Glass transition in inorganic glasses, polymers, and crystals

Two simple approaches to sol–gel transition

“…In naive manner it is possible to assume, that a glass transition is caused purely by kinetic effect of a liquid freezing, for which viscosity η gets infinite value for a finite value of the shear modulus G [2]. However in the course of usual second-order phase transition, where infinite increase of the τ at critical point is also observed the situation is reverse.…”

“…In such a case, thermodynamic peculiarities are observed as, e.g., appearance of the shear modulus when the system reaches a critical point. 2 The first theoretical representations of such type transitions have been elaborated in classical works by Flory [5] - [7]. Modern description of the glassy state of the macromolecule networks (see [8] - [10]) is based on pioneering contributions to the theory of soft condensed matter: the Deam-Edwards theory [11] of a cross-linked tangled macromolecule, and the Edwards-Anderson theory [12] of spin glass.…”

Temperature dependence effect of viscosity on ultrathin lubricant film melting

“…At derivation of equation (3) the simplest temperature dependence of viscosity η was defined in relation to the critical temperature [12]:…”

“…In works [4][5][6][7][8][9][10]] the boundary friction is described which is realized in the case of ultrathin films with thickness less than four diameters of molecules, at smooth or rough surfaces, high loads and small shear rates. It is known that shear viscosity of lubricant layer depends on a temperature [11][12][13][14]. Thus, at the derivation of basic equations describing the process of friction, it is necessary to define the explicit form of temperature dependence of viscosity.…”

“…However, actually, it takes different forms for specific systems. According to the experimental results this function is usually fixed by either Vogel-Fulcher relationship or by power dependence [11][12][13][14]. In particular, the Vogel-Fulcher empirical formula is explained within the framework of theories of free volume and excess configuration entropy [11].…”