Effects of mechanical recycling on PET stretchability

• Published in: Polymer (Guilford) Vol. 307; p. 127256
• Main Authors: Sylvestre, Nathan, Bouvard, Jean-Luc, Derrien, Mikaël, Monnier, Xavier, Combeaud, Christelle
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 24.07.2024
• Subjects: Mechanical recycling; PET stretching; Time/temperature equivalence; Mechanical recycling; Time/temperature equivalence; PET stretching
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2024.127256

Two commercial polyesters, a virgin (VPET) and a recycled (RPET), were mechanically recycled in a closed loop with a pilot recycling line designed for bottle-to-bottle recycling. The stretchability after one, two and four loops were measured by uni-axial drawing experiments above the glass transition temperatures of the polymers. Thanks to the time-temperature equivalence principle, the materials were deformed in a physical state equivalent to the one encountered during the injection stretch-blow molding (ISBM) process. The mechanical recycling of the commercial VPET leads to a significant loss of drawability. The lower drawability of RPETs (commercial or produced by the pilot line) could explain the more numerous bottles explosions during ISBM. A microstructural interpretation is proposed through SEC chromatography and DSC analysis. [Display omitted] •Increase in hot crystallization of PET over mechanical recycling.•Decrease of PET stretchability in its rubbery state over mechanical recycling.•Time/temperature superimposition principle.•Variations of drawability upon mechanical recycling in correlation with first-order microstructural parameters.