Thermal study of glass transitions in binary systems of simple hydrocarbons

Abstract

Glass transition phenomena of four binary systems composed of simple hydrocarbons were studied by means of the differential thermal analysi s (DTA). For all the systems, a definite glass transition was observed and a monotonous relation between the glass transition temperature (Ts) and composition (x) was obtained. The composition dependence of T s was analyzed in terms of the entropy theory based on the regular solution model. The theoretical prediction could not reproduce our results other than (l-butene)x(1-pentene)~-x system. This disagreement is considered to be due to deviations of the present systems from the regular solution, and the accompanying excess configurational entropy S~ was estimated as a function of composition.Extraordinarily large values of S~ were obtained for (propene)x(propane)l-x and (propene)~(1 -pentene) 1-~ systems.

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

“…The result that the composition of T g cannot be reproducible with RSM implies the irregular nature of these systems. We evaluated the excess configurational entropy S c E in the same way as described before. , The quantity S c E is the configurational part of the excess configurational entropy Δ mix S E , the change in the degree of structural variation on mixing. The evaluated S c E values for (12PDA) x (Gly) 1 - x and (12PDA) x (13PDO) 1 - x were shown in Figure .…”

Structural Relaxation Dynamics in Binary Glass-Forming Molecular Liquids with Ideal and Complex Mixing Behavior

“…The composition dependence of T g has been extensively studied in associated and nonassociated liquids, indicating positive (i.e., an increase in T g ), zero, and negative deviation from the linear compositional averages of the component T g ’s, − however the interpretations have not provided a complete understanding. , It has been pointed out that the glass transition temperature relates to the strengths and nature of the intermolecular interactions in the liquid state, where strong intermolecular interaction/association could account for significant excess glass transition temperatures with the implication of large mixing enthalpies. , …”

Glass transition and mixing thermodynamics of a binary eutectic system

“…Whereas the positive T g deviations are considerably observed, 14,[16][17][18][63][64] negative deviations are relatively less documented in binary molecular systems. [13][14][15] Recently, we have studied the glass transition in binary isomeric mixtures between methyl m-toluate (MMT) and methyl o-toluate (MOT). 64 This binary system might serve as an ideal mixing case since earlier studies of mixing thermodynamics indicate that DH mix values in isomeric mixtures are remarkably small, close to zero.…”

“…[8][9][10][11][12] The dependence of T g on composition has been extensively investigated for a variety of binary miscible mixtures with the diverse manifestations of negative, zero and positive deviations of the composition dependence of T g from the ideal mixing law. [13][14][15][16][17][18][19][20][21][22] The theoretical accounts have shown certain success, in particular, for the models such as the Gordon-Taylor (GT) model, 23 and the Couchman-Karasz (CK) model. 24 The GT model is initially proposed for polymer blends on the basis of ideal volume of mixing and the linear change in volume with temperature, 17,25,26 and has proven to give a satisfactory prediction for polymer blends.…”