Volume and enthalpy recovery measurements have been performed to study the physical aging behavior of a polystyrene using capillary dilatometry and differential scanning calorimetry, respectively. Isothermal aging temperatures from 94 to 100°C were studied with aging times ranging up to several days. The volume decreases during physical aging and levels off at equilibrium. Analogously, the difference between the enthalpy of aged and unaged DSC curves increases and levels off at equilibrium. For comparison purposes, both sets of data are normalized to yield the departure from equilibrium which varies from unity at very short aging times to zero when equilibrium is reached. It appears that both volume and enthalpy come into equilibrium at the same time at 97°C. However, the approach to equilibrium differs, with volume recovery being faster than the enthalpy recovery at short times.
|Number of pages||2|
|Journal||Polymeric Materials Science and Engineering, Proceedings of the ACS Division of Polymeric Materials Science and Engineering|
|State||Published - 1997|
|Event||Proceedings of the 1997 Spring ACS Meeting - San Francisco, CA, USA|
Duration: Apr 13 1997 → Apr 17 1997