US-20260125332-A1 - THERMOPLASTIC-BASED ENERGETIC MATERIAL PRODUCTION

US20260125332A1US 20260125332 A1US20260125332 A1US 20260125332A1US-20260125332-A1

Abstract

An energetic material includes a matrix of a thermoplastic polymer and an oxidizer distributed in the thermoplastic polymer matrix. The energetic material can be produced, for example, by a method that includes adding the oxidizer to the thermoplastic polymer while the thermoplastic polymer is in a softened state to form a mixture, which is then cooled to produce the energetic material.

Inventors

Michael Joseph Baier
Nicholas Shane Podany

Assignees

FIREHAWK AEROSPACE, INC.

Dates

Publication Date: 20260507
Application Date: 20241101

Claims (20)

1 . A method comprising: dissolving a thermoplastic polymer in a solvent to form a slurry; adding an oxidizer to the slurry; and after adding the oxidizer to the slurry, removing the solvent from the slurry to produce an energetic material comprising the oxidizer distributed in a matrix of the thermoplastic polymer.
2 . The method of claim 1 , wherein the energetic material comprises a solid propellant material for a solid rocket engine.
3 . The method of claim 1 , comprising forming the energetic material into filaments or pellets.
4 . The method of claim 3 , comprising forming the energetic material into pellets having at least one dimension in the range of 2-4 mm.
5 . The method of claim 3 , wherein forming the energetic material into pellets comprises: extruding the energetic material to produce an extrudate; and cutting the extrudate into pellets.
6 . The method of claim 5 , wherein extruding the energetic material comprises generating a melt mix slurry of the energetic material and extruding the melt mix slurry using a piston or screw extruder.
7 . The method of claim 3 , comprising storing the pellets for at least 6 months.
8 . The method of claim 3 , comprising using the pellets as feedstock in an additive manufacturing process, wherein the additive manufacturing process comprises extruding the pellets of the energetic material through a nozzle of an additive manufacturing system.
9 . The method of claim 8 , comprising using the pellets as feedstock for additive manufacturing of an explosive device or a solid propellant grain for a solid rocket motor.
10 . The method of claim 1 , comprising pulverizing the energetic material to form a powder of the energetic material.
11 . The method of claim 1 , wherein removing the solvent from the slurry comprises washing the slurry with an antisolvent, wherein the thermoplastic polymer and the oxidizer are insoluble in the antisolvent.
12 . The method of claim 1 , wherein removing the solvent from the slurry comprises evaporating the solvent from the slurry by at least one of applying heat to the slurry or exposing the slurry to a vacuum.
13 . The method of claim 1 , wherein the method is performed as a continuous process.
14 . The method of claim 1 , comprising dispersing an energetic additive in the slurry of the thermoplastic polymer and the solvent, wherein the oxidizer is added to the slurry after dispersing the energetic additive in the slurry.
15 . The method of claim 14 , wherein the energetic additive comprises a solid fuel additive comprising nanoscale or microscale metal particles.
16 . The method of claim 14 , comprising adding the energetic additive and the oxidizer at a stoichiometric ratio with respect to combustion of the energetic additive.
17 . The method of claim 14 , comprising: adding the energetic additive to the slurry such that the energetic material comprises from about 10 wt. % to about 20 wt. % of the energetic additive; and adding the oxidizer to the slurry such that the energetic material comprises from about 50 wt. % to about 75 wt. % of the oxidizer.
18 . The method of claim 14 , comprising adding the energetic additive to the slurry from a first hopper connected to a flow channel containing the slurry; and adding the oxidizer to the slurry from a second hopper connected to the flow channel downstream from the first hopper.
19 . The method of claim 1 , wherein the energetic material comprises from about 10 weight percent (wt. %) to about 25 wt. % of the thermoplastic polymer.
20 . The method of claim 1 , wherein the oxidizer comprises one or more of potassium nitrate, potassium perchlorate, ammonium nitrate, ammonium perchlorate, or sodium perchlorate, and the thermoplastic polymer comprises a thermoplastic polyurethane.

