Molecular dynamics simulation on diffusion of 13 kinds of small molecules in polyethylene terephthalate

Abstract

Understanding the diffusion of migrants in polyethylene terephthalate (PET) and calculating the diffusion coeffi cients are very important for migration research. In this study, the diffusion coeffi cients of 13 kinds of small molecules with molecular weights ranging from 32 to 339 g/mol in amorphous PET are calculated based on molecular dynamics (MD) simulation. By comparison of diffusion coeffi cients simulated by MD simulation techniques, predicted by the Piringer model and by experiments, the accuracy of the Piringer model and MD simulation techniques for the estimation of diffusion coeffi cients of migrants in PET is evaluated. The MD simulation shows that D simu is very close to D exp , within one order of magnitude of the experimental diffusion coeffi cients except for a few samples. The possible reasons for the differences among D simu , D pred and D exp are analysed from the molecular weight and temperature. The results show that the Piringer-model-predicted values at high temperatures overestimate signifi cantly higher than that at lower temperatures. The activation energy is calculated by the Arrhenius equation, which shows the relationship between diffusion coeffi cient and temperature. It is shown that the MD simulation yields acceptable activation energy. The study suggests that MD simulation may be a useful approach to calculate the diffusion coeffi cients of small molecules in PET.

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

“…There are also some reports about the diffusion of small non-polar gases (oxygen, carbon dioxide) and water in PET (Pavel & Shanks 2005;Eslami & Müeller-Plathe 2009b;Liao et al 2013). However, MD simulation methods based on the prediction of diffusion coefficients are scarce and rarely applied to molecules as large as polymeric plastic additives; there is only one scientific study published about the diffusion of 13 kinds of molecules with molecular weight ranging from 32 to 339 g mol −1 (Wang et al 2010b). …”

Interacciones empaque-alimento: migración

“…Un estudio en el que fueron comparados los valores de migración obtenidos con el modelo Piringer y los experimentales reportó que dicho modelo sobre-estimó los valores experimentales sobre todo a bajas temperaturas [23]. En otro estudio se encontró que para el 95 % de los casos de migración evaluados, el modelo Piringer generó valores más altos que los valores reales de migración [24].…”

Temperature dependency of gas barrier properties of biodegradable PP/PLA/nanoclay films: Experimental analyses with a molecular dynamics simulation approach

“…Moreover, molecular dynamics (MD) simulation of oxygen permeability was accomplished for the neat polymers and the blends . Furthermore, the barrier properties of blends can be predicted by MD simulation which gives a theoretical insight into the diffusion of gases through polymeric films …”