Energetic Molding Powder with Partially Cured Thermoset Binder
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Solution Overview
Problem
Existing manufacturing methods for plastic bonded explosives (PBXs) are time-intensive, hazardous, wasteful, and require difficult-to-source binders, leading to inefficiencies and suboptimal energy density.
Innovation Solution
A method involving direct mixing of energetic particles with partially cured thermoset binders, such as HTPB, followed by compaction and partial curing, to create molding powders without solvent suspension, allowing for controllable microstructural properties and reduced binder content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional solvent-based thermoplastic binders are used to coat energetic particles, then the molding powder can be manufactured with established processes, but the process becomes time-intensive, hazardous, and wasteful due to solvent evaporation
Solution Approach 1:
The patent extracts and eliminates the solvent component from the traditional binder application process. By using solvent-free thermoplastic binders, the hazardous and time-consuming solvent evaporation step is completely removed, directly resolving the contradiction between safety and manufacturing time.
Solution Approach 2:
The patent changes the physical state parameters of the binder system by transitioning from solvent-based liquid suspensions to solvent-free thermoplastic formulations. This parameter change eliminates the need for evaporation while maintaining coating effectiveness, simultaneously improving safety and reducing manufacturing time.
2Ease of manufacture
If thermoset slurries are used to mix energetic particles with binders, then the mixture can be cast into molds, but large amounts of binder (more than 10% by weight) are required resulting in lower energy density
Solution Approach 1:
The patent changes the thermal state parameter by using partially cured (not fully cured) thermoset binders. This parameter change allows the binder to provide sufficient adhesion and processability during molding while containing enough unreacted functionality to complete curing later, thereby reducing the overall binder content required and increasing energy density.
Solution Approach 2:
The patent applies preliminary curing to the thermoset binder before final molding, creating a partially cured state that provides adequate handling properties. This preliminary action eliminates the need for excessive binder content while maintaining manufacturability, as the partial cure structure already provides necessary cohesion.
3Ease of manufacture
If traditional thermoplastic binders are used, then the molding powder can be formed with good manufacturability, but the binder is difficult to source due to limited manufacturers
Solution Approach 1:
The patent employs thermoplastic binders that serve multiple functions: providing adhesion, enabling processing, and offering flexibility in formulation. These multi-functional binders are commercially available from multiple suppliers, resolving the contradiction between manufacturability and availability by using materials that can be sourced from diverse manufacturers.
4Strength
If high temperature curing is applied to thermoset slurries, then the mixture solidifies and forms the final product, but the process requires large amounts of binder and produces suboptimal energy density
Solution Approach 1:
The patent applies preliminary curing to develop sufficient structural integrity before final molding, eliminating the need for excessive binder content. The partial cure provides early strength development that allows processing with lower binder quantities, while the remaining uncured functionality completes the strengthening process later.
Solution Approach 2:
The patent changes the curing parameter from complete high-temperature curing to partial low-temperature curing followed by final curing. This parameter change enables the use of less binder material while achieving the required structural integrity, thereby increasing energy density.
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
The method results in easier, less wasteful, and more efficient production of molding powders with improved manufacturability and safety, achieving higher energy density and tailored mechanical properties.
Implementation Method 1
partially cured thermoset binders
Implementation Method 2
compaction is involved to consolidate the powder
Data Source
AI summary
Methods for manufacturing explosives and the explosives manufactured by the methods are disclosed. Embodiments include mechanical mixing energetic particles with a thermoset binder material. Some embodiments include mixing the particles and binder using a bladeless mixer until homogeneous. Embodiments may also include heating a mixture of high energetic molding powder and a binder material at a low temperature (e.g., 70° C.) until the binder material is partially cured. Some embodiments include breaking up the mixture into pieces about 1 mm in size to form an energetic molding powder. And some embodiments include pressing a mixture of energetic molding powder into a die.