Understanding solubility and diffusion phenomena of compounds extracted from polymer matrixes in high temperature and pressure conditions

Plastics recycling is a major current issue, making it possible to reduce the ecological and environmental impacts linked to their production and consumption. This involves developing specific recycling processes depending on the plastics. Present in great variety in all plastics, additives cause an issue in mechanical recycling (the most widely used recycling method): their presence and mixture results in poor quality recycled material. Some additives, which have become regulated, pollute the recycled material and prevent its further use. The project concerns deformulation recycling, that is to say the removal of all possible additives in the plastic material in order to reuse it. Some old plastics contain additives that are now banned, so their total extraction is becoming a major issue. This thesis will concern the study of solid / liquid extractions, considered to eliminate additives present in plastics. Extractions can be selective or involve the widest possible range of compounds.
More precisely, the thesis subject concerns the study of solid / liquid extraction in temperature and pressure (ASE or PFE method). After a bibliographical work on plastics and their formulation, migration and its modelling, and analytical techniques, the candidate will combine experimental strategy, analysis and modelling to study the phenomena of swelling, migration and extraction taking place within a plastic particle at high temperature and pressure. The student will be responsible for carrying out laboratory experiments, ensuring the smooth running of his manipulations as well as their operation. Good communication with the analysis team will be key for the development of new methods, the exploitation of the results and the understanding of the phenomena. The proposed research strategy will be based on the experimental and analytical resources available within IFPEN, but also on the modelling resources (ASPEN).
Knowledge of the diffusion processes within a polymer matrix and the parameters involved can lead to concrete solutions aimed at improving the purification of recycled plastics.

Keywords: polymer, plastic, recycling, diffusion, solid/liquid extraction, purification, separation, migration, additive, modelling

Academic supervisor    PhD, CHAUMMONOT Alexandra, IFPEN      
Doctoral School    ED206 - Ecole doctorale Chimie, Procédé, Environnement
IFPEN supervisor     PhD, SIBEAUD Mathilde, Research Engineer, Catalysis, Biocatalysis and Separation Direction, Separation Department, mathilde.sibeaud@ifpen.fr    
PhD location    IFP Energies nouvelles, Lyon, France  
Duration and start date    3 years, starting in fourth quarter 2022
Employer    IFP Energies nouvelles, Lyon, France
Academic requirements    University Master degree in relevant disciplines , for example material sciences, polymer sciences…
Language requirements    Fluency in French or English, willingness to learn French 
Other requirements     Previous experience un formulation, characterisation, analysis or recycling of plastics would be appreciated. Taste for experimentation. Knowledge in data processing. 
Experience in characterizing or modelling diffusion phenomena would be a plus.