Focke, Walter Wilhelm2024-09-052024-09-052024-09-022024-01-26Pretorius, F (2024) Refractometry models for compositional analysis of binary and ternary mixtures, Dissertation, Department of Chemical Engineering, University of PretoriaSeptember 2024 (S2024)http://hdl.handle.net/2263/98046Dissertation (MEng (Chemical Engineering))--University of Pretoria, 2024.A review of existing compositional binary mixture models for refractive indices was undertaken and showed that they can be recast in forms that are linear in mole or volume fraction. Typically, mole fractions proved to be the better composition descriptor when analysing literature data and the molar refraction was shown to be virtually temperature independent. Depending on whether temperature, density or refractive index measurements of the mixture are available, different correlations were developed to predict the composition (as shown below). Furthermore, refractive index measurements on mixtures of n-alkanes with DEET were taken to determine phase equilibrium behaviour. With extrapolation to infinite molar mass, these alkanes approach polyethylene, which is the material from which DEET-containing mosquito-repellent devices were made. The results show that the microporous structure was likely formed by liquid-liquid phase separation. Lastly, it was shown that Padé approximants provide good representations of binary and ternary refractive index data. The temperature dependence of the pure components was elegantly subsumed in a pure component property, namely, the molar volume. Various constraints were applied to reduce the number of adjustable parameters even further and this proved to be successful.en© 2023 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.UCTDSustainable Development Goals (SDGs)Refractive indexPolymer solutionPhase equilibriumN-alkanesMixing rulesDissertationu15076238Datasets not our own. Submitted with articles.