Papers by Keyword: Parallel Superposition

Abstract: Multi-function and all-electric rheometer (MAR) was designed by the authors to study the nonlinear viscoelasticity of polymer melts at high shear rate. It is important to design suitable size of capillary and barrel because it is the calculation basis for some other important parts and determines the shear rate range of MAR. Considering the shear rate range, the entrance pressure correction and the wall slip correction, the length and diameter of capillary and barrel of MAR were designed through particular analysis and precise calculation.

Abstract: In order to study the nonlinear viscoelasticity of polymer melts at high shear rate, multi-function and all-electric rheometer (MAR) was designed by the authors. Development of temperature control system of MAR is important because rheological behavior of polymer melts is affected by temperature significantly. The design principle of the temperature control system of MAR was studied. According to the temperature upper limit the barrel need to reach, and the power the heating system can offer to maintain the temperature, the suitable type of heating system was determined. Considering the requirement of heater and the measurement error, the suitable type of temperature transducer was determined. The measured values of temperature were compared with the set values of them to evaluate the temperature control error of MAR. The results show that the temperature fluctuation is smaller than ±0.4°C in 3.5 minute. Therefore, the temperature control error of MAR is small enough for rheological test. And the temperature control stability of MAR is very well.

Abstract: A newly developed resonator in combination with a UDS 200 rheometer allows performing different kinds of measurements. The characteristics of the resonator are its resonant frequency slightly above conventional rheometers, the high sensitivity allowing measurement of fluids with viscosities as low as that of water and the very small oscillation amplitudes. The nonlinear behavior of viscoelastic liquids can be analyzed using parallel superposition of shear. It is known that the parallel complex shear modulus differs from the complex modulus of a fluid at rest. First measurements have shown the ability of the instrument to quantify this effect. At the same time, normal force, shear rate viscosity and complex viscosity can be measured on a sample.