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Ignition Delay Reduction with Sodium Addition to Imidazolium-Based Dicyanamide Ionic Liquid
Anna Thomas1, Steven D Chambreau2, Ghanshyam L Vaghjiani3
1Department of Aeronautics and Astronautics , Stanford University , Stanford , California 94305 , United States.
The Journal of Physical Chemistry. A
|December 14, 2018
Summary
Adding sodium cations to ionic liquids significantly reduces ignition delay with white fuming nitric acid (WFNA). This finding supports theoretical predictions about cation influence on hypergolic reactions.
Area of Science:
- Propellants and Energetic Materials
- Physical Chemistry
- Materials Science
Background:
- Ionic liquids (ILs) are being investigated as potential hypergolic propellants.
- The role of specific cations in hypergolic ignition is not fully understood.
- Previous theoretical studies suggested sodium cations could enhance ignition.
Purpose of the Study:
- To experimentally validate the predicted role of sodium cations in the hypergolic ignition of ionic liquids.
- To quantify the effect of sodium dicyanamide addition on ignition delay with white fuming nitric acid.
Main Methods:
- Synthesis of sodium dicyanamide (Na+DCA-) and 1-butyl-3-methylimidazolium dicyanamide (BMIM+DCA-).
- Preparation of IL mixtures with varying weight percentages of Na+DCA-.
- Measurement of ignition delay times using white fuming nitric acid (WFNA) as an oxidizer.
Main Results:
- Addition of Na+DCA- to BMIM+DCA- demonstrably lowered ignition delay.
- A reduction of 11 ms in ignition delay was observed at 7 wt % Na+DCA-.
- Experimental results align with prior density functional theory predictions.
Conclusions:
- Sodium cations play a crucial role in promoting hypergolic ignition.
- The presence of sodium cations may facilitate favorable reaction energetics by orienting anions.
- This study provides experimental evidence for cation-engineered hypergolic performance in ionic liquids.
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