Time-temperature superposition in viscous liquids

Dielectric relaxation measurements on supercooled triphenyl phosphite show that at low temperatures time-temperature superposition (TTS) is accurately obeyed for the primary (alpha) relaxation process. Measurements on 6 other molecular liquids close to the calorimetric glass transition indicate that TTS is linked to an ${\omega }^{-1\mathrm{/}2}$ high-frequency decay of the alpha loss, while the loss peak width is nonuniversal.