Great care must be taken in selecting the specific heat temperature dependence of the liquid around which the specific heat response of the sample
with temperature is used as the baseline for integration Degradation and volatile production from the polymer in the melt or on partially crystalline samples prior to heating negates the use of a specific heat baseline derived from the sample above the melting point or close to the glass transition. Instead the specific heat temperature dependence must be determined separately either from amorphous samples, or from the literature. method, the initial and By using the First Law measured of m-PE and PET have been by density found to be consistent with values determined at ambient temperature.