Comparison of crystal growth rates

Comparison of crystal growth rate coefficients measured in ISC and FBC... 

Figure 4-7 Comparison of crystal growth rate (dashed curve) and nucleation rate (solid curve) as a function of temperature. The equilibrium temperature (marked by the vertical dashed line) is 1664.15 K. The peak crystal growth rate is attained at an undercooling of 120 K, but the peak nucleation rate is attained at an undercooling of 845 K. At a mere undercooling of 10 K, the crystal growth rate is 20% of the peak crystal growth rate. For the nucleation rate to be 20% of the peak nucleation rate, an undercooling of 750 K is necessary.

The structure of a experimental fluidized bed crystallizer (FBC) is shown in Fig. 12.4, where the crystallizer is actually a universal equipment for the measurement of crystal-growth rate. The solution enters the FBC at its bottom, and leaves the FBC by overflow. All the other parts of the experimental system are the same as shown in Fig. 12.3, and so are not shown in Fig. 12.4. The operation procedure for the FBC is the same as for the ISC. For convenience of comparison, the corresponding conditions, temperature and concentration of the solution, operated in the ISC and the FBC are rigorously controlled to be the same, with the deviation of the operating temperature no greater than 0.05 °C. 

Figure 5-2 Comparison of the growth rate of hexamethylene tetramine crystals as a function of super-saturation in aqueous solution and in ethanol solution. (Reproduced with permission from Davey et al. 1982.)...

Figure 10.17(a) Comparison of the growth rates of potassium hydrogen tartrate (KHT) occurring in a fluidized bed and in a stirred vessel, as reported by Ratsimba and Laguerie (1991). Initial (10.42) crystal mean size Lj = 1.125 x 10 m, ethanol content = 10% volume, crystallization temperature T = 273 K. 

The effect of block chain architecture on crystallization kinetics was studied by comparing the OBC H84 with a statistical EO copolymer, E02.8. Both have the same total octene content of about 3.0 mol % and about the same crystallinity. Table 1. The comparison of spheruhte growth rates of H84, E02.8 and HS is shown in Figure 9. At 110 °C the growth rate of H84 is more than two orders of magnitude faster than E02.8. This indicates that statistical sequences crystallize much slower than long ethylene blocks of the OBC. The HS control which has 1.3 mol % octene was much faster than E02.8 because of its lower octene content. 

Figure 4-7 Comparison of crystal nucleation and growth rate 350...

P-08 - Comparison of crystal linear growth rates for silicalite-1 in thermal and microwave syntheses... 

In comparison to the undoped base glass, the Pt-doped glass showed a shifting of the DTA crystallization peak to lower temperatures (Fig. 3-24) than the undoped glass. This result is a very good indication that heterogeneous nucleation (in this case Pt) increases the crystal growth rate... 

Figure 11.10 Comparison of experimentally determined growth rates of spherulites of i-polystyrene with ( ) experimental (— ) theoretical values. (From J. Polym. Sci. Polym. Phys. Ed., 21, Kennedy, M. A., G. Turturro, G. R. Brown, and L. E. St.-Pierre Retardation of spheralitic growth rate in the crystallization of isotatic polystyrene due to the presence of a nucleant, Copyright 1983 hy John Wiley Sons, Inc. Reprinted by permission of John Wiley Sons, Inc.)...

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