Use of Migration Modelling for food contact materials :
Exercises
Download SML Exercises : Use of Migration Modelling for food contact materials (pdf, 6.7 MB)
Guideline for the Mathematical Estimate of the Migration of Individual Substances from Organic Material in Drinking Water
Introduction
The mathematical estimate of migration can be used in place of experimental proof to verify the requirements of KTW, Coating or Lubricant Guidelines for the migration of individual substances.
Organic material, such as plastics, which comes into contact with drinking water, can release substances into the water (mass transfer or migration). This lowers the concentration of substances in the organic material and increases it in water (mass transport). The stage that determines the speed of the mass transfer is the diffusion of the substance in organic material. The transfer of substances from organic material in drinking water can be measured in a laboratory (performance of the migration test and analysis of the test water on formulation-specific individual substances with a migration restriction) under standard conditions (surface-volume ratio, number of change cycles, time, temperature) or can be calculated by simulation using diffusion models (modelling). Annex 1 illustrates the involvement of simulation in assessing organic material in contact with drinking water.
Leitlinie zur mathematischen Abschätzung der Migration von Einzelstoffen aus organischen Materialien in das Trinkwasser
Einleitung
Die mathematische Abschätzung der Migration kann verwendet werden, um die Anforderungen der KTW-Leitlinie, Beschichtungsleitlinie oder der Schmierstoffleitlinie an die Migration von Einzelstoffen anstelle eines experimentellen Nachweises zu überprüfen.
Organische Materialien – zum Beispiel Kunststoffe –, die Kontakt mit Trinkwasser haben, können Stoffe an das Wasser abgeben (Stoffübergang oder Migration). Dabei sinkt die Konzentration der Stoffe in dem organischen Material und nimmt im Wasser zu (Stofftransport). Der geschwindigkeitsbestimmende Schritt des Stoffübergangs ist die Diffusion der Stoffe im organischen Material. Der Übergang von Stoffen aus organischen Materialien ins Trinkwasser kann einerseits unter standardisierten Bedingungen (Oberflächen-Volumen-Verhältnis, Anzahl Wechselzyklen, Zeit, Temperatur) im Labor gemessen (Durchführung des Migrationstests und Analyse des Prüfwassers auf rezepturspezifische Einzelstoffe mit einer Migrationsbeschränkung) oder andererseits durch Simulation auf der Basis von Diffusionsmodellen (Modellierung) berechnet werden. In der Anlage 1 ist die Einbindung der Simulation bei der Beurteilung von organischen Materialien im Kontakt mit Trinkwasser dargestellt.
Application of Finite Element Analysis (FEA) for the simulation of release of additives from multilayer polymeric packaging structures
1AKTS AG – Advanced Kinetics and Technology Solutions, TECHNOArk 1, Siders, Switzerland, and
2Swiss Federal Office of Public Health, Division of Food Science, Bern, Switzerland
Abstract
Computer programmes are available to predict, for consumer protection purposes, the migration of additives from a polymeric package during its contact with food. However most of these programs were developed to estimate migration only from single layer polymeric packaging under isothermal conditions. In this work a diffusion model was developed to simulate the migration from multilayer packaging and under non-isothermal temperature conditions, too. Finite Element Analysis (FEA) is used as a numerical approximation method to solve the diffusion equations describing such processes. The possibilities and limitations of the FEA method are presented and the correlation between experimental and computed results is discussed.
Simulation of Deterrent Diffusion in Double Base Propellant Under Different Temperature Profiles
1AKTS AG, http://www.akts.com, TECHNOArk 1, 3960 Siders, Switzerland, b.roduit@akts.com
2MDCTec Systems GmbH, Gutenbergstrasse 5, 82205 Gilching, Germany
3armasuisse, Science and Technology Centre, 3602 Thun, Switzerland
4Nitrochemie Wimmis AG, 3752 Wimmis, Switzerland
5Royal Military Academy, Avenue de la Renaissance 30, 1000 Bruxelles, Belgium
6PB Clermont s.a., Rue de Clermont 176, 4480 Engis, Belgium
Abstract
Propellants can burn so rapidly that the initial rise of pressure in weapons may be faster than desired. To avoid this unwanted effect, burning rate of the propellants is moderated by applying a surface coating. Coating agents are usually deterrents (moderants), substances that gelatinize or plasticise the nitrocellulose matrix of the propellants decreasing its initial burning rate, therefore, in turn, the rate of gaseous phase formation. The knowledge of the diffusion rate of deterrents helps therefore in developing propellants with superior ballistic performance. Another parameter, namely the rate of the migration of deterrent into the propellant matrix during ageing / storing is also important as it influences the ballistic shelf-life i.e. the period of time during which the ballistic requirements are fulfilled. As migration measurements are often difficult, expensive and timeconsuming the development of the simulation tools of above processes seems to be of a great importance. The present paper describes the simulation method for deterrent and blasting oil diffusion in double base propellant applying the temperature dependence of the diffusion coefficients D determined in isothermal experiments and taking into account the influence of the swelling effect of the propellant matrix. The simulations were done using the AKTS-SML software [1], which allowed considering the migration of both, deterrent and nitroglycerine through the swollen matrix of the propellant. Furthermore, after determination of the temperature dependence of the diffusion coefficient D, it was possible to predict the deterrent migration under any, arbitrarily chosen temperature profile such as oscillatory temperature mode, real atmospheric temperature profiles or under temperature mode corresponding to atmospheric changes according to STANAG 2895 [2].
Download: Simulation of Deterrent Diffusion in Double Base Propellant Under Different Temperature Profiles (pdf, 239 KB)
Diffusion Coefficients of Antimony Catalyst in Polyethylene Therephthalate (PET) materials :
Download: Diffusion Coefficients of Antimony Catalyst in Polyethylene Therephthalate (PET) materials (pdf, 75 KB)
Food Contact Materials Compliance Database :
Risk assessment and management tool
Download: Food Contact Materials Compliance Database (pdf, 564 KB)
Presentation and Exercises