Experimental direct evaluation of functional barriers in PET recycled bottles: comparison of migration behaviour of mono‐ and multilayers

Publisher Website
Google Scholar
Abstract
Recycling of used bottles into new bottles is associated with possible migration of pollutants arising from the previous life of the packages. To reduce or delay such migration, the recycled resin is depolluted or a functional barrier layer made of virgin plastics is used. Testing migration from such recycled bottles relies on the use of model pollutants (surrogates). In order to enable modelling of migration kinetics, each step of the use of surrogates is carefully investigated here in the case of PET. First, criteria underlying the selection of surrogates are carefully examined; together with volatility, polarity and diffusion behaviour, it is shown here that their solubility in the food simulant and their chemical stability strongly influence migration results. For aqueous test media, 2,4‐pentanedione and phenol should be used as surrogates. Second, a procedure is developed to impregnate surrogates at very large concentrations (several thousands of mg/kg PET) which are necessary to monitor migration kinetics. This procedure, which uses dichloromethane as solvent, allows a quick and reproducible impregnation, not sensitive to temperatures between 11–23°C, factors which favour its use at a plant scale. Third, flakes impregnated with this procedure are processed into bottles, and their physicochemical properties are compared to those of commercial bottles. Last, monolayer and tri‐layer polluted bottles (model pollutants in inner layer) are tested for migration for more than 1.5 years. With multilayers, the migration lag time of the fastest surrogates is 6 months with 3% acetic acid and 3 months with ethanol as the simulant, due to plasticization of PET by ethanol. The sequence of migration of surrogates is different with monolayer and multilayer bottles, which shows that partition effects (solubility) play an essential role, especially with monolayer materials. Copyright © 2005 John Wiley & Sons, Ltd.
Funding Information
  • ECO-EMBALLAGES, France
  • ADEME, France
  • INRA, France
  • Région Champagne Ardenne

This publication has 21 references indexed in Scilit: