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What is the glass transition temperature (Tg)?
The glass transition point or glass transition temperature Tg is a point on the temperature scale at which a polymer or glass changes into a rubbery, viscous state. However, this is not the same as the melting point.
In the case of amorphous metals, it is referred to as the glass transition temperature and in the case of inorganic non-metallic glasses as the transformation temperature.
For polymers in particular, the glass transition point is a fixed parameter. A glass transition in plastics is not a real phase transition, as only a small part of the sample changes its aggregate state. To be more precise, individual polymer chains can be moved against each other without changing to the molten state.
As the glass transition cannot be precisely assigned to a specific temperature, but depends on the measuring method and the prevailing conditions, it is important to adhere to standards when determining it and to be able to precisely control the measurement parameters.
The measurement method used in the thermal analysis must therefore be specified for each glass transition temperature.
Measuring methods for determining the glass transition temperature
- Dynamic Mechanical Analysis (DMA)
- Dynamic differential calorimetry (DSC)
- Combined thermal analysis (TGA+DSC)
- Dilatometry (DIL)
