Ostwald ripening


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Ostwald ripening

[′ȯst‚vält ¦rīp·ə·niŋ]
(chemistry)
Solution-crystallizer phenomenon in which small crystals, more soluble than large ones, dissolve and reprecipitate onto larger particles.
References in periodicals archive ?
Ostwald ripening can be reduced by adding oils of very low polarity to very polar oils.
The crystal grew under a process known as Ostwald ripening.
O diametro medio das esferas aumenta pela eliminacao das esferas menores com o consequente crescimento das maiores pelo processo conhecido por Ostwald ripening.
The cause of Ostwald ripening is due to that the solubility of monomers in water increases with a decreasing monomer droplet size, and larger monomer droplets therefore grow in size at the expense of smaller ones through monomer diffusion (10-12).
As a result, monomer diffusion induced by the Ostwald ripening effect occurred during the course of polymerization and significant homogeneous/micellar nucleation would be observed.
The monomer diffusion from the smaller droplets to the larger droplets took place continually in the unstable droplets via Ostwald ripening.
Keywords: Miniemulsion, Ostwald ripening, enhanced nucelation, hybrid latexes, encapsulation, droplet and particle size distributions, reaction kinetics, reaction mechanisms
This is an Ostwald ripening effect, as described earlier, but is substantially limited by the hexadecane.
This includes chapters on morphology, drainage, Ostwald ripening, coalescence, rheology, and pneumatic foams.
D, the most effective substances against emulsion breakdown (creaming, flocculation, Ostwald ripening, coalescence and phase inversion) are block and graft polymers, such as hydrophobically modified inulin in oil-in-water (o/w) emulsions and chains of polyhydroxy-stearic acid and polyethyleneoxide in water-in-oil emulsions (w/o).
Ostwald ripening (10, 11) based on dissolution of the minor phase molecules from the surface of smaller domains having higher surface energy, diffusion of the molecules through the liquid matrix, and condensation on the more thermodynamically stable larger domains was recently proposed (7-9, 12, 13) as the dominant coarsening mechanism in quiescent melts (as encountered in compression molding) of polymer blends of high molecular weight and high viscosity matrices.
Since the extended drops present in the extrudates were not at thermodynamic equilibrium, at least three interfacial tension-driven changes should have taken place during compression molding, namely: 1) disintegration by capillary instability of highly extended fibrils into chains of small spheres, each with a diameter approximately twice that of the original fibril, 2) shape relaxation with elongated particles contracting back into spheres with volume conservation, and, subsequently, 3) minor phase coarsening either by Ostwald ripening when molecular diffusion allows particles to tend toward their thermodynamic equilibrium or by coalescence when particle motion and collision are responsible for particle growth.