Description

TECHNICAL FIELD This disclosure relates to production of thermoplastic-based energetic material. BACKGROUND There are various types of chemical rocket propulsion systems. Liquid rocket engines use liquid-phase propellants. Solid rocket motors use solid-phase propellants. In some cases, additive manufacturing can be used to deposit propellant material and solidify to form a structure composed of a stacked set of layers for forming a solid propellant material. Additive manufacturing allows for the ability to produce complex shapes or geometries that may otherwise be infeasible to construct by hand, including hollow parts or parts with internal structures. SUMMARY This disclosure describes technologies relating to thermoplastic-based energetic material. The subject matter described in this disclosure can be implemented in particular implementations, so as to realize one or more of the following advantages. The energetic material described is shelf-stable and can be stored for extended periods of time (e.g., for at least six months) after production and before use. The energetic material described includes thermoplastics, which allows the energetic material to be re-processable. The re-processability of the energetic material provides flexibility in that characteristics of the energetic material can be altered, if desired, by re-processing the energetic material (e.g., by melting) and introducing additional components into the formulation and/or diluting components of the formulation. In contrast, other conventional energetic materials including thermoset material(s) cannot be re-processed because once cured, thermosets remain permanently cured. In such conventional energetic materials, if there are any flaws or concerns with certain units produced from a batch of materials, such units cannot be re-processed and would likely need to be disposed. The re-processability of the energetic material provides flexibility in manufacturing as well. For example, the energetic material can be re-processed by an additive manufacturing system for depositing the energetic material onto the surface of another material, such as a solid rocket motor. As another example, the energetic material can be re-processed by an additive manufacturing system for 3D printing the energetic material to form a desired shape of the energetic material. The systems and processes described are flexible in that they can be operated in a batch process or a continuous process. A continuous process can achieve the same production throughputs as an analogous batch process, but at any specific moment in time, less of the active material (e.g., combustion material) is in use in comparison to the analogous batch process, resulting in less waste of base materials and enhanced safety. In some cases, the energetic material includes a solid fuel additive that increases an energy density of the energetic material, which can be particularly useful for solid rocket motors or hybrid rocket engines. The details of one or more implementations of the subject matter of this disclosure are set forth in the accompanying drawings and the description. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims. DESCRIPTION OF DRAWINGS FIG. 1A is a schematic diagram of an example thermoplastic-based energetic material. FIG. 1B is a schematic diagram of an example feedstock supply kit including the thermoplastic-based energetic material of FIG. 1A. FIG. 2 is a schematic diagram of an example system for producing a thermoplastic-based energetic material. FIG. 3 is a flow chart of an example method for producing a thermoplastic-based energetic material. FIG. 4 is a flow chart of an example method for producing a thermoplastic-based energetic material. FIG. 5 is a flow chart of an example method for producing and using a thermoplastic-based energetic material. FIG. 6 is a flow chart of an example method for producing and storing a thermoplastic-based energetic material. DETAILED DESCRIPTION This disclosure describes production of thermoplastic-based energetic material. The thermoplastic-based energetic material can be used, for example, to fabricate solid propellant grains for solid rocket motors or to fabricate hybrid rocket engine fuel grain assemblies including both hybrid fuel grain material and solid propellant. FIG. 1A is a schematic diagram of an example thermoplastic-based energetic material 100. The energetic material 100 includes a thermoplastic polymer matrix 102. The energetic material 100 includes an oxidizer 104 that is distributed in the thermoplastic polymer matrix 102. In some implementations, as shown in FIG. 1A, the energetic material 100 is in the form of pellets. The pellets of the energetic material 100 can be sized, for example, to be used as feedstock for additive manufacturing (e.g., 3D printing). In some implementations, the pellets of the energetic material 100 have at least o