溶剂在交联硅橡胶中无限稀释扩散系数测定

气相色谱法测定溶剂与聚合物材料之间的相互关系是一个快速、准确、方便的方法，为此利用气相色谱法测定了小分子溶剂在不同交联剂含量的交联硅橡胶中的无限稀释扩散系数，并研究了交联剂用量对无限稀释扩散系数的影响，这为研究交联硅橡胶特性提供了新方法。     

3种芳香烃在聚乙烯膜中的无限稀释扩散系数

基于Hadj-Romdhane和Danner色谱过程的数学模型 ,采用反相气相色谱法在 348.2～ 36 3.2K温度范围内测定了苯、甲苯和乙苯 3种芳香烃溶剂在聚乙烯膜中的无限稀释扩散系数 .实测数据的关联结果表明 ,采用空穴自由体积替代Vrentas-Duda自由体积理论方程中自由体积项的修正方程 ,能很好地描述溶剂分子的无限稀释扩散系数随温度的变化关系 .同时在修正方程的基础上建立了一般化自由体积方程 ,并对该方程的预测能力进行了探讨     

反相气相色谱法测定溶液在高分子中的无限稀释活度系数

1 INTRODUCTI0NDue to its short experimental time,little sampleneeded,suitable for broad temperature range,inversegas chromatography(IGC)has been widely used tomeasure variety of properties of polymer systems,suchas the infinite diluted activity coefficients of solvent inpolymer,the glass transition temperature of polymerand the surface properties of polymer,etc.Those     

用改进的Eyring方程推算无限稀释扩散系数

在Ｅｙｒｉｎｇ绝对速率理论的基础上，提出一个关联扩散自由体积的关系式，从而得到改进的扩散系数计算方程，可从纯物质粘度推算无限稀释扩散系数，方程不含任何待定参数．对８２个各类体系共３３２点扩散系数数据，计算平均相对偏差为１２．１％，而Ｗｉｌｋｅ－Ｃｈａｎｇ方程对同样体系的计算偏差为１４．８％，Ｓｉｄｄｉｑｉ－Ｌｕｃａｓ方程的偏差为１２．３％．     

气相色谱法测定沙格列汀中残留溶剂

目的:建立气相色谱法测定沙格列汀中5种残留溶剂的方法.方法:采用Agilent DB-624毛细管柱,检测器为氢火焰离子化检测器,检测器温度250℃,采用程序升温,测定沙格列汀中残留的甲醇、乙腈、异丙醇、二氯甲烷和乙酸乙酯.结果:5种残留溶剂均完全分离,在所考察的浓度范围内线性关系良好,平均回收率在99.87 ％～10...     

有机物在超临界CO2中无限稀释扩散系数的分子动力学模拟

根据物质的实验临界常数或与物质最基本分子结构相关的Joback或Lydersen临界常数估算法得到物质的临界常数,结合Lennard-Jones流体的对比状态方程,按照对应态原理得到了38种有机物分子的新的Lennard-Jones位能参数。由这些位能参数结合简单的组合规则,首次对一些高附加值的复杂实用有机物在313.15　K、16MPa的超临界CO     

气相色谱法测定塑料复合食品包装袋中的溶剂残留

采用气相色谱法对10种不同的塑料复合食品包装袋中可能残留的溶剂如甲苯、二甲苯(邻、间、对)、丙酮、乙醇、乙酸乙酯、丁酮、正丁醇、乙酸丁酯进行分析。方法采用HP-5色谱柱分离,氢火焰离子检测器FID检测,结果显示10种溶剂分离效果好,线性相关性高,样品加标回收率中苯系物介于78%~80%,其他溶剂介于86%~94%,最低检出限可达0.003 mg/m2。     

气相色谱法测定分子筛扩散系数

气相色谱法测定分子筛扩散系数是根据色谱VanDeemeter过程，将被测分子筛装人色谱柱中，以测得的色谱往理论板高度（H）和相应的线速度（u）作图，求得在高线速度部分的斜率（C），计算分子筛的扩散系数（Dp）。本文测定了8种5A型和4种13X型分子筛对氧和氛的扩散系数，证明用不同制各方法得到的产品其扩散系数有很大的差异，故其应用的工艺条件亦不应雷同。     

有机物在超临界CO_2中无限稀释扩散系数的分子动力学模拟

根据物质的实验临界常数或与物质最基本分子结构相关的Joback或Lydersen临界常数估算法得到物质的临界常数,结合Lennard-Joned流体的对比状态方程,按照对应态原理得到了38种有机物分子的新的Lennard-Jones位能参数.由这些位能参数结合简单的组合规则,首次对一些高附加值的复杂实用有机物在313.15 K、16 MPa的超临界CO_2中的无限稀释扩散系数采用分子动力学模拟的方法进行了研究.模拟结果表明,采用这种新思路可以有效地预测超临界体系的扩散性质,满足超临界萃取工艺开发和设计的需要.     

