Herstellung,Stabilität und Spaltung multipler Emulsionen

Production, stability, and breaking of multiple emulsions . The production, stability and breaking of multiple emulsions are dependent on many factors, some of which are definable theoretically, some empirically. The stability of an emulsion is characterized by the interplay and superposition of interparticular interactive forces and rheological properties of the continuous phase. Interface-active substances are adsorbed at the phase boundary and form an interfacial film, whose mechanical properties exert a strong influence on the stability of the droplets. Repulsive forces and interfacial film form an energy barrier. If this is overcome by increasing the thermal energy, by increasing the mobility of the particles or by external energy influences, the film breaks and the droplets coalesce. These processes are demonstrated theoretically and practically with the aid of individual methods of demulsification.     

Elementarprozesse bei der Herstellung und Stabilisierung von Emulsionen

Elementary processes in the production and stabilization of emulsions. When developing new emulsifying agents with a specially low environmental impact, when using emulsifying agents in various branches of industry, and when breaking down emulsions (a very frequent requirement), an understanding of the elementary processes which take place is of great help. The paper provides a comprehensive account of the various elementary processes involved in the production and stabilization of emulsions otherwise scattered throughout the literature. The interplay of the individual elementary processes shows how emulsifying agents and stabilizers differ in their modes of operation. In discussing the structures which occur in aqueous tenside systems, it is pointed out that the swelling of micelles is an elementary process responsible for solubilization and cream formation.     

Stabilität von Dispersionen

Stability of Dispersions The importance of production and application of disperse systems in the industry is steadily growing. On the other site colloidale systems surround us every day (for example foodstuffs, pharmaceutica, and so on). With the knowledge about the mechanism of interaction forces we are able to develope new materials and improve available systems. The stability of such systems is one of the central point of research. One of the well known physical models of colloid stability is given by DLVO‐Theory. With this theory we have a tool to influence the stability of such dispersion systems. In this paper electrokinetic methods are used to investigate interaction forces in disperse systems. The influence of pH‐value, electrolyte concentration, and valency is shown. But, not in all cases the DLVO‐model works satisfactoryly. Some reasons of this behavior will be discussed.     

Dynamik und Stabilität verfahrenstechnischer Prozesse

Dynamics and stability of chemical engineering processes. Peculiarities of dynamic behaviour as well as stability phenomena in the field of chemical engineering are reviewed with emphasis on the stability of single evaporator tubes and on the stability and dynamics of chemical reactors with strongly exothermic reactions. It is shown that the basic behaviour can be explained in both cases by fairly simple considerations. Some new aspects of general stability theory are also discussed briefly.     

Stabilität und Dynamik heterogen-katalytischer Reaktionssysteme

Stability and Dynamics of Reactors with Heterogeneously Catalyzed Reactions . Our knowledge of causes and consequences of problems arising from instability and dynamic effects in reactors with heterogeneously catalyzed reactions has increased remarkably in recent years. Especially thermal effects, caused by the self-acceleration of an exothermic reaction in combination with heat and mass transport, are now well unterstood. In addition kinetic effects, i. e. phenomena which have to be explained by the kinetic peculiarities of surface reactions, have attracted increasing interest. For both cases the state of the art will be reviewed, highlighting the physical and chemical causes of the observed phenomena.