Fast determination of critical eluent composition for polymers by gradient chromatography

Gradient chromatography was applied in order to calculate the composition at elution for different methacrylates on normal phase columns. In addition the composition at elution was determined for polyethyleneoxide on a reverse phase column. It is shown that high molar mass polymers elute for a given homopolymer irrespective of their molar mass at the same eluent composition, which varies only slightly with gradient slope. In general the composition at elution in gradient chromatography is expected to be slightly lower than the true critical composition. For high molar mass polymers we found this composition to be close to the critical composition determined by isocratic experiments. The difference between the composition at elution and the true critical composition for a variety of polymethacrylates and for polyethyleneglycol was found to be only between 0.2 and 5%. Thus, after estimating the composition at elution, only a small number of additional isocratic experiments is needed to find the exact critical composition.     

Special cases of determination of the minimum reflux ratio for distillation of binary mixtures

Specific features of the representation of liquid-vapor equilibrium data for binary mixtures and the realization of a pinch regime in minimum reflux calculations are considered. The pinch regime at minimum reflux is possible provided that the second derivative of the vapor composition with respect to the liquid composition is positive between the composition of the final product and the feed composition.     

光谱图像分析法在镀层成分识别中的应用

镀层成分识别可以为镀液配方改进和电镀工艺优化提供参考依据。提出了一种基于光谱图像分析的镀层成分识别方法。通过获取镀层光谱图像信息,应用小波分解实现特征提取,采用光谱图像分析方法并结合图像处理算法,对镀层成分进行识别。设计了镀层成分识别系统,介绍了该识别系统的硬件结构,阐述了镀层的光谱图像特征提取与成分识别过程,并进行了实验与分析。     

辉石矽嘎岩于陶瓷生产中的应用

介绍了辉石矽嘎岩处理废渣的矿物组成、化学组成和粒度组成,叙述了这种废渣于陶瓷砖、颜料和釉及过滤材料生产中的试验应用情况。     

玻璃组成的设计与控制技术探讨

玻璃组成决定玻璃特性,根据玻璃性能要求进行科学快速的成分设计,当玻璃组成确定后,商业化生产时如何确保玻璃组成稳定以保证玻璃特性稳定,进而确保玻璃质量稳定十分重要。通过对玻璃用途以及性能要求,探讨组成的设计与控制技术,并利用科学手段实现组成的优化设计和快速控制,达到节省时间和成本、提高效益的目的。     

pH-response of chitosan, κ-carrageenan, carboxymethyl cellulose sodium salt complex hydrogels

We synthesized the polyelectrolyte complex hydrogel consisting of chitosan, κ-carrageenan, and carboxymethyl cellulose sodium salt (NaCMC) and investigated the swelling properties of the gel varying with carrageenan/NaCMC compositions. In a lower composition of carrageenan, heterogeneous gels were obtained indicating strong electrostatic interactions among these polyelectrolytes. Oppositely, in a higher composition of carrageenan, a gelation did not occur. It was cleared that a homogeneity of the gel strongly depended on the carrageenan/NaCMC composition. The degree of swelling at the equilibrium decreased proportional to the carrageenan composition. The gels showed a maximum degree of swelling in the range of pH 11-12. The maximum degree of swelling discontinuously decreased with increasing the NaCMC composition and was independent of the composition at a higher composition of NaCMC. Swelling properties in pure water and in alkaline solutions were also affected by salt concentrations of each polyelectrolyte aqueous solutions.     

Accelerated ageing of SR‐562 pyrotechnic composition and investigation of its thermo kinetic parameters

Pyrotechnics are used to produce some special effects in various military and civilian applications. High temperatures and elevated humidity levels influence the thermal decomposition and kinetic behaviour of pyrotechnics. The present work describes the effect of ageing on SR‐562 military pyrotechnic composition. The composition contains magnesium, sodium nitrate and calcium oxalate and it is used as a flare. The composition was aged for 30 days at a temperature of 70 °C and relative humidity (RH) of 70%. The experimental results show noteworthy variations in the thermal cum kinetic behaviour as well as in the morphology of the aged composition. Activation energy of the aged composition decreased to 189 kJ mol^?1 from 239 kJ mol^?1 for the fresh composition. Thermal decomposition temperature was found to increase by 51 °C after the ageing. X‐ray diffraction results confirm the presence of magnesium hydroxide in the aged composition showing that some of the magnesium reacted with water vapours at high temperatures. Some micro sized cracks have been seen in the scanning electron microscopy micrographs of the aged composition. Copyright © 2016 John Wiley & Sons, Ltd.     

