The Rheometrics Dynamic Spectrometer (RDS) is an oscillatory rheometer by which viscous-elastic properties of the polymer melt can be measured between two oscillating plates (both parallel- and cone-plate available). This technique is very suitable to obtain rheological data in the lower shear rate range (appr. 10 - 1000 s-1), using only very limited material (typically <500 g.). Elastic and viscous modulus data can be discriminated, by which it is possible to ascertain if the material behaves more elastic or more viscous. These measurements can be done at different temperatures and frequencies allowing for good characterization of the flow behavior of the polymer melt. By making a so-called Van Gurp-Palmen plot, branching or cross-linking can be determined as well.
A recent practical example of how we used this method was in the field of 3D printing. The rheological data obtained from measuring monofilament (3D printer ink) was linked to printing behavior. This revealed that tweaking a single parameter was needed to result in a perfect printing experience.
|Maximum shear rate (s-1)||10|
|Minimum shear rate (s-1)||1000|
|Minimum sample amount||500 gram|
Other available rheological methods can be found in the tabel below.
|Rheometer||Type||Shear rate range (s-1) (aprox.)||Material needed|
|RDS||Oscillatory||10 – 1,000||500 g|
|Göttfert||Capillary die||10 – 10,000||1.5 kg|
|Haake Polylab extruder||Capillary die||100 – 50,000||10 kg|
|Haake Polylab extruder||Slit die||10 - 1,000||10 kg|