Measurement of the limiting fictive temperature over five decades of cooling and heating rates

Siyang Gao, Sindee L. Simon

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29 Scopus citations

Abstract

The fictive temperature (Tf) was defined by Tool in the 1940s as a measure of glassy structure. Tf is generally measured on heating and can be calculated from the enthalpy overshoot in calorimetric studies using a method developed by Moynihan. Prior work has demonstrated that the limiting fictive temperature (Tf′) is similar to Tg (measured on cooling) and depends on the cooling rate in a manner consistent with the Williams-Landel-Ferry (WLF) relationship. Theoretically, the limiting fictive temperature should not depend on heating rate, but this has been experimentally verified only for a very limited range of heating rates. Here, rapid-scanning chip calorimetry and conventional differential scanning calorimetry (DSC) are combined to investigate Tf′ for polystyrene over a broad range of heating rates ranging from 0.017 to 3000 K/s after cooling at different rates. The results show that Tf′ depends on cooling rate following the WLF equation. On the other hand, Tf′ is not a function of heating rate, consistent with theoretical predictions, in spite of the change in the magnitude and placement of the enthalpy overshoot.

Original languageEnglish
Pages (from-to)123-127
Number of pages5
JournalThermochimica Acta
Volume603
DOIs
StatePublished - Mar 10 2015

Keywords

  • Cooling and heating rate dependence
  • Glass transition temperature
  • Limiting fictive temperature
  • Polystyrene
  • WLF equation

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