Page 676 - Handbook of Thermal Analysis of Construction Materials

644 Chapter 16 - Paints and Coatings

Intumescent coatings have also been studied by Taylor [19] using
STA. The mechanism of thermal decomposition of three single components
[ammonium polyphosphate (APP), pentaerythritol (PER), and melamine]
then binary, and ultimately ternary mixtures were investigated by STA and
evolved gas analysis. The DTA traces for ammonium polyphosphate
showed that decomposition steps involved different processes as previ-
ously reported. [15][17]
The STA traces for the pentaerythritol also showed a two-stage
reaction as shown in Fig. 9. [19] The first one corresponds to the endotherm
at 185°C due to the melting of PER. The second one was characterized by
an exotherm under air and an endotherm under nitrogen. Therefore, it was
suggested that the burning or decomposition process is dependant upon the
oxygen present in the gas atmosphere. The melamine traces were also
obtained by STA. They indicated a sublimation process at 291°C. The STA
curves for the binary systems (APP/PER and APP/melamine) showed that
the two components undergo several reactions following more than one
mechanism (e.g., cross-linking), giving rise to a complex random cross-
linked polymeric structure.

Figure 9. TG/DTA traces for pentaerythritol. (Reprinted with permission.) [19]