Glass pressure dependency

The site entropy is thus a sensible candidate for describing fluid relaxation outside the immediate vicinity of the glass transition. In a more precise language, is actually an entropy density, and the maximum in Sc T) derives from an interplay between changes in the entropy and fluid density as the temperature is varied. Explicit calculations demonstrate that the maximum in Sc T) disappears in the limit of an incompressible fluid, which is physically achieved in the limit of infinite pressure. The pressure dependence of Sc T) is described in Section X, where it is found that the maximum in Sc T) becomes progressively shallower and 7a becomes larger with increasing pressure. 

Fig. 6. Specific volume pressure curves for the l.c. polymer shown in Fig. 5. Thin dashed lines pressure dependence of the phase transformation temperatures l.c. to isotropic, Tc, and the glass transition temperatures, T , full line specific volume-temperature cut at 2000 bar (isothermal measurements)...

Taking the e (T) peak temperature (Tm) to be representative of the dynamic glass transition temperature of pmn, the inset in Figure 15.6 shows the pressure dependence of Tm. The... 

Figure 5. The pressure dependence of the structure factor for Si02 glass at room temperature (from Ref. [17] with the authors permission)...

Apart from the low-resolution vapor spectrum reported by Glass, Robertson and Merritt 46>, no other study of the second system is available. It is therefore not possible to discuss line shapes in the vapor-phase spectrum in relation to the decay rates of the two-component fluorescence. More information is avEiilable for the crystal, but in the condensed phase the decay rate of the intermediate pressure-dependent fluorescence may have been considerably increased, as is the case for benzophenone. 

The system pressure dependence of the deposition rate onto the electrode surface in DC, 40-kHz, and 13.56-MHz discharges are shown in Figure 8.8. In order to see the influence of electrical contact, some silicon wafers were electrically insulated from the substrate plate used as the cathode by placing a thin slide cover glass between the silicon wafer and the substrate. The influence of the electrical contact on deposition rate onto the electrode and onto the floating substrate is shown in Figures 8.8-8.10 as a function of system pressure. In the lower part of the figures, the influence of the same factors on the refractive index is shown. The scale of the deposition rate axis is different for each case in order to show the system pressure dependence clearly in each case. 

The excess internal pressure required to expand this bubble will be PI where Pi > P. Since X for any type of glass will depend on the temperature only, then at any given temperature... 

Figure 18 Pressure dependence of the CO2 permeability through a microporous glass membrane. Experimental results are compared to theory of combined gaseous and surface flow. (I Barrer = 3.35 X 10" mol m m Pa -sec". ) (Adapted from Ref. 38.)...

We now discuss the impact of this general property on theories and models of the glass transition. The primary concern of most theories is to explain the temperature and pressure dependences of the structural relaxation time ra. The dispersion (n or >kww) °f the structural relaxation is either not addressed or... 

There are also glass-formers that have a resolved secondary relaxation that is not the JG relaxation according to the established criteria [38], but lack an apparent JG peak in their loss spectra at ambient pressure. These glass-formers include BMPC [75], dibutyl phthalate (DBP) [77], diethyl phthalate (DEP) [76], 2PG, 3PG [101,102], m-fluroaniline (m-FA) [44], and bis-5-hydroxypentylphthalate (BHPP) [228,229]. One criterion is the lack of a pressure dependence of their relaxation times, as shown for BMPC in Fig. 30. NMR measurements of molecular motion in BMPC had shown [230] that the... 

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