Thermodynamic Study of the Glass Transition in Polyamine−Polyalcohol Mixtures: Entropy−Theoretical Interpretation of Anomalous Glass Transition Behavior

Abstract

The glass transition temperatures of binary mixtures of polyamines and polyalcohols are investigated by differential scanning calorimetry (DSC). For all systems, the composition dependence of the glass transition temperature Tg shows clear maxima, in stark contrast to those of polyalcohol−polyalcohol mixtures reported previously. A thermodynamic analysis based on the entropy theory is carried out for (1,2-propanediamine)x(glycerol)1-x and (1,2-propanediamine)x(1,3-propanediol)1-x systems. The composition dependence of Tg predicted from the entropy theory of regular solutions (regular solution model, RSM) is not able to reproduce the anomalous behavior, and the excess configurational entropies ScE are negative and larger than 20 J K-1 mol-1 in absolute value at the minima. The origin of the large value of ScE is discussed with respect to the change of hydrogen bond network structure on mixing.