Free volume from the positron annihilation lifetime spectroscopy method and its relationships with the various microscopic and macroscopic dynamic properties of ortho-terphenyl

A phenomenological model linking the macroscopic volumetric behaviour found from dilatometry to the microscopic free-volume hole properties found from positron annihilation lifetime spectroscopy is applied to a set of dynamic properties of a fragile low-molecular-weight glass former: ortho-terphenyl. A number of correlations between the free-volume hole fractions derived from this model and the various dynamic properties such as viscosity, self-rotational diffusion, and tracer translational diffusion can be established over the temperature range from the glass-liquid transition temperature T-g up to similar to 1.2T(g) via a Williams-Landel-Ferry (WLF)Doolittle-type equation.