Parallel Plate Rheometry

Shear Rate

Viscoelastic characterization of polymer matrices requires operating within the linear viscoelastic region to prevent structural disruption of the polymer network. Using parallel plate rheometry, the operator applies a strain sweep to determine the critical strain limit before starting frequency sweeps. This step prevents non-linear responses from distorting the elasticity measurements.

Thermal Stability

Viscoelastic analysis demonstrates how polymer viscosity changes during prolonged exposure to processing temperatures. Through parallel plate rheometry, the changes in complex viscosity over time are tracked to assess polymer degradation or thermal crosslinking. This test establishes the maximum allowable dwell time for the resin in an injection molding barrel.

Sample Preparation

Bubble-free disk specimens must be molded before test execution to ensure full contact with the rheometer plates. During parallel plate rheometry, any air pockets in the specimen cause an artificial decrease in measured viscosity. Squeezing the sample to the target gap and trimming the excess melt creates the required boundary conditions.

This technique ensures high repeatability between successive runs and generates reliable data for process simulation software.