Modeling phase equilibria for polymer recycling processes

Recycling plastic materials is essential for reducing the amount of waste, but currently used mechanical recycling processes have very important limitations (sorting control, color). Chemical recycling will allow a more complete material recovery and this PhD thesis aims at contributing to its development. For the solvent dissolution processes, it is essential to model the polymer blend + solvent mixtures so as to identify the limits of solubility. In this context, the PhD student will develop a thermodynamic tool able to correctly represent polymers and compute the phase equilibria between polymers and solvents. A tool for such calculations has been developed in literature and at IFPEN but improvements are to be made in order to deal with more complex systems. First of all, a methodology needs to be improved for representing the polymer blends flowing in the process by a mixture of pseudo-polymers so that both the chemical structure and the polydispersity are represented. Then, since the feed may also contain organic additives, the phase equilibria tool will also need to be able to estimate in which phase these products are concentrated during the separation. Generally, the phase equilibria of a system are calculated by associating an equation of state with a mathematical algorithm. Hence, the second aspect the PhD student will investigate concerns the algorithm itself. Finally, the tool will be used to help selecting the most adequate solvent for the targeted polymer. 

Keywords: Recycling, equilibrium, polymer.

• Academic supervisor    IFP-School Professor, PhD in Chemical engineering, DE HEMPTINNE Jean-Charles, IFP Energies nouvelles
• Doctoral School    ED 388 Chimie Physique et Chimie Analytique de Paris-Centre, Sorbonne Université, http://ed388.sorbonne-universite.fr/fr/index.html
• IFPEN supervisor    PhD in Physical Chemistry, WENDER Aurélie, Thermodynamic and molecular simulation department, aurelie.wender@ifpen.fr
• PhD location    IFP Energies nouvelles, Rueil-Malmaison, France
• Duration and start date    3 years, starting in fourth quarter 2022
• Employer    IFP Energies nouvelles, Rueil-Malmaison, France
• Academic requirements    University Master degree in Physical chemistry or Chemical engineering 
• Language requirements    Fluency in French and English
• Other requirements    Knowledge of thermodynamics, process engineering, C++ programming skills