Dynamic Mechanical Shift Factor Extraction for Thermosetting Polymer Physical Aging Analysis
Extracting physical aging shift factors in thermosets requires momentary loading below Tg, sub-tenth Kelvin stability, and frame compliance corrections.
Shift Factor Extraction
Analytical Procedure
Mathematical alignment of viscoelastic material properties measured at different temperatures along a logarithmic time axis is used to build a master curve. Performing shift factor extraction allows engineers to quantify the temperature-dependent acceleration of material aging and mechanical relaxation. This analytical step is fundamental in polymer characterization and sensor longevity analysis.
Numerical Modeling
Logarithmic scaling coefficients are determined by minimizing the discrepancy between overlapping segments of experimental data. During shift factor extraction, these coefficients are plotted against temperature to fit models like the Williams-Landel-Ferry equation. This fitting provides a continuous function for predicting long-term behavior.
Reference State
Selection of a baseline temperature is required before starting the curves-alignment calculations. The process of shift factor extraction yields factors of unity at this chosen baseline temperature, with larger or smaller values determined for temperatures above or below this point. This baseline selection ensures that all subsequent curves are shifted relative to a fixed metrological state.
Accuracy Validation
Sensitivity to experimental noise and temperature fluctuations must be minimized to ensure the reliability of the master curve. If shift factor extraction relies on sparse data, the resulting model can yield incorrect predictions of sensor drift. Regular validation against slow-rate laboratory tests helps confirm the calculated coefficients.