Calorimetric Investigations of a Series of Energetic Polyphosphazenes

摘要

Energetic, fluorinated, linear polyphosphazenes are currently under investigationas potential, high-density binders for new, polymer bonded explosivecompositions. A series of such polymers was synthesised and the enthalpy ofcombustion of each member of the series was measured by static bombcalorimetry. This was performed after combusting appropriate secondarythermochemical standards to model the combustion stoichiometry of the heteroatomsnitrogen, fluorine and phosphorus. The water-soluble combustion productswere identified and quantified using 19F NMR spectroscopy and IonChromatography. Since some of the combustion products are hydrolyticallyunstable, it was found necessary to stabilise the initial combustion productmixtures by using a buffer solution instead of pure water in the bomb, and then todetermine the composition of the stabilised product mixtures in order to obtainmeaningful values for the enthalpies of combustion and thence enthalpies offormation. The thermochemical measurements themselves were made with purewater in the bomb. The composition and structures of the variouspolyphosphazenes were correlated with their energies of combustion andenthalpies of formation. The latter were calculated using the latest CODATAvalues of enthalpy of formation of the combustion products. The ‘combustion’ ofthe polyphosphazenes under a nitrogen atmosphere was also investigated with theview to calculating the enthalpies of detonation of each member of the series.Three conference papers which include the results of this work have beenpublished and are included in Appendices C-E.