关联二元体系超额焓的改进模型

在已提出的二元体系超额焓分子热力学模型基础上,用体积分数表征溶液宏观组成以校正由于分子尺寸不同引起的分子之间特殊交互效应,推导出关联二元溶液超额焓的三参数改进模型.用近10年发表的有代表性的上百个二元非对称体系实验数据,主要是含不同分子尺寸、形状、结构组分的复杂体系实验数据,对所提超额焓改进模型进行了检验.结果表明,对含不同分子尺寸、形状、结构组分的非对称体系,改进模型的关联精度明显优于原模型.同时,在φ→0 或φ→1的极限条件下,改进模型同样成立.     

含醇体系超额性质模型TDAM的导出和应用

本文针对含醇体系的特性,基于缔合溶液理论,导出了一个形式简单、物理意义明确的溶液模型——TDAM.由于TDAM模型中引入了较为合理的温度关系,仅需两套不同温度下的超额焓数据,即可进行其它温度下超额焓数据以及汽液平衡数据的推算.将TDAM模型对非极性、极性体系超额焓的关联结果与其它常见溶液模型(Wilson、W-C和QCSM等)进行了比较,以TDAM模型为最佳;对含醇体系汽液平衡数据也进行了同样的比较,TDAM模型关联结果优于或相当于其它溶液模型.将该模型用于超额焓和汽液平衡的推算,结果令人满意.     

α-蒎烯-蒎烷-长叶烯体系汽液平衡及其过量Gibbs自由能与超额焓

采用改进Ellis平衡釜测定了α-蒎烯-蒎烷、α-蒎烯-长叶烯、蒎烷-长叶烯三个二元体系及α-蒎烯-蒎烷-长叶烯三元体系常压汽液平衡数据,经Herington规则检验符合热力学一致性。由汽液平衡数据求出每个二元体系中各组分的活度系数,再关联得到相应的过量Gibbs自由能与超额焓实验值。结果表明,α-蒎烯-蒎烷体系的Gibbs自由能对理想溶液呈现较小的正偏差,而α-蒎烯―长叶烯和蒎烷-长叶烯体系Gibbs自由能对理想溶液呈现负偏差。根据Wilson方程对三个二元体系的过量Gibbs自由能和超额焓进行了计算,关联值与实验值吻合,对α-蒎烯-蒎烷体系最大超额焓为120.48 J×mol~(-1),α-蒎烯―长叶烯体系最大超额焓为401.09 J×mol~(-1),蒎烷-长叶烯体系最大超额焓为685.75J×mol~(-1)。由关联得到的二元体系能量参数推算了α-蒎烯-蒎烷—长叶烯三元体系的过量Gibbs自由能和超额焓,过量Gibbs自由能的实验值与计算值基本吻合,平均相对偏差为1.7147%,该三元体系的最大超额焓为627.16 J×mol~(-1)。     

用FRKS状态方程关联高度非对称二元系超额焓

引言对于组分分子大小、形状、结构相差较大的高度非对称混合物,迄今仍未有计算其超额焓的满意的方法．最近Lin等用转子链立方状态方程计算了高度非对称二元系的超额焓．在他们的工作中,使用两个可调参数虽然明显改进了计算,但对大多数体系,误差仍较大．对于这一类体系,立方状态方程失败的两个主要原因是：一、对于纯物质,立方状态方程中的引力参数α通常表为温度T和偏心因子ω的函数．对于复杂化合物,特别是长链碳氢化合物,由于其性质偏离正常流体较远,偏心因子已不可靠,另外,对于高沸点物质,也难以得到可靠的ω数值;因此,…     

Flory溶液理论中待定参数的决定

用反相色谱法(IGLC)测定聚合物和溶剂的相互作用参数X,推算出Flory聚合物溶液理论中的交换能参数X_(12),结合本文估算的聚合物和溶剂的接触表面之比S_1/S_2,计算了聚二甲基硅氧烷(PDMS)、天然橡胶(NR)、聚苯乙烯(PS)和聚异丁烯(PIB)等溶液体系中,X和聚合物链节分率φ_2的关系,结果能与实验值很好符合,并且还计算了溶液的体积变化V~(?)/V~(?)和无限稀混合焓△H_(?)~∞.     

