Physical Properties of Aromatic Hydrocarbons. III. A Test of the Adam—Gibbs Relaxation Model for Glass Formers Based on the Heat-Capacity Data of 1,3,5-tri-α-Naphthylbenzene

The specific heat of 1,3,5-tri-α-naphthylbenzene (TαNB) was measured from 200° to 560°K with a differential scanning calorimeter. The glassy, liquid, and crystalline phases of this material were studied. The latent heat of fusion was found to be 10.14±0.14 kcal mole−1 and the entropy of fusion, 21.5±0.3 cal mole−1·deg−1. The temperature dependence of the viscosity measured by Plazek and Magill is compared with that predicted from an analysis of the Cp data according to the theory of Adam and Gibbs. The temperature dependences of the calculated and experimental viscosities diverge in the vicinity of the melting temperature where presumably space requirements necessary for molecular motions in the melt are less critical than at the lower temperatures. The viscosity temperature dependence of cooperative relaxation processes (based on configurational entropy considerations) in glass-forming liquids is applicable to TαNB over essentially the same temperature range as the well-known empirical free-volume relationships, although the Adam—Gibbs model more closely represents the data outside this range.