SURFACE RHEOLOGY AT HIGH DEFORMATION SPEEDS AND HIGH FREQUENCY WITH THE HFDT 500

The TRACKER makes it possible to record the response of interfacial or surface tensions to controlled perturbations of the area of the interfaces. Sereval perturbations profiles are available : sinusoidal, steps, saw type profiles, etc. Frequency range is up to 1 hertz.

This device, the HFDT 500, makes it possible to go far beyond this limit in the exploration of the dynamic behaviour of interfaces at high deformation speeds and high frequencies.

DESCRIPTION

Its principle of running is simple. The capillary at the tip of which the drop or bubble) is formed is connected to a vessel whose volume can be controlled. Indeed, this vessel is closed by a membrane, which can be bent by a piezo-electric quartz. The control system of the quartz makes it possible to generate any volume variation of the vessel, then any area variation of the interface of the drop or bubble.

KEY PERFORMANCES

• Any kind of interfacial area profiles : sinusoids, steps, saw type profiles, etc.

• Frequency range : up to several hundreds hertz (see note) .

• Deformation amplitudes of interfacial areas : up to 10 mm².

• Temperature control device up to 70°C (circulation bath).

Note

At such frequencies, the interpretation of the measurement results of the interfacial tension are more complex as soon as the viscosity of the fluids are involved.

EXAMPLES :

Record at 5 Hz :

Record at 10 Hz :