E. D. Kozlovskaya

Secondary nucleation in the formation of methane crystal hydrate

The kinetic data on crystallization and a morphological analysis of a layer of CH4 · 6H2O hydrate crystals formed on the surface of water as a result of methane absorption showed that secondary nucleation occurred during hydrate crystallization. The mutual arrangement of crystals in the layer revealed photographically in situ was evidence that part of nuclei produced on the surface of previously formed crystals went away from the surface into solution and grew there independently of “mother” crystals, although the probability of such transfer into an immobile solution remained low. In view of this, a model of crystal growth generating secondary crystals was developed.

Morphological Memory of Dispersed Solid Phases

A formalism of the morphological memory of disperse systems was formulated. Using CsI as an example, it was established that a dispersed solid phase formed by vapor condensation stores information on the nucleation, growth, and aggregation of its particles for a long time. Therefore, the determination of distribution functions of properties and the texture of particles at the end of the condensation allows us to qualitatively describe the genesis of the phase. Basic equations and conditions relating properties of crystals of the dispersed phase, which are necessary for the extraction of information on the genesis from data on final distribution functions of crystal states, were considered.

Periodical crystallization variability

Origins of nonreproducibility of kinetic characteristics and crystallization product properties during repeated processes are reviewed. The distribution functions of repeated crystallizations based on the kinetic parameters are introduced. Four models of variability, caused by variation of supersaturation, impurity quantity, nucleation activity of crystallizer walls and alteration of suspension flow inside the crystallizer, are analyzed. An experimental study of ammonium perchlorate crystallization in water solution demonstrated the variability of crystal size distribution due to negligible changes in a well-stirred batch crystallizer.

Morphological memory of polymers and their use in developing new materials technology

The problem of the formation of a microrelief on the surfaces of polymeric bodies has been considered. The basis for a mesokinetic model of the formation of macromolecules, their aggregates, and polymeric bodies in a device filled with a monomeric solution has been reported. An equation for changes in the function of the distribution of structural elements of the body microrelief over states in the process of its formation is formulated. Experimental data have been reported on the microrelief of polymeric bodies that confirm the prevalence of morphological memory phenomena among polymers and can be used to create new materials.

A kinetic model for the formation of hierarchical nanostructures during the evaporation of phase-forming compound solutions

A kinetic model for the precipitation of a dispersed compound from solutions is formulated, based on a description of the evolution in the function of its particle distribution according to its states during precipitation. A boundary problem about the precipitation of a compound during the evaporation of a solvent from a solution under conditions in which the rate of aggregate formation is high is considered. The solution to this boundary problem can be used to describe the formation of a film of polystyrene during the evaporation of its solution in toluene and o-xylene deposited onto a substrate.

The kinetics of formation of aerosols in gas flows

It was shown for the example of CsI aerosol that the aggregation of primary aerosol particles could be described in terms of either the discrete or continuum model. This conclusion was drawn on the basis of experiments performed by the method that allowed primary particles to be observed against the background of their aggregates and transfer of primary particles from aerosol volume to a collector to be provided. The size of primary particles on the collector was determined by transmission electron microscopy. It was found that, under the conditions used, the size distribution of primary particles corresponded to the Fokker-Planck equation.

Kinetics of aerosol formation in gas flows

Discrete and continual versions of the rate equation for the size distribution function of primary aerosol particles were formulated. With the CsI aerosol as example, it was shown that coarsening of primary aerosol particles can be described in terms of both discrete and continual models. This conclusion is based on the results of experiments performed by the procedure that makes it possible to reveal primary particles against the background of their aggregates, ensures complete transfer of primary particles from the aerosol volume to the collector, and allows determination of their size on the collector by electron microscopy. Under the examined conditions, the size distribution of primary particles is described by an exponential function.