热重量法分析石墨成分

研究了用热重分析仪进行石墨成分分析的方法 ,摸索了仪器的适宜分析条件 ,并对试验结果进行了讨论。针对仪器系统误差对挥发分测定的影响 ,采用一元线性回归对测量数据进行了校正。方法的精密度和准确度试验证明 。

阻燃处理木材燃烧残余物的热分解特征

为了弄清楚阻燃处理木材燃烧残余物的热分解特征，将阻燃处理木材在模拟的典型火灾中燃烧后，取距燃烧表面不同位置的试样，采用热失重法研究了阻燃处理木材燃烧残余物的热分解过程，结果表明：①阻燃处理木材及其燃烧残余物的热分解开始温度没有明显的差别，未处理木材燃烧残余物的热分解开始温度比未燃烧木材高；②阻燃处理木材中阻燃剂的热分解峰值温度为200℃，随着燃烧过程的进行，归属于阻燃剂的峰消失；③阻燃处理木材燃烧残余物热分解温度曲线中，在230℃附近归属于半纤维素的峰消失，在210～240℃出现了一个缓慢的肩；④阻燃处理木材及其燃烧残余物的质量损失速度曲线主峰温度比未处理木材及其燃烧残余物降低100℃，质量损失速度大幅度减少；⑤阻燃处理木材在600℃时的热分解残存质量比未处理木材显著增大，随着燃烧时受热温度的增高，燃烧残余物热分解的残余质量显著增大；⑥阻燃处理木材及其燃烧残余物的热分解温度区间，与未处理木材及其燃烧残余物存在显著差异．

30种商品阿胶的质量比较

目的 比较商品阿胶质地的优劣真伪。方法 对阿胶进行商品调查 ,收集正品阿胶及伪品胶样品共 30件 ,分别进行性状鉴别 ,采用《中国药典》方法和热重量法对商品阿胶分别进行水分、灰分及挥发分的测定及定量分析。结果 阿胶水分不得>15 %、灰分不得 >1.5 %、挥发分不得 >2 .0 %、氨基氮不得 <0 .6 %。结论 通过 30件商品阿胶分析结果表明 ,正品阿胶以山东、河南产品质地佳 ,与本草考证相一致。伪品阿胶质地劣等。

Apparent activation energy for spontaneous combustion of sulfide concentrates in storage yard

In order to evaluate the spontaneous combustion hazard of sulfide concentrates in storage, three different kinds of sulfide concentrates （sulfur-rich sulfide concentrate, iron sulfide concentrate and copper sulfide concentrate） were obtained from a storage yard in Dongguashan Copper Mine, China. The reaction processes at different heating rates of 5, 10, 15, 20, and 25 ℃/min in air flow from ambient temperature to 1 000 ℃ were studied by TG-DTG-DSC analysis. By the peak temperatures of DTG curves, the whole reaction process for each sample was divided into different stages, and the corresponding apparent activation energies were calculated by the Ozawa-Flynn-Wall method. It is found that the reaction process of each sample is considerably complex; the apparent activation energy values change from 36 to 160 kJ/mol in different temperature ranges; sulfur-rich sulfide and iron sulfide concentrates have lower apparent activation energy than copper sulfide concentrate below 150 ℃; so they are more inclined to cause spontaneous combustion at ambient temperature.

MoSi_2低温氧化动力学研究

通过热重量分析法测定了MoSi2 在低温下氧化不同时间后的重量变化 ,并根据曲线拟合分析了MoSi2 的低温氧化过程 结果表明 :在 5 0 0℃时MoSi2 材料的氧化过程受扩散和反应双重影响 ,氧化速率呈阶段式变化 :先主要受扩散控制 ,氧化增重与时间呈指数关系 ;随后反应成为主要控制因素 ,氧化增重与时间呈线性关系 ;如此反复 ,表现出比 40 0℃和 6 0 0℃时快得多的氧化速率 在 40 0℃、6 0 0℃时MoSi2 的氧化速率主要取决于氧化反应 ,且与反应进行的时间呈线性关系 ,氧化 14 4h后因钝化质量维持不变 图 3 ,表 1,参

