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Developing a Group-Contribution Thermodynamic Model Based on the SAFT-Type Equation of State for Solvent-Polymer Systems

Mahmoudinasab, Reza | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40198 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ghotbi, Cyrus; Taghikhani, Vahid; Behzadi, Bahman
  7. Abstract:
  8. The usual method for determination of pure component parameters of SAFT-type Equation of State (EoS) is to fit them to experimental vapor pressure and liquid density data. Since high-molecular-weight compounds, like polymers, do not have a detectable vapor pressure, there is a need for a predictive calculation method for parameters of polymers and other complex compounds. In 2008, Tihic et al. proposed a Group Contribution (GC) method for estimating molecular parameters of PC-SAFT EoS. In this thesis, it is attempted to extend the suggested method of Tihic et al. by adjusting molecular parameters of PC-SAFT EoS for about 120 new non-associating compounds using experimental data extracted from DIPPR database and then adding them to pure component parameters of non-associating compounds, which their parameters previously reported in other literatures. In this work, group parameters of 52 First-Order Groups (FOG) and 27 second-Order Groups (SOG) are adjusted, which among them, the seven FOGs and one SOG were obtained for the first time. In order to evaluate the performance of obtained group parameters, molecular parameters for a number of common homopolymers are calculated and then used for prediction of density of pure homopolymers and Vapor-Liquid Equilibrium (VLE) of polymer-solvent systems. The results that obtained from using the group parameters, which are reported in this work, indicate that prediction of pure polymer densities provides a less error in comparision with the work of Tihic et al. In the case of VLE of polymer-solvent systems, the molecular parameters for some of polymers, e.g. PS, clearly show better prediction ability; however, for some of polymers, e.g. PIB and PMMA, there is no substantial difference between the performance of parameters which are obtained from this work and the work of Tihic et al. For many binary mixtures are investigated, a small binary interaction parameter, kij, is needed before the model accurately correlates the experimental data. Finally, it can be said that by the newly developed GC scheme in hand to calculate parameters for complex non-associating compounds which required vapor pressure and/or liquid density data may not be available, the PC-SAFT model has become a relevant and useful engineering tool for the design and development of complex products.

  9. Keywords:
  10. Vapor-Liquid Equilibrium (VLE) ; Statistical Assosiating Fluids Theory (SAFT) ; State Equation ; Group Contribution ; Polymeric System

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