Dynamic-Mechanical Study of the Dynamics of Polymer Blends near the Glass Transition

Abstract

Poly(methyl acrylate) (PMA) and its blends with poly(4-hydroxystyrene) and a poly(4-hydroxy-co-4-methoxystyrene) have been studied by dynamic-mechanical spectroscopy at temperatures close to the calorimetric T g and frequencies between 0.3 and 30 Hz. The results for the imaginary part of the elastic modulus lead to broad master curves, which width increases with the content of the concentration of the second polymer. Even though the results can be described reasonably well using a Kohlrausch-Williams-Watts relaxation function, rather low values of the stretching parameter β are necessary in order to obtain good agreement with the experimental data. The Havriliak-Negami relaxation function leads to slightly worse agreement with experiment. The fragility parameter of the blends decreases with the concentration of PMA. The qualitative trend of the results may be interpreted in terms of the existence of concentration fluctuations in the blends