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SynopsisSix vinyl phosphonates have been synthesized and evaluated as grafts on poly(ethy1ene terephthalate) for their flame retardance properties. Diethylvinyl phosphonate was used as a model for phosphorus-containing flame retardants in developing the methodology for localizing flame retardants either on the surface of the filament or uniformly throughout it. SEM-X-ray microprobe techniques were used in the verification of the location of the flame retardant in the filament. The flame retardance efficiency of poly(diethy1 vinyl phosphonate) was then correlated with its location in the filament. Other grafted phosphorus-containing flame retardants showed a range of efficiencies that depended not only upon the location of the graft within the filament but also upon the %P in the compound. The wide variations in flame retardance efficiencies of copolymers and terpolymers were attributed to large variations in the melt viscosity of the different grafted materials. The grafts showed only small changes in tenacity and large increases in elongation.

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Homopolymers and copolymers of fumaronitrile, maleonitrile, and succinonitrile have been prepared by using medium high temperature free‐radical initiators. Black, nonfusible but soluble polymers were obtained. The spectroscopic and chemical evidence indicated a structure containing α‐pyrrolenine rings and no free nitrile groups in the fumaronitrile and maleonitrile polymers and 1‐pyrroline rings and free nitrile groups in the succinonitrile polymers. The polymers possessed good thermal stability, free spin concentration of 1017–1018 spins/g, and an ac conductivity at room temperature in nitrogen of 10−6 to 10−8 ohm−1 cm−1.

An overview of commercially used flame retardants is give. The most used flame retardants are illustrated and the seven major markets, which use 96% of all flame-retarded polymers, are described. Annual flame retardant growth rate for each major market is also projected. Toxicity data are reviewed on only those compositions that are considered commercially significant today. This includes 18 compounds or families of compounds and four inherently flame-retarded polymers. Toxicological studies of flame retardants for most synthetic materials are of recent origin and only a few of the compounds have been evaluated in any great detail. Considerable toxicological problems may exist in the manufacturing of some flame retardants, their by-products, and possible decomposition products.