Polyphosphazenes: Flame-Retardants for Aircraft Applications

To develop new fire-retardant polymers that can be incorporated into blends, IPN’s and composites with existing commodity polymers to improve their fire resistance when used in aircraft applications. Approach: The polymers being developed are based on the inherently fire-retardant polyphosphazene platform, in which the phosphorus-nitrogen polymer backbone confers fire-resistance not only on the phosphaze e but also on the second (organic) polymer component in the mixture. In this way, the valuable properties of the polyphosphazene can be transposed to the composite as a whole, while retaining the low cost and processing advantages of the commodity material. Three approaches are being examined. First, new methods for the synthesis of polyphosphazenes are being developed that are expected to give greater control over the polymer chain length and polymer architecture, and to lower the costs for the large-scale production of po yph sphazenes. Second, a range of different polyphosphazenes, with different side groups, are being synthesized and examined to determine their behavior under combustion conditions. Third, these same polymers are being incorporated into polymer blends with classical polymers that are currently used in the interiors of commercial aircraft, and their combustion behavior is monitored. As part of this aspect, fundamental studies are being conducted on the compatibility of the different polyphosphazenes with other polymers to determine the ways in which different polymer side groups influence polymer-polymer interactions in blends and IPN’s. Infrare spectroscopy is used as one method to determine the miscibility of polymer blends. Accomplishment Description: A new method for the synthesis or polyphosphazenes has been developed. This involves the roo