Sliding plate and sliding cylinder rheometers

This chapter describes rheometers that are particularly advantageous for the generation of large, rapid, transient shear deformations in rheologi-cally complex materials. Such deformations are particularly useful for the study of time dependent structural changes and non-linear viscoelasticity. Sliding plate (plane Couette) flow is also useful when non-mechanical measurements, such as optical and small-angle neutron scattering analyses, are being made to monitor structural changes during shearing. Finally, this type of instrument has been found useful in studies of wall slip and shows promise for the study of the effect of pressure on slip and rheological properties. The rheometers described here are thus of particular value for evaluating materials such as molten plastics, elastomers, concentrated polymer solutions, asphalts, bread doughs and other concentrated suspensions.