Some Chemical and Physical Factors Influencing Flame Retardancy

Abstract

Information is given to explain why or how bromine or nitrogen contributes to phosphorus-containing flame retardants. Amide and amine nitrogen generally increase flame resitance, whereas, nitrile nitrogen can detract. Essentially, all of the phosphorus in a flame retardant is accounted for in the char or solid phase and this is also true when amide or amine nitrogen is present. Nitrile nitrogen can cause a significant reduction in percent phosphorus accounted for in the char. The amount of nitrogen accounted for in the char is dependent upon the type of nitrogen and the atomic ratio of N to P in the flame retardant. When large proportions of amide or amine nitrogen are present they also contribute to flame resistance in the gas or vapor phase. Bromine makes its contribution to flame retardants by acting mainly in the vapor phase, and its action appears independent of phosphorus.