t-A thermomechanical analysis (TMA) technique is presented for the measurement of the glass
transition temperature (T,) of glassy pitch materials. Pitches with varying mesophase content have been
used for the T, determination. In this technique, the linear expansion of a mesophase pitch sample with
respect to temperature is determined by means of a dilatometer. The change in the coefficient of thermal
expansion (CTE) of the pitch materials was found to be significant at the glass transition temperature.
Therefore, the measurement of the CTE of the specimen with respect to temperature revealed the glass
transition temperature. This technique was found to be very sensitive and easily executable. Results from
the TMA technique show good agreement with those from differential scanning calorimetry (DSC). The
TMA technique was found to reproduce the TB value for the mesophase pitch samples within &2”C. In
many cases, the value of Ts from the dilatometer was much more definitive than that obtained from
DSC, especially for the mesophase pitch samples. A linear correlation for Tg as a function of Mettler
softening point temperature (T,) is developed and compar