ИСТИНА

In 1926 Tamman [1] proposed to mark a temperature of viscous flow liquid transformation into solid brittle glassy state as Tg (Tglass). Glass transition region lies between this transformation temperature of viscous flow liquid to the solid fragile glassy state Tg and the temperature of its conversion to a normal fluid Tf. In the middle of this area Tamman located the temperature Tw – the temperature of winding on the "property-temperature" dependence curve. Tamman’s Tg is below Tw. After the Lindig’s (1959) works, Tamman’s Tg - Tg(T) - has been forgotten, and his Tw was unreasonably called the glass transition temperature Tg. According to Winter-Klein (1953), Nemilov (1971), Mazurin and others (1987), the glass transition region lies within the viscosity of cooling liquid η = 107-8...1014-16 Pa∙s. Common today Tg (Tamman’s Tw) characterizes the viscous-flow liquid at η = 1012,3 Pa∙s, ie located approximately in the middle of the glass transition region. The physicochemical essence of this temperature is the ascertaining of intertransformation direction reverse of the structure fragments of high and low temperature polymorphic modifications (polymorphoids), that is the structure basis of glassforming substance (Minaev, 1987). This temperature is marked by us as Tw-rev, which shows Tamman’s priority in its establishment and highlights the physicochemical essence of the process characterized by its. Fig.1. The scheme of relaxation processes of condensed glass-forming substance. Below this Tg at η = 1014 ... 1016 Pa∙s the true glass transition temperature (Tamman’s Tg(T)) is located. At this temperature in the glass on heating the heat capacity dramatically increases. This process requires additional energy generated during the heating of the glass. Exactly that energy we detect as sub-endoeffect – when the brittle glassy solid state transforms into viscous flow liquid at viscosity ≤ 1015 Pa∙s. Sub-endoeffect in glass is located from 10 to 70°C below the conventional Tg (Ping Chen, P.Boolchand et al, 2010) and obviously coincides with Tamman’s Tg(T). Sub-endoeffect – another cogent evidence of Tamman’s Tg(T) existence and the unconditional reason for this term to return into modern science usage. References [1] G.A. Tamman, Der Glaszustand. Leipzig (1933).