计算液体及其混合物的C_p-C_v的方法

建立了一个能够计算各种温度下液体恒压热容与恒容热容之差的关系式C_p-C_v=RTV~2a/(V~2-AV+B)A和B是两个相关的特性常数,它们的值可由基团贡献法和分子的拓外指数确定.计算结果与实验值相一致.倘若应用A和B的简单混合规则,上述关系式亦适用于液体混合物.     

分子的拓扑与饱和烷烃的溶解度参数

本文提出了一个能从分子的拓扑指数确定饱和烷烃特性常数的方法,据此能够预测饱和烷烃从三相点到临界点广阔温度范围内的溶解度参数.预测的结果表明,计算值与实验值吻合很好.     

基于K-K方程的CO2-离子液体吸收制冷工质对相平衡特性预测

基于Krichevsky–Kasarnovsky(K-K)方程,首先通过将实验测得的溶解度数据与K-K方程相关联,得到不同温度下CO_2的亨利常数和无限稀释偏摩尔体积,然后运用改进的K-K(MKK)方程计算了温度为293.15～333.15 K及压力为0～5.0 MPa内CO_2在离子液体[emim][FAP]、[bmim][FAP]和[hmim][FAP]中的溶解度。结果表明:降低温度和升高压力都有助于提高CO_2的溶解度;同族离子液体阳离子的烷基链长度越长,CO_2的溶解度越大;当压力为5 MPa及温度为293.15 K时,CO_2在离子液体[hmim][FAP]中的溶解度值达到最大值为0.764 1;在相同条件下,CO_2在以上3种离子液体中的亨利常数与CO_2的溶解度大小次序相反,表明亨利常数越小,溶解度越大。由MKK方程计算得到的CO_2在3种离子液体中的溶解度值与实验值之间的总相对偏差绝对平均值分别为1.55%、2.09%和2.73%,表明MKK方程能以较好的精度预测CO_2在所研究离子液体中的溶解度。     

多取代苯胺溶解度和电离常数的单参数预测

采用DFT理论方法与基组B3LYP/3-21+G,模拟了10种单取代苯胺分子的骨架结构。计算了其苯胺环上氮和氢原子的自然轨道电荷(NBO)和密立根电荷(Mul)值。结果发现,该电荷值与其实验溶解度系数(pK_s)和实验电离平衡常数(p Ka)值间有好的单参数关联性。另外还计算了10个多取代基的苯胺分子的氮和氢原子的自然轨道电荷和密立根电荷参数,使用拟合出的两线性方程,结果显示新方法预测值与ACD/Labs方法得到的多取代苯胺分子的pK_a/pK_s值接近。     

CO2在醇中溶解度的测定与分子连接性指数的关联

用恒定溶剂法测定了303.15K下CO2在乙醇、正丙醇、异丙醇、正丁醇、正戊醇、异戊醇、正己醇、正辛醇、乙二醇、1,2-丙二醇中的溶解度。实验表明:随着碳链的增长,吸收CO2的效果越好,CO2在正辛醇中的溶解度最大,CO2在二元醇中的亨利常数显著大于一元醇。利用线性回归方法建立CO2在醇中的亨利常数lgH与分子连接性指数的相关关系模型,模型计算简单易行,对CO2在醇中的亨利常数有良好的估算和预测能力,相关系数R>0.99,计算值和实验值吻合良好。研究表明:用一阶分子连接性指数1χv、羟基的个数N、经验参数COH三个参数可以描述CO2在醇中的溶解特性lgH,且精确度很高。     

薄层色谱法测定聚合物溶解度参数的研究

本文应用薄层色谱法(TLC法)测定了聚苯乙烯、聚对苯二甲酸酚酞酯和聚环氧氯丙烷的溶解度参数。该法与溶胀法、粘度法和浊度滴定法等相比,设备简单、操作方便、快速准确,所测结果与文献报导值和理论计算值基本一致,是一种测定聚合物溶解度参数的好方法。所测上述三种聚合物的溶解度参数分别为18.6(J/cm~3)~(1/2),18.35(J/cm~3)价和19.64(J/cm~3)~(1/2)。     

反气相色谱法与汉森三维溶解度参数软件法测定四种咪唑基离子液体的溶解度参数

采用反气相色谱法(IGC)研究四种咪唑基离子液体在温度333.15、343.15、353.15、363.15、373.15 K时的溶解度参数,同时,采用汉森三维溶解度参数软件(HSPiP)模拟四种咪唑基离子液体在333.15 K时的三维溶解度参数。333.15 K时,IGC测得的四种咪唑基离子液体的溶解度参数分别为δt(EMIMOTF)=23.51(J×cm-3)1/2,δt(BMIMOTF)=23.39(J×cm-3)1/2,δt(HMIMOTF)=22.79(J×cm-3)1/2,δt(OMIMOTF)=22.31(J×cm-3)1/2,333.15 K时,HSPiP得出的四种咪唑基离子液体的溶解度参数分别为δt(EMIMOTF)=24.28(J×cm-3)1/2,δt(BMIMOTF)=23.26(J×cm-3)1/2,δt(HMIMOTF)=22.79(J×cm-3)1/2,δt(OMIMOTF)=22.08(J×cm-3)1/2,IGC与HSPiP得出的溶解度参数值一致。根据HSPiP可以模拟出离子液体的三维溶解度参数球,并依据三维溶解度参数球可以快速准确地选取离子液体的良溶剂或混合溶剂。研究结果为离子液体的热力学性质研究及其溶剂选择等应用提供了参考。     

