Cellulose Nano-fibril Fiber Alignment via Nematic Phase Transition
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Solution Overview
Problem
Current methods for manufacturing cellulose fibers from nano-fibrils fail to fully realize the high strength potential of crystalline cellulose due to the chiral nematic phase structure, which prevents complete orientation of nano-fibrils along the fiber axis, leading to defects and reduced strength.
Innovation Solution
A method involving the extraction of cellulose nano-fibrils from cellulose-rich materials, followed by hydrolysis with acid to create surface charges, fractionation, and dialysis to achieve a stable Zeta potential, allowing the formation of a lyotropic suspension that is spun into continuous fibers under extensional forces, aligning nano-fibrils and forming large crystalline structures during drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cellulose nano-fibrils are extracted from natural material, then high strength to weight ratio is achieved, but chiral nematic phase structure prevents complete orientation along fiber axis
Solution Approach 1:
The patent applies parameter changes by modifying the suspension concentration to exceed the isotropic-nematic transition concentration, inducing a nematic phase that enables complete orientation of cellulose nano-fibrils along the fiber axis during spinning, thereby resolving the orientation problem while preserving high strength properties
Solution Approach 2:
The patent employs periodic action through the spinning process that induces nematic phase formation and orientation, creating a periodic structural transformation from random dispersion to aligned nematic structure during fiber formation
2Stability of the object's composition
If chiral nematic phase is formed in suspension, then nano-fibrils are suspended stably, but twists in structure lead to inherent defects in fibre
Solution Approach 1:
The patent changes the concentration parameter to induce nematic phase formation, which reorganizes the chiral nematic structure into a more stable and defect-free configuration during spinning, eliminating the harmful twists while maintaining suspension stability
3Ease of manufacture
If isotropic phase is used for spinning, then processing is easier, but nano-fibrils cannot orient along main axis of fibre
Solution Approach 1:
The patent exploits phase transitions by inducing the isotropic-nematic transition through concentration control during spinning, allowing the suspension to transform from isotropic (easy to process) to nematic (high orientation) phase, thereby achieving both ease of manufacture and precise fibril orientation
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
Results in cellulose fibers with a high content of crystallized cellulose, achieving high tensile strength and minimal defects, with the process being economically and environmentally friendly due to its water-based nature.
Implementation Method 1
hydrolysis with acid to create surface charges
Implementation Method 2
alignment achieved through extension of the extruded fibre from a die or needle
Implementation Method 3
the aligned nano-fibrils aggregate form a continuous structure
Data Source
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AI summary
A method for the spinning of a fibre comprising cellulose nano-fibrils being aligned along the main axis of the fibre from a lyotropic suspension of cellulose nano-fibrils, said nano-fibril alignment being achieved through extension of the extruded fibre from a die, spinneret or needle, wherein said fibre is dried under extension and the aligned nano-fibrils aggregate to form a continuous structure.The fibrils used in this method can be extracted from a cellulose-rich material such as wood. The invention also related to acellulose-based fibreobtained according to this method and to a cellulose fibrewhich contains at least 90 % wt of crystallised cellulose.