Study shows PET bottles can benefit from clean recyclates
Researchers from the Wageningen Food & Biobased Research in the Netherlands are discovering the effects of rPET on the properties of the bottles and on the quality of the contents of the bottles.
Polyethylene terephthalate (PET) is a widely used packaging material for beverage bottles, and these days more and more recycled PET (rPET) is used for the production of PET bottles, in order to make these packages more circular.
But an unanswered question is what the effects of the use of rPET are on the bottle properties and where possible limits lie. And the answer is not unimportant, because it determines the level of rPET that businesses can use in their bottles.
Researchers from the Wageningen Food & Biobased Research, located in Wageningen, Netherlands, are now considering this issue – their 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 and discolouration of the bottles, and the strength of the bottle.
The study is part of the scientific research program 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 organization FWS (soft drinks, water and juices).
Three types of rPET available on the market, with different qualities, were used in the study, with hundreds of bottles being created at a small production location. 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.
The researchers concluded that 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, which 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.