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1997
Conference Paper
Titel
Testing and Evaluation of Recycled PET for Direct Food Contact Application
Abstract
Due to modern enviromental packaging requirements the question of recyclability of used packaging plastics into new food packaging applications is of increasing interest. This question is currently still enforced since usual market applications for recycled plastics in the non-food area seem to approach saturation. Indeed, recycled plastics have already been used in food-contact plastics since several years around the world. However, these cases must be considered to have more pilot character than real market value, and, in most cases, the mass fraction of recycled plastics in these applications was relatively low, due to blending with virgin plastics or sandwiching with functional barrier layers of relatively high thickness extruded also from virgin polymer. Although considerable progress has been made from a scientific point-of-view in understanding and physico-mathematical modeling of diffusion processes of adventitious hazardous compounds from a recycled plastic in direct contact with food or from a core layer across a functional barrier, the translation into action of this knowledge about migration into industrial solutions remains still in a waiting position. One of the reasons has more "European" character and can be substantiated by the fact that the European legal requirements in this respect are not yet precisely defined. Whereas in the US a very concrete concept, the so-called "threshold-of-regulation" principle has been established and adopted by FDA. Another reason is clearly the non-availability of simple and economic test methods which in addition would need to have the status of generally accepted procedures and in the best case of standard test procedures. The aim of this work was to challenge the recycling process of OHL Paul Stehning GmbH, Limburg/Lahn, Germany, for used polyethylene terephthalate (PET) soft drink bottle with respect to its cleansing efficiency for artificially introduced model contaminants. The practical question was to investigate the potetial of this process to provide purified post-consumer PET suitable again for direct food contact application. Another point of interest was to design the challenge test in a most economic way thus saving time and unnecessary amounts of hazardous waste.
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