Physical aging in amorphous polymers: comparison of observations in calorimetric and mechanical tests

Constitutive equations are derived for the kinetics of physical aging in polymeric glasses. An amorphous polymer is treated as an ensemble of cooperatively rearranging regions (CRR) which relax at random times as they are thermally agitated. Structural recovery is modeled as fragmentation and aggregation of CRRs. To verify the governing equations, results of numerical simulation are compared with experimental data in calorimetric and dynamic tensile tests for three commercial grades of poly(ether imide). Fair agreement is demonstrated between observations and predictions of the model.