液体内压的预测和新溶解度参数值

引　言在作者先前的工作[1]中 ,已由液体混合的热力学模型导得一个比Ｓｃａｔｃｈａｒｄ -Ｈｉｌｄｅｂｒａｎｄ正规溶液理论更加严格的过量Ｇｉｂｂｓ自由能表达式 .据此 ,定义了一个新的溶解度参数Δ =λ/ｍ =δ2 /λ (1 )式中　δ2 =ΔＶａｐ Ｕｍ/Ｖｍ,为液体的内聚能密度 ;λ =ｐ1/2ｉ ,为液体内压的平方根 ;ｍ =ｐｉＶｍ/ΔＶａｐＵｍ,为Ｈｉｌｄｅｂｒａｎｄ参数 .不难看出 ,当ｍ =1时 ,Δ =δ ,故传统的Ｈｉｌｄｅｂｒａｎｄ溶解度参数δ只是式( 1 )的一种特殊情况 ,由于一般液体的ｍ不等于1 ,故Ｈｉｌｄｅｂｒａｎｄ溶解度参数必须…     

氢气在烃类混合溶剂中高压溶解度的测定

为了研究氢气在煤液化油中的溶解规律和煤液化反应过程中的氢耗,选择煤液化油中几种代表性物质的混合组分十六烷-四氢萘、四氢萘-喹啉、十六烷-喹啉作为溶剂,利用平衡液相取样法气体溶解度测定装置,测定了氢气在上述溶剂中不同温度和压力下的溶解度数据(453.15 K～623.15 K,1 MPa～10 MPa),同时给出了氢气在这些混合溶剂体系中的溶解度规律.利用数学模型lnxH2=-a/T+6T+clnT+dlnPH2+e(式中参数可由氢气在相应溶剂中的溶解度数据关联得到)和P/N/A方法计算相关溶解度数据,发现该数学模型的计算预测值与实验值的平均绝对误差(η)在5.52%左右,而通过P/N/A方法的计算,预测值与实验值的平均绝对误差较大,这表明该数学模型在计算氢气在有机混合溶剂中的溶解度方面具有很好的应用价值.     

聚合物共混掺合的相容性与溶解度参数(下)

溶解度参数 本章着重讨论无定形高聚物的共混相容问题。并对溶解度参数相近(匹配)原则进行讨论。 一、溶解度参数δ 两种液体分子相容时所产生的热效应△H_m可由半经验式计算     

聚合物的内压与新溶解度参数

由文献发表的pVT数据回归得到了许多液态聚合物的Tait方程参数。据此能够获得各种密度下聚合物的等容线。将这些等容线斜率的对数与密度作图,则无例外地发现这些作出的线是很好的直线,故可建立一个聚合物的通用内压方程。它有两个特性常数,分别决定于直线的斜率和截距。它能用来准确地计算298．15K时各种液态聚合物的内压;据此,得到了90个聚合物的新溶解度参数值。     

计算聚合物内压和新溶解度参数的基团贡献法

将298.15 K时各种液态聚合物的内压平方根λ和重复单元的摩尔体积Vm的乘积对它们的van derWaals体积作图时,发现是一条通过坐标原点的直线.这意味着聚合物的λVm具有良好的基团加和性.据此,建立了一个能满意地预测聚合物内压的基团贡献法.结合Small的基团摩尔引力常数,该基团贡献法也能用来计算液态聚合物在298.15 K时的新溶解度参数值.     

INTERNAL PRESSURE AND SOLUBILITY PARAMETER FOR LIQUIDS

Based on a modified van der Waals model, in which the excluded volume is expressed as a linear function of density, the internal pressure and the physical contribution of two - dimensional solubility parameter suggested by Bagley et al. can be expressed as functions of density and a size dependent parameter A. A group contribution method for estimating parameter A and then the solubility parameter has been developed. Average relative deviation of the predicted solubility parameters in comparison will the experimental values for more than sixty liquids including non- polar and polar species as well as those with strong hydrogen bonding is 0.8%. Further correlation with topological indices of molecules makes this method applicable to various isomers of saturated alkanes. Average relative deviation of prediction for 34 saturated alkanes is only 0.6%.     

