Abstract: Pentaerythritol phosphate melamine salt (PPMS) as an expansion-type flame retardant was synthesized through a two-step pathway by using pentaerythritol, melamine and phosphoric acid as raw materials, and its chemical structure was characterized by Fourier-transform infrared spectroscopy. The effects of raw material ratio, the time and temperatures for esterification and saltforming reactions on the molecular structure of the product were investigated. The results indicated that the optimum synthetic condition was determined as a molar ratio of pentaerythritol/phosphoric acid/melamine at 1∶3∶1.09, an esterification temperature of 100 ℃, a reaction time of 1.5 h, a salt-forming temperature of 80 ℃, and a salt-forming reaction time of 6 h. The resultant PPMS achieved an expansion degree of 25.5 cm3/g and a char yield of 54.3 % while being synthesized at such an optimum condition.

Key words: flame retardant, pentaerythriol phosphate melamine salt, expansion degree, char yield