The diffusion of simple penetrants in tangent site polymer melts
- Department of Materials and Metallurgical Engineering, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801 (United States)
- Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)
The diffuse behavior of penetrants in simple polymer melts was investigated by molecular dynamics simulation. For the case where the polymer melt consisted of pearl-necklace chains, the diffusive behavior of the loose pearl penetrants was seen to be qualitatively different than would be expected in realistic models of polymer melts. In particular, there was little or no {open_quotes}non-Fickian{close_quotes} region; the variation of the diffusion coefficient with the penetrant diameter was what one would expect for diffusion through small molecular liquids; and, finally, the long time tail of the velocity autocorrelation displayed a {open_quotes}{minus}3/2{close_quotes} power law form, also as in the small molecular liquid case. When the chains{close_quote} backbone motion was further constrained by the introduction of a bond angle potential, the qualitative nature of the penetrant diffusion became more {open_quotes}polymer-like.{close_quotes} A non-Fickian region developed; the diffusion coefficient varied more rapidly with penetrant diameter; and the velocity autocorrelation function developed a {open_quotes}{minus}5/2{close_quotes} power law tail. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 690698
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 21 Vol. 111; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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