Physical aging of atactic polystyrene as seen by dielectric relaxational and low-frequency vibrational Raman spectroscopies

The physical aging of atactic polystyrene at a temperature close to the glass transition temperature and at room temperature (storage conditions) was investigated by low-frequency Raman scattering, broadband dielectric spectroscopy and differential scanning calorimetry. A consistent relation between changes in molecular dynamics and nanostructure caused by physical aging has been found. The results suggest that the structure after aging becomes more cohesive and more homogeneous at the nanoscale, while the α-relaxation seems to be mainly affected by the mentioned structural changes.