CeO_2-CuO/ZnO/Al_2O_3催化合成二乙基甲苯二胺及性质

采用柠檬酸为络合剂,溶胶-凝胶法制备系列CeO_2-CuO/ZnO/Al_2O_3,在3.0 MPa压力和220~230℃反应条件下,甲苯二胺(TDA)和乙烯催化合成二乙基甲苯二胺(DETDA)为探针反应,考察其催化性能,其中CeO_2掺杂量为3%,催化活性最高。通过X射线衍射(XRD)、傅里叶红外光谱(FT-IR)、差热重量分析法(DTG-DTA)、核磁氢谱1 H NMR对CeO_2-CuO/ZnO/Al_2O_3、DETDA、TDA进行检测和表征,揭示了它们的微观结构和内在规律性。XRD检测发现CeO_2掺杂量增多,CeO_2-CuO/ZnO/Al_2O_3衍射峰强度增强,提高了晶化程度,金属原子存在协同效应,增多了活性中心。FT-IR揭示了DETDA内部化学键键型,拥有甲基、亚甲基的多取代芳胺。DTG-DTA检测出的质量变化与热效应两种信息,DETDA的DTG-DTA曲线在66.0、271.0℃存在二个吸热峰,分别为氨基脱离苯环、DETDA的分解产生。通过1 H NMR对DETDA、TDA检测,得到DETDA、TDA的氢原子的数目分别为18和10,分子中各个氢核对应所归属的吸收峰,分别和它们分子式中的氢原子数目吻合。CeO_2-CuO/ZnO/Al_2O_3催化合成DETDA,反应条件温和,工艺流程简单,容易实现高效率和连续化工业生产,因此具有广阔的发展前景。

Measurement and engineering application of adsorbed water content in fine-grained soils

In this paper,the content and density of adsorbed water in fine-grained soil are determined.According to the test results,the calculation method of compaction degree of the solid-phase and void ration of soil is improved.Four kinds of fine-grained soils from different regions in China were selected,and the adsorbed water content and density of four kinds of fine-grained soils were determined by thermogravimetry and volumetric flask method.Furthermore,SEM and XRD experiments were used to analyze the differences in the ability of each soil sample to absorb water.In order to study the compression characteristics of adsorbed water,four saturated soil samples were tested by consolidation method.The results show that the desorption temperature range of the adsorbed water and its density were equal to 100−115℃and 1.30 g/cm^(3),respectively.Adsorbed water plays a positive role in keeping the compressibility of fine-grained soil at a low rate when it has high water content.Besides,adsorbed water can be a stable parameter and is difficult to discharge during the operation period of subgrade.The settlement of fine-grained soil embankment is predicted by engineering example,and compared with the result of conventional calculation method.The results show that it is more close to the field monitoring results by using the improved void ratio of soil as the parameter.

硝基化合物的测定

本文首次提出以亚硫酸钠为发色剂,用于粉状铵梯炸药中进行硝基化合物的测定。其中论述了具体的操作方法和实验过程,该检测工艺灵敏度,选择性和准确度均高,而且操作简便,是一很有应用前途的测试方法,利用该原理也可以进行其它项目中的硝基化合物的验测。

国内外科技简讯

大豆制油过程中尿素酶活性 与蛋白质变性关系 尿素酶是一种能影响动物生理活性的物质,如牲畜食用过多,则会影响牲畜体内蛋白质的分解以及消化吸收,从而引起腹泻,同时它还会催化分解尿素并放出大量的氨和二氧化碳;如部分氨进入血液将会提高血氨浓度而导致性畜中毒。 为此,在大豆制油过程中必须控制适当的工艺条件,使之既能保持蛋白质不发生过热破坏,又能使抗营养因子纯化并使失去其活性。

优化在金红石TiO_2纳米棒作为水解离的光阳极上表面电荷的传输过程

电化学阻抗谱(EIS)研究了二氧化钛纳米棒在水光电解系统中的光催化性能,提出双通道传输线模型诠释主要电荷转移过程的频率响应,过程在纳米棒/电解质和铂/电解质界面上产生。采用EIS来确定退火处理对光电流密度的有吸引力影响,起因于二氧化钛/电解质界面上只有很少电荷传输。X射线光电子谱和热重量分析法测量证明这与从TiO_2纳米棒合成过程存在氯有关。

Preparation and characterization of Al/B/Fe_2O_3 nanothermites

A sol-gel synthetic approach combined with an ultrasonic method was utilized to prepare Al/B/Fe2O3 nanothermites.The structure and properties of the prepared nanothermites were characterized by thermogravimetric analysis,differential scanning calorimetry,scanning electron microscopy,X-ray diffraction,and an impact sensitivity test.The results verified that the nano-aluminum and the micro-boron were uniformly dispersed in the pores of the iron oxide gel.The heat of the prepared Al/B/Fe2O3 nanothermites was 1.3 times that of the simple physically mixed sample.In addition,the heat of the combustion test showed that these materials were indeed energetic.Small-scale safe experiments also showed that the prepared materials through sol-gel were relatively insensitive to standard impact.