Broadband Dielectric Study on Glass Transition of 1-Propanol-Water Mixture

Abstract

We performed broadband dielectric measurements for pure 1‐propanol (PrOH) and 80 wt% PrOH‐water mixture in the temperature range of 78 K and 300 K and frequency range of 1 μHz and 30 GHz. For pure PrOH, Debye‐type primary process and two small processes at higher frequency than the primary loss peak are observed in whole the temperature range. For 80 wt% PrOH‐water mixture, the KWW‐type primary process and two small processes similar to the pure PrOH are observed above crossover temperature, TC. Below TC, additional process is observed at lower frequency range than the primary loss peak frequency. The relaxation time of the primary process for the 80 wt% PrOH‐water mixture agrees with that for pure PrOH below TC, while it is smaller than that for the pure PrOH above TC. For 80 wt% PrOH‐water mixture, the cooperative motion of PrOH and water by hydrogen bonding and/or clathrate‐like structure occurs above TC, and it leads to the KWW‐type primary process. On the other hand, this cooperative motion does not occur below TC, and the motion of PrOH and water molecules leads to the primary and low‐frequency processes, respectively.