Polyacrylonitrile Solutions Using Rotor-Stator Shearing to Limit Gels
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Solution Overview
Problem
Existing processes for producing polyacrylonitrile-based polymer solutions for carbon fiber production face challenges such as the formation of agglomerates and gels, leading to viscosity increases