A new method for the prediction of diffusion coefficients in poly(ethylene terephthalate)

Abstract

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

Molecular surface area based predictive models for the adsorption and diffusion of disperse dyes in polylactic acid matrix

“…The present work has three distinctive advantages. First, the previous models typically overestimated the diffusion coefficients [48]. The degree of overestimation was not known.…”

“…Other studies had also suggested that the activation energies of penetrant diffusion could be described by the molecular volume or mass of penetrant [47,48]. In this study, the molecular surface area is chosen as the molecular size parameter since it gives a better fitting result.…”

A model study into the migration potential of nanoparticles from plastics nanocomposites for food contact

“…Although the nanoscale substance used in this study is not a molecule but a particle, it can be reasonably assumed that an increasing particle size results in a higher free cross section of the particle which leads to a lower mobility of the nanoscale migrant. The size dependent mobility has recently been demonstrated for chemical substances in polyethylene terephthalate (Welle, 2013). Therefore, we consider monochemical nanoparticles (existing of carbon) as quasi-molecules for which, depending on the particle size quasi-molecular weights can be calculated.…”

Molecular dynamics simulation of three plastic additives’ diffusion in polyethylene terephthalate

“…However, migration experiments are commonly time consuming, expensive and often hard to carry out at extreme conditions. Consequently, some empirical and semiempirical equations have been developed to estimate the diffusion coefficient of migrants from food-contact substances (Welle 2013). The currently general accepted equation is the so-called Piringer equation (European Commission 2015).…”