Functional barriers: Properties and evaluation

Abstract

Functional barriers are multilayer structures deemed to prevent migration of some chemicals released by food-contact materials into food. In the area of plastics packaging, different migration behaviours of mono- and multilayer structures are assessed in terms of lag time and of their influence of the solubility of the migrants in food simulants. Whereas barriers to oxygen or to aromas must prevent the diffusion of these compounds under conditions of use, a functional barrier must also be efficient under processing conditions, to prevent diffusion of substances when the polymer layers are in contact at high (processing) temperatures. Diffusion in melted polymers at high temperatures is much slower for glassy polymers, than in polymers that are rubbery at ambient temperature. To evaluate the behaviour of functional barriers under conditions of use, a set of reference diffusion coefficients in the 40-60 degrees C range were determined for 14 polymers. Conditions for accelerated migration tests are proposed based on worst-case activation energy in the 40-60 degrees C range. For simulation of migration, numerical models are available. The rules derived from the models can be used both by industry (to optimize a material in terms of migration) or by risk assessors. Differences in migration behaviour between mono- and multilayer materials are discussed.

The future of simulants in compliance testing regarding the migration from food contact materials into food

“…Such solvent substitutes not only render the determination of overall migration more simple and reproducible, but are also a prerequisite for comprehensive migrate analysis (Grob, 2002). For multilayers, the lag time must be considered for components migrating from inner layers, particularly if migration is hindered by a functional barrier (Feigenbaum et al, 2005). Long-term storage is probably not correctly simulated by testing at 40°C during 10 days.…”

Simulation of the migration of mineral oil from recycled paperboard into dry foods by Tenax®?

“…Secondly, internal bags may function as a barrier. For some materials, the barrier efficiency is known from previous experience (Biedermann, Ingenhoff, Dima, et al 2013;Biedermann, Ingenhoff, Zurfluh, Forthcoming 2013); for others, it can be deduced from diffusion coefficients (e.g., Feigenbaum et al 2005) or determined by a test (e.g., Fiselier & Grob 2012).…”

Diffusion of homologous model migrants in rubbery polystyrene: molar mass dependence and activation energy of diffusion

“…Both models are able to describe the diffusion of additives in polyolefins, but prediction errors become significant when dealing with less mobile polymers or when enlarging the extrapolation range to high temperatures or M W values (Feigenbaum et al 2005;Dole et al 2006).…”