Green Manufacture

The manufacture of these multi-layer Nano-Structured Energetic Particles using a cost effective, flexible, controllable, scalable and green technology led to development of a novel micro-encapsulation technique that involved a circulating supercritical fluidized bed. The technique was demonstrated by microencapsulation of AN by HTPB.

Supercritical fluids provide a unique processing medium for high volume micron and nano-scale manufacture due to tunable solvation and favorable transport properties, resulting in defect-free nano-scale thin-film formation with minimal surface roughness.

Supercritical Fluids have been used in energetic materials development, comminution, and re-processing for over three decades. A judicious use of supercritical fluid aided materials processing techniques allow tailored manufacture of particles with desired particle size, particle size distributions, layer-by-layer particle structuring, efficient compounding of formulations, and precise component ratios. Compounding of the various layers in an N-SEP can be performed, allowing the intimate mixtures of components such as single or mixed oxidizers, with burn rate modifiers, and ingredients
for reduction and elimination of combustion instabilities.

Features and Benefits of the N-SEP Propulsion Technology

N-SEP Propellant Features:

PMBAC N-SEPs can:

1. allow for the safe combination of a large variety of highly energetic oxidizers and fuels subject only to the limitations of the manufacturing technology;
2. allow for balancing the chemical ingredients with high accuracy to achieve ingredient ratios that will provide the best performance for the propellant blend;
3. possess a perfect micron thin protection barrier of low energy polymer fuel, integral to the N-SEP, which prevents the highly energetic ingredients from
   mixing and destabilizing the propellant prior to controlled ignition;
4. control the ignition temperature of the N-SEP, and maintain that temperature by restricting N-SEP ignition to the barrier/oxidizer reactions, thereby meeting
   ignition temperature requirements of current commercial solid propellants;
5. provide a “thick” shell or rind of outermost layer polymeric (fuel) material which can strongly chemically bind to neighboring N-SEPs, polymeric propellant
   binder, and rocket motor casings;
6. standardize the chemical identity of the N-SEP outer rind polymeric (fuel) material so that all completed N-SEPs are identical, and can be identically
   processed into propellant grains, regardless of propellant ingredients used internally;
7. provide the ability to pre-produce and “stockpile” in safe and secure storage facilities complete N-SEP propellants for later casting into propellant grains;
8. provide the ability to ship the protected environment and safe, essentially insensitive, N-SEP propellants to offsite storage facilities using conventional
   hazardous chemical shipping procedures;
9. potentially allow accurate close-form solutions for prediction of both thermodynamic (Specific Impulse and Thrust) and kinetic (burn rates) properties
   of solid propellant formulation for rapid screening and modeling of both N-SEP and propellant grain performance based on the NSEP composition, blend and, grain configuration; and
10. potentially allows employment of Green propellants that restrict formation of both polluting propulsion gases and airborne nanoparticulate polluting products of combustion the way current propellants do.