Within the last five years, investigators using NMR and forced Raleigh scattering techniques have found that the Stokes–Einstein (S–E) relation breaks down in supercooled liquids. It has been pointed out that the shear viscosity has a significantly stronger temperature dependence than either the self-diffusion coefficient, D(T), or the translational diffusion coefficient of tracer molecules of comparable size (not shape) to the host liquid. These observations confirm our results on trinaphthylbenzene (TNB) and 1,2 diphenylbenzene (OTP), published in a series of papers more than 30 years ago. An analysis of crystal growth rate measurements on these materials demonstrated that the transport-dominated crystal growth rate, G′(T), exhibited a weaker temperature dependence than the shear viscosity, η(T). Where the expression G(T)=f(T)/η(T) is often substituted for the more basic growth rate relationship G(T)=D(T)f(T). We showed that this practice (often used) is invalid. Here, f(T) is a nucleation/growth free energy term. Reexamination of our earlier work has shown that the extent of the S–E “breakdown,” as revealed by crystal growth rate data, is consistent with the answers that are now provided by modern NMR and forced Rayleigh scattering techniques. Employing the derivative procedure of Stickel and co-workers to fit our TNB viscosity data over more than 15 orders of magnitude, requires an Arrhenius temperature dependence at high temperatures, a “crossover” to a Vogel–Fulcher–Tammann–Hesse dependence at some temperature TA, and a further “crossover” to another Vogel–Fulcher–Tammann–Hesse form at a lower temperature, TB. Below TB a disparity occurs between the temperature dependences of the transport-dominated crystal growth rate and viscosity. Where our old and the recent results coincide, the techniques represent or measure similar parameters.

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The torsional creep and creep recovery behavior of amorphous 1,3,5-tri-α-naphthyl benzene was studied, while at metastable equilibrium density, along a specified glassy volume—temperature line, and during isothermal volume contraction below the conventional glass transition temperature Tg. Dilatometric measurements confirmed the conventional Tg to be 69°C. The viscosity measurements of Magill and Ubbelohde were extended from 185°C to below Tg, covering viscosity values from 10−1 to 1016 P. In a region of time scale the mechanical response was found to be dominated by Andrade creep. The retardation spectrum found was over 9 logarithmic decades wide in contrast to reportedly narrow spectra exhibited by other liquids with similar molecular weights. A steady-state compliance Je of 2.6×10−10 cm2/dyn at 64.2°C was measured. Although compliances as low as 8×10−11 cm2/dyn were measured, no time-independent glassy compliance Jg could be ascertained. Free-volume theory was found applicable to all measurements made below 120°C. The occupied volume v0 was deduced to be temperature insensitive.

The kinetics of solidification of 1,3,5-tri-α-naphthylbenzene have been studied from 25° above the glass temperature (69°C) almost to the crystal thermodynamic melting point (199°C). The crystal growth rate has been analyzed using current theories of crystallization and a mechanism for crystal growth has been proposed. It has been demonstrated that mass transport in crystal growth and viscous flow do not have the same temperature dependence. The morphology of the solid phase is discussed. Pertinent parameters pertaining to the glassy state of this material are also reported.

The viscosity measurements on 1,3,5-tri-α-naphthylbenzene have been extended to 407°C, in order to establish the limiting high-temperature Arrhenius activation energy. Diverse functions have been used to fit the viscosity results on this material which range over 15 orders of magnitude. From the temperature dependence of viscosity and crystal-growth rate in the transport-controlled temperature region below the growth-rate maximum, a temperature dependence of the limiting high-frequency modulus (for the dominant viscoelastic relaxation process) is predicted.