Translation-rotation paradox for diffusion in glass-forming polymers: The role of the temperature dependence of the relaxation time distribution. Hall, David B.; Dhinojwala, Ali; Torkelson, John M. Dep. Chem. Eng., Northwestern Univ., Evanston, IL, USA. Phys. Rev. Lett. (1997), 79(1), 103-106. CODEN: PRLTAO ISSN: 0031-9007. Journal written in English. CAN 127:162339 AN 1997:434152 CAPLUS

Comparisons are made of the translational and rotational diffusion of small-mol. probes in a polymer near its glass transition temp., Tg. In the rubbery state, 1.1 Tg > T > Tg, translational diffusion is much less temp. dependent than rotational reorientation; in a "quenched" glass, translation and rotation have similar temp. dependencies. This is explained to be a consequence of the fact that in the rubbery state near Tg the breadth of the polymer relaxation distribution is strongly temp. dependent, while in the quenched glass it is temp. invariant.