Page 680 - Handbook of Thermal Analysis of Construction Materials

Section 3.0 - Coatings 647

Figure 11. DSC curves showing the different glass transition, recrystallization melting
transition, temperatures, and heats of recrystallization and melting for silicone samples
with different levels of cure. (a) under-cured sample; (b) medium-cured sample; and (c)
well-cured sample. (Reprinted with permission.) [21]

3.3 Organic Coatings Degradation (Service-Life)

The thermal stability of formulations may be important due to
possible exposure conditions of the coating. The nature of failure depends
on the material, but a measurable thermal effect is inevitable. This would
yield the stability limit for short-term exposure and provide a limit for long-
term exposure studies. Both thermal stability limits may be quite different
because the possible reactions involved are slow. The degradation process
responsible for the failure of the coatings may involve entirely different
reactions. Hence, both kinds of data may be needed. [2]
The weight loss of a material as a function of temperature is used
to obtain information on thermal decomposition characteristics. The use of
TG is naturally limited to those decompositions or other reactions in which
there is a gain or loss in weight. The technique is useful in providing
information on the thermal stability of coatings and paints.