Mechanical response of a simple molecular glass former in the glass transition region

Dynamic shear modulus measurements have been performed on a simple glass forming liquid, m-toluidine, as a function of frequency at low temperatures, down to the glass transition region. This approach, based on isothermal experiments, has allowed the study of various aspects of the mechanical response of the supercooled liquid: the glass-like behaviour (low temperatures/high frequencies), the liquid-like behaviour (viscous flow at high temperatures/low frequencies), and the relaxational behaviour. The information obtained from the analysis of the complex frequency-dependent shear modulus has been exploited to focus on: (a) the properties of the α-relaxation process in the supercooled liquid around its glass transition temperature, (b) the possible existence of a β-relaxation process, and (c) the low viscosity of m-toluidine at the glass transition, compared to other glass-formers.