Dynamic Interfacial Tension & Interfacial Rheology Youssef Akil, Technical Consultant, Krüss GmbH
22nd January 2019, Tuesday, 3:00‐4:00 pm, ChE Seminar hall
Abstract: The talk is divided into two parts, covering two areas of surface and interfacial science. 1. Dynamic Interfacial Tension When two immiscible phases get into contact, the interfacial tension (IFT) is one of the main properties to characterize how the two phases will behave. The dynamic IFT describes the science at freshly formed interfaces within the first few seconds. This can be measured by the drop volume technique, which is an evolution from the widely known stalagmometers. Dynamic IFT is an important aspect for many different applications in food, oil, cosmetic and household care industries. In the talk, the basics of surface and interfacial tensions will be introduced. The measurement technique and important aspects of the KRÜSS Drop Volume Tensiometer (DVT50) are shown. Application examples will be explained, including the evaluation of food oils as well as the development and qualification of emulsifiers. 2. Interfacial Rheology Interfacial rheology is the method to examine the behavior of surface active substances at the interface. By oscillatory expansion and compression of a droplet, information about viscous and elastic properties of interfaces can be obtained. These informations are useful for the understanding of foams (stability, decay of bubbles, drainage, etc.) and emulsions, characterizing their behaviour in dependence of viscous and elastic properties. A general introduction into the topic will be given, followed by theory about rheology of foams and emulsion and application examples for food applications and emulsion behaviours.