Table 3 – Results of frequency sweeps with non-Newtonian viscosity standard at 25 °C
Figure 4 – Storage modulus G’, loss modulus G’’ and complex viscosity Iη*I as a function of the angular frequency for the NIST non-Newtonian stan- dard sample at 25 °C.
Results from the frequency sweep indicated <7% diff erence between the two calculated crossover modulus values (see Table 3).
Conclusion Oscillatory experiments on standard materials have generally been limited
to high-priced rheometers with limited accessibility. The tests described
in this article, conducted using the HAAKE Viscotester iQ rheometer in CD and CS modes, establish that oscillatory experiments can be done with a mechanical-bearing rotational rheometer. While there are some limita- tions, such as the measuring range, in comparison to a high-performance air-bearing rheometer, the mechanical-bearing rotational viscometer gives quality control personnel the ability to conduct oscillatory tests more economically without compromising the integrity of results.
Fabian Meyer is senior application specialist, Thermo Fisher Scientific, Material Characterization Products, Dieselstr. 4, 76227 Karlsruhe, Germany; e-mail:
fabian.meyer@thermofi
sher.com;
www.thermoscientifi
c.com
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AMERICAN LABORATORY • 25 • AUGUST 2015
The only simpler sequence at 7 AM... is making coffee
• UV Persulfate
• High Temperature Combustion
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