Fri, 25 Jul 2008 09:04:03 BST CiteULike: dchens glass-transition http://www.citeulike.org/user/dchen/tag/glass-transition CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2067349 <i>Physical Review Letters, Vol. 79, No. 1. (7 July 1997), 103.</i><br /><br />Comparisons are made of the translational and rotational diffusion of small-molecule probes in a polymer near its glass transition temperature; T g . In the rubbery state; 1.1 T g > T > T g ; translational diffusion is much less temperature dependent than rotational reorientation; in a “quenched” glass; translation and rotation have similar temperature dependencies. This is explained to be a consequence of the fact that in the rubbery state near T g the breadth of the polymer relaxation distribution is strongly temperature dependent; while in the quenched glass it is temperature invariant. Translation-Rotation Paradox for Diffusion in Glass-Forming Polymers: The Role of the Temperature Dependence of the Relaxation Time Distribution David Hall Ali Dhinojwala John Torkelson doi:10.1103/PhysRevLett.79.103 Physical Review Letters, Vol. 79, No. 1. (7 July 1997), 103. 2007-12-06T15:38:54-00:00 1997 Physical Review Letters 79 1 103 American Physical Society diffusion glass-transition journalclub polymer rotation transition http://www.citeulike.org/user/dchen/article/1875802 <i>The Journal of Chemical Physics, Vol. 116, No. 12. (2002), pp. 5158-5166.</i><br /><br />We present molecular dynamics simulations of a binary Lennard-Jones mixture at temperatures below the kinetic glass transition. The "mobility" of a particle is characterized by the amplitude of its fluctuation around its average position. The 5% particles with the largest/smallest mean amplitude are then defined as the relatively most mobile/immobile particles. We investigate for these 5% particles their spatial distribution and find them to be distributed very heterogeneously in that mobile as well as immobile particles form clusters. We suggest that this dynamic heterogeneity may be due to the fact that mobile/immobile particles are surrounded by fewer/more neighbors which form an effectively wider/narrower cage. The dependence of our results on the length of the simulation run indicates that individual particles have a characteristic mobility time scale which can be approximated via the non-Gaussian parameter. ©2002 American Institute of Physics. Dynamical heterogeneities below the glass transition Vollmayr Lee W Kob K Binder A Zippelius doi:10.1063/1.1453962 The Journal of Chemical Physics, Vol. 116, No. 12. (2002), pp. 5158-5166. 2007-11-07T01:07:08-00:00 2002 The Journal of Chemical Physics 116 12 5158 5166 AIP glass-transition heterogeneity