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Differential scanning calorimetry can be used to measure a number of characteristic properties of a sample. Using this technique it is possible to observe fusion and crystallization events as well as glass transition temperatures T g. DSC can also be used to study oxidation, as well as other chemical reactions. [15] [16] [19]
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]
ISO 11357 Plastics – Differential scanning calorimetry (DSC) ISO 11357-1:2009 General principles; ISO 11357-2:2013 Determination of glass transition temperature and glass transition step height; ISO 11357-3:2011 Determination of temperature and enthalpy of melting and crystallization; ISO 11357-4:2005 Determination of specific heat capacity
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.
When the supercooled liquid is further cooled, it becomes a glass. [1] The temperature at which a polymer becomes a glass by fast cooling is called the glass transition temperature T g. At this temperature, viscosity reaches up to 10 13 poise depending upon cooling-rate.
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 ...
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.