N ‐chloro and N ‐nitroso compounds as synergists for the self‐extinguishing action of bromine compounds in polystyrene

Compounds other than peroxides may be used to enhance the self‐extinguishing action of organic bromine compounds on polystyrene. The addition of certain chloramides or nitrosoamines converts some bromide‐containing polystyrene compositions from flammable to instantly self‐extinguishing. Two effective chloramides were N,N ‐dichlorotoluene sulfonamide or N,N′ ‐dichloro‐ N,N′ ‐diphenyl urea but they were of limited value because of hydrolysis by atmospheric moisture. The more effective nitrosoamines were N ‐nitroso‐ N ‐methylaniline, N ‐nitrosocarbazole and N ‐nitroso‐diphenylamine. An undesirable characteristic of the three compounds is their inhibition of polymerization of styrene. The interaction of a nitrosoamine and an aliphatic bromine compound is apparent from the evolution of nitrogen, nitric oxide, and nitrous oxide. If the minimum temperature for gas evolution falls in the range of about 145–180°C. in a prescribed simple test, the nitrosoamine and bromine compound may be used for rendering polystyrene self‐extinguishing.