Dynamics of glass-forming liquids. VII. Dielectric relaxation of supercooled tris-naphthylbenzene, squalane, and decahydroisoquinoline

We have measured the dielectric relaxation of several molecular organic supercooled liquids, ααβ-tris-naphthylbenzene (C36H24 and C36H10D14), squalane, and decahydroisoquinoline. The dynamics is studied in the frequency range 10−2–107 Hz, equivalent to temperatures between Tg and approximately 1.2×Tg. For the very low dielectric loss materials, a resolution of tan δ≈3×10−5 is required in order to observe the details of the relaxation behavior. Characteristic quantities like fragility, relaxation time dispersion, time–temperature superposition, and the slow Johari–Goldstein type β relaxation are among the properties discussed.