Drop Shape Analyzer – DSA30R
Analyses in interfacial rheology – time-saving and reproducible
Emulsions and foams are constantly in motion during production or transport. The interfaces of droplets or bubbles are stretched during these processes. How such deformations impact on the stability of food and bodycare products or influence the yield in tertiary crude oil production depends on how the surface tension or interfacial tension (SFT/IFT) responds to the stretching. Interfacial rheology measurements with the Drop Shape Analyzer – DSA30R provide the key to answering this question.
Elasticity and viscosity analysis in a wide dynamic range
The measuring principle involves evaluating video images of drops or gas bubbles at a dosing needle to measure the surface or interfacial tension. The interface size is sinusoidally changed during this process. The SFT/IFT is measured as a function of the surface change and is also sinusoidal in the case of samples containing surfactants.
The dosing unit’s extremely precise piezo drive enables exact sine waves in a frequency spectrum of 0.001 to 20 Hz, so the measurements cover a very wide dynamic range.
The elastic modulus E’ and the viscous modulus E’’ result from the evaluation. E’ goes hand in hand with the change to the surfactant’s surface concentration due to stretching and compression; E’’ reflects the change in SFT/IFT with respect to time due to diffusion and interfacial adsorption of the dissolved surfactant. Both quantities are related to the mechanical and temporal stability of foams and emulsions.