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Welle F.,Fraunhofer Institute for Process Engineering and Packaging
Resources, Conservation and Recycling | Year: 2011

Polyethylene terephthalate (PET) has become the most favourable packaging material world-wide for beverages. The reason for this development is the excellent material properties of the PET material, especially its unbreakability and the very low weight of the bottles compared to glass bottles of the same filling volume. Nowadays, PET bottles are used for softdrinks, mineral water, energy drinks, ice teas as well as for more sensitive beverages like beer, wine and juices. For a long time, however, a bottle-to-bottle recycling of post-consumer PET packaging materials was not possible, because of the lack of knowledge about contamination of packaging polymers during first use or recollection. In addition, the decontamination efficiencies of recycling processes were in most cases unknown. During the last 20 years, PET recollection as well as recycling processes made a huge progress. Today, sophisticated decontamination processes, so-called super-clean recycling processes, are available for PET, which are able to decontaminate post-consumer contaminants to concentration levels of virgin PET materials. In the 1991, the first food contact approval of post-consumer PET in direct food contact applications has been given for post-consumer recycled PET in the USA. Now, 20 years after the first food approval of a PET super-clean recycling process, this article gives an overview over the world-wide progress of the bottle-to-bottle recycling of PET beverage bottles, e.g. the recollection amount of post-consumer PET bottles and the super-clean recycling technologies. © 2011 Elsevier B.V. All rights reserved. Source


Welle F.,Fraunhofer Institute for Process Engineering and Packaging
Journal of Applied Polymer Science | Year: 2013

Poly(ethylene terephthalate) (PET) is used in several packaging applications, especially for beverages. Due to the low concentration of potential chemical compounds like polymer additives or monomers leached out of the polymers and found in food or beverages, the compliance of a PET packaging material is shown often by use of migration modeling. Diffusion coefficients for migrants, however, are rare in the scientific literature. The aim of the study was to develop an equation for the prediction of diffusion coefficients in PET on the basis of activation energies of diffusion for possible migrants in PET. As a result, a correlation between experimentally determined activation energies of diffusion EA and the volume of the migrant V was established for PET. In addition, a correlation of the pre-exponential factor D0 with the activation energy EA was found. Combining both correlations lead to an equation where the diffusion coefficients DP are predictable from the molecular volume V of the migrant. The equation might be useful for migration prediction and consumer exposure estimations. © 2012 Wiley Periodicals, Inc. Source


Schmid M.,Fraunhofer Institute for Process Engineering and Packaging | Schmid M.,TU Munich
Materials | Year: 2013

Whey protein isolate (WPI)-based cast films are very brittle, due to several chain interactions caused by a large amount of different functional groups. In order to overcome film brittleness, plasticizers, like glycerol, are commonly used. As a result of adding plasticizers, the free volume between the polymer chains increases, leading to higher permeability values. The objective of this study was to investigate the effect of partially substituting glycerol by hydrolysed whey protein isolate (h-WPI) in WPI-based cast films on their mechanical, optical and barrier properties. As recently published by the author, it is proven that increasing the h-WPI content in WPI-based films at constant glycerol concentrations significantly increases film flexibility, while maintaining the barrier properties. The present study considered these facts in order to increase the barrier performance, while maintaining film flexibility. Therefore glycerol was partially replaced by h-WPI in WPI-based cast films. The results clearly indicate that partially replacing glycerol by h-WPI reduces the oxygen permeability and the water vapor transmission rate, while the mechanical properties did not change significantly. Thus, film flexibility was maintained, even though the plasticizer concentration was decreased. © 2013 by the authors; licensee MDPI, Basel, Switzerland. Source


Welle F.,Fraunhofer Institute for Process Engineering and Packaging
Resources, Conservation and Recycling | Year: 2016

The cleaning efficiency of a PET recycling process is typically investigated by artificial contamination of post-consumer PET flakes within a so-called challenge test. Challenging of pilot plants or industrial scale lines is done be introducing a certain amount of contaminated flakes while running the process with non-contaminated flakes of different colour. After decontamination the contaminated flakes are separated from the non-contaminated flakes and only the contaminated flakes were analysed due to their residual contamination level. The European Food Safety Authority (EFSA), however, raised the question about cross-contamination, which might reduce the overall cleaning efficiency of the recycling process. Cross-contamination is defined as the transfer of surrogate contaminants from the initially contaminated to the initially not contaminated material during a challenge test. Data for the phenomenon of cross-contamination are not available in the scientific literature. Aim of the study was to close this gap by providing experimental data for cross-contamination by use of several challenge tests. As a result cross-contamination was found only at ratios of 1:1 between contaminated and non-contaminated PET flakes. At higher ratios which were typically applied in challenge tests on pilot plant or industrial scale line cross-contamination do not play a significant role. In addition, the results show that cross-contamination is negligible for volatile compounds. © 2016 Elsevier B.V. All rights reserved. Source


Herbig J.,IONICON Analytik GmbH | Beauchamp J.,Fraunhofer Institute for Process Engineering and Packaging
Journal of Breath Research | Year: 2014

Despite growing interest and considerable progress in breath research over the last decade, standardized practices for the sampling and analysis of breath gas volatiles remain elusive. The primary reasons for this are (a) the rich chemical diversity of exhaled breath that covers an extensive range of volatile organic compounds at highly varied concentrations, (b) the vast disparity in the analytical tools employed, (c) diverse study goals and (d) the presence of (unidentified) confounders. These aspects place stringent but divergent demands on sampling and analysis: each analytical tool, target compound and concentration range requires its own specific protocol and in many cases the latter two are not even known a priori. The ongoing rapid developments and constant discoveries in the field of breath research and the lack of established best practices in breath gas sampling and analysis currently preclude an acceptable overall standardization of these methods. This paper addresses these manifold issues and suggests a framework that separately considers individual stages of sampling and analysis with a view to establishing standardization in the analysis of breath gas volatiles to suit different target compounds and analytical technologies. © 2014 IOP Publishing Ltd. Source

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