Synthesis, Characterization And Application Of Novel Phosphorus And Nitrogen Containing Fire Retardants For Polyacrylonitrile

There are many fire retardants that are suitable for polyacrylonitrile, but many of them are halogen containing compounds. However, the halogen containing fire retardants can cause severe toxicological problems. With the increasing protective sense of eco-friendly and the eco-friendly laws being settled down, this type of fire retardants distinctly can not adapt to the requirements nowadays. Therefore, it has been a serious task in social development to find little toxic, non-halogen and high effective fire retardant compounds.Phosphorus-nitrogen compounds which contain abundant acid source and gas source show excellent fire retardance. They have many advantages, such as low smoking and low toxicity and conform to the trends of ecological environment today. Phosphorus-nitrogen flame retardants have a rapid development in recent years and have increasingly attracted many interests of the fire retardant producers and consumers. Thus, we have synthesized 12 types additive phosphorus and nitrogen containing fire retardants and 3 types reactive fire retardants in order to find the novel intumescent flame retardants which have a great prospect. The major works are as follows:1 , I have synthesized the additive fire retardants, 1,4-di(O, O-diethyl thiophosphoryl imine)benzene, 1,3-di(O,O-diethyl thiophosphoryl imine)benzene, tri( 1 -sulfur-2,6,7-trioxa-1 -phosphabicyclo[2,2,2] octane-methyl) phosphate, l,2-di(l-sufur-2,6,7- trioxa-l-phosphabicyclo[2,2,2]- octane-4- methyl-2- amido) ethane, 1,4-di(5,5-dimethyl-2-oxy-1,3-dioxaphosphorinane imine)benzene. 2, I synthesized the reactive fire retardants, N-diethyl phosphonomethyl acrylamide,allyl diethyl phosphate, N-diethyl phosphoryl acrylamide3, All the synthesized compounds were characterized by IR, ~1H NMR and MS analysis, and the result show that the structure of the compounds is consistent with what we anticipate respectively. The studies of the thermal performance indicate that most of the compounds decompose rapidly during 220-400℃ which overlapps many polymer materials' decomposition temperature range and show good fireproofmg for materials.4, I applied some of the additive flame retardants into polyacrylonitrile or by the method of copolymerization of acrylonitrile and the reactive compounds to getthe fireproofing film. The results of the vertical burning method indicate that the limiting oxygen index (LOI) value of the additive film can arrive to 29, while the weigh percent of the additive flame retardant get to 20%, and the limiting oxygen index values of the reactive fire retarded film are 29. TG and DSC thermo-analysis of polyacrylonitrile and fireproofing polyacrylonitrile were discussed. The decompose temperature of polyacrylonitrile was higher than the fireproofing polyacrylonitrile. The polyacrylonitrile char residue is lower than the fireproofing polyacrylonitrile, which indicate that the fire retardant decompose before the polyacrylonitrile, and it reduce the system temperature through heat absorption, melting, decomposing, and make the curves turn to mild by the action of fire resistance. For the additive fire retardant, the additive polyacrylonitrile has excellent char forming and fire resistance. SEM photographs also show that the surface of the reactive polyacrylonitrile film has good foam and intumescent effect, and the surface and cross-section form the foam char layer. This indicates that the fire retardant is the intumescent flame retardant and it mostly acts in the condensed phase.