气相色谱法测定分子筛扩散系数

气相色谱法测定分子筛扩散系数是根据色谱VanDeemeter过程，将被测分子筛装人色谱柱中，以测得的色谱柱理论板高度（H）和相应的线速度（μ）作图，求得在高线速度部分的斜率（c），计算分子筛的扩散系数（D_p）。本文测定了8种5A型和4种13X型分子筛对氧和氛的扩散系数，证明用不同制各方法得到的产品其扩散系数有很大的差异，故其应用的工艺条件亦不应雷同。     

Determination of the infinite dilution diffusion and activity coefficients of alkanes in polypropylene by inverse gas chromatography

Infinite dilution diffusion and activity coefficients of n‐hexane, n‐heptane, and n‐decane in polypropylene were measured from 373.15 to 393.15 K by inverse gas chromatography. The influences of small molecule solvent and temperature on the infinite dilution diffusion and activity coefficients were investigated. The results showed that the infinite dilution diffusion coefficient decreased but the infinite dilution activity coefficient increased with an increasing number of CH₂ group in the aliphatic solvents. The temperature increase resulted in the increase in the infinite dilution diffusion coefficient and the decrease in the infinite dilution activity coefficient. The graphs plotted according to the results of the infinite dilution diffusion coefficient versus temperature were in agreement with the Arrhenius equation. Diffusion constant and activation energy were obtained from the Arrhenius equation. Also, the interdependence on the infinite dilute activity coefficient and temperature accorded with Gibbs‐Helmholtz equation. From the temperature dependence of the limiting activity coefficients partial molar excess enthalpy at infinite dilution H^E,∞ was obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1925–1930, 2006     

Study on the surface properties of grafted polyethylene particles by inverse gas chromatography

Inverse gas chromatography (IGC) studies on the surface of polyethylene (PE) particles grafted with acrylic acid and acryl amide have been reported. Surface properties of the virgin and grafting‐modified PE were compared by IGC. The dispersive contributions of the surface free energy γ and the K_A and K_B parameters expressing the ability of the stationary phase to act as Lewis acid or Lewis base were calculated. The results showed that the γ value increased significantly after grafting. The PE samples grafted with acrylic acid and acrylamide showed a predominantly basic character while the virgin PE was acidic. All of these suggested that the surface of PE has been modified through the grafting reaction, and thus is expected to improve its adhesions with other polymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Single and multi-component diffusion at infinite dilution in polyisobutylene

An Erratum has been published for this article in Polymer International 49(4) 2000, 419. In this study, diffusion coefficients of acetone, benzene, chloroform, cyclohexane and methyl ethyl ketone (MEK) in polyisobutylene (PIB) have been measured at temperatures in the range 40–70 °C using capillary column inverse gas chromatography (CCIGC). The measured diffusion coefficients for the PIB/MEK system, considered to be at infinite dilution of the solvent, agree very well with those determined previously from gravimetric and spectroscopic techniques when extrapolated to the limit of zero MEK concentration. The Vrentas–Duda free-volume theory for diffusion is used to correlate the diffusivity data at infinite dilution as a function of temperature, and the effect of solvent size on the diffusion process in PIB is studied. In addition, diffusion coefficients of MEK/toluene and MEK/ethanol mixtures in PIB have been measured at 50 °C. The CCIGC model for binary systems is used to determine diffusion coefficients for each solvent individually over a wide range of mixture compositions. The resulting values are identical to those determined from pure component data, confirming the hypothesis that the diffusion coefficient at infinite dilution is independent of a second infinitely-dilute component, with or without solvation between mixture components. © 1999 Society of Chemical Industry     

反相气相色谱法表征HDPE的表面性质

采用反相气相色谱技术,分别测定不同分子探针在不同温度下通过高密度聚乙烯(H DPE)的保留时间,计算HDPE表面色散自由能与表面Lewis酸碱常数.HDPE表面色散自由能随温度的升高呈线性降低,且为弱碱性的Lewis两性聚合物材料.     