氢化松节油体系过量Gibbs自由能及超额焓

利用α-蒎烯-β-蒎烯、α-蒎烯-蒎烷二元体系常压汽液平衡数据,研究氢化松节油体系过量G ibbs自由能及超额焓的关联与计算。由汽液平衡数据求出体系中各组分的活度系数,从而关联得到相应的常压过量G ibbs自由能实验值,结果表明,α-蒎烯-β-蒎烯、α-蒎烯-蒎烷体系对理想溶液呈现较小的正偏差。根据W ilson方程对α-蒎烯-β-蒎烯、α-蒎烯-蒎烷体系的常压过量G ibbs自由能和超额焓进行了计算,计算值与实验值吻合良好,对α-蒎烯-β-蒎烯体系最大超额焓为12.663 1 J/mol,α-蒎烯-蒎烷体系最大超额焓为126.783 7 J/mol。     

三维溶解度参数和MOSCED模型相结合预测液相活度系数

提出活度系数预测的新方法，用纯物质的一些性质参数按三参数溶解度参数法结合ＭＯＳＣＥＤ模型计算的无限稀释活度系数，选合适的单参数方程求得过量自由焓模型的两个参数，对１１７个二元溶液体系的２２２３个组成点的液相活度系数作了预测。与由文献数据相应方程求得的结果相比，平均相对误差约５％。     

某些酮醇体系过量焓测定及其汽液平衡的推算

本工作对流动型微量热计测定过量焓的常见方法进行了较为有效的改进,并实测了四个酮醇体系在308.16K下的过量焓数据。又用本文作者以前提出的过量热力学性质计算模型和三参数NRTL模型对上述测定的三个体系进行了汽液平衡推算。最终表明:本文作者模型的计算结果明显优于NRTL模型的计算结果。     

甲酰胺+乙醇/丙醇/异丙醇/乙酸乙酯二元混合物的体积及黏度性质

为理解含甲酰胺二元溶液的超额性质变化及分子间相互作用,常压下测定了甲酰胺(FA)分别与乙醇、丙醇、异丙醇和乙酸乙酯组成的二元系在293.15~318.15 K的密度和黏度,计算了超额摩尔体积(VE)和黏度偏差(Δη)。采用半经验的黏度方程对实验黏度数据进行了关联和预测,并基于Eyring绝对速率理论方法计算了黏滞性活化参数。结果表明,四个二元系的超额摩尔体积均为负值,且都随温度升高而偏差增大。FA-乙醇和FA-乙酸乙酯两个体系的黏度偏差为负值,且随温度降低而偏差增大。FA-丙醇和FA-异丙醇两个体系的黏度偏差随FA组分增加呈‘S’形变化,在甲酰胺低浓度区由负值变为正值,也均随温度降低而偏差增大。Mc Allister模型对黏度数据的关联结果最好,预测值与实验值的平均相对偏差最小。黏滞性活化参数说明混合过程中焓驱动起主导作用。     

1-丁基-3-甲基咪唑磷酸二丁酯+甲醇/乙醇+水三元工质溶液混合焓的测量及预测

采用绝热量热法测量了由离子液体1-丁基-3-甲基咪唑磷酸二丁酯([bmim][DBP])分别与CH₃OH、C₂H₅OH和H₂O所组成的3个二元工质溶液体系[bmim][DBP](1)+ CH₃OH(2)/C₂H₅OH(2)/H₂O(2),以及2个三元工质溶液体系[bmim][DBP](1)+ CH₃OH(2)/C₂H₅OH(2)+ H₂O(3)在298.15 K和常压下的摩尔混合焓H_m^E。利用Gibbs-Helmholtz方程和NRTL活度系数模型,对每个二元溶液体系摩尔混合焓的实验数据进行关联,获得模型方程中的组分作用参数。摩尔混合焓的模型拟合值与实验值的平均相对偏差分别为1.81%、1.44%和0.72%。在此基础上预测了2个三元工质溶液体系的摩尔混合焓。结果表明:三元工质溶液体系的摩尔混合焓在实验浓度范围内均为负值,混合为放热过程。表明三元工质溶液具有成为吸收制冷循环新工质溶液的基本特征;采用NRTL模型预测2个三元溶液体系摩尔混合焓的计算值与实验值的平均相对误差分别为2.31%、2.49%。     

VAPOR-LIQUID EQUILIBRIA OF POLYMER SOLUTION USING UNIQUAC

The UNIQUAC excess Gibbs energy model of Abrams and Prausnitz(1975)is extended to represent thevapor-liquid equilibria of polymer solution with only two adjustable parameters.Discussions on the application ofthe Staverman-Guggenheim and the Flory-Huggins combinatorial contribution in the UNIQUAC model are givenin this paper.The UNIQUAC model with either Staverman-Guggenheim or Flory-Huggins combinatorial expres-sion presents results with about the same accuracy for polymer solutions.Comparisons between the UNIQUAC model and the Flory equation show that theUNIQUAC model can give some better results than the Flory equa-tion in general.     

Theoretical consideration on the number of external degrees of freedom and its application to poly(dimethylsiloxane) solutions

Summary The Flory theory of polymer solution was modified by assuming the non-additivity of the number of the degree of external freedom for a binary mixture and applied the modified Flory theory to poly (dimethylsiloxane)-solvent systems. This theory can reproduce the experimental results of the interaction parameter and the excess volume of mixing, which the Flory theory failed to reproduce.     

