TGA/SDTA 851e热分析仪炉箱部分常见故障的剖析

热分析仪的炉箱部分因受到高温老化和样品腐蚀双重影响,是该仪器多发故障的部位之一。介绍了该区域的常见故障及其排除方法。     

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，采用一无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，用热重量法可有效地应用于日常检验工作。     

"仪器论坛"全面改版

互联网的互动性可以帮助身在不同地方的人就某个问题共同进行讨论交流。“仪器论坛”给分析测试工作者提供了一个网上交流讨论技术问题、结交业界同仁的平台。自开通以来,受到了大家的欢迎,很多人通过论坛,解决了工作中遇到的一些实际问题,并因此与网上的同行成为了好朋友。近期,仪器信息网与本会青年学术委员会、北京大学化学与分子工程学院将“仪器论坛”进行了全面改版,将论坛分为:分析测试、样品处理、数据处理、使用维护、采购交流分论坛,并按仪器的具体种类,分为气相色谱、液相色谱、原子吸收光谱等几十个子论坛。欢迎大家前往讨论交…     

高温比热容测试常见问题及误差分析

介绍了同步热分析仪(STA449F3)测试高温比热容过程中的常见问题及误差分析.采用差示扫描量热三步法测试高温比热容.试验结果表明,提高仪器的稳定性和升温速率可减小比热测试值与理论值之间的误差.此外,将常规一段升温测试分割成若干个窄温区间,提高了高温比热容测试的准确性.     

在线烟气分析仪常见故障处理及防范

简要介绍了烟气分析仪的工作原理,对仪器使用过程中出现的几种常见故障进行分析,对两种重复性的疑难故障进行研究,提出了可行的改造方案及解决方法,同时提出了烟气分析仪故障的防范措施。     

TAG高温氧化腐蚀分析仪原理及应用

介绍了TAG高温氧化腐蚀分析仪的结构特点、工作原理及具体应用. TAG高温氧化腐蚀分析仪能够在可控气氛(干燥、潮湿和腐蚀)和可控温度的条件下实现原位测试. 双炉体设计最大程度上减小了浮力效应的干扰,并且悬挂样品设计全面积接触气氛,精确测量质量微弱变化. TAG高温氧化腐蚀分析仪可用于研究无机和有机材料等的高温分解问题,也可用于研究金属和陶瓷等材料在单一或多种气氛下的氧化腐蚀机理.     

第三届北京分析测试学术报告会及展览会仪器评议报告

为了促进国内分析仪器的研制及技术的提高,了解、跟踪国际分析技术及仪器的发展动态,为进口仪器提供咨询服务,经国家科委倡导,中国分析测试协会咨询委员会在第三届BCEIA’89展览会上举办了分析技术及仪器专题性评议活动。此次评议的主要题目是:1、能量色散X射线光谱仪。2、图象分析仪。3傅     

X射线荧光光谱法石油产品硫含量分析仪校准方法

探讨X 射线荧光光谱法石油产品硫含量分析仪的校准方法,确定了标准曲线相关系数、示值误差、仪器测量重复性、仪器稳定性校准指标.该方法合理、简便易行,各项指标评价结果基本符合仪器的设计性能和实际工作测试要求.     

L-8900氨基酸分析仪分析柱重新填充方法

2008年引进的L-8900高速全自动氨基酸分析仪由于使用过久、维护不当,导致泵1压强过高不能正常运行.通过更换线性过滤器,逆洗分析柱,仍没有解决问题,最后重填分析柱使仪器恢复正常.重填分析柱操作较复杂、容易出错,会造成树脂损失,因此,在重填过程中详细记录拆卸、清洗树脂、安装分析柱的完整过程,为今后工作和同行积累经验.     

