https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Sat, 06 Jun 2026 19:52:33 GMT 2026-06-06T19:52:33Z http://hdl.handle.net/10985/17918 A kinetic model for predicting PET macromolecular changes during its mechanical recycling NAÏT-ALI, Linda K.; BERGERET, Anne; COLIN, Xavier The rheometer cavity has been used to analyse, in carefully controlled exposure conditions, the macromolecular changes generated by the mechanical recycling of PET during its extrusion. Isothermal ageing tests at 280 °C, under constant or variable oxygen partial pressures (between 0% and 21% of the atmospheric pressure), have allowed to establish that two types of oxidative macromolecular changes take place successively in an extruder reactor. Chain scissions predominate in the "highly oxygenated" zones (at the feeder and die), whereas chain welding predominates in "poorly oxygenated" zones (in the middle) of reactor. Thus, it appears that the relative predominance of both types of modifications is sharply linked to the extruder geometry and size (in particular, to the feeder and die diameter, and screw length). A kinetic model of thermal ageing of molten PET has been built to check these assumptions. It describes satisfyingly all the rheometric results obtained in the present study. Sat, 01 Jan 2011 00:00:00 GMT http://hdl.handle.net/10985/17918 2011-01-01T00:00:00Z NAÏT-ALI, Linda K. BERGERET, Anne COLIN, Xavier The rheometer cavity has been used to analyse, in carefully controlled exposure conditions, the macromolecular changes generated by the mechanical recycling of PET during its extrusion. Isothermal ageing tests at 280 °C, under constant or variable oxygen partial pressures (between 0% and 21% of the atmospheric pressure), have allowed to establish that two types of oxidative macromolecular changes take place successively in an extruder reactor. Chain scissions predominate in the "highly oxygenated" zones (at the feeder and die), whereas chain welding predominates in "poorly oxygenated" zones (in the middle) of reactor. Thus, it appears that the relative predominance of both types of modifications is sharply linked to the extruder geometry and size (in particular, to the feeder and die diameter, and screw length). A kinetic model of thermal ageing of molten PET has been built to check these assumptions. It describes satisfyingly all the rheometric results obtained in the present study. http://hdl.handle.net/10985/17919 Kinetic analysis and modelling of PET macromolecular changes during its mechanical recycling by extrusion NAÏT-ALI, Linda K.; BERGERET, Anne; COLIN, Xavier The rheometer cavity has been chosen to analyze, in carefully controlled exposure conditions, the PET macromolecular changes generated during its mechanical recycling by extrusion. Isothermal ageing experiments at 280 °C, under constant or variable oxygen partial pressures (between 0% and 21% of the atmospheric pressure), have allowed us to establish that two types of oxidative macromolecular changes take place successively in an extruder reactor. Chain scissions predominate in the "strongly oxygenated" zones (at the feeder and die), whereas chain couplings (mainly chain branching) predominate in "poorly oxygenated" zones (in the middle of the reactor). Thus, it appears that the relative predominance of both types of modifications is closely related to the extruder geometry and size (in particular, the feeder and die sections and the screw length). A kinetic model of thermal ageing of molten PET has been built to check these assumptions. It describes satisfyingly all the rheometric results obtained in the present study. Sat, 01 Jan 2011 00:00:00 GMT http://hdl.handle.net/10985/17919 2011-01-01T00:00:00Z NAÏT-ALI, Linda K. BERGERET, Anne COLIN, Xavier The rheometer cavity has been chosen to analyze, in carefully controlled exposure conditions, the PET macromolecular changes generated during its mechanical recycling by extrusion. Isothermal ageing experiments at 280 °C, under constant or variable oxygen partial pressures (between 0% and 21% of the atmospheric pressure), have allowed us to establish that two types of oxidative macromolecular changes take place successively in an extruder reactor. Chain scissions predominate in the "strongly oxygenated" zones (at the feeder and die), whereas chain couplings (mainly chain branching) predominate in "poorly oxygenated" zones (in the middle of the reactor). Thus, it appears that the relative predominance of both types of modifications is closely related to the extruder geometry and size (in particular, the feeder and die sections and the screw length). A kinetic model of thermal ageing of molten PET has been built to check these assumptions. It describes satisfyingly all the rheometric results obtained in the present study.