Ionic Liquid Cellulose Carbon Fiber Production
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Solution Overview
Problem
Traditional methods for producing carbon fibers for thermal protection systems, such as those used in spacecraft, rely on viscose rayon that involves toxic chemicals, leading to environmental concerns and depletion of stockpiles, necessitating a safer and more sustainable production method.
Innovation Solution
The use of ionic liquids to dissolve cellulose and produce carbon fibers, eliminating the need for caustic chemicals and enabling the creation of high-strength, low-thermal-conductivity fibers suitable for high-temperature applications, including rocket nozzles and heat shields, through a wet spinning process that preserves the polymer's molecular weight and structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional viscose rayon method is used to produce carbon fibers, then the fibers have good mechanical properties and low thermal conductivity, but the process uses toxic chemicals and produces harmful waste
Solution Approach 1:
The patent changes the chemical parameters of the manufacturing process by replacing traditional viscose chemistry with ionic liquid-based dissolution and regeneration. This substitution eliminates toxic chemicals like carbon disulfide while maintaining the ability to produce high-quality carbon fiber precursors through controlled dissolution and regeneration of cellulose
Solution Approach 2:
Ionic liquids serve as an intermediary solvent that enables the dissolution and regeneration of cellulose without the need for toxic chemicals. The ionic liquid acts as a temporary medium that can be removed and regenerated, leaving no harmful residues in the final carbon fiber product
2Productivity
If viscose rayon is used as precursor, then carbon fibers have desired properties for thermal protection, but stockpiles are depleted and production is no longer commercially viable in the US
Solution Approach 1:
The patent enables self-sufficient production by using naturally abundant cellulose sources (wood, cotton, agricultural waste) as precursors. This eliminates dependence on imported viscose rayon stockpiles and allows domestic production of carbon fiber precursors through a commercially viable process using ionic liquids
3Object-affected harmful factors
If ionic liquids are used to dissolve cellulose, then toxic chemicals are eliminated and environmental impact is reduced, but the process must preserve polymer molecular weight and structure
Solution Approach 1:
The patent carefully controls the dissolution parameters (temperature, concentration, ionic liquid composition) to dissolve cellulose without breaking down the polymer chains. The regeneration parameters are also precisely controlled to ensure the recovered cellulose maintains its molecular weight and structural integrity, which is critical for producing high-quality carbon fibers
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 method produces carbon fibers with properties similar to traditional viscose rayon fibers but with reduced environmental impact, maintaining high strength and low thermal conductivity, and allows for the recycling of ionic liquids, addressing the limitations of traditional production methods.
Implementation Method 1
dissolving the cellulose in an ionic liquid, producing a solution
Implementation Method 2
The filament yarns are manufactured from cellulose solutions in ionic fluids as part of a wet spinning process
Implementation Method 3
the fibers are produced by the carbonization of cellulose carbon fiber precursors
Data Source
AI summary
The present invention relates to a method for the continuous production of low thermal conductivity endless filament yarns with a compact, homogeneous structural morphology. The presently disclosed methods utilize safe and recyclable ionic liquids (IL) to produce carbon fiber precursors from cellulose. The fibers are produced by the carbonization of cellulose carbon fiber precursors. The precursor fiber filaments have an increased tear resistance with simultaneously sufficient elongation, a round or crenulated cross-section, and homogeneous fiber morphology. The filament yarns exhibit performance characteristics similar to those produced from traditional viscous rayon. The resulting fibers are especially suited for aerospace applications in composite materials used at the limits of high temperatures, for instance in structures found in rocket nozzles or atmospheric reentry heat shields on spacecraft.