Nitrate Ester Energetic Compositions Stabilizer Phase Control

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Solution Overview

Problem

Nitrate ester compositions used in energetic formulations are chemically unstable, leading to decomposition and potential autocatalysis, which can be accelerated by incompatible materials, reducing their useful lifetime and requiring additional stabilizers to control decomposition rates.

Innovation Solution

The method involves forming energetic compositions with a nitrate ester, a polymer, and a stabilizer, where a portion of the stabilizer is dissolved in the nitrate ester and another portion remains in a crystalline state, allowing for a higher concentration of stabilizer than conventional compositions, and using a combination of nitrate esters with different decomposition rates to enhance stability against foreign object debris.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If stabilizer concentration is increased to control decomposition, then stability is improved, but crystallized stabilizer adversely affects physical properties

Engineering Contradiction:

ImprovestabilityVSAvoidphysical properties

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

The patent changes the physical state parameter of the stabilizer from completely dissolved to a mixed state with crystalline portions, allowing higher concentrations without the adverse effects of full crystallization. This parameter change enables the stabilizer to remain partially solid while maintaining stability benefits.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite system where the stabilizer exists in multiple phases (dissolved and crystalline) within the same composition. This composite structure allows the stabilizer to function at high concentrations while the crystalline portions remain dispersed rather than forming adverse crystallized structures.

Inventive Principle:

Principle #40Composite materials

2Duration of action of stationary object

If stabilizer concentration is increased to extend useful lifetime, then decomposition resistance is improved, but the stabilizer remains solvated in the binder limiting maximum concentration

Engineering Contradiction:

Improveuseful lifetimeVSAvoidstabilizer concentration

Core Design Contradiction:

Duration of action of stationary objectVSQuantity of substance

Solution Approach 1:

The patent utilizes phase transitions of the stabilizer, allowing it to exist in both dissolved and crystalline phases. This enables the stabilizer concentration to exceed the solubility limit while maintaining uniform distribution, as the crystalline portions remain dispersed throughout the binder matrix.

Inventive Principle:

Principle #36Phase transitions

3Object-affected harmful factors

If nitrate ester composition is made more stable to resist FOD, then decomposition rate is reduced, but conventional formulations lack sufficient stability

Engineering Contradiction:

Improveresistance to FODVSAvoidstability

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary anti-action by incorporating high concentrations of stabilizer and using nitrate esters with inherently lower decomposition rates before FOD contamination can occur. This pre-established stability provides resistance to decomposition even when exposed to incompatible materials like FOD.

Inventive Principle:

Principle #9Preliminary anti-action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach significantly increases the stability and useful lifetime of nitrate ester compositions by doubling or tripling the stabilizer content and using nitrate esters with lower decomposition rates, resulting in a substantial delay in the onset of decomposition when exposed to incompatible materials.

Implementation Method 1

Nitrate esters are chemically unstable, decomposing slowly in a homolytic reaction

Methodology Applied

Scientific EffectHomolytic reaction:

Implementation Method 2

The stabilizer may limit or prevent autocatalysis by scavenging the byproducts of the homolytic reaction of the nitrate esters

Methodology Applied

Scientific EffectScavenging:

Implementation Method 3

a premix comprising a nitrate ester, a polymer, and a stabilizer dissolved in the nitrate ester

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 4

A portion of the stabilizer remains in a crystalline state after the combining

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS8778103B2Energetic compositions including nitrate esters and articles including such energetic compositions

Publication Date: 2014.07.15 NORTHROP GRUMMAN SYSTEMS CORP

AI summary

Methods of forming energetic compositions include forming a premix comprising a nitrate ester, a polymer, and a stabilizer, and combining solids with the premix. Additional stabilizer may be added with the solids and may remain in a crystalline state. Some methods include dissolving a stabilizer in at least one of a plurality of nitrate esters. Energetic compositions include a continuous matrix and a stabilizer. The continuous matrix includes a nitrate ester and surrounds a solid energetic material. Some compositions include a first nitrate ester, a second nitrate ester having a decomposition rate lower than the first nitrate ester, and a stabilizer. An article includes a housing and an energetic composition in the housing.