The component dynamics of miscible binary mixtures of glass formers: New features

Opposite effects on the width of the dispersion of the alpha-relaxation and the separation on the time scale of the Johari-Goldstein beta-relaxation from the alpha-relaxation are predicted for guest molecules dissolved in a host, depending on whether the glass transition temperature of the host is higher or lower than that of the guest. These predictions are tested by dielectric relaxation measurements on mixtures of two glass-forming liquids. The results are in agreement with the predictions.