Polyazide Binder Crosslinking for Propellant Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The development of composite pyrotechnic products for tube weapons faces challenges with vulnerability due to nitrocellulose-based binders, which can ignite under physical stress, and the use of inert thermosetting binders is complicated by the need for solvents and precise crosslinking agent dosages, making industrial-scale production difficult.
Innovation Solution
The use of a polyazide-based crosslinked binder with a polymeric gum, crosslinked via alkyne functions using 'Click chemistry', allowing for high energetic charge loading without solvents or pre-crosslinking, and enabling the substitution of RDX with less erosive fillers like EDNA, optimizing strength, vulnerability, and erosivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If nitrocellulose-based binders are used in composite pyrotechnic products, then mechanical strength and cohesion are improved, but vulnerability increases due to ignition under physical stress
Solution Approach 1:
The patent removes nitrocellulose from the binder composition entirely, extracting the harmful component while maintaining binder functionality through alternative materials (synthetic resins like polyurethanes, epoxies, or polyester) that provide mechanical strength without the vulnerability to ignition under physical stress
Solution Approach 2:
The invention uses composite binder systems combining synthetic resins with crosslinking agents to achieve both mechanical strength and low vulnerability. The crosslinked network structure provides robust mechanical properties while the inert nature of synthetic resins eliminates the ignition hazard associated with nitrocellulose
2Object-affected harmful factors
If inert thermosetting binders are used to reduce vulnerability, then vulnerability is reduced, but manufacturing complexity increases due to solvent requirements and precise crosslinking agent dosing
Solution Approach 1:
The patent modifies the chemical parameters of the binder system by selecting thermosetting resins with inherent pot lives that enable direct shaping without solvents. The crosslinking agent dosage is optimized to achieve complete crosslinking during the shaping process itself, eliminating the need for separate pre-crosslinking and curing steps
Solution Approach 2:
The invention performs preliminary mixing of all components (thermosetting resin, crosslinking agent, and energetic charges) in the correct proportions before shaping. The resin is selected to have sufficient pot life to allow complete mixing and shaping, then crosslinks during or immediately after shaping, eliminating the need for separate pre-crosslinking steps
3Quantity of substance
If high charge rates (close to 80%) are used in inert binder composites, then energy performance is improved, but mechanical working difficulty increases due to insufficient binder content
Solution Approach 1:
The patent changes the physical parameters of the binder system by using thermosetting resins that transition from liquid/paste state during mixing to solid crosslinked network after curing. This allows high charge rates (70-80%) to be achieved while maintaining sufficient binder content to enable mechanical working in the uncured state, with the crosslinked structure providing final mechanical strength
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 results in composite pyrotechnic products with high energetic charge loading, reduced vulnerability, and simplified production processes, maintaining mechanical strength and cohesion without solvent use, suitable for propellant powders in tube weapons.
Implementation Method 1
crosslinked via alkyne functions using 'Click chemistry'
Data Source
AI summary
The present invention relates to a composite pyrotechnical product, in particular a propellant powder for barrelled weapons, containing organic energy loads in a crosslinked binder. The composition of said product, expressed in weight percentages, typically includes: 78 % to 90 %, advantageously 80 % to 86 %, of organic energy loads; and 10 % to 22 % of an energetic crosslinked binder obtained by crosslinking, via only 8 % to 12 % of the azide functions thereof, a glycidyl polyazide having an average molecular weight of 700 to 3,000 g/mol, with at least one crosslinking agent containing at least two propargyl functions in the chemical formula thereof, in the presence of a polymer gum, selected among the polyurethane-polyester gums, the polyurethane-polyether gums and the mixtures thereof, in which the average molecular weight by number is higher than 20,000 g/mol and in which the Mooney viscosity is from 20 to 70 ML (5 + 4) at 100 °C; said at least one polymer gum making up 1 wt % to 5 wt % of the composition of said pyrotechnical product. The invention also relates to the method for obtaining said products. Said products are particularly useful given the properties thereof and how easily they can be obtained.