Interrupted shear experiment

There are several other transient flow experiments which can be instructive in identifying relaxation of orientation and structure. These experiments are summarized in Figure 3. In the interrupted shear experiment the fluid is initially sheared and then allowed to rest for a time The amount of recovery of... 

An interesting variant on start-up and cessation of steady shear is interrupted shear, which is used to monitor relaxation processes that occur at very long times. The time at which data can no longer be obtained in a relaxation experiment is governed by the sensitivity of the stress or... 

Many years of experience with sliding plate rheometers have revealed several phenomena that limit their utility under certain conditions. First, the normal stress differences create a pressure gradient in the sample that tends to pump melt in from the ends of the sample and out toward the edges. [ 147-149]. This flow can be prevented by the use of fluorocarbon side- rails. More serious limitations are imposed by slip, cavitation and rupture, which interrupt experiments at sufficiently high strains and strain rates. At the same time, however, sliding plate rheometers have been found to be useful tools for the study of melt slip [150]. Elastomers are particularly resistant to shearing deformations and even the use of deep grooves in the plates does not ensure their adherence [146]. 

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