Aryloxyphosphazene elastomers

Properties and Applieations. Aryloxyphosphazene elastomers using phenoxy and J-ethylphenoxy substituents have found interest in a number of appHcations involving fire safety. This elastomer has a limiting oxygen index of 28 and contains essentially no halogens. It may be cured using either peroxide or sulfur. Peroxide cures do not require the allyhc cute monomer. Gum physical properties are as follows (17) ... 

Polv(Arvloxyphosphazene) Elastomers. Poly(aryloxyphosphazene) elastomers, III, prepared by the reaction of chloropolymer with mixed phenoxides, offer excellent fire resistance without the incorporation of halogens in the polymer or as an additive. In addition, in a fire situation smoke evolution from these polymers... 

Poly(aryloxyphosphazene) elastomers can be cured with peroxides, sulfur and radiation. The resulting vulcanizates are resistant to attack by moisture and oils and have been found to have desirable characteristics for electrical insulation applications where fire safety is a concern (Table II) (12). Fire resistant, low smoke, closed cell foams with excellent properties (Table III) have also been developed from poly(aryloxyphosphazene) elastomers (13). Applications for these foams, which can be produced as either slabstock or tube stock, are being developed for military, aerospace and commercial uses. (See Table II and III.)... 

Poly(aryloxyphosphazene) elastomers offer outstanding fire resistance without the presence of halogen. In a fire these elastomers produce low levels of smoke as well as low toxicity and non-corrosive off-gases. 

Fire Resistant Elastomers. The poly(aryloxyphosphazene) elastomers offer excellent fire resistance without incorporating halogen in the polymer or as an additive. These polymers are self-extinguishing in air and generate only moderate non-corrosive smoke and a minimum of toxic combustion products upon combustion (50-53). The poly(aryloxyphosphazene) elastomers (APN ) have excellent potential for applications such as... 

Other Applications. Thus far the phosphazene fluoroelastomers (PNF) and aryloxyphosphazene elastomers (APN) have moved to the commercial stage. In addition to elastomers, phosphazenes are being investigated as fluids, resins and plastics. Other areas which hold promise include fire resistant paints (55), fiber blends and additives, agrichemicals and herbicides, drug release agents and electrically conducting polymers (6). 

Figure 7. Aryloxyphosphazene elastomers (APN) offer excellent potential.

Two commercial phosphazene elastomers were developed and marketed in the mid-1980s, namely, poly(fluoroalkoxyphosphazene) elastomer (ASTM International designation FZ) and poly(aryloxyphosphazene) elastomer (ASTM International designation PZ) [109]. The structure of the fluorinated product is as follows [110] ... 

Eypel A Acoustic Barrier Sheet. [Ethyl] Poly(aryloxyphosphazene) elastomer fire-resistant acoustic mass sheeting. 

Figure 8. Aryloxyphosphazene elastomers (APN) offer excellent potential for applications such as A, closed cell foam thermal insulation with high fire retadancy and low smoke generation (32.34) B, pigmented APN coatings in aluminum substrates with low flanmablllty, low flame spread, and low smoke (35) C, APN Insulation and cable Jacketing (36) D, open cell APN comfort cushioning (37). Photograph courtesy of Firestone Tire and Rubber Company ( ).

Economic Considerations. Gum production by Ethyl Corp. is under 20 metric tons per year. Products are sold primarily for use in U.S. and N.A.T.O. naval appHcations. The materials are sold as finished goods, and thus elastomer pricing is not appropriate. Ethyl Corp. has aimounced that it will either divest or exit this business. Atochem has developed their technology and has constmcted a pilot plant to produce aryloxyphosphazenes. 

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