Recyclage du PVC : compréhension et caractérisation de sa dissolution

To successfully recycle our plastic waste nowadays, we need to develop specific regeneration processes for each of them. Among all plastics, PVC has a special place, since it is mainly used in the construction industry, via the elaboration of products (windows, floor coverings, pipes, etc.) with long life spans. However, the evolution of European regulations over time has led to the control, or even prohibition, of the use of certain PVC additives widely used in the past (metallic stabilizers, phthalate plasticizers). Today, there is no doubt that "old" PVC-based waste contains these dangerous additives, which greatly limit its recycling using current techniques. To address this issue, regeneration by deformulation is promising: it usually consists in dissolving the PVC plastic and extracting the polymer fraction in order to come back to the purest possible resin (thus reusable). 
The aim of this thesis is to understand and characterize the dissolution stage of PVC plastic, by focusing on the behavior of polymer chains in the presence of a solvent and a set of given operating conditions (swelling, disentanglement of chains). The impact on the polymer fraction of the chosen solvent and of the additives present in the studied PVC will be particularly studied, with a methodical approach allowing to screen the effects of each one. For this, after a bibliography focused on PVC deformulation (including solvents and ad hoc analytical techniques), the candidate will combine experimental, analytical and computational strategies (e.g. based on Hansen's solubility parameters) to qualify swelling and dissolution phenomena during polymer-solvent interaction, aiming at mild experimental conditions, but also taking into account the toxicity of solvents and their availability.
The PhD student will be responsible for the realization of the experiments, for the collection and interpretation of the results (with conceptualization of the supposed involved phenomena), as well as for the good communication between the various actors of the team. The proposed research strategy will be based on the means available at IFPEN and will take advantage of the PEPR "Recycling" framework, favourable to external academic contacts.