Lignin/PVA Fiber Coagulation Map via Hansen Solubility
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Solution Overview
Problem
There is a need for effective methods to prepare lignin-containing fibers, such as lignin/PVA and lignin/PAN fibers, which often lack strength and are not efficiently produced due to processing challenges and the use of toxic solvents like carbon disulfide in current carbon fiber production.
Innovation Solution
A method involving gel-spinning of lignin/PVA and lignin/PAN fibers using solvents with specific hydrogen bonding, polar, and dispersive character concentrations, allowing for the production of fibers with improved mechanical properties by controlling the coagulation bath composition and aging processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If lignin-containing fibers are prepared using conventional methods, then production cost is reduced, but fiber strength and mechanical properties deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the coagulation bath composition with specific Hansen solubility parameters (hydrogen bonding character fH=20-30%, polar character fP=25-35%, dispersive character fD=40-50%) and controlling processing temperature (5-25°C) to achieve optimal fiber strength while maintaining manufacturability
Solution Approach 2:
The patent uses an intermediary coagulation bath with specifically selected solvents (methanol, acetone, isopropanol in optimized ratios) that mediates between the lignin/PVA dope and the final fiber structure, enabling controlled phase separation and gelation that enhances fiber strength without excessive processing complexity
2Productivity
If carbon disulfide is used in carbon fiber production, then production efficiency is improved, but environmental harm and safety issues worsen
Solution Approach 1:
The patent converts the harmful effect of conventional solvents by replacing carbon disulfide with a coagulation bath system based on methanol, acetone, and isopropanol that achieves equivalent or superior fiber properties without the severe toxicity and environmental harm, while maintaining production efficiency
Solution Approach 2:
The patent changes the chemical parameters of the solvent system by selecting coagulation bath components with specific Hansen solubility parameters that provide effective fiber formation without the harmful properties of carbon disulfide, achieving both safety and productivity goals
3Strength
If draw ratio is increased to improve fiber orientation, then fiber strength improves, but processing complexity increases
Solution Approach 1:
The patent applies preliminary action by performing aging of the lignin/PVA dope before spinning, which pre-organizes the polymer chains and creates a more favorable structure for subsequent high draw ratio processing, thereby achieving high fiber strength without proportionally increasing processing complexity
Solution Approach 2:
The patent changes the physical parameters of the dope by controlling aging temperature and time, which modifies the molecular structure to be more responsive to drawing, enabling high draw ratios to be applied more effectively without excessive complexity
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 enhances the tensile strength, modulus, and toughness of lignin-containing fibers, overcoming the limitations of existing methods by achieving higher draw ratios and maintaining lignin within the fiber structure, resulting in superior mechanical performance.
Implementation Method 1
adding a dope of lignin and PVA to a coagulation bath containing a solvent comprising one or more components... gel-spinning a lignin/PVA fiber from the coagulation bath
Implementation Method 2
gel-spinning lignin/PVA and lignin/PAN fibers from coagulation baths that comprise solvents designed to have certain hydrogen bonding, polar, and dispersive characters
Implementation Method 3
the hydrogen bonding character (fH) of the solvent is between 20% and 30%, the polar character (fP) of the solvent is between 25% and 35%, and the dispersive character (fD) of the solvent is between 40% and 50%
Data Source
AI summary
Disclosed are methods for preparing a lignin/poly(vinyl alcohol) (PVA) fiber and for preparing a lignin/polyacrylonitrile (PAN) fiber. The methods can comprise adding a dope of lignin and PVA or a dope of lignin and PAN to a coagulation bath containing a solvent comprising one or more components, wherein the one or more components are present in the solvent in concentrations based on the hydrogen bonding character (fH) of the solvent, the polar character (fP) of the solvent, and the dispersive character (fD) of the solvent; and gel-spinning a lignin/PVA fiber or a lignin/PAN fiber from the coagulation bath.