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The glass transition of a liquid to a solid-like state may occur with either cooling or compression. [10] The transition comprises a smooth increase in the viscosity of a material by as much as 17 orders of magnitude within a temperature range of 500 K without any pronounced change in material structure. [11]
The Flory–Fox equation relates the number-average molecular weight, M n, to the glass transition temperature, T g, as shown below: =, where T g,∞ is the maximum glass transition temperature that can be achieved at a theoretical infinite molecular weight and K is an empirical parameter that is related to the free volume present in the polymer sample.
Fragility characterizes how rapidly the viscosity of a glass forming liquid approaches a very large value approximately 10 12 Pa s during cooling. At this viscosity, the liquid is "frozen" into a solid and the corresponding temperature is known as the glass transition temperature T g. Materials with a higher fragility have a more rapid increase ...
The onset temperature of the transition zone, moving from glassy to rubbery, is known as the glass transition temperature, or T g. In the 1940s Andrews and Tobolsky [ 6 ] showed that there was a simple relationship between temperature and time for the mechanical response of a polymer.
The heat capacity of amorphous materials has such a behaviour near the glass transition temperature where the universal critical exponent α = 0.59 [33] A similar behavior, but with the exponent ν instead of α, applies for the correlation length. The exponent ν is positive. This is different with α. Its actual value depends on the type of ...
Crystal growth is achieved by the further addition of folded polymer chain segments and only occurs for temperatures below the melting temperature T m and above the glass transition temperature T g. Higher temperatures destroy the molecular arrangement and below the glass transition temperature, the movement of molecular chains is frozen. [6]
Vitrification (from Latin vitrum 'glass', via French vitrifier) is the full or partial transformation of a substance into a glass, [1] that is to say, a non-crystalline or amorphous solid. Glasses differ from liquids structurally and glasses possess a higher degree of connectivity with the same Hausdorff dimensionality of bonds as crystals: dim ...
The Vogel–Fulcher–Tammann equation, also known as Vogel–Fulcher–Tammann–Hesse equation or Vogel–Fulcher equation (abbreviated: VFT equation), is used to describe the viscosity of liquids as a function of temperature, and especially its strongly temperature dependent variation in the supercooled regime, upon approaching the glass transition.