Fragility and glass transition for binary mixtures of 1,2-propanediol and LiBF_4

摘要

The fragility and glass transition for binary mixtures of 1,2-propanediol and LiBF_4 were investigated by measuring the heating rate dependence of glass transition temperature (T_g) using differential scanning calorimetry. With increasing LiBF_4 mole fraction, x, up to 0.25, fragility, m, increased rapidly from 53 to 85, and then remained approximately unchanged for x > 0.25. The concentration dependences of T_g and heat capacity jump at T_g also showed anomalies around x = 0.25. We suggest this mixture transformed from a moderate to quite fragile liquid at x = 0.25 because of a structural change from a hydrogen- bonding- to ionic-interaction-dominant system.