The aging of glassy polymers as determined by scanning calorimeter measurements

Abstract

A model successfully applied to explain the volumetric relaxation of amorphous polymers near the glass transition has been used to predict the behavior in a scanning calorimeter of amorphous polymers annealed or aged below their glass transition. Although the predictions are incomplete because of the uncertainty of several critical parameters, the calculations indicate that caution is needed in interpreting scanning calorimeter data. Possible problems interpreting such data include (1) underestimation of the conformational heat capacity, (2) incorrect comparison of specimens aged at different temperatures, and (3) uncertain energy of the quenched state, against which aging is often compared.