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[June 2003]
Updated Rheology Software from Bohlin Instruments
Bohlin Instruments Ltd (Cirencester, Glos, England) has introduced a version of software for its rotational rheometers that greatly expands testing capabilities, but also retains a simple user interface.
In the viscometry and oscillation modes, a customised table enables users to design tests with greater flexibility. In a flow curve test, traditionally the start and end values and the number of steps were specified. Now, individual values of the shear rate and interval time at each step can be pre-programmed. This means, says Bohlin, that just about any viscosity vs. shear rate measurement can be replicated on a Bohlin Rheometer.
In a frequency sweep measurement, the sampling rate can be changed during the actual test enabling better resolution of the viscoelastic data. This is said to be of particular benefit when studying subtle changes in phase angle for weakly structured systems. The oscillation test also has a rapid sampling option (Partial Wave Analysis) to provide fast tracking of data for applications such as curing and gelation. This enables discrete material transitions to be identified by collecting several points per second.
It is also possible to combine oscillation and flow in one test by superimposing a defined steady shear on the oscillatory waveform. This parallel superimposition test allows the viscoelastic content of the test material to be measured while under shear. Storage stability and transportation are applications where this technique has proved particularly beneficial.
The software operating modes are supported by an advanced set of data analysis tools. The new Time Temperature Superposition (TTS) module extrapolates dynamic data outside the range of the rheometer by automatically generating a Master Curve at a specified reference temperature.
www.bohlin.com
ENDS