The deformation behavior of poly(dimethyl siloxane) networks. II. Equilibrium swelling

The equilibrium swelling behavior of end-linked silicone networks has been studied, using low molecular weight silicone oils as diluents. Using the phantom and affine versions of the Flory–Rehner elasticity theory, the predictability of the equilibrium swelling has been examined. It was found that a modified version of the Flory–Rehner equation can be used to predict the equilibrium swelling behavior, provided the interaction parameter is known or measured. The modification is the use of the measured elastic shear modulus of the network prior to swelling, to calculate the density of network chains needed in the equation for swelling. This implies that both entangled and chemically linked chains contribute to the swelling behavior, since the modulus itself is predicted by the use of an equation that incorporates the contribution of entanglements. © 1994 John Wiley & Sons, Inc.     

A Hydration Shell‐Based Thermodynamic Model for Aqueous Two‐Phase Systems

In this work a Flory‐Huggins model modified to account for some unique features of Aqueous Two‐Phase Systems is presented. The model takes into account observed solvation between water and polymer molecules through the incorporation of a hydration shell to express the number of water molecules bonded to each polymer molecule. The parameters of the modified equation were determined using experimental data of ATPS containing poly (ethylene glycol) and dextran. The results revealed remarkable improvement in the correlation ability of the model. A general expression that defines the number of water molecules in the hydration shell was also obtained.     

Expansion coefficients and conformational properties of heterodisperse poly(acrylamide-co-sodium acrylate)

Calculations of expansion coefficients from light scattering and viscometric data on heterodisperse samples of poly(acrylamide-co-sodium-acrylate) satisfactorily describe the solution properties of these polymers across the entire copolymer range, from polyacrylamide to poly(sodium acrylate). Light scattering results correlate well with the viscosity data provided that corrections are made for polymer heterodispersity and that a modified Krigbaum equation is used to estimate the unperturbed dimensions of the molecules. The expansion coefficients deduced from light scattering and Flory–Fox hydrodynamic theory were inaccurate and insensitive to fluctuations in charge density and molecular weight.     

基于新α表达式的实用PT方程

提出了范德华型方程中引力项参数α的一种新的实用表达式,给出了基于新α表达式的ＰＴ方程。３０种物质饱和蒸汽压及饱和液体密度同时关联的结果表明,修正的ＰＴ方程较原始的有较大改进,特别是对极性物质。还给出了普遍化的ＰＴ方程,其对极性物质及非极性物质都有较高的预测精度。     

Swelling behavior of thermosensitive N-isopropylacrylamide–ethyl N-acryloylglycine submicron-sized copolymer gel particles

Submicron-sized N-isopropylacrylamide (NIPA)–ethyl N-acryloylglycine (ENAG) copolymer gel particles with various compositions were prepared by precipitation polymerization in water. Their swelling behaviors were determined by photon correlation spectroscopy (PCS). Our results showed that the volume transition temperature of copolymer gel particles decreased with increasing the mole ratio of ENAG. In model development, we modified the extended Flory–Huggins theory as a free energy of mixing term and employed the modified Flory–Rehner theory for the elastic contribution and compared the proposed model with our swelling data. The model predicted fairly well the swelling behaviors of copolymer gel particles. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 799–806, 1998     

Lower Critical Solution Temperatures,Part I Polymethylene in n-alkanes

Lower critical solution temperatures (LCST's) of three linear polyethylenes of differing molecular weights were measured visually in various n-alkanes ranging from n-hexane to n-tridecane. The LCST observed increases with decreasing molecular weight of polyethyline and with increasing the chain length of the n-alkanes. The limiting LCST's, θL for polyethylene/n-alkane systems were obtained by extrapolating to the infinite molecular weight of polyethylene using a Shultz-Flory plot. Flory's equation of state theory is discussed in conjunction with the conventional Flory-Huggins theory and the equation of state parameters for the pure solvents are obtained according to the Flory theory. The θL temperatures for polyethylene in n-hexane, n-heptane, and n-octane are calculated in accordance with Flory's and Patterson's equations and compared with the experimental values. The θL temperatures are found to be well predicted by one version of the Flory theory.     

Degradation behavior of hydrogel based on crosslinked poly(aspartic acid)

The degradation behavior of hydrogel based on poly(aspartic acid) (PASP) which crosslinked by 1, 6‐hexamethylene diamine (HD) was studied in α‐chymotrypsin solution. The degradation behaviors of PASP under different crosslinking levels were evaluated as a function of biodegradation time by monitoring the changes of crosslinking density, molecular weight, rheological behavior, interior morphology, mass loss, and swelling ratio. It was found that the degradation behaviors relied heavily on the crosslinking density which calculated from the Flory‐Rehner equation. A pseudo first‐kinetic equation was proposed to model the mass loss behavior and the degradation rate constant was calculated under different crosslinking levels. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

On the theory of the ising model of the macromolecular solution

The partition function of a macromolecular binary solution is transposed in the partition function in Ising's model. On the basis of this model the macrocanonical function is explained by the presence of the interaction forces, in the one-dimensional as well as in the two-dimensional cases. The chemical potential of the macromolecular solution is calculated in both cases and compared with the results obtained by Flory and Huggins.