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Sicherheits- und Funktionsbewertung von Treibmitteln durch Messen von Wärmeentwicklung, Stabilisatorverbrauch und Molmassenabbau

: Bohn, M.A.; Volk, F.

Fraunhofer-Institut für Chemische Technologie -ICT-, Pfinztal:
Technology of polymer compounds and energetic materials
Pfinztal: ICT, 1990 (Proceedings of the International Annual Conference of ICT 21)
ISSN: 0722-4087
Fraunhofer-Institut für Chemische Technologie (Internationale Jahrestagung) <21, 1990, Karlsruhe>
Fraunhofer ICT ()
Alterung; autokatalytische Zersetzung; Lebensdauer; Molmassenabbau; nitrocellulose; Raketenfesttreibstoff; Salpetersäureester; Stabilisator; Treibladungspulver; Treibstoff; Wärmeentwicklung; Zersetzung

During the storage of nitric acid ester based propellants at elevated temperatures the splitting probability of the CO-NO sub 2-bond is increased with the formation of nitric oxides and a degradation of the polymeric nitrocellulose. This reduces the values of the mean molar masses Mn, Mw an Mz and the stabilizer content. Therefore the chemical as well as the mechanical properties of the propellants are changed, normally worsened. In addition, decomposition gases are produced and heat is generated by exothermal reactions. Three double base rocket propellants and a single base gun propellant were used to find out stabilizer consumption, molar mass degradation and heat generation between 50 to 90 degree C and 40 to 110 degrees C respectively. Stabilizer depletion was measured by HPLC, molar mass degradation by GPC and heat generation by microcalorimetry using a Thermal Activity Monitor by Thermometric AB, Sweden. The conditioning times at different temperatures were determined with one of the rocket propellants and the influence of a long storage at 60 degree C, 2191 days, on the heat production was investigated. In addition, a correlated experiment between stabilizer consumption during prestorage and heat generation showed, that the heat production does not increase substantially until the stabilizer has been consumed almost completely. Both, molar mass degradation of the nitrocellulose and stabilizer consumption were investigated of one the double base rocket propellants. The experimental values of the molar mass Mw are described by a kinetic model base on statistical chain scission caused by the decomposition of chain segments. Parts of the paper were presented at the ADPA-Symposium on Compatibility and Processing, 23-25 Oct. 1989, Virginia Beach, Va, USA.