STUDY OF FUNCTIONAL BARRIER PROPERTIES OF MULTILAYER RECYCLED POLY(ETHYLENE-TEREPHTHALATE) BOTTLES FOR SOFT DRINKS

Poly(ethylene terephthalate) (PET) flakes were ground, contaminated, w ashed, manufactured into multilayer preforms and bottles, and then tes ted for migration. The model contaminants were toluene, trichloroethan e, chlorobenzene, phenyldecane, benzophenone, phenylcyclohexane, and c opper(II) acetylacetonate. No migration was detected through a barrier of virgin PET (186 +/- 39 mu m) into 3% acetic acid food simulant usi ng general methods of testing with a detection limit of 1 mu g kg(-1). Migration was < 1 mu g kg(-1) even for 6-month-old bottles placed in contact with the simulant for a further 6 months; that is, a test peri od considerably in excess of the shelf life of soft drinks. Neither wa s migration detectable in the more severe simulating solvents (e.g., 5 0% aqueous ethanol and 100% ethanol). Targeted analysis by gas chromat ography-mass spectroscopy was then used to achieve a sub microgram per kilogram Limit of detection and establish the performance of the barr ier. Three-layer bottles with the contaminated PET buried were compare d with 1-layer bottles in which contaminated PET contacted the food si mulant directly. Migration into 3% acetic acid from 1-layer bottles wa s from (0.2 to 57 mu g kg(-1), and the worst-case substance was chloro benzene. Migration from 3-layer bottles was from <0.2 up to 0.4 mu g k g(-1), and the worst-case substance was toluene. Therefore, the virgin PET layer reduced migration from an already low level, by more than 2 orders of magnitude.