ISBN 9783843943345

978-3-8439-4334-5, Reihe Thermodynamik

Niklas Haarmann
Thermodynamic Modeling of Long-Chain Molecules and Related Mixtures

229 Seiten, Dissertation Technische Universität Dortmund (2019), Softcover, A5

Zusammenfassung / Abstract

A broad range of long-chain compounds such as methyl alkanoates or n-alcohols can be synthesized based on triglycerides which occur in natural fats and oils. Saturated and linear representatives of these individual families are composed of an identical functional head moiety which is connected to an n-alkyl residue that only varies in chain length within a homologous series. In this work, this fact was taken into account for the modeling of thermodynamic properties using a new heterosegmental approach of the Perturbed Chain Polar Statistical Associating Fluid Theory. For this purpose, the n-alkyl residue within a homologous series was modeled using the pure-component parameter set of the respective n-alkane, whereas the parameter set of each identical head domain was universally determined. Within this heterosegmental approach, polar and self-associating interactions among the identical head domains were explicitly considered. Due to its group-contribution-like character, the new heterosegmental approach enables the prediction of thermodynamic properties of other compounds within a homologous series. Furthermore, the new approach was combined with the Density Gradient Theory. Applying the new approach, vapor pressures, liquid densities, and surface tensions of the pure long-chain compounds could be represented in very good agreement with the available experimental data. Also, the excess enthalpies and the excess volumes of the binary mixtures long-chain compound + n-alkane were predicted in remarkable agreement with the available experimental data for a broad range of chain lengths. As a key idea of the new heterosegmental approach, the interactions between the n-alkyl residues of the long-chain compounds and water can be described using independent solubility data of the binary mixtures n-alkane + water. Hence, the mutual solubilities, the liquid densities, and the interfacial tensions of the binary mixtures long-chain compound + water were satisfyingly described.