Dynamic-mechanical and light scattering study of the glass transition of poly(vinylacetate) and a poly(vinylacetate) +poly(4-hydroxystyrene) blend

Abstract

The dynamics of poly(vinylacetate) (PVAc) and of a blend of PVAc and 20% in weight of poly(4‐hydoxystyrene) have been studied in the glass transition region using dynamic‐mechanical and photon‐correlation spectroscopies. Both kinds of data show the overlapping of the main α relaxation with a faster one. The complex part of the elastic modulus shows the existence of a β’ sub‐T_g transition overlapping with the α one in the high‐frequency region. The light scattering data show some degree of overlapping of the α and β transitions. As a consequence, at least two Kohlraush–Williams–Watts terms are needed to describe the relaxation functions. The results show a good agreement with the predictions of the mode coupling theory except for the fact that the calculated critical temperature seems to be lower than the calorimetric glass transition temperature.