A newly designed coaxial cylinder-type dynamic rheometer

Abstract

A newly designed dynamic rheometer is described. This apparatus is designed for the purpose of the investigation of the physical ageing process of gels and for the determination of the viscoelastic properties of polymer melts. With this instrument the dynamic moduli can be determined very accurately in a range of about' 8 decades (-2 < log G' < 5.3 and -3 < log G" < 5.4; G' and G" in N/m 2) and in a frequency range of more than 6 decades (5 • 10 -s -100 Hz) with an accuracy and stability of 0.025%. Results are shown of measurements on a silicon oil (with loss angles deviating only little from 90°), on a gel of polyvinyl chloride in Reomol (with loss angles deviating only little from 0 °) and on a polystyrene melt for which, at low frequencies, the dependencies of the storage and loss moduli on the frequency are quadratic and linear, respectively.

On the time‐concentration superposition of the linear viscoelastic properties of plasticized polystyrene melts using the free volume concept

“…2, as function of the polymer weight fraction w2. The Note, in all figures shown below the decadic logarithm (lg) is used, whereas in Eqs (3). and (11) the natural logarithm (ln) is favoured for sake of simplicity and of lucid arrangement.…”

Rheometry for non-Newtonian fluids

“…Alternatively, the frequency of deformation can be varied at constant maximum shear strain amplitude. Rheometers capable of performing oscillatory shear are widely available as commercial instruments, in addition to more specialized devices ( Te Nijenhuis and van Donselaar, 1985 ). An example of the latter is an oscillating plate rheometer ( Eggers and Richmann, 1995 ) which requires a very small liquid sample volume ( Ͻ 0.3 ml) and has a (potentially) great frequency range (2 Hz to 1 kHz).…”

The role of short chain molecules for the rheology of polystyrene melts.

“…Because parameters B and c 9 are both independent of molar mass and temperature and form polymer specific constants, the product (9) should be the same for all molar masses and reference temperatures [7]. *) According to the Maxwell-model one obtains for the zero-shear viscosity '7o of a monodisperse polymer melt the relation t/0 = G0r.…”

“…The dynamic viscometer used for the measurements is of the concentric cylinder type [9]. It was manufactured by Rodem Instrumentenfabriek (Netherlands).…”