Fire Safety Science Digital Archive

A systematic study of the intumescent process occurring on heating mixtures of char-forming nitrogen containing compounds with ammonium polyphosphate is undertaken. Preliminary results show that the chemical structure strongly affects the char yield of the char-forming compounds. Furthermore, chemical reactions take place on heating them in mixture with ammonium polyphosphate, which may modify their char yield. The structure of the intumescent char is shown to depend on the chemical structure of the char-forming component and on whether the char is formed on heating the ammonium polyphosphate/char-forming mixture alone or within the polymer matrix. KEYWORDS: fire retardants, intumescent additives.