Measurement of activity coefficients at infinite dilution for hydrocarbons in imidazolium-based ionic liquids and QSPR model

The separations of olefin/paraffin, aromatic/aliphatic hydrocarbons or olefin isomers using ionic liquids instead of volatile solvents have interested many researchers. Activity coefficients γ ^∞ at infinite dilution of a solute in ionic liquid are generally used in the selection of solvents for extraction or extractive distillation. In fact, the measurement of γ ⁻⁸ by gas-liquid chromatography is a speedy and cost-saving method. Activity coefficients at infinite dilution of hydrocarbon solutes, such as alkanes, hexenes, alkylbenzenes, styrene, in 1-allyl-3-methylimidazolium tetrafluoroborate ([AMIM][BF₄]) and 1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM][PF₆]), 1-isobutenyl-3-methylimidazolium tetrafluoroborate ([MPMIM][BF₄]) and [MPMIM][BF₄]-AgBF₄ have been determined by gas-liquid chromatography using ionic liquids as stationary phase. The measurements were carried out at different temperatures from 298 to 318 K. The separating effects of these ionic liquids for alkanes/hexane, aliphatic hydrocarbons/benzene and hexene isomers have been discussed. The hydrophobic parameter, dipole element, frontier molecular orbital energy gap and hydration energy of these hydrocarbons were calculated with the PM3 semi-empirical quantum chemistry method. The quantitative relations among the computed structure parameters and activity coefficients at infinite dilution were also developed. The experimental activity coefficient data are consistent with the correlated and predicted results using QSPR models.     

Determination of the diffusion coefficients of organic solvents in polyepichlorohydrin: A comparative study of inverse gas chromatography and sorption methods

The diffusivity of organic solvents in polyepichlorohydrin was studied with two different experimental setups: inverse gas chromatography (IGC) with packed columns and sorption measurements in gravimetric experiments monitored in a Cahn electrobalance. The aim of this work was to test the possibility of solving an inherent problem in the data reduction of IGC measurements, that is, the necessity of characterizing the morphology of the polymer coated on the support (usually given in the so‐called geometric factor of the column). Temperatures between 35 and 65°C were used in the IGC experiments, whereas the sorption measurements were performed between 30 and 40°C. Glass beads were used as supports in IGC for obtaining data concerning the variation of the plate height with the average gas velocity, with which the use of the Van Deemter equation allowed the determination of the diffusion coefficient if the geometric factor was known. In the sorption experiments, the diffusion coefficients at different penetrant activities were directly measured. For their extrapolation within the same concentration range used for IGC (infinite dilution of the penetrant), the theoretical model of Vrentas and Duda was used. By a combination of sorption and IGC experiments, the geometric factor of an IGC column could be adjusted, and this allowed the determination of the diffusion parameters of any other solvent in the same column. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2216–2223, 2003     

Determination of infinite dilution diffusion and activity coefficients of solvents in polystyrene by inverse gas chromatography on a capillary column

Infinite dilution activity and diffusion coefficients of several solvents in polystyrene have been measured by inverse gas chromatographic on a capillary column for temperatures between 110 and 170°C. Chromatographic data have been treated according to Khan's model, evaluating the contribution to the peak broadening due to radial and axial molecular diffusion in the mobile phase, radial diffusion in the stationary phase, and interfacial mass transfer resistance. Four capillary columns have been prepared with coating thickness ranging from 0.5 to 3.3 microns in order to determine the minimum thickness necessary to obtain reliable measurements of the diffusion coefficient of the solvent in the polymer in every possible experimental condition. Our experimental data are in considerable agreement with the data already available in the literature, obtained by static and chromatographic methods. © 1994 John Wiley & Sons, Inc.     

四氢呋喃等物质在1，4－丁二醇中γ~∞的测定

用色谱法对四氢呋喃等物质在溶剂１，４－丁二醇（ＢＤ）中的无限稀释活度系数进行了测定，采用同一柱温下固定液的流失量与实验测定的时间成正比的方法来推算固定液的流失，经过验证，此校正方法对本文测定是适用的