Organic glass formers

Figure 3,17 Correlation between the characteristic temperature To (= To, in the text) and the glass transition temperature T for a scries of organic glass formers. (After Richert and Basslcr, 1990)...

For many organic glass formers, = (constant/7) and can therefore be calculated at Tg (or any single temperature), permitting Tito be estimated. 

Hansen, C., Richer , R., and Fischer, E. W, Dielectric loss spectra of organic glass formers and Chamberlin cluster model, J. Non-Cryst. Solids, 215, 293-300 (1997). 

FIGURE 5.23 Mean spin-lattice relaxation time ( H NMR experiments) as a function of temperature of neat polystyrene PS-tij and with addition of 13% of benzene. (Adapted from J. Mol. Liquid., 86, Vogel, M., Medick, R, and Rbssler, E., Slow molecular dynamics in binary organic glass formers, 103-108, 2000, Copyright 2000, with permission from Elsevier.)... 

Vogel, M., Medick, R, and Rossler, E. 2000. Slow molecular dynamics in binary organic glass formers. J. Mol. Liquid. 86 103-108. 

Although the temperature dependence of r for amorphous polymers is described well by the WLF equation, as shown in Fig. 2.19, this is usually not the case for small-molecular organic glass-formers. Over an extended temperature range with r varying from say 10 U or shorter to 10 s or longer, the temperature dependence is of Arrhenius form at short r, but at longer times it is necessary to use one VFTH equation followed by another in order to describe the temperature dependence fully [158,159]. 

KUDLIK A, BENKHOF s, BLOCHOWicz T, TSCHiRwrrz c, ROSSLER E (1999), The dielectric response of simple organic glass formers , / Mol Struct, 479,201-218. 

A number of nuclear magnetic resonance (NMR) textbooks and review articles that focus on the dynamics in supercooled liquids comprised of organic molecules [2,11,12,15], on polymer specific dynamics [71-75], and on ionic or inorganic glasses [76-79] exist. In these contributions, the theoretical background of NMR techniques and models of molecular motion have been comprehensively discussed. Therefore, we curtail the theoretical part and concentrate on selected NMR techniques applied most frequently to the investigation of molecular glass formers. 

There exist a number of both inorganic and organic substances which form glass when cooled from the liquid state at a rate that does not provide conditions for the formation of a regular structural lattice. The following inorganic glass formers can be mentioned ... 

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