Use of Hildebrand and Lamoreaux's theory to predict solubility and related properties of gas-liquid systems

There is a need in many fields such as chemical engineering, process chemistry and pharmacology for reliable data on the solubility, entropy of solution and partial molar volume of gases in liquids. Experimental data are not available for many systems of practical and academic importance and consequently a reliable theory to predict values for these properties would be of great use. Recent refinements of solubility parameter theory have been successful in predicting such values for several systems and in this paper results obtained from this theory are compared with experimental measurements on a large range of gas-liquid systems. The agreement found is satisfactory in the most part, but for helium, neon, xenon, hydrogen and deuterium, the predicted results deviate consistently from the experimental values. This is to be expected on the basis of some of the earlier results of solubility parameter theory and an empirical modification is proposed that yields significant improvements in the predicted values. This has also been used to predict values for carbon dioxide, tetrafluoromethane and sulphur hexafluoride to which the theory is not directly applicable. Values predicted by solubility parameter theory are compared with those obtained by Battino and co-workers from scaled particle theory. In general, the two theories are equally successful in predicting solubilities, but refined solubility parameter theory yields better values of entropy of solution. It is concluded that the theory provides a useful means of predicting solubility and entropy of solution but that prediction of partial molar volume results is limited because of the paucity of data for the thermal pressure coefficients of the solvents. Attention is drawn to apparent inaccuracies in certain experimental measurements. The interrelationship between the various forms of the entropy of solution used by different workers is clarified. A value of the energy of vaporisation of carbon dioxide, δE₂^v=2.64±0.15 kcal/mol is calculated.     

Prediction of environmental stress cracking of polycarbonate from solubility considerations

Simple thermodynamic relationships as well as semiempirical solubility parameter plotting techniques were examined as methods for predicting critical crazing strains of polycarbonate exposed to linear and branched alkanes. In general, measured critical strains correlated with predicted solubilities based on the Flory–Huggins equation. Solubility parameters could also be used to predict critical strains if molecular size differences between specific alkanes were taken into account. These techniques were then extended to polar and hydrogen bonding liquids using two-dimensional solubility parameter plotting representations. A comprehensive listing of critical strains for polycarbonate exposed to over 80 liquids and liquid mixtures is included.     

Estimation of supercritical fluid-liquid solubility parameter differences for vegetable oils and other liquids from data taken with a stirred autoclave

Fujishiro and Hildebrand developed a procedure for determining the solubility parameter difference between the components of a partially miscible binary mixture, knowing the molar volumes of the components and the composition of each phase. Using this procedure, the solubility parameter differences between supercritical carbon dioxide (SCCO2) and each of three vegetable oils and four hydrogen bonding liquids have been determined. For the vegetable oils the solubility parameter differences at 72 C over the pressure range 5,000–10,000 psi were low, of the order of 2.0, and decreased only slightly with increasing pressure. For the hydrogen-bonding liquids at 52 C, over the same pressure range, the solubility parameter differences were much larger, of the order of 4 to 7 units, and independent of pressure except for ethylene glycol for which the difference increased from 5.7 to 6.7 from 5,000 to 10,000 psi.     

Sorption and Diffusion of Organic Liquids into Fluoroelastomer Membranes

Abstract

Sorption and diffusion of organic liquids into fluoropolymer (FC-2179) membranes have been investigated from 30 to 60°C using a gravimetric method. Diffusion coefficients, percent mass uptake, and apparent activation energies for the transport processes have been estimated. Diffusion coefficients of the liquids into the membrane have been computed from Fick's relation. A Flory–Huggins-type interaction parameter was obtained from the solubility parameter concept. Furthermore, the activation parameter values and heat of sorption data have been studied in terms of heat of mixing. The values of diffusion coefficients did not show any considerable dependence on solvent concentration. However, solvent transport as analyzed from an empirical equation was found to be of the anomalous type. Molecular transport also showed a dependence on the chemical nature of the liquids. The concentration profiles of liquids have been calculated at different penetration depths of the membrane at different time intervals by solving Fick's differential equation under suitable initial and boundary conditions. A numerical method based on the finite difference technique was also used to predict the concentration profiles of liquids, and these are compared with the profiles computed from an analytical solution of Fick's equation.     

The Interaction Parameter and the Strength of Adhesive Joints

A “blister test” technique has been used to determine the fracture surface energy of a range of adhesive joints formed using a polyurethane adhesive and a range of solid substrates. For each adhesive pair examined the work of adhesion was calculated from the contact angles formed by liquids for which the polar and dispersion force components of the surface tension are known. For each adhesive pair, the solubility parameter of adhesive and substrate were determined by swelling measurements in a range of liquids. Although cohesive failure of the joints was observed for some of the pairs for which the solubility parameters were matched, this was not true for all such pairs and an explanation of this behaviour has been sought in a new calculation of the volume interaction component of the molecular interaction parameters.     

液体和聚合物的内压预测

如同先前报道的液态聚合物一样,298．15K时一般小分子液体的内压平方根A与摩尔体积Vm的乘积亦正比于它们的van der Waals体积Vvdw,而且两者有相同的比例系数。这说明各种液体的λVm具有相同的基团加和性。据此,利用它们的内压和摩尔体积的实验值建立了一个λVm的基团贡献法,它能用来预测各种液态有机物,包括聚合物在298．15K时的内压值。本法不仅适用于非极性和弱极性液体,而且也适用于强极性和缔合液体。熟知的Small溶解度参数基团贡献法只不过是本工作的一个特例。对120种有机液体和液态聚合物的λ值预测结果表明,其与实验值的一致性令人满意。