Effect of association complexes on the glass transition in organic halide mixtures

Abstract

Publication costs assisted by St. Cloud State UniversityThe glass transition temperatures of binary mixtures of chloroform, dichloromethane, and trichloroethylene with several Lewis bases have been measured as a function of composition. The glass transition temperatures of the mixtures are shown to be increased by complex formation between the chloride and the base, and the glass transition temperature is shown to increase with base strength. The chloroform mixtures show the greatest effect of complex formation. A cusp is found in the composition dependence of the glass transition temperature T , of mixtures of chloroform with triethylamine. The cusp is found at the equimolar composition. It is taken as evidence for the complete association of chloroform with triethylamine into a 1:l complex at T,. The trichloroethylene mixtures show greater effects of complex formation than do the dichloromethane mixtures, although evidence from the literature seems to indicate that dichloromethane is the stronger acid.

The effects of selected gases upon ethanol: hydrogen bond breaking by O2 and N2

“…The temperature range of most figures, 75-160 K, covers two distinct ethanolic domains: (i) the glass domain which exhibits a normal transition range (3, 16) of 90-100 K and (ii) the crystal domain which consists of crystalline ethanol, possibly containing entrapped islets of phenanthrene, extending The onset of the low-temperature luminescence-loss for the non-degassed sample occurs in the region 90-100 K and corresponds well to the accepted values (3,16) for the glass transition of ethanol. The primary observation is that the low-temperature onset in the degassed ethanol solution shifts upwards by + 15 to +20 K. However, it is not clear at this point (i.e., from Fig.…”

Entropy of Mixing and the Glass Transition of Amorphous Mixtures

“…The strong interaction between components results in strong positive deviations from the predicted T CK values. Strongly interacting mixtures give place to structured mixtures [12,26] and a negative entropy of mixing can be expected. The contribution of the entropy of mixing obtained from Equation 18 reflects such a character for this mixture.…”

“…which has been used as the simplest estimate used for the glass transition of mixtures [12]. Equations 2 through 6 can all be directly obtained from the general Equation 1.…”

“…The T g values of amorphous mixtures are generally interpreted in terms of intermolecular interactions [5,12,[14][15][16][17]. Strongly interacting compounds tend to give mixtures whose glass transition is higher than would be expected from predictions from the different variants of (the general) Equation 1 [12].…”

“…Strongly interacting compounds tend to give mixtures whose glass transition is higher than would be expected from predictions from the different variants of (the general) Equation 1 [12]. It is interesting to note that mixing effects on the glass transition are typically studied from an enthalpy perspective, even though it is entropy the quantity that plays a central role in glass formation [6].…”