Viscoelasticity compression clamp

Figure 7.4.4 shows data from the rotating clamp device for the transient equibiaxial viscosity at three different extension rates. For comparison, the linear viscoelastic viscosity and the uniaxial viscosity are shown. Results for the biaxial viscosity compare well to those measured in lubricated compression on the same polyisobutylene sample as in Figure 7.4.4 (Chatraei et al., 1981). So far, only results with the rotating clamp method have been reported for this sample. Maximum strains were 2.5 in the biaxial and multiax-ial tests and k < 0.1 s. Friction on the talcum powder may limit the total strain and the detectable stress values. Much larger, more homogeneous samples are required than were used in the lubricated squeezing experiments. However, because the rotating clamps can...

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