high-performance liquid chromatography analysis proved that the main peaks representing the molecular weight of polysaccharides in extractives of exploded WFS shifted markedly to a lower range of polymerization. MgCl2 was determined to be an effective additive chemical for restraining the inhibitory influences. Addition contents of 2%–3% and 4%–5% were available and acceptable for quick-curing cement and ordinary Portland cement, respectively. As for the furnace-slag cement, the composite additive chemicals of MgCl2 (4%) and CaO (2%) were found to have an obvious accelerating effect.Part of this report was presented at the 51th Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001 相似文献
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Anatta Patcharawijit Ram Yamsaengsung Nuttaporn Choodum 《Wood material science & engineering》2020,15(5):261-268
ABSTRACT This research was aimed to investigate mechanical properties, color and cell-wall components changes, and durability of pre-dried rubberwood (Hevea brasiliensis) after superheated steam (SS) treatment. Wood samples were treated at different SS temperatures (140–180°C) for 1–3?h. The highest compression strength parallel-to-grain, hardness and impact strength were found for samples treated at 160°C for 3?h (30.7% higher than untreated), at 150°C for 1?h (26.6% higher than untreated) and at 150°C for 2?h (52.6% higher than untreated), respectively. The surface color became darker after each treatment in comparison with the untreated wood. The number of accessible hydroxyl groups decreased and the relative cellulose crystallinity increased with SS temperature, indicating decreased hygroscopicity of the treated wood. Also, SEM micrographs of wood surface showed consistent decrease in starch particles with treatment temperature. Both decay and termite resistances of treated rubberwood improved with treatment temperature. All the analyzes showed that dried rubberwood treated with SS had some improvements in the mechanical properties, decreased hygroscopicity, and increase resistance to decay. 相似文献
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对水蒸气剥离法去除污染土壤中多环芳烃(PAHs)进行了研究,研制了实验室规模的污染土壤中PAHs水蒸气剥离法试验装置,获得了多环芳烃脱附的基本试验数据,考察了泥浆质量流量、泥浆浓度和反应温度对脱附效率的影响,对上述影响因素进行了分析,确定了分离工艺的最佳参数范围,为大规模治理污染土壤提供了可靠依据。试验结果表明,泥浆流速增加会显著降低脱附效率,一般应取G≤2 kg/s为好。另外,提高反应温度则会使脱附效率有所增加,故反应器内温度保持在150~200℃范围内较好。 相似文献
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对于地方热电企业及各中小型热电厂、各大企业中的自备电站,提高发电设备的检修质量,降低发电设备的检修费用消耗,大力开展技术革新,利用自己企业的技能,解决汽轮发电机叶轮更换叶片后的围带切削加工,不仅能够缩短了去外地加工的时间,同时也为发电设备的抢修降低了费用消耗。 相似文献
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蒸汽喷射处理植物纤维成形体的降解液物理化学特性研究 总被引:1,自引:0,他引:1
通过自行研制的蒸汽喷射成形技术理论与装备,以蒸汽喷射处理后的松木纤维/MPU-20树脂(一种聚氨酯类化合物)成形体的降解液为研究对象,采用试验观察和pH值测定、傅立叶红外光谱(FT-IR)及紫外可见光谱(UV-Vis)的分析方法,研究了其物理化学结构的特征与变化,并对纤维表面进行了扫描电镜(SEM)分析.试验结果表明:降解液具有酸性的特征,其pH值随蒸汽喷射压力和保存时间的增加而降低,随喷射时间的增加而增加的趋势;FT-IR分析表明,降解液主要是以降解的可溶性混合多糖为主的混合物,而沉淀物质是以树脂类为主的混合物,其结构特征类似于石炭酸松香树脂;SEM分析表明,喷射蒸汽处理纤维表面出现明显的"沟痕"或"凹槽"的现象;UV-Vis分析表明,蒸汽喷射处理过程中会产生酸性降解的含不饱和单位共轭体系的中间分子色素,且木质素也发生了降解或溶出,而木质素吸收峰的偏移表明,纤维内添加的树脂在蒸汽喷射过程与木质素之间发生了化学反应或与木质素大分子链进行了化学结构连接. 相似文献
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锅炉设备在食品工业中的应用范围很广,很多的食品企业都应用锅炉的蒸汽进行加热操作。介绍了中小型食品生产线对锅炉设备的选型标准及安装形式,以及锅炉蒸汽管路与食品生产线成套设备安装的工程监理,以期为在实际生产操作中选择合适的锅炉设备和降低安装成本提供参考。 相似文献