Overcoming solvent evaporation/drying during rheological testing on rotational rheometer
This paper shows how using a solvent trap can be used to prevent sample drying/solvent loss during extended testing, helping to ensure that only rheological changes are being measured and not artifacts resulting from drying of the sample at the air/sample interface.
Overcoming solvent evaporation/drying during rheological testing on rotational rheometer
This paper shows how using a solvent trap can be used to prevent sample drying/solvent loss during extended testing, helping to ensure that only rheological changes are being measured and not artifacts resulting from drying of the sample at the air/sample interface.
Introduction
Solvent evaporation or sample drying can occur in a variety of samples during long term rheological testing or when testing at elevated temperatures. This is particularly problematic for volatile samples containing organic solvents but even aqueous based materials such as ketchup or pastes have been seen to ‘dry out’ quickly when exposed to the atmosphere.
Parallel plate or Cone-Plate measuring systems are most susceptible to evaporation and drying since the materials at the plate or cone edge are directly exposed. The issue is further exaggerated by the fact the measured or applied torque (M) varies with the radius (r) to the power of four (r4) for a plate and to the power of three (r3) for a cone, when measuring a Newtonian material. Consequently any change in sample properties at the edge caused by crust formation or loss of sample will have a significant impact on the measurement result. Problems may be encountered with concentric cylinder systems also, albeit to a lesser extent.
