LOCAL MODE OF MOTIONS IN AMORPHOUS SOLID .3. CONTRIBUTION OF HYDROGEN-BONDS IN D-SORBITOL

Dielectric properties of the local mode of motions (the beta relaxation process) in two D-sorbitol glasses are presented as a function of temperature and pressure. The glasses were vitrified from the liquid by isobaric cooling at a rate of - 0.2 K/min under 0.1 and 78.5 MPa. The following results are different from those observed in molecular and polymer glasses: the relaxation magnitude of the higher-density glass vitrified under 78.5 MPa is larger than that of the lower-density glass vitrified under the atmospheric pressure; the distribution of the relaxation time of the higher-density glass is narrower than that of the lower-density glass; and the relaxation magnitude of each glass appears to increase slightly with pressure. The results are interpreted by the difference in the distribution of intermolecular hydrogen bonds frozen-in at the vitrification points. It is also suggested that the hydrogen bonds in the glasses may be slightly decomposed and/or weakened by external pressure.