Crystallization time shift

Along with this lengthening of the crystallization time the particle size maximum is shifted towards larger diameters (Figure 3, bottom). 

If we could arrange the demixing experiment (Fig. 8-2) such that the vacancy flux (caused by the activity difference at opposite surfaces) remains constant and the crystal therefore shifts with constant velocity, we could calculate the time required to attain the steady state with... 

As-received UD90 was oxidized for 2, 6,17, 26, and 42 h at 430°C, which is the temperature for slow ND oxidation as discussed in Sect. 5.3.3 [94]. Figure 12.18a shows the HRTEM images of two ND powders oxidized at 430°C for 2 and 42 h, respectively. The weight loss due to oxidation was 13% and 74% after 2 and 42 h, respectively. While oxidation for 2 h removes mainly amorphous carbon and other non-diamond species [95], longer oxidation times result in selective oxidation of smaller crystals, thus shifting the size distribution toward larger values. 

Figure 5.149 (right) shows the profile of melt and crystallization behavior prior and subsequent to irradiation for a PA 6-GF30. Irradiation causes a shift in melt temperature to lower temperatures because the crystalline structure is disturbed. Only amorphous zones can be crosslinked. The crosslinking points act as interruption points for a higher order level. At the same time, melt enthalpy is reduced and crystallization temperature shifts to lower temperatures [720]. 

The crystallization time dependence of the T s is similar to the behavior of crystallinity. This means that the molecular motion of the crystalline phase is restricted as soon as the stable crystalline structure is formed. In other words, after the size of the crystallite reached a certain size, the molecular mobility of the crystalline phase is fixed. In Figure 8.21b, the crystallization time dependence of for the amorphous phase is shown. The T s for the amorphous phase are less than 5 s, which is much shorter than those for the crystalline phase, and means that the molecular mobility is high compared with that for the crystalline phase. The TjS for all the carbons in the amorphous phase are about 1 s or less and do not change very much until 6h. After crystallization for 6h, the T s of ccg (CH2 directly bonded to nitrogen) and CO increased. This means that the molecular motion of the amorphous phase is restricted after the T s for the crystalline phase became constant. The mobility of the amorphous phase is affected by the surrounding crystalline phase. From the chemical shift differences, the gauche conformation exists and the distribution of the structure is large in the amorphous phase. 

Figures 5.24 and 5.25 contain measurements at different crystallization temperatures and indicate a specific temperature dependence of the crystallization time. The shifts of the isotherms with temperature correspond to the law...

Figure 4.8 Fraction of amorphous polyethylene as a function of time for crystallizations conducted at indicated temperatures (a) linear time scale and (b) logarithmic scale. Arrows in (b) indicate shifting curves measured at 126 and 130 to 128°C as described in Example 4.4. [Reprinted with permission from R. H. Doremus, B. W. Roberts, and D. Turnbull (Eds.) Growth and Perfection of Crystals, Wiley, New York, 1958.]...

The increase in the Cd content in the Sn + Cd alloy surface layer can also be deduced from the shift with time in the negative direction of polarization (log i,E) curves of SjOl" reduction. X-ray radiation investigations of Sn + Cd alloys show that the alloy consists of Sn crystals (of average size 2 to 3 fim) and substantially smaller Cd crystals arranged along the grain boundaries.824... 

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