Crystal growth rate studies

Garside, J., Gaska, C. and Mullin, J.W. (1972) Crystal growth rate studies with potassium sulphate in a fluidized bed crystallizer. Journal of Crystal Growth, 13/14, 510-516. 

Several authors have presented methods for the simultaneous estimation of crystal growth and nucleation kinetics from batch crystallizations. In an early study, Bransom and Dunning (1949) derived a crystal population balance to analyse batch CSD for growth and nucleation kinetics. Misra and White (1971), Ness and White (1976) and McNeil etal. (1978) applied the population balance to obtain both nucleation and crystal growth rates from the measurement of crystal size distributions during a batch experiment. In a refinement, Tavare and... 

Mulliii, J.W. and Garside, J., 1967. Crystallization of aluminium potassium sulphate a study in the assessment of crystallizer design data I Single crystal growth rates, II Growth in a fluidised bed. Transactions of the Institution of Chemical Engineers, 45, 285-295. 

One of the more important uses of OM is the study of crystallization growth rates. K. Cermak constructed an interference microscope with which measurements can be taken to 50° (Ref 31). This app allows for study of the decompn of the solution concentrated in close proximity to the growing crystal of material such as Amm nitrate or K chlorate. In connection with this technique, Stein and Powers (Ref 30) derived equations for growth rate data which allow for correct prediction of the effects of surface nucleation, surface truncation in thin films, and truncation by neighboring spherulites... 

Batch crystallization studies of D-fructose from aqueous ethanolic solutions demonstrate that crystal growth rate is dependent on supersaturation (possibly to the 1.25 power), ethanol content and temperature. It appears that solution viscosity also has an effect. Growth rates of up to 1 pm/mln were measured. 

No study has been made to discover which of the several resistances is important, but a simple rate equation can be written which states that the rate of the over-all process is some function of the extent of departure from equilibrium. The function is likely to be approximately linear in the departure, unless the intrinsic crystal growth rate or the nucleation rate is controlling, because the mass and heat transfer rates are usually linear over small ranges of temperature or pressure. The departure from equilibrium is the driving force and can be measured by either a temperature or a pressure difference. The temperature difference between that of the bulk slurry and the equilibrium vapor temperature is measured experimentally to 0.2° F. and lies in the range of 0.5° to 2° F. under normal operating conditions. 

Studies on PEO fractions in the molecular weight range between 1500 and 12 000 have shown [18] that the slope of the increasing crystal growth rate with supercooling dG/d(AT) does indeed increase abruptly at a series of spe-... 

Optical microscopy (inverted microscope) Study crystallization processes in situ Monitor transformations in suspensions Determine transformation times Screen and characterize additive/solvent interactions with specific crystal faces Identify nucleation mechanisms Measure crystal growth rates... 

Carlo simulation of ice-crystal growth to study the mechanism of inhibition of AFPs on the surface of the THF hydrate and propane hydrate. They found that most of the octahedron surfaces of the THF hydrate were covered with AFP molecules, which could reduce the growth rate of the THF hydrate only allowing plate growth perpendicular to that surface. It is thus necessary to look for other experimental evidences to clarify the common features of AFPs on the inhibition of the clathrate hydrate formation. 

As shown in Fig. 10-11, the occluded residual solvent was found to be a sti ong function of time constants for crystal growth rate/nucleation rate over the entire range of parameters studied. Specifically, it was shown that the higher the ratio of (fi//xo)/(G/4> which means more rapid nucleation rate, the higher the residual solvent, and vice versa. This finding cleai ly shows the importance of properly controlling the nucleation rate and the crystal growth rate in the process. 

Accordingly, the influence of MW on the crystallization behaviors of semicrystalline polymers has been studied in various articles. For example, linear crystal growth rates of poly(ethylene oxide) and poly(ethylene succinate) (PES) reach a minimum value at a critical MW. This value is related to the crystallization transition from an extended chain to a folded chain conformation [96,97], suggesting that high MW polymers require sufficient reconformation time to achieve an ordered structure. As evidence of this MW dependence of the semicrystalline polymer on... 

Black and Davey used Eq. (3.22) to study the effect of the tailor-made additive L-glutamic acid on L-asparagine monohydrate crystals. With the use of a linear adsorption isotherm, Eq. (3.22) fit the crystal growth rate data. Consistent with a structural model in which impurities are embedded in the growing crystal surface, the growth rate of the crystals tended to zero at a high L-glutamic level. 

A primary conclusion from the above results is that the standard methods for determining intrinsic crystal growth rates are well-suited for biochemical compounds. At present there are limited data on which to generalize with respect to growth mechanisms and the effects of various thermodynamic variables. Indeed, the large number of variables that may affect solubility and kinetics in these systems suggests that extensive and careful laboratory studies... 

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