Submicron Graphitic Fibrils via Fiber Segmentation
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Solution Overview
Problem
Current methods for producing carbon nano-fibers and nano-tubes are expensive, inefficient, and result in materials with high impurity levels, catalyst residues, and structural instabilities, limiting their applications due to poor purity, orientation, and functionalization capabilities.
Innovation Solution
A process involving the splitting of micron-scaled carbon or graphite fibers along the fiber axis to produce submicron-scaled graphitic fibrils, which are free of catalysts and thermal carbon overcoats, and are isolated to enhance their electrical, thermal, and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CVD or CCVD processes are used to produce carbon nano-fibers, then the fibers can be manufactured, but the material costs are extremely expensive and production rates are low
Solution Approach 1:
The invention segments the continuous carbon fiber into individual nano-fibrils through chemical treatment and mechanical processing. This segmentation allows the fibrils to be produced more efficiently while maintaining their unique properties, resolving the contradiction between production rate and manufacturing cost.
Solution Approach 2:
The invention extracts the carbon nano-fibrils from the parent fiber matrix through chemical dissolution of the binder material. This extraction process enables high-yield production of pure carbon fibrils without the expensive CVD/CCVD processes, improving both productivity and cost-effectiveness.
2Manufacturing precision
If CVD or CCVD processes are used to produce carbon nano-fibers, then the fibers can be manufactured, but the purity is low due to significant catalyst residues and impurities
Solution Approach 1:
The invention removes catalyst residues and impurities by chemically dissolving the binder material that holds the fibrils together in the parent fiber. This extraction process yields high-purity carbon nano-fibrils (greater than 90% pure) while maintaining high production efficiency, resolving the contradiction between manufacturing precision and productivity.
Solution Approach 2:
The invention applies localized chemical treatment to specific regions of the parent fiber where binder material and catalyst residues are concentrated. This targeted approach efficiently removes impurities without affecting the bulk carbon fibril structure, achieving high purity while maintaining production efficiency.
3Strength
If conventional carbon fibers are used, then the fibers have adequate mechanical strength, but they lack the enhanced electrical and thermal conductivity of submicron-scale fibrils
Solution Approach 1:
The invention segments carbon fiber into submicron-scale fibrils, which enhances electrical and thermal conductivity while maintaining mechanical strength. The segmentation increases the surface area to volume ratio and improves electron and heat transport pathways, resolving the contradiction between strength and reliability.
Solution Approach 2:
The invention creates local quality variations by producing fibrils with different diameters and orientations within the composite material. This local variation optimizes both mechanical strength (through load-bearing fibrils) and electrical/thermal conductivity (through highly conductive aligned fibrils), resolving the contradiction between these properties.
Data Source
AI summary
The present invention provides a submicron-scaled graphitic fibril having a diameter or thickness less than 1 μm, wherein the fibril is free of continuous thermal carbon overcoat, free of continuous hollow core, and free of catalyst. The fibril is obtained by splitting a micron-scaled carbon fiber or graphite fiber along the fiber axis direction. The diameter or thickness is preferably less than 500 nm and can be greater or less than 100 nm. These graphitic fibrils exhibit exceptionally high electrical conductivity, thermal conductivity, elastic modulus, and strength. The present invention also provides several products that contain submicron graphitic fibrils: (a) paper, thin-film, mat, and web products; (b) rubber or tire products; (c) energy conversion or storage devices, such as fuel cells, lithium-ion batteries, and supercapacitors; (d) adhesives, inks, coatings, paints, lubricants, and grease products; (e) heavy metal ion scavenger; (f) absorbent (e.g., to recover spill oil); (g) sensors; (h) friction and brake components; (i) radiation-shield components; and (j) nanocomposite materials.