We present the discovery of an unusually large isotope effect in the structural relaxation and the glass transition temperature Tg of water. Dielectric relaxation spectroscopy of low-density as well as of vapor-deposited amorphous water reveal Tg differences of 10 ± 2 K between H2O and D2O, sharply contrasting with other hydrogen-bonded liquids for which H/D exchange increases Tg by typically l...

Glass transition parameters can be used to study the miscibility, or lack of it, in polymer-modified asphalt binders. In this study, contribution thermodynamics mixing glass was quantitatively assessed a differential scanning calorimeter for four binders partially and fully replaced by an epoxy system. The values heat capacity (Cp) and, subsequently temperature (Tg) all were determined quantify...

Photoinduced intramolecular charge separation (CS) in a polar polymer glass, cyanoethylated pullulan (CN-PUL), was studied below the glass transition temperature (Tg=395 K). A series of three carbazole (Cz: donor)-cyclohexane (S: spacer)-acceptor (A: acceptor) molecules (Cz-S-A) was used as intramolecular donor-acceptor dyads. The photoinduced CS rate was evaluated by the fluorescence decay mea...

In a review of the present title, the first requirement is to ensure that the title words are understood. While the term “glass” is broadly familiar, and the origin of the “glass transition” in terms of the crossing of system and experimental time scales is generally agreed upon, there are at least three different definitions of the material property “glass transition temperature” (Tg) in curre...

Amorphous materials are inherently unstable and tend to crystallize upon storage. In this study, we investigated the extent to which the physical stability and inherent crystallization tendency of drugs are related to their glass-forming ability (GFA), the glass transition temperature (Tg) and thermodynamic factors. Differential scanning calorimetry was used to produce the amorphous state of 52...

The paper discusses a model of viscosity η of glassforming melts in an attempt to predict the dependence of η on temperature T and on pressure P. The equation, derived here, describes with excellent accuracy all existing experimental viscosity data including those of glassforming melts, igneous materials and polymers. It is demonstrated that the activation energy E(Tg) can be expressed through ...

In simple terms, the wood cell wall is a composite made of a rigid cellulose polymer in a matrix of lignin and the hemicelluloses. The lignin polymer in the middle lamella and S2 layer is thermoplastic; that is, it softens upon heating. The glass transition temperature Tg of the lignin in the matrix is approximately 170°C (338°F). Above the matrix Tg, it is possible to cause the lignin to under...

We report the linear increase in the glass transition temperature, Tg, with nanofiller weight content. ZnO quantum dots dispersed by melt-blending in a poly(methyl methacrylate) host were characterized by differential scanning calorimetry and dynamic mechanical analysis showing that the Tg of the system is described by a power law of the interparticle distance, hp, where the percolation exponen...

Many molecular glass forming liquids show a shift of the glass transition Tg to lower temperatures when the liquid is confined into mesoporous host matrices. Two contrary explanations for this effect are given in literature: First, confinement induced acceleration of the dynamics of the molecules leads to an effective downshift of Tg increasing with decreasing pore size. Second, due to thermal ...

epoxy – polysulfide copolymers without or with low amounts of epoxy in their structure have poor mechanical properties in oxidative curing system.to strengthen the mechanical properties of polysulfide elastomer inclusion of epoxy resin (epon828) as hard segment was studied. ft-ir spectroscopy and rheometry were used to verify the formation of epoxy-polysulfide copolymer.  results obtained from ...