Viscosity intumescent systems

The study of the viscosity of intumescent systems appears, as a consequence, to be an important way to better understand the carbonization process. The data obtained from this technique agree and complement the results obtained during the examination of the chemical composition of the intumescent shield. Moreover, it has to be highlighted that, to the contrary of most of the chemical investigations of the carbonization process, this technique studies the material in situ whereas most of the charred chemical compositions are evaluated after combustion and cooling of the sample. 

At 360°C-370°C, an important increase in the apparent initial viscosity begins that corresponds to the complete degradation of the initial material and to the carbonization of the system. The foamed material appears to be constituted by solid particles only. From 450°C-460°C, the viscosity value is more stable and increases slightly. At this temperature, a char oxidation/degradation probably starts. Complementarity, the viscosity can be analyzed versus temperature and versus time (Figure 10.10) in order to better visualize the mechanical and thermal stabilities of the protective intumescent layer and to have a better understanding of the carbonization process. 

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