Propellant formulation
A solid heterogeneous, high performance rocket propellant, operable at high pressure with a burn rate relatively insensitive to changes in pressure and temperature, is disclosed. The propellant includes a binder formed from the reaction of a hydroxy terminated polybutadiene with a diisocyanate, ammonium perchlorate as an oxidizer, aluminum as a fuel, and iron oxide as a burn rate modifier. The ammonium perchlorate is a multimodal mixture of large paryticles with a weight mean diameter of about 70 to about 110 μm and small particles having a weight mean diameter of about 7.5 to about 15 μm. The propellant may also include bonding agents, curing catalysts, a plasticizer, antioxidant/peroxide scavengers, and pot life extenders.
1. A propellant, comprising:
a binder formed in-situ by reacting a prepolymer and a curing agent;
ammonium perchlorate particles;
metal particles; and
iron oxide,
wherein the ammonium perchlorate particles are in a form of a multimodal mixture of rounded particles having a weight mean diameter of from about 70 μm to about 110 μm and of nonrounded particles having a weight mean diameter of from about 7.5 μm to about 15 μm.
2. The propellant of claim 1 , wherein the binder is a polyurethane formed by reacting in-situ a hydroxy functional prepolymer and a multi-functional isocyanate curing agent.
3. The propellant of claim 2 , wherein the hydroxy functional prepolymer is a hydroxy terminated polybutadiene having a hydroxy functionality of from about 2 to about 3 and a specific average molecular weight of less than about 10,000 and wherein the multi-functional isocyanate curing agent is a diisocyanate.
4. The propellant of claim 3 , wherein the hydroxy functional prepolymer makes up from about 7 percent to about 15 percent of the weight of the propellant.
5. The propellant of claim 3 , wherein the multi-functional isocyanate curing agent makes up a sufficient amount of the propellant so that the isocyanate/hydroxy (“NCO/OH”) moiety ratio between the prepolymer and the multi-functional isocyanate curing agent is from about 0.8 to about 1.2.
6. The propellant of claim 1 , wherein a weight ratio of rounded ammonium perchlorate particles to nonrounded ammonium perchlorate particles is from about 40/60 to about 60/40, respectively.
7. The propellant of claim 1 , wherein the metal particles are aluminum particles that have a weight mean diameter of from about 3 μm to about 10 μm.
8. The propellant of claim 1 , wherein the iron oxide provides from about 0.5 percent to about 3 percent of the weight of the propellant.
9. The propellant of claim 1 , further comprising at least one of a bonding agent, a curing catalyst, a plasticizer, antioxidant/peroxide scavengers, and a pot life extender.
10. The propellant of claim 9 , wherein the bonding agent is a reaction product of tetraethylenepentamine, acrylonitrile and glycidol.
11. The propellant of claim 9 , wherein the binder is a polyurethane and wherein the curing catalyst is selected from the group consisting of triphenyl bismuth (“TPB”), dibutyltin dilaurate, and mixtures thereof.
12. The propellant of claim 9 , wherein the plasticizer comprises dioctyl sebacate, dioctyl adipate (“DOA”), isodecyl perlargonate, dioctyl phthalate (“DOP”), or mixtures thereof.
13. The propellant of claim 9 , wherein the antioxidant comprises 2,2-methylene-bis-(4-methyl-tert-butylphenol).
14. The propellant of claim 9 , wherein the pot life extender is maleic anhydride.
15. The propellant of claim 1 , wherein the propellant has a Young's modulus of from about 450 psi to about 800 psi, a tensile strength of from about 70 psi to about 180 psi, and an elongation of at least about 30%.
16. The propellant of claim 1 , wherein a pressure exponent of the propellant is less than about 0.5 ips/psi at pressures up to about 10,000 psi.
17. The propellant of claim 1 , wherein a burn rate of the propellant is about 3±0.5 ips at 10,000 psi.
18. The propellant of claim 1 , wherein the propellant comprises the following components in the following amounts:
COMPONENT
WEIGHT %
Binder
About 7 to about 15
Antioxidant
About 0.1 to about 0.4
Peroxide Scavenger
About 0.005 to about 0.2
Curing Catalyst
About 0.01 to about 0.25
Bonding Agent
About 0.05 to about 0.15
Plasticizer
About 2.5 to about 4
Pot Life Extender
About 0.01 to about 1
Aluminum
About 10 to about 20
Iron Oxide
About 0.5 to about 3
Ammonium Perchlorate
About 65 to about 75
Curing Agent
About 0.5 to about 5.
19. The propellant of claim 1 , wherein the propellant comprises the following components in the following amounts:
INGREDIENT
WEIGHT %
Hydroxy-terminated Polybutadiene
About 8.503
2,2-methylene-bis-(4-methyl-tert-
About 0.130
butylphenol)
Trinonylphenyl phosphite
About 0.130
Triphenyl Bismuth
About 0.015
Reaction Product of
About 0.100
Tetraethylenepentamine,
Acrylonitrile, and Glycidol
Dioctylsebacate
About 3.470
Aluminum
About 14.000
Maleic Anhydride
About 0.030
Red Iron Oxide
About 2.000
Aluminum Perchlorate (90 μm)
About 46.150
Aluminum Perchlorate (10 μm)
About 24.850
Isophorone Diisocyanate
About 0.622.
20. A rocket motor comprising a rocket motor casing and a propellant in contact with the rocket motor casing, wherein the propellant comprises:
a binder formed in-situ by reacting a prepolymer and a curing agent;
ammonium perchlorate particles;
metal particles; and
iron oxide,
wherein the ammonium perchlorate particles are in a form of a multimodal mixture of rounded particles having a weight mean diameter of from about 70 μm to about 110 μm and of nonrounded particles having a weight mean diameter of from about 7.5 μm to about 15 μm.
21. A ballistic trajectory guided munition comprising a projectile having a rocket motor attached thereto, the rocket motor including a propellant in contact with a rocket motor casing, wherein the propellant comprises:
a binder formed in-situ by reacting a prepolymer and a curing agent;
ammonium perchlorate particles;
metal particles; and
iron oxide,
wherein the ammonium perchlorate particles are in a form of a multimodal mixture of rounded particles having a weight mean diameter of from about 70 μm to about 110 μm and of nonrounded particles having a weight mean diameter of from about 7.5 μm to about 15 μm.
22. The propellant of claim 1 , wherein the ammonium perchlorate particles comprise from about 65 percent to about 95 percent of the weight of the propellant.
23. The propellant of claim 7 , wherein the aluminum particles comprise from about 10 percent to about 20 percent of the weight of the propellant.