The Fictive Temperature and Enthalpy Loss on Annealing

Tgr = the glass transition at the mid-point of the reversing signal A//nr = the area under the non-reversing curve (i.e. the area between the reversing and total curves) 

Tgfr = fictive temperature of the reference state Tgfm = fictive temperature of the measured sample. 

Equations (54) and (55) can be criticised because they assume a unique value for ACp whereas this varies slightly as the liquid and glass heat capacities have different slopes. (For highest accuracy ACp should be determined for the mean of Tgf and T gr). Alternatively, enthalpy loss on annealing is often measured by using a result from a sample with low annealing (say 

However, any debate on this subject is redundant for two reasons. The first is that the changes in the reversing signal can easily be compensated for using the following correction. 

In summary, the important concepts that should be born in mind when considering glass transitions are as follows. 

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The Fictive Temperature and Enthalpy Loss on Annealing The fictive temperature (Tgf) can be obtained by extrapolation of the linear portions of the enthalpy lines above and below the glass transition as illustrated in Figure 1.18. This can be calculated in the case of MTDSC from the following approximate relationship. 

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