The effect of hydrothermal pretreatment on the structure and fast pyrolysis behaviors of ShengLi lignite

The structure and composition of coal determine its fast pyrolysis characteristics,and the study of the relationship between them can play an important role in the efficient and clean utilization of coal.So,in this work,hydrothermal pretreatment was used to artificially change the structure and composition of ShengLi (SL) lignite,which was used to investigate the influence of structural changes on pyrolysis.The physicochemical structure and composition of samples were characterized by X-ray diffraction,specific surface area and porosity analyzer,solid-state 13C nuclear magnetic resonance,Fourier transform infrared spectroscopy,and elemental analyzer.Pyrolysis experiments were carried out in a powder-particle fluidized bed reactor,and the distribution and composition of the pyrolysis products were ana-lyzed.The gasification activity of char was investigated by thermogravimetric analysis with a CO2 atmo-sphere.The results show that hydrothermal pretreatment (HTP) can destroy the cross-linking structure of SL lignite,and affect its aromaticity,pore structure,functional group,and carbon structure to change the distribution and composition of pyrolysis products of SL lignite,especially the composition of tar.Finally,the structure-activity relationship between the structure,composition,and pyrolysis characteristics of coal was comprehensively studied.     

苯酐催化剂载体的研究

通过对两种进口催化剂所用载体样品的化学组成、相组成和显微结构系统的分析研究，探明了优质载体的组成和结构特点，并在此基础上对实验载体材料进行了组成和结构设计，试制成功了化学组成、相组成和显微结构与进口催化剂载体相似的镁质陶瓷载体。经实际应用证明，其理化指标和实用性能都已达到国外优质载体的水平。     

无皂乳液聚合的技术进展

综述了无皂乳液聚合的技术进展及发展趋势，对无皂乳液聚合的制备方法以及无皂聚合乳液的性能、特点和影响其稳定性的因素等均作了详细介绍。     

浅谈结构分析的几点技巧

通过对几何组成分析基本组成规则的学习归纳,总结出几何组成分析中存在的几个误区和几种分析技巧,以提高几何组成分析的速度和效率。     

The triglyceride composition of linseed oil

The triglyceride composition of linseed oils obtained under different ecological conditions and having different fatty acid compositions was determined by a combination of several chromatographic techniques. The triglyceride mixture was first separated in 8 fractions of different polarity by reversed-phase paper chromatography. Each glyceride fraction was then separated in a partition chromatographic system as the triglyceride coordination complexes with silver ions into individual compounds. The fatty acid compositions of the original oil, single glyceride fractions, and individual triglycerides were determined by gas-liquid chromatography. The molar ratio between the two neighboring glyceride fractions was determined by relating the fatty acid composition of each fraction to the fatty acid composition of their sum. The triglyceride composition of the total oil was then calculated from these results. The presence of 18–19 triglycerides was ascertained in the samples studied, and the molar concentration of each glyceride was estimated. Linseed oil contains only triunsaturated and monosaturated-diunsaturated triglycerides. Within each of these types the fatty acid distribution is close to random. At the same time, the content of some triglycerides departed regularly from a random pattern. A method for calculation of linseed oil triglyceride composition from the fatty acid composition is given. The same general pattern of glyceride formation in linseed is followed regardless of ecological conditions; therefore, the qualitative and quantitative triglyceride composition reflects the differences in fatty acid composition of linseed oil.     

焦炭显微结构及矿物质存在下反应性变化规律探讨

分析了焦炭显微结构及其对焦炭反应性的基本影响,探讨了矿物质的存在对焦炭显微结构的影响机理及催化作胛特征。焦炭光学显微结构对焦炭反应性影响顺序为各向同性、类丝炭和破片〉细粒镶嵌〉粗粒镶嵌〉流动型片状结构。当有矿物质存在时,其顺序恰好相反。     

点火药的老化性能

通过测试点火药金属粉的含量、发火性、导热系数及静电火花感度,研究了某电爆管用点火药在老化过程中性能的变化.结果表明,在温度60℃、相对湿度95%条件下,点火药的发火性能及铝粉含量均随老化时间增加而降低;热扩散率随老化时间增加而增大,但在低湿环境条件下,静电火花感度随老化时间增加而升高.     

