After a reminder on the different forms of polymer recycling, the mechanical recycling of 4 polymers PE, PP, PET and HIPS will be presented. This second processing of polymer waste from sorting plants is generally based from food packaging. The modification of the macromolecular structure of the different polymers presented is not the same: it depends on the conditions of the process (temperature, shear, residence time). 

Course's structure : 

Introduction : 

1. Evolution of production global plastic, 

2. European production of plastic, 

3. Recycling of plastics from packaging, 

4. Methods of recycling. 

PP recycling : 

From research papers found on SCOPUS with “multiple & extrusions & polypropylene” and ‘’reprocessing & polypropylene’’ as keywords, 5 papers have been selected. Mains results are presented and discussed with the students. 

Recyclability of polyethylene 

• The different architecture of polyethylene, 
• Viscosity in shear and elongation of polyethylene, 
• PE degradation mechanism during reprocessing (by injection). 

Polyethylene terephthalate

• PET Structure and Properties, 
• Chain splitting by hydrolysis,  
• Minimum properties recommended before reprocessing, 
• Regeneration of viscosity by chain extension, 
• Optimization of settings (residence time and concentration), 
• Long Chain Branching at high concentration of chain extenders. 

Two papers on reprocessing of high impact polystyrene are read at the end of this lecture. 

À la fin de cette UE, vous serez capable de : 

• Understand effects of mechanical recycling on food packaging waste, 
• Limit the thermo-degradation by adding appropriate additives or adequate processing parameters. 

Unit "Recyclage des polymères" (M1 IMECA), or equivalent. 

First session :

• 30% written ongoing exam, 
• 70% written final exam. 

Second session : 100% written final exam.