 | The viscosity of an aqueous WalocelŪ HM solution is defined by the frictional resistance of a fluid to shear forces or to compressive stress, hence to flow.
The viscosity of HPMC solutions is determined using Ubbelohde viscometers or rotary viscometers. The viscosity is stated in Pas or mPa·s.
Depending on the method applied, the viscosity stated may vary considerably. The more viscous the solution is, the more distinct the difference is likely to be.
Measuring the viscosity of a 2% aqueous solution, e.g. using WalocelŪ HM 100.000, will result in a reading of 100,000 mPa·s on the Ubbelohde viscometer. If the viscosity of this solution is determined using a rotary viscometer at a shear rate of 10 1/s, the reading will be approx. 18,000 mPa·s.
This shows very clearly that the viscosity of an aqueous HPMC solution is not an absolute value, but depends very much on the measuring parameters. In order to ensure that the stated viscosity areviscosity is comparable, Dow Wolff Cellulosics generally specifies WalocelŪ HM using Ubbelohde viscometers at 20°C.
The measured viscosity of an aqueous HPMC solution depends very much on the test method.
To cater to the requirements of the many different applications, Dow Wolff Cellulosics offers a broad product range of WalocelŪ HM grades. The viscosity range from 3 mPa·s to 100,000 mPa·s as a 2% aqueous solution.
The properties of WalocelŪ HM are essentially based on the specific behaviour of WalocelŪ HM solutions in water. The WalocelŪ HM solutions are pseudoplastic and - at higher concentration levels - thixotropic.
Aqueous WalocelŪ HM solutions can be produced with a wide viscosity range. These solutions are non-Newtonian, i.e. their viscosity is dependent in the shear rate.
For some applications, not only the viscous but also the elastic properties are of importance. Do you have any questions or requests? Would you like some more detailed information? If you contact us, we would like to assist you further.
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