智能手机微孔板分析仪的开发与HSA的定量检测

研究开发了基于智能手机的便携式96微孔板检测技术与仪器,并利用所开发仪器实现了人血清白蛋白(HSA)的高通量快速定量检测。该文首次通过设计大孔径聚焦透镜和均匀面光源,利用智能手机实现了对通用96微孔板的全范围准确成像,结合开发的手机应用程序可实现对检测样本的自动分析。所开发分析仪对HSA标准样品的检测结果与酶标仪检测结果具有高度的线性关系,相关系数为0.989 3,证明其具有良好的准确性与可靠性。开发的分析仪的检测范围为21.45～60.06 g/L,对病人血清样品中HSA的检测结果与医院使用的生化分析仪检测结果一致,证明分析仪可用于临床中HSA的检测。该仪器具有成本低和体积小的特点,可推广至经济不发达地区、基层医疗机构和普通用户家中,对疾病的现场快速诊断具有重要意义。     

Tensile behavior of quasi-unidirectional glass fiber/polypropylene composites at room and elevated temperatures

In the present study, the tensile behavior of quasi-unidirectional glass fiber/polypropylene composites at room and elevated temperatures were investigated by both micro- and macromechanical test methods. In the micromechanical studies, a single fiber fragmentation test was employed for measuring the interfacial shear strength at fiber-polypropylene interface in the temperature range from 23 °C to 90 °C. The results show that interfacial shear strength decreases with increasing testing temperature. In the macromechanical studies, experimental results show that the elastic modulus of polypropylene and transverse elastic modulus of composites are sensitive to the testing temperature. The weakened fiber-polypropylene interface due to elevated temperatures led to the vanishing of “knee” in transverse tensile stress-strain curves. A function was proposed to evaluate the dependence of the elastic modulus of quasi-unidirectional glass fiber/polypropylene composites on the testing temperatures and tested against experimental data. Tensile failure mechanisms of composites were demonstrated to evolve with the testing temperature.     

聚丙烯酸酯/环氧树脂互穿网络聚合物的研究Ⅲ.橡胶态弹性模量和互穿缠结

采用一步法（Ｓｉｍｕｌｔａｎｅｏｕｓｌｙ）合成了双组分的聚丙烯酸酯／环氧树脂互穿网络聚合物（ＩＰＮｓ）．选择预溶胀方法制备了聚丙烯酸酯和环氧树脂两种组分网络．测定了各种组分比的ＩＰＮ和不同溶胀度下的组分网络的动态力学性能，从橡胶态弹性理论出发讨论了ＩＰＮ和预溶胀网络之间在橡胶态弹性模量上的关系，并据此指出互穿缠结增加了网络的有效“交联密度”，因此，它对ＩＰＮ的橡胶态弹性模量有较大的贡献．密度测量的结果也提供了另一方面的证据     

咪唑基表面活性离子液体在气/液界面的扩张粘弹性

合成了两种咪唑基表面活性离子液体,通过界面膨胀流变法研究了其在气/液界面的聚集行为,考察了咪唑基表面活性离子液体浓度、无机盐和温度对聚集行为的影响。研究发现,咪唑基表面活性离子液体在吸附过程中吸附控制占主导作用,而弛豫过程不是单一指数函数;加入无机盐或升高温度可以提高咪唑基表面活性离子液体的表面活性、增强其在界面的吸附能力、降低表面张力。扩张流变结果显示扩张模量、弹性模量和粘性模量随震荡频率增加而增加;随表面活性离子液体浓度增大,扩张模量先增大后减小。扩张模量随温度升高或无机盐(NaBr或CaBr₂)的加入而降低。表面活性离子液在气/液界面形成的吸附膜以弹性模量为主,而且C₁₄mimBr的界面膜弹性模量大于C₁₂mimBr的界面膜弹性模量。     

Elastic and viscoelastic properties of sugarcane bagasse-filled poly(vinyl chloride) composites

Elastic and viscoelastic properties of sugarcane bagasse-filled poly(vinyl chloride) were determined by means of three-point bending flexural tests and dynamic mechanical and thermal analysis. The elastic modulus, storage modulus, loss modulus, and damping parameter of the composites at fibre contents of 10, 20, 30, and 40% in mass were determined, as well as those of the unfilled matrix. There was a correlation between the elastic modulus and storage modulus of the composites. Moreover, the elastic and viscoelastic properties of the composites were highly influenced by fibre content.     

Elastic properties of YAG: First-principles calculation and experimental investigation

The hardness and elastic stiffness of Y₃Al₅O₁₂ (YAG) were investigated by first-principles calculations and experiments. The mechanical properties including the second-order elastic coefficients, hardness, bulk modulus, Young's modulus and shear modulus were calculated by density functional theory (DFT). The calculated results were in good agreement with the experimental values. The hardness of YAG is mainly attributed to Al_tet–O bonds. The elastic anisotropy of YAG was discussed. Zener anisotropy parameter of YAG is close to unit and its universal anisotropy index is very close to zero, which indicates the structure of YAG is nearly centrosymmetric. The longitudinal and transverse sound velocities and Debye temperature were also investigated.     

