Glycerol has

PHYSICS · Multi-part · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Crystal structure, bonding and diffraction · Crystal structure, bonding and diffraction

Solid State Physics, Ch Solids without a lattice: glasses and quasicrystals

Problem

Glycerol has Tg=190 KT_g=190\,\mathrm{K}, measured at the standard cooling rate that defines η(Tg)=1012 Pa s\eta(T_g)=10^{12}\,\mathrm{Pa\,s}, and a Vogel-Fulcher fragility m=53m=53. A calorimetry run cools the sample 10410^4 times more slowly than the standard rate. ((a)) Using the result that one decade of cooling rate shifts TgT_g by about Tg/mT_g/m, find the size of the shift in TgT_g produced by this change in rate. ((b)) State the new TgT_g for the slow run and explain, in terms of the kinetic-arrest condition τrelax(Tg)=texp\tau_{\rm relax}(T_g)=t_{\rm exp}, why the shift is downward rather than upward.

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