Closed cavity torsional rheometer

Fourier Transform Rheometry with an Updated Closed Cavity Torsional Rheometer. 823... 

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. 

FOURIER TRANSFORM RHEOMETRY WITH AN UPDATED CLOSED CAVITY TORSIONAL RHEOMETER... 

Fig. 8 Linear elastic and viscous modulus functions G co, T) and G"(a>, T) of gum EPDM2504, drawn using the G of a six elements generalized Maxwell model and the respective Cl, C2 parameters of a WLF type equation with 100 °C as reference temperature experimeutal data from a frequency-temperature sweep protocol at 1 deg. strain amplitude with a closed-cavity torsional harmonic rheometer are displayed for comparison with the calculated maps...

Fig. 14 Strain sweep tests on a pure atactic polypropylene and an unfilled styrene-butadiene rubber compound using either an open-gap (VCOR) or a closed-cavity (RPA) torsional dynamic rheometer (authra- s experimental data)...

With a closed-cavity dynamic torsional rheometer, typical nonlinear viscoelastic experiments are Strain Sweep (SS) tests in the widest strain range at fixed firequency and temperature. Figure 15 shows complex modulus vs. strain curves as measured... 

J.L. Leblanc and A. Mongmel, A thorough examination of a commercial torsional dynamic rheometer with a closed oscillating cavity, Prog. Rubber Plast. TechnoL, 17, 162-185, 2001. 

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