Gas Diffusion in Polyethylene Terepthalate By Molecular Dynamics

Molecular dynamics simulations of the diffusion of small penetrants through PET have been performed utilising the anisotropic united atom model [1] and a virtual liquid technique. [2] The accuracy and reliability of these two approaches has been assessed in terms of the improvement in equation of state behaviour and of diffusion co-efficients and solubilities. The effect of the diffusion of nitrogen, carbon dioxide, and oxygen on the local dynamics of PET have been investigated as a result. Attention has been focused on the dual mode effect [3] observed during mixed gas diffusion. \newline \newline [1] \textit{Molecular dynamics calculation of the equation of state of alkanes}, J. Chem. Phys. \textit{93}, 6 (1990) \newline [2] Kikuchi, Kuwajima, Fukada, \textit{Novel method to estimate the solubility of small molecules in cis-polyisoprene by molecular dynamics simulations}, J. Chem. Phys, \textit{115}, 13 (2001) \newline [3] Lewis, Duckett, Ward, Fairclough, Ryan, \emph{The barrier properties of polyethylene terephthalate to mixtures of oxygen, carbon dioxide and nitrogen}, Polymer, \emph{1631}, 44 (2003)