Polyethylene terephthalate (PET) is a widely used packaging material for beverage bottles. More and more recycled PET (rPET) is used for the production of PET bottles, in order to make these packages more circular. The question is what the effects are of the use of rPET on the bottle properties and where possible limits lie.
Wageningen Food & Biobased Research researched the effects of rPET on the properties of the bottles and on the quality of the contents of the bottles. Based on the results of this research, businesses can make a well-founded decision to use a certain level of rPET in their bottles. This study is part of the scientific research programme of the Netherlands Institute for Sustainable Packaging and the Top Institute Food and Nutrition. The research was supervised by an industrial advisory board with representatives from three soft drink manufacturers and the branch organisation FWS (soft drinks, water and juices).
The main research question was whether and to what extent the use of rPET influences the migration of substances to the contents of the bottle, the degree of haze (a technical term for the optical transparency of the bottle) and discolouration of the bottles, and the strength of the bottle. Three types of rPET available on the market, with different qualities, were used in the study. Hundreds of bottles were created at a small productionlocation. The bottles were produced with different concentrations of rPET, specifically: 25%, 50%, 75% and 100% rPET. In addition, bottles were produced with 100% virgin PET.
Conclusions and recommendations
The material properties of PET bottles are influenced by the quality of the recycled material (rPET) and the grade in which it is used in the bottles. Recycled PET contains contaminants that can accumulate through successive recycling. This causes PET bottles to become darker, yellower, and less transparent with every cycle. Furthermore, more substances migrate. These risks can be limited by opting for high-quality rPET, e.g. from a mono-collection system such as the deposit refund system.