Stepwise isothermal crystallization

As examples, experimental F(E) isotherms at = constant for Pb and T1 UPD in acidic perchlorate electrolyte on AgQikl) single crystal faces with Qtkl) = (111) and (100) are shown in Figs. 3.9 and 3.10, respectively [3.97, 3.105]. These isotherms were measured stepwise, waiting for equilibrium conditions according to polarization routines illustrated in Fig. 3.11 using the twin-electrode thin-layer technique" (TTL) for Pb UPD and the flow-through thin-layer technique" (FTTL) for T1 UPD. 

In conditions of high viscosity of the metastable phase the time of establishment of a stationary concentration of nuclei becomes longer. The process of non-stationary nucleation may be characterized by the stationary nucleation rate J and the lag time. Non-stationary nucleation shows up in the crystallization of amorphous layers of water. The crystallization of such layers proceeds during continuous heating or an isothermal allowance after a stepwise rise in the temperature. 

In the case of g-CyD, the adsorption isotherm appears stepwise. That is, the moisture content is found to be about 12%(w/w) at 30% R.H. and is finally reached to about 20%(w/w). It is interesting to note that the 20%(w/w) moisture content corresponds to twelve water molecules on the crystallization of one g-CyD molecule as expected from a X-ray... 

Figure 21 Tg2 vs. T max for the PEEK samples isothermally cold-crystallized at low temperature (153 C, 3.0 h) and progressively reheated stepwise to increasingly higher temperature, rcmax- Filled sq uares correspond to the initially cold-ctystallized sample and to Tcmax of 170,176,186,194,205,227,257,271, and 305 °C. The lines are guides to the eye. With permission from Ivanov, D. A. Jonas, A. M. Legras, R. PolymerZm, 41,3719. ...

Fig. 5.49. Crystallization isotherms observed in density measurements on a PE sample with short chain branches. Note the difference in shape between the primary crystallizations at 100 °C or 96 °C and the subsequent crystallizations on stepwise cooling from 100 °C to 75 °C and 50 °C [58]...

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