Structure of intumescent epoxy composites with expandable graphite

Currently, thermoset-based polymer matrix composites are widely used for production of fire protective coatings. Intumescent properties of such coatings are highly dependent on composition. Expandable graphite is a prospective intumescent admixture; unfortunately, admixture of expandable graphite alone can lower the integrity of char residue down to unacceptable levels. The objective of the present work is to present the method that can be used for elimination of the mentioned drawback. The limiting values of expandable graphite in composite with two different admixtures - ammonium polyphosphate and ceramic cenospheres - were determined by means of study the structure of both intumescent epoxy composites and char residues of such composites. It was revealed that admixture of ceramic cenospheres leads to notable improvement of integrity of char residue. This improvement is mostly due to features of heat transfer in material with cenospheres which are characterized by low particle size and, at the same time, low heat conductance