N092-109 TITLE: Improved Stability of Double Base Propellants

TECHNOLOGY AREAS: Air Platform, Materials/Processes, Human Systems, Weapons

ACQUISITION PROGRAM: PMA-201, Precision Strike Weapons Program Office

OBJECTIVE: Reduce stabilizer depletion rates of double-base propellants in order to increase elevated temperature resistance and exposure requirements at or above 200°F.

DESCRIPTION: Current Navy Cartridge Actuated Devices (CADs) and Propellant Actuated Devices (PADs) use double-base propellants as either a main energetic output charge or an intermediate gas generating energetic charge. Elevated temperatures have long been known to produce degradation in both the service life and ballistic performance and can lead to a potential cook off safety hazard when stabilizer depletions rates are exacerbated through high temperature environmental exposure. A need exists to address these concerns and to improve double-base propellant safe life characteristics through innovations related to the long standing chemical problem of the complex reaction mechanisms known as nitrate ester degradation and its control through chemical stabilizer interaction. During storage of double-base propellants at elevated temperatures, the stabilizer reacts more and more with the nitrogen oxides (NOx) released by the nitrate esters (nitrocellulose and nitroglycerin) present in the propellant until it has depleted completely. Although the decrease of the primary chemical stabilizer is accompanied by the additional formation of daughter stabilizer reaction products which also possess a residual stabilization capability, the depletion of the primary chemical stabilizer can lead eventually to autocatalytic decomposition of the propellant, self-heating, and cook-off. The need exists for increased propellant performance to support missions requiring high duty cycles at elevated temperatures and years of operation. The most commonly used double-base stabilizers are Diphenylamine (DPA), 2-Nitrodiphenylamine (2-NDPA), and Ethyl Centralite (EC).

PHASE I: Investigate and identify double base propellant stabilizer depletion reaction rate kinetics and define, determine and prove feasibility of innovative and novel approaches for reducing stabilizer depletion rates in double base propellants at elevated temperatures.

PHASE II: Based upon Phase I results, formulate, develop and test proposed materials, processes and approaches for reducing double base propellant stabilizer depletion rates. Characterize ability of propellant composition to withstand elevated temperature exposure to 200°F high heat service exposure environment. Demonstrate developed technology on selected Navy cartridges and/or rocket motors (e.g., NACES Primary Cartridge, F-18 Parachute Drogue Rocket Motor)

PHASE III: Transition technology to the fleet.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Potential market for technology exists in commercial automotive safety restraint application (e.g., seat belt pretensioner, side impact inflator), gun ammunition, etc. This system has direct applicability to commercial automotive airbag safety systems including seat belt pretensioner systems, driver side, passenger side, and side impact airbag inflator system applications as well as ammunition and in numerous solid propellant gas generator systems (airline inflatable slides, cartridge driven power tools, etc.).

REFERENCES:
1. Mitchell, Kermit J., et al, Effects of Desert Thermal Environment on Army Propulsion Systems, U.S. Army Missile Command, Redstone Arsenal, AL https://webdatabase.cpia.jhu.edu/cpin/PIRS/template.php

2. Ark, Fun and Robertson, Dudley, Treatment of Accelerated Aging Data using First Order Reaction Equations, Picatinny Arsenal, Picatinny, NJ, https://webdatabase.cpia.jhu.edu/cpin/PIRS/template.php

3. Volk, F., Life Determination of Doublebase Propellant for Inflator Systems, Fraunhofer-Institut fur Chemische Technologie, ICT, D-76327 Pfinztal, FRG

4. Drummond, J., Lawhon, J., et al, Spheroidal Propellant Stabilizer Studies, St. Marks Powder, General Dynamics Company, CPIA, 30th Propellant Development & Characterization Subcommittee Proceedings. http://www.jannaf.org/meetings.php

KEYWORDS: Double-base propellant; stabilizer degradation; accelerated aging; diphenylamine; 2-nitrodiphenylamine; ethyl centralite

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