Parallel plate rheometry

Capillary rheometry and parallel-plate rheometry use the fact that wall slip will manifest itself as a geometry-dependent phenomenon. That is, wall slip will appear as a geometric effect on apparent rheological properties. In the capillary-rheometer technique, slip will manifest itself as an effect of capillary diameter ( )) on the shear stress (t, ). Wall slip in capillary rheology can be calculated from an analysis that involves the following ... 

The Du Pont Model 943 TMA module is shown in Figure 11.4. The apparatus uses a LVDT to sense linear displacements of the sample probe. A thermocouple in direct contact with or in close proximity of the sample is used to detect the sample temperature. The sample and probe are surrounded by a temperature-controlled cylindrical heater and Dewar assembly. Various probe configurations allow the apparatus to be used in the expansion, compression, penetration, tension, stress relaxation, parallel plate rheometry, and fiber tension. The temperature range of the instrument is — 180-800°C an optional furnace can be used to extend the range to 1200 C. 

Mutel, A.T. Kamal, M.R. (1986). Characterization of the Rheological Behavior of Fiber-Filled Polypropylene Melts under Steady and Oscillatory Shear using Cone-and-Plate and Rotational Parallel Plate Rheometry. Polymer Compwsites, Vol.7, No.5, pp. 283-294ISSN0272-8397... 

Thermomechanical analysis (TMA) measures the deformation of a material contacted hy a mechanical prohe, as a function of a controlled temperature program, or time at constant temperature. TMA experiments are generally conducted imder static loading with a variety of probe configurations in expansion, compression, penetration, tension, or flexime. In addition, various attachments are available to allow the instrument to operate in special modes, such as stress relaxation, creep, tensile loading of films and fibers, flexural loading, parallel-plate rheometry, and volume dilatometry. The type of probe used determines the mode of operation of the instrument, the manner in which stress is apphed to the sample, and the amount of that stress. 

Dynamic mechanical methods (typically oscillatory parallel plate rheometry) are commonly used to measure the dynamic mechanical properties from the liquid state to the solid state. By using small-amplitude oscillatory deformations (linear viscoelastic regime), the dynamic storage and loss moduli can be obtained. From these quantities, the viscosity and modulus can be calculated (71) (see Dynamic Mechanical Analysis). 

A.T. Mutel, M.R. Kamal. Characterization of the rheological behavior of fiber-filled polypropylene melts imder steady and oscillatory shear using cone-and-plate and rotational parallel plate rheometry. Polym. Compos., 7 (5), 283-294, 1986. 

VISCOSITY CHANGES ASSOCIATED WITH THE CHEMICALLY INDUCED CROSSLINKING OF PLASTICISED POLYVINYL CHLORIDE MEASURED BY PARALLEL PLATE TORQUE RHEOMETRY INFLUENCE OF MAGNESIUM AND BARIUM MERCAPTIDES Rosales-Jasso A Arias G Rodriguez O S Allen N S Centro de Investigacion en Quimica Aplicada Manchester,Metropolitan University... 

Dynamic mechanical analysis in the rheology mode (oscillatory rheometry in cone and plate or parallel-plate geometries see Fig. 5.50) can be used to... 

Cone/Plate Viscometry Co-Axial Cylinder Viscometry Parallel Plate Viscometry Tensile or Extensional Viscometry Dynamic or Oscillatory Rheometry Morphological Analysis... 

Rides, M., AHen, C. R. G. Round robin for parallel plate oscillatory rheometry using polyethylene and polypropylene melts. Report CMMT( A) 11, Centre for Materials Measurement and Technology, Natl. Phys. Laboratory, Teddington, United Kingdom... 

In order to characterize the rheological properties of a polymer melt over a very large range of shear rates, data obtained in mnltiple rheometer contignrations are typically combined. Cone-and-plate and parallel plate shear measnrements are, for example, the most accurate at low shear rates. However, the shear rates accessible in a capillary rheometer are well above those that can be achieved in any other configuration. Capillary rheometry, cone-and-plate shear, and parallel plate shear rheometry provide complementary information abont polymer flow response. In the example shown in Figure 8.14, an uncross-linked silicone rnbber was measnred nsing three... 

FIGURE 8.14 Comparison of Cross model prediction with experimental viscosity data for a high-molecular-weight poly(dimethylsiloxane) using parallel plate, cone-and-plate, and capillary flow rheometry at 23°C. The fitted parameters are A, = 34.5 s, = 0.604, and t (, = 98.0 kPa s. 

When compared to standard (open cavity) cone-plate or parallel disks rheometers, closed cavity torsional rheometers such as the RPA or the PPA have unique high-strain capabilities, which prompted us to modify the instmment in order to investigate the promises of FT rheometry, as outlined a few years ago by the pioneering works of Wilhelm. The technique consists of capturing strain and torque signals and in using FT calculation algorithms to resolve it into their harmonic components, as detailed below. 

FIGURE 3. Data obtained on non-Newtonian viscosity of an aqueous solution of hexylethylcellulose by four different viscometric methods capillary rheometry, concentric cylinder, cone-plate and parallel disk. 

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