非共沸混合工质在制冷循环中浓度偏移分析

非共沸混合工质在制冷循环中应用越来越广泛,其工质的浓度偏移对制冷机的性能影响显著。为此建立了非共沸混合工质两相区流动换热工质浓度偏移数学模型,推导出两相流动中气液相流速不同是发生浓度偏移的必要条件,得到了混合工质两相区当地浓度偏移规律并根据流动工质浓度计算出两相区的当地浓度,通过J-T制冷机蒸发器的工质浓度偏移实验进行了验证,计算与实验结果吻合较好。数学推导和实验结果均表明,当j组分工质在当地气液相中浓度相等时,两相流动中j组分工质浓度不存在浓度偏移,而当j组分工质在当地气相中的浓度大于当地液相中的浓度时,j组分工质当地总浓度小于其循环流动浓度,反之亦相反。J-T制冷循环中低沸点工质当地浓度低于循环流动浓度,而高沸点工质当地浓度将高于循环流动浓度。进一步分析表明混合工质J-T制冷循环中低沸点工质循环浓度高于其充注浓度,而高沸点工质循环浓度低于其充注浓度。因此,为了获得既定运行浓度的循环系统,需要充注相比此浓度更多的高沸点组分。     

竖直管内重力对非共沸工质组分迁移的影响

为探究重力对非共沸混合工质组分迁移的影响,在竖直管式色谱分析实验台上,以R290/R600(Z1、Z2、Z3,质量比分别为25%/75%、50%/50%、75%/25%)为工质,通过改变配比、温度和静置时间等变量进行了不同工况下的实验研究,对组分变化的规律做出了理论分析并提出了进一步的研究建议。实验发现:对于工质Z1、Z2、Z3,组分迁移度受混合物配比的影响很小;温度28.0℃的条件下,将静置的时间由3 h延长至24 h后,液相中丙烷递减率由"大-小-大"的趋势向"逐渐减小"变化,同时丙烷组分迁移度增大了70.13%;静置3 h的条件下,将温度由28.0℃升高至40.0℃后,丙烷的组分迁移度减小了61.25%。     

Pervaporation of acetone‐chlorinated hydrocarbon mixtures through polymer blend membranes of natural rubber and epoxidized natural rubber

Transparent nonporous membranes were prepared by blending natural rubber (NR) with epoxidized NR (ENR). These blend membranes were evaluated for the selective separation of chlorinated hydrocarbons from acetone. The flux and selectivity of the membranes were determined both as a function of the blend composition and feed mixture composition. Results showed that polymer blending method could be very useful to develop new membranes with improved permselectivity. Pervaporation properties could be optimized by adjusting the blend composition. NR/ENR 70/30 and NR/ENR 30/70 composition showed a decrease in flux and selectivity, whereas the 50/50 composition showed increased flux and increased selectivity. Chlorinated hydrocarbons permeated preferentially through all the tested membranes. The feed mixture composition also strongly influenced the pervaporation characteristics of the blend membranes. Permselectivity was found to depend on the molecular size of the penetrants. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2365–2379, 1999     

Determination of the reactive component of fly ashes for geopolymer production using XRF and XRD

Geopolymers are a class of versatile materials that have the potential for utilisation as a cement replacement, fireproof barriers, materials for high temperatures, and biological implant applications. This study investigated methods for determining the formulation for manufacturing geopolymers made with fly ash from coal-fired power stations. The accepted method of determining the formulation of geopolymers to get the desired matrix chemistry uses the bulk composition of the feedstock materials. This formulation method is widely used in investigations using feedstock materials that almost completely react during processing. It is widely considered that amorphous components of fly ash are the reactive components in the geopolymerisation reaction. However, quantification of the amorphous components is challenging and generally avoided with the concomitant problem that the formulation is far from optimum. For the work presented here, the composition of the amorphous part is determined accurately and this information utilised to synthesise geopolymers. The bulk composition is first determined using X-ray fluorescence spectroscopy (XRF) and then the amorphous composition determined using XRF and quantitative X-ray diffraction (QXRD). Formulating the mixture based on amorphous composition produced samples with a significantly higher compressive strength than those formulated using the bulk composition. Using the amorphous composition of fly ash produced geopolymers with similar physical properties to that of metakaolin geopolymers with the same targeted composition. We demonstrated a new quantitative formulation method that is superior to the accepted method.     

熔铸锆刚玉制品的特征及质量判定

熔铸锆刚玉制品中各部位化学成分、矿相组成及体积密度不均匀性是它区别于烧成和不烧成致密定型耐火制品的主要特征;在玻璃熔窑上使用后的原砖残存部分的矿相组成和化学成分已有变化,因此每一批熔铸锆刚玉制品在使用前必须严格按照出厂检验、判定检验及落地检验的检验程序,完成产品是否合格及能否使用的判定工作。     

Implementation of an Indirect Control Structure for Composition in a Hybrid Distillation Column

In this paper a PID controller is proposed to ensure the fuel ethanol composition at desired value, above 92.5°INPM, at the same time as saving energy through the minimal use of reboiler power. Due to the fact that composition analyzers are expensive and have a high response time, an inference model was developed in which the product composition is inferred from the product temperature and thermodynamics equations, enabling the monitoring and the indirect control a posteriori of this variable. In addition, the inference of composition allows defining the reference value of the product temperature, which ensures the fuel ethanol production at the desired composition.