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ASTM Recommendations in the Area of Rotational Rheometry

Although the flow in a capillary rheometer is regarded as pressure-driven flow, namely, the shear is generated by the pressure difference along the capillary length, in rotational rheometers the shear is generated between a moving and a fixed surface [9]. [Pg.630]

ASTM D 4440-01, Standard Test Method for Plastics Dynamic Mechanical Properties Melt Rheology  [Pg.631]

This test method employs nonresonant forced vibration techniques for determining the complex viscosity (see below) and viscoelastic characteristics of thermoplastic resins as a function of frequency, strain amplitude, temperature, and time. A wide range of frequencies can be used, typically from 0.01 to 100 Hz. [Pg.631]

In these cases the relative velocity of the shearing plates is not constant but varies in a sinusoidal manner so that the shear strain and the rate of shear strain are both cyclic, and the shear stress is also sinusoidal. For non-Newtonian fluids, the stress is out of phase with the rate of strain. In this situation a measured complex viscosity (rf) contains both the shear viscosity, or dynamic viscosity (t] ), related to the ordinary steady-state viscosity that measures the rate of energy dissipation, and an elastic component (the imaginary viscosity ij that measures an elasticity or stored energy)  [Pg.631]

These two viscosities are calculated using the following equations  [Pg.631]


See other pages where ASTM Recommendations in the Area of Rotational Rheometry is mentioned: [Pg.630]    [Pg.631]   


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