Dynamic surface tension at the touch of a button
27 Jul 2004
Compact standalone device offers whatever is necessary to present simple, precise and reproducible dynamic surface measurements in the laboratory or in the field
The Lauda family of tensiometers has been extended by a further bubble pressure tensiometer, the new MPT C.
In the form of the little brother to the MPT 2 PC-controlled model, the step towards the complete automation of dynamic surface tension measuring has been completed.
This achieves a directly optimum level of user-friendliness, says Lauda.
Time-consuming settings, calibrations or corrections are not needed.
As with the MPT2, the measuring method according to Fainerman ensures exact surface tension and the accompanying true bubble ages.
The external, handy control panel with large graphic display is intuitively easy to use and does not require any prior knowledge, says Lauda. The program in the integrated microcontroller offers a range of useful experimental procedures formerly only realisable with the MPT 2.
These make it possible to, for example, automatically carry out a scan of the dynamic surface tensions in the range of one millisecond to several seconds, to ascertain the surface age within just a few minutes in order to fully and completely record the adsorption kinetics of very fast surfactants.
The control offers the user customised measuring procedures.
The evaluation of the measurements and the necessary corrections, such as for the dead time calculation and the viscosity, are carried out on a scientific basis.
There is the choice of constant, flow-controlled bubble formation time, the constant flow mode for practical reaction control, for example, and the decrement mode. A specified flow area is gradually gone through in order to cleanly register the dependency of the dynamic surface tension of the surface age and to represent it.
The flow is thereby re-set at each individual measuring point and displayed as a measured value.
Thanks to the self-explanatory user guide, the simple cleaning of the capillaries and the compact structure of the device, the device is especially suitable for the quality control of dynamic-critical surfactant solutions or for the fast determination of the surfactant content in concentrations above the critical micelle concentration.
The support for the capillaries, pre-moistener and test tubes which are part of the standard delivery is integrated in the basic equipment.
The optional temperature sensor in conjunction with the connected Lauda thermostats ensures accurate maintenance of temperature. The measuring capillaries can be inserted directly into the reaction vessel or in a flow cell in the bypass by means of a hose connection up to one metre in length in order to monitor surfactant reactions online.
This enables, for example, the control of the surfactant consumption during the washing process. In addition to the PVDF-coated glass capillaries of the MPT 2 also suitable for the MPT C, steel capillaries (such as for extremely alkaline samples) are also available.
Its robustness, user-friendliness and high level of precision predestine the MPT C for use in quality control.
Measurements are carried out by the user in a completely independent manner and documented with the necessary settings, therefore complying with the strict specifications of the GLP guidelines.
