Effect of recycled content and rPET quality on the properties of PET bottles, part III: Modelling of repetitive recycling

• Published in: Packaging technology & science Vol. 33; no. 9; pp. 373 - 383
• Main Authors: Brouwer, Marieke T., Alvarado Chacon, Fresia, Thoden van Velzen, Eggo Ulphard
• Format: Journal Article
• Language: English
• Published: Bognor Regis Wiley Subscription Services, Inc 01.09.2020
• Subjects: Accumulation; Bottles; Chlorine; Contaminants; contamination; Mathematical models; Modelling; Parameters; PET bottles; Polyethylene terephthalate; Properties (attributes); recycled content; Recycling; Recycling programs; Yellowing
• ISSN: 0894-3214; 1099-1522
• DOI: 10.1002/pts.2489

The presence of contaminants in polyethylene terephthalate (PET) bottles and derived materials from the various steps in the recycling loop is studied. Based on these measurements, a model is proposed to generically describe the accumulation of these contaminants within closed‐loop recycling schemes for PET bottles. The measured levels of particle contamination and chlorine content of PET bottles, pellets, and intermediate recycling products are used to derive the modelling parameters. Previously determined relations between these measured parameters and critical bottle properties are used to model the effect of the accumulation of the contaminants on the bottle properties. The measurements reveal that the type of collection system influences the accumulation of contaminants in PET bottles greatly. PET bottles in mono‐collection systems accumulate less contaminants than PET bottles in co‐collection systems do. Therefore, PET bottles within recycling schemes using mono‐collection systems can contain more recycled content than those from co‐collection systems, without exceeding acceptation limits on critical bottle properties such as haziness, yellowing, and migration. Within a closed‐loop recycling system for PET bottles contaminants enter the recycling loop at various stages of recycling.