总磷测定仪校准方法

建立总磷测定仪的校准方法。介绍了总磷测定仪的工作原理。总磷测定仪的校准包括温度示值误差和温场均匀性、消解时间示值误差、仪器示值误差、测量重复性、示值稳定性5个项目。利用实验数据确定了总磷测定仪的技术指标:温度示值误差不超过±2℃,温场均匀性不大于3℃,消解时间示值误差为不超过±2%,仪器示值误差为不超过±10%,仪器重复性为不大于5%,示值稳定性为不超过±8%FS。该方法可用于总磷测定仪的校准,保证测量数据的准确可靠。     

Dynamic mechanical analysis of ethylene tetrafluoroethylene (ETFE) foils in use for transparent membrane buildings

Glass transition temperature and tan delta (the ratio of loss modulus to storage modulus) are indispensable parameters for determining appropriate application range of ETFE foils. In this study, ETFE foils in terms of specimen number, material direction and thickness were investigated with dynamic mechanical analysis (DMA) over a temperature range of -70-100 °C at frequencies of 0.1, 1, and 10 Hz. Glass transition temperatures were obtained with storage modulus, loss modulus and tan delta curves. It is found that frequency effect on glass transition temperature was proportional and that frequency effect was more significant than material direction effect. Moreover, a comparison study showed that elastic modulus determined with quasi-static experiments was greater than storage modulus calculated with dynamic mechanical experiments. To propose suitable glass transition temperature ranges for engineering application, an approach to determine confidence interval based on statistical analysis was employed. The resulting intervals with confidence coefficient of 95% were 31.2–32.7 °C, 60.5–66.4 °C and 79.6–83.3 °C for storage modulus, loss modulus and tan delta, respectively. In general, this study could provide useful observations and values for evaluating dynamic mechanical properties of ETFE foils.     

炭黑填充聚苯乙烯熔体流变行为

研究了炭黑(CB)填充聚苯乙烯(PS)熔体的稳态和动态流变行为. CB/PS复合体系在CB体积分数φ=0.06时发生逾渗转变. 结果表明, 低应变区熔体模量降低主要归因于粒子-粒子及粒子-高分子间作用力的破坏, 高应变下模量的急剧下降则主要与高分子链间解缠结有关. 采用“两相”模型拟合线性动态流变行为, 发现应变放大因子A_f(φ)、填充相模量及松弛指数与温度有关. A_f(φ)~φ关系符合Guth方程和扩散控制的粒子簇聚集模型. “粒子相”形状参数与聚集体分维度均随温度升高而有所降低, 说明CB粒子聚集体因团聚而趋于各向同性, 应变放大效应减弱. “粒子相”特征模量G'_f1(φ)和G"_f0(φ)与φ关系满足标度律. 当φ > 0.06时, G'_f1(φ)和G"_f0(φ)及其标度指数均随温度升高而明显降低, 其G'_f1(φ)变化幅度略大于G"_f0(φ), 说明“粒子相”弹性与黏性组分具有不同的温度依赖性. 随着温度升高, 扩散控制的CB粒子团聚过程加快, 应变放大效应减弱.     

理化分析测试实验室仪器设备的管理

仪器设备是实验室的重要资产,仪器设备管理是实验室正常运行的重要组成部分。从仪器设备的管理架构以及仪器设备的采购、验收、量值溯源、维护维修、报废等方面讨论了理化分析测试实验室仪器设备管理工作的重点和注意事项。     

Drawing and dynamic-mechanical behavior of syndiotactic polystyrene an introduction

The drawing behavior of syndiotactic polystyrene was analyzed at different temperatures. Amorphous films were used and, depending on drawing temperature, strain-induced or thermal-induced cold crystallization was observed. This phenomenon, when present, greatly affects the drawing behavior. The dynamic-mechanical behavior of drawn samples was analyzed, and the obtained results indicate that the glass transition is affected by drawing, and that the effect depends drastically on the drawing temperature. Particularly interesting is the dynamic behavior at high temperature where the elastic modulus is weakly affected by temperature also near the melting point.