Solute mobility and packing fraction: A new look at the Doolittle equation for the polymer glass transition

J Budzien and JD McCoy and DB Adolf, JOURNAL OF CHEMICAL PHYSICS, 119, 9269-9273 (2003).

DOI: 10.1063/1.1615231

Molecular dynamics simulations of the diffusion of penetrants in bead- spring polymers were performed along both constant volume and constant pressure paths at several temperatures. By using an effective hard sphere diameter, the packing fractions of these systems were calculated. It was found that all the data for a given polymer type collapsed to a single curve that can be well described using a modification of the Doolittle equation. Data on polymer simulations from the literature was analyzed in this manner and showed similar results. In this work we demonstrate that the packing fraction analysis that is used to describe hard sphere and colloidal systems can also be extended to polymeric systems. (C) 2003 American Institute of Physics.

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