Glass Transition Temperature

Used when describing temperature curves of polymers. At low temperatures, the polymer occurs in a glassy state (it appears as a rigid and brittle solid). With increasing temperature it is in the glass transition range which is particularly important and is mostly specified in terms of just one temperature value which is referred to as glass transition temperature. It is assumed to be approximately in the middle of the temperature range in which the glass transition is taking place. In this range the molecules are showing more and more mobility and the polymer occurs in a soft-elastic, rubber-like state.

Value = Tg

Unit = [°C]


  • MEZGER, Thomas: The Rheology Handbook, 3rd revised edition. Hanover: Vincentz Network, 2011
  • MEZGER, Thomas: Angewandte Rheologie: Mit Joe Flow auf der Rheologie Straße, 1. Auflage Juli 2014. Anton Paar GmbH, Österreich.