Nucleation Technologies

Hyper nucleating agents have been developed recently and offer the combined benefits of high crystallization rates and isotropic shrinkage control, which leads to improved production and part quality performance, in addition to the traditional mechanical property-related enhancements. Hyper nucleating agents are formulated compounds. For example. Hyperform HPN-68L is a blend of fixe disodium salt of bicyclo[2.2.1]heptane-23-dicarboxylic acid, Eruc-amide and amorphous silicon dioxide (11). 

Typically, dynamic crystallization experiments are carried out by cooling down to subambient temperature at a cooling rate of 10 Krnin , after melting the samples and keeping them above melt temperature in order to erase the thermal history. 

The transition temperatures are simply taken as the peak maxima in the calorimetric curves. In blends of isotactic PP, the crystallinity Xc is determined from the crystallization exotherms by using the following relation (3)  

The nucleation efficiency can be calculated from dynamic DSC measurements at a constant cooling rate by comparing the crystallization temperatures of the nucleated system with that of the self-nucleated matrix. 

The two extremes of the efficiency scale are considered as the non-nucleated and the self-nucleated matrix. Then, the nucleation efficiency, NE, can be considered as a percentage value, and this is given as 

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Nucleating Agents Milliken s nucleating technology for PP is approved for food contact by the FDA, the Canadian Health Protection Board and the BGA. 

The Borstar PP process concept combined with a special nucleation technology broadens the product flexibility in terms of MFI, molecular weight distribution, comonomer distribution, softness and rigidity. Due to the high operating temperature, the catalyst activity is typically 60 - 80 kg PP/g catalyst. 

PloB, R. and Mersmann, A., 1989. A New Model of the Effect of Stirring Intensity on the Rate of Secondary Nucleation. Chemical Engineering Technology, 12, 137-146. 

Epitaxial nucleation, with nonchemical technology 340 Equilibrium phosphate concentration theory 472... 

Another thin film technology based nanoparticle preparation route is gas condensation, in which metal vapor is cooled to high levels of supersaturation in an inert gas ambient [126-128]. In these experiments particles necessarily nucleate in the gas phase. In a promising extension of this technique a pulsed laser beam replaces the conventionally used thermal metal vapor source [120,121,129-134]. 

For mixed homogeneous/heterogeneous primary nucleation, the following empirical expression can be used to describe its rate Kirk-Othmer Encyclopedia of Technology, 1978-1984) ... 

Dean, R A., R. S. Dougall, and L. S. Tong, 1971, Effect of Vapor Injection on Critical Heat Flux in a Subcooled R-l 13 (Freon) Flow, Proc. Int. Symp. on Two-Phase Flow Systems, Haifa, Israel. (6) Deane, C. W., and W. M. Rohsenow, 1969, Mechanism and Behavior of Nucleate Boiling Heat Transfer to the Alkali Liquid Metals, USAEC Rep. DSR 76303-65, Massachusetts Institute of Technology, Cambridge, MA Also in 1970, Liquid Metal Heat Transfer and Fluid Dynamics J. C. Chen and A. A. Bishop, Eds., ASME Winter Annual Meeting, New York. (4)... 

Marto, P. J., and W. M. Rohsenow, 1965, The Effect of Surface Conditions on Nucleate Pool Boiling Heat Transfer to Sodium, Ph.D. thesis, MIT Rep. 5219-33 (USAEC Rep. MIT-3357-1), Massachusetts Institute of Technology, Cambridge, MA. (2)... 

Jung, H.C., Park, J.H., Park, S.H. et al. (1998) Expression of carboxymethylcellulaseonthe surface of Escherichia coli using Pseudomonas syringae ice nucleation protein. Enzyme and Microbial Technology, 22, 348-354. 

Solid polymer and gel polymer electrolytes could be viewed as the special variation of the solution-type electrolyte. In the former, the solvents are polar macromolecules that dissolve salts, while, in the latter, only a small portion of high polymer is employed as the mechanical matrix, which is either soaked with or swollen by essentially the same liquid electrolytes. One exception exists molten salt (ionic liquid) electrolytes where no solvent is present and the dissociation of opposite ions is solely achieved by the thermal disintegration of the salt lattice (melting). Polymer electrolyte will be reviewed in section 8 ( Novel Electrolyte Systems ), although lithium ion technology based on gel polymer electrolytes has in fact entered the market and accounted for 4% of lithium ion cells manufactured in 2000. On the other hand, ionic liquid electrolytes will be omitted, due to both the limited literature concerning this topic and the fact that the application of ionic liquid electrolytes in lithium ion devices remains dubious. Since most of the ionic liquid systems are still in a supercooled state at ambient temperature, it is unlikely that the metastable liquid state could be maintained in an actual electrochemical device, wherein electrode materials would serve as effective nucleation sites for crystallization. 

The book is divided into 18 chapters, presented in a logical and practical order as follows. After a brief introduction (Chapter 1) comes the discussion of ionic solutions (Chapter 2), followed by the subjects of metal surfaces (Chapter 3) and metal solution interphases (Chapter 4). Electrode potential, deposition kinetics, and thin-fihn nucleation are the themes of the next three chapters (5-7). Next come electroless and displacement-type depositions (Chapter 8 and 9), followed by the chapters dealing with the effects of additives and the science and technology of alloy deposition... 

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