Parallel plate oscillatory shear

ISO 6721-8 1997 Plastics - Determination of dynamic mechanical properties - Part 8 Longitudinal and shear vibration - Wave-propagation method ISO 6721-10 1999 Plastics - Determination of dynamic mechanical properties - Part 10 Complex shear viscosity using a parallel-plate oscillatory rheometer ISO 9311-2 2002 Adhesives for thermoplastic piping systems - Part 2 Determination of shear strength... 

ISO 6721 1999 Plastics — Determination of dynamic mechanical properties — Part 10 Complex shear viscosity using a parallel-plate oscillatory rheometer. 

Plastics—Determination of Dynamic Mechanical Properties. Part 10 Complex Shear Viscosity Using a Parallel Plate Oscillatory Rheometer Plastics—Determination of Tensile-Impact Strength... 

Dyna.mic Viscometer. A dynamic viscometer is a special type of rotational viscometer used for characterising viscoelastic fluids. It measures elastic as weU as viscous behavior by determining the response to both steady-state and oscillatory shear. The geometry may be cone—plate, parallel plates, or concentric cylinders parallel plates have several advantages, as noted above. 

The RMS-800 provides steady-shear rotational rates from 10 to 100 rad/s and oscillatory frequencies from 10 to 100 rad/s. An autotension device compensates for expansion or contraction. With the standard 25- and 50-mm parallel plates, the viscosity range is 50-10 mPa-s, and the shear modulus range is 8 x 10 to 10 N/m. These ranges can be expanded with nonstandard plates, cones, and a Couette system. The temperature range is 20-350°C (-150 0 optional). 

Experimentally, the dynamic shear moduli are usually measured by applying sinusoidal oscillatory shear in constant stress or constant strain rheometers. This can be in parallel plate, cone-and-plate or concentric cylinder (Couette) geometries. An excellent monograph on rheology, including its application to polymers, is provided by Macosko (1994). 

The evolution of the dynamic viscosity rp (co, x) or of the dynamic shear complex modulus G (co.x) as a function of conversion, x, can be followed by dynamic mechanical measurements using oscillatory shear deformation between two parallel plates at constant angular frequency, co = 2irf (f = frequency in Hz). In addition, the frequency sweep at certain time intervals during a slow reaction (x constant) allows determination of the frequency dependence of elastic quantities at the particular conversion. During such experiments, storage G (co), and loss G"(co) shear moduli and their ratio, the loss factor tan8(co), are obtained ... 

Rheological Experiments. Melt viscosity and low-strain oscillatory experiments were performed on a Rheometrics RDS-7700 dynamic spectrometer equipped with a 0.2-2.0-g-cm torque transducer. The samples were mounted on 25-mm-diameter parallel-plate fixtures with a gap of 0.5 mm. Prior to each scan, samples were heated to 50 °C and then cooled slowly to room temperature. Steady-shear... 

However, the use of the parallel plate geometry is not recommended for viscosity measurements, because the shear strain rate variation along the gap between the plates is larger than that experienced in concentric cylinder systems.However, there might be advantages when using the geometry in oscillatory studies. ... 

Viscoelastic measurements in oscillatory shear were performed using a Rheometrics System Four rheometer in the frequency range 10 3 rad/sec < co < 102 rad/sec. 8 mm diameter parallel plates were used for temperatures below 80°C and 25 mm diameter parallel plates were used for T>80°C, with plate separations of 1.1 0.2 mm. Comparison of... 

The shear rate (/) is defined as the change in the fluid s oscillatory velocity (V=aoj cos (of)) the gap between infinite parallel plates that is normal to the flow,... 

The effect of temperature on the mechanical properties of a liquid can be investigated using a special type of dynamic mechanical analyser called an oscillatory rheometer. In this instrument the sample is contained as a thin film between two parallel plates. One of the plates is fixed while the other rotates back and forth so as to subject the liquid to a shearing motion. It is possible to calculate the shear modulus from the amplitude of the rotation and the resistance of the sample to deformation. Because the test is performed in oscillation, it is possible to separate the shear modulus (G) into storage (G ) and loss modulus (G") by measuring the phase lag between the applied strain and measured stress. Other geometries such as concentric cylinders or cone and plate are often used depending on the viscosity of the sample. 

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