Nonrandom Hydrogen-Bonding Model of Fluids and Their Mixtures. 1. Pure Fluids

Abstract

A unified treatment of the phase equilibria and interfacial properties of fluids is presented. This is done through the development of a framework model, which is applicable to nonpolar systems as well as to highly nonideal systems with strong specific interactions, to systems of small molecules as well as to polymers, glasses, and gels, to liquids as well as to vapors and supercritical systems, and to homogeneous as well as to inhomogeneous systems. One key characteristic of this equation-of-state model is its capacity to estimate the nonrandom distribution of the free volume in the system. A quasi-thermodynamic approach of inhomogeneous systems is used for modeling the fluid-fluid interface. The present model is referred to as the nonrandom hydrogen-bonding model. The key differences between this model and the previous quasi-chemical hydrogen-bonding model are the following: (1) The combinatorial term is replaced by the generalized Staverman term. ( 2) The nonrandomness factor is also generalized. Two alternative expressions are presented in this work. (3) The shape factor, s, is no longer an adjustable parameter. It is set equal to the UNIFAC q/r ratio and obtained from the corresponding UNIFAC compilations in the literature. (4) A most recent quasi-thermodynamic approach is used for the fluid-fluid interface. In the first part of this series of papers, the model is applied for the estimation of basic thermodynamic properties of pure fluids, such as vapor pressures, orthobaric densities, heats of vaporization, surface tensions, and glass transition temperatures.

Water Sorption Thermodynamics and Mass Transport in Poly(ϵ‐Caprolactone): Interactional Issues Emerging from Vibrational Spectroscopy

“…In particular, the NRHB model [ 24 ] is considered, which takes into account the various polymers. [ 8 ] In particular, as demonstrated in Figure 2 , a close similarity exists with the system polyimide/ water, which has been systematically investigated by vibrational spectroscopy and gravimetric techniques.…”

Modeling the solid–liquid equilibrium in pharmaceutical‐solvent mixtures: Systems with complex hydrogen bonding behavior

“…Finally, the shape factor is defined as the ratio of molecular surface to molecular volume, s 5 zq/zr 5 q/r, and is calculated from UNIFAC group contribution method. 18 In case of mixtures, the following mixing and combining rules are used:…”

New Group-Contribution Method for Predicting Temperature-Dependent Properties of Pure Organic Compounds

“…The NRHB (non-random hydrogen-bonding) model [9] is a novel equation-of-state model which, in addition to the capabilities of the similar lattice-fluid type models [10], is able to estimate the non-random distribution of free volume in a system. This model can predict phase equilibria and interfacial properties of fluids.…”

“…where ε * is the average interaction energy per molecular segment, v * is the average segmental volume, v * sp is the hard-core specific volume, T * is the scaling temperature, P * is the scaling pressure, ρ * is the scaling density, and R is the universal gas constant [9,10]. For the estimation of surface tension at any temperature, the influence parameter, κ, is also needed.…”

“…It is a combination of the Constantinou-Gani [8] group-contribution method with the novel NRHB equation-of-state theory [9]. The estimation of properties is exclusively based on the molecular structure of each organic compound.…”