General
Thermostable heterocyclic polymers

The resistance of polymers to heat and oxidation is generally measured using thermogravimetric analysis, which records the variation in mass of a polymer sample as a function of temperature (dynamic thermogravimetric analysis) or as a function of time at a constant temperature and in a controlled atmosphere (isothermal thermogravimetric analysis). This second technique provides an indication of the maximum operating temperature, as experience shows that important polymer properties, such as dielectric properties or mechanical properties, are significantly degraded when the mass loss of the material exceeds 5%. This value is often taken as a reference for the useful life of the polymer at a given temperature. To illustrate the results of this type of experiment, thermal degradation curves in air, determined on polyphenylquinoxaline films (Cemota IP 200 ^® ...