Abstract: In order to improve its flame retardancy and smoke suppression properties, an intumescent fireproof coating was prepared by using ammonium polyphosphate-pentaerythritol-melamine as an intumescent flame retardant and a clam shell bio-filler as a synergist. Then, effects of clam shell filler on flame retardancy and smoke suppression properties were analyzed by cabinet method test, big panel method, smoke density test, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and elemental analysis. The results show that addition of such filler can synergistically improve flame retardancy and smoke suppression of intumescent coatings, which will be best when added fillerg content is 2%, but will diminish for an excessive addition. Presence of clam shell filler can promote formation of more cross-linking structures during burning process and therefore enhance compactness and thermal insulation of intumescent char, thus exhibiting superior thermal stability and char-forming ability. And char residue of coatings will reach as high as 33.7% at 800 ℃ while adding 2% of filler.

Key words: clam shell, intumescent fire-retardant coating, flame retardancy, smoke suppression, synergistic effect