Interfacial instability temperature, effect

Polycondensation at room temperature between two or more fast-reacting intermediates is becoming widely used because of its convenience and speed. The interfacial polycondensation system, in particular, which employs two immiscible liquids, is applicable to a wide voriety of chemical structures amides, urethanes, esters, sulfonates, sulfonamides, and ureas. Many products can be made at low temperature which could not be formed by melt methods because of their infusibility or thermal instability. The low temperature procedures are subject to the effect of many variables, but these are readily controlled and acceptable conditions for use with new polymers or intermediates can usually be found. The processes are readily scaled up in simple batch equipment or continuous reactors. Special areas of application are the direct formation of fibers from the reactants and polycondensation on fiber substrates. 

In the following discussions the published experimental findings are presented interrelatedly first in terms of internal oil chemistry at the interface and instabilities based on its composition, secondly in terms of effects of water chemistry, and thirdly in terms of demulsifier interaction. We include the activity of interfacial components involved in the structure of the protective skin, the behavior(s) of this structure with changes to water chemistry or solvency, or the effects of changes in film stmeture itself due to modification of relative proportions of interfacially active components. In some examples, developments in interfacial rheology, which is both a tool for understanding stable films and a means of rationalizing the effects of demulsifiers in demulsification, are discussed interrelatedly. Films may be sensitive to crude oil type, gas content, aqueous pH, salt content, temperature, age, and the presence of demulsifiers. Demulsifier performance is also influenced by many of these variables. 

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