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Nigrosin - Best opacifier by mass.
TiO2 - Opacifier. Rejects radiative heating. Creates white propellant.
Fuels
Aluminum - More energetic than magnesium but requires a larger motor to properly take advantage of. Large incompletely burned particle can damage nozzle. Tendency to deposit slag inside motor.
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Magnesium Oxide
Phenylnaphthalene
DTBHQ - 2,5-ditert-butylhydroquinone
Processing Aids
Lecithin
Silicon Oil - Reduces adherence to mixing bowl. Makes propellant pour better.
Polydimethylsiloxane (PDMS) - Surfactant, reduces sticking to the bowl and aeration during mixing. Allows for mixing at higher speeds. Improves particle wetting.
Binding Agents
Binding agents form a bond between the surface of Ammonium Perchlorate particles and the polymer matrix, embedding the particles strongly in the propellant web. This slightly slows burn rate and increases hardness.
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HX-878 (Tepanol) - May cause foaming due to ammonia generation during curing.
HX-868 - (Dynamar) Co-active with HX-752, increases functionality and decreases migration
Cross Linking Agents
Castor Oil - provides additional sites for the polymer chains to cross link with the curative and castor oil. Increases cured propellant hardness.
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Strontium Carbonate - Red.
Flame Retardants
Melamine - Used when using HTPB as a liner material
Zinc Borate - improves char layer formation