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Binders form the mechanical linkage in the rocket fuel. Some binders are also used as fuels. These binders are known as "energetic binders" and are normally hazardous.
R-45M 45 M - A type of Hydroxyl Terminated Polybutadiene commonly used as a binder(HTPB) . Contains a pre-mixed anti-oxidant for long term storage
R-45 HTLO - A type of HTPB that contains no anti-oxidants. Lower viscosity than R-45M
Low Molecular Weight HTPB - Very low viscosity HTPB. Lower molecular weight. May improve castability and performance. May detrimentally affect density.
Polybutadiene Acrylonitrile (PBAN) - Common hobby binder. Requires Cure schedule. Also used in the Space Transportation System's Solid Rocket Boosters.
Polydimethylsiloxane (PDMS) -
Curative
These chemicals begin the polymerization of the binder
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These chemicals reduce the viscosity of the uncured propellant. They make mixing and casting of propellants easier and facilitate higher solids loading.
Isodecyl PelargonatePelargonate
Dioctyl Adipate (DOA)
Dioctyl Sebacate
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Prussian Blue - Blue Powder. Produces a blue tinted propellant after curing.
Methylene Blue - Blue stain. Liquid. Helps lower solid loading.
Nigrosin - Very blackBest 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.
Magnesium - Powdered. Burns completely, faster than aluminum. Useful in smaller motors.
Oxidizers
Substances which oxidize the fuel and binder to facilitate combustion.
Ammonium Perchlorate - Most common in amateur and professional composite propellants
Ammonium Nitrate - Extremely hygroscopic. Tends to produce a slower burning propellant than ammonium perchlorate.
Potassium Nitrate - Used commonly in "rocket candy" formulations. Lower performance than ammonium perchlorate or ammonium nitrate.
Stabilizers
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.
HX-752 - Does not cause foaming. Requires refrigeration. Smells bad.
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.
Chromatic Burn Additives
Copper Oxychloride - Blue (5%-10% by mass)
Strontium Carbonate - Red.
Flame Retardants
Melamine - Used when using HTPB as a liner material
Zinc Borate - improves char layer formation