Meaning
Graphical representation of polymer properties over an extended range of time or frequency describes the analytical tool. In viscoelastic characterization, a master curve allows engineers to predict long-term performance from short-term experimental tests. This tool is generated by shifting dynamic mechanical analysis data collected at different temperatures.
Time-Temperature Superposition
Equivalence between the effects of time and temperature on polymer behavior forms the underlying physical principle. A test run at a high temperature for a short duration yields the same molecular response as a test run at a low temperature for a very long duration. By applying shift factors, disparate data sets are combined into a single continuous plot that spans several decades of frequency.
Material Characterization
Mechanical properties such as storage modulus and loss modulus are plotted against frequency or time. This chart is used by designers to evaluate how a plastic part will behave during rapid impact events or over decades of constant load. Sourcing specialists use the plot to verify that a cheaper regrind blend holds its modulus over the required operating frequency of the application.
Moulding Significance
Melt rheology during high-shear injection moulding relates to the high-frequency end of the plot. This relationship helps molders predict how the polymer will flow into thin-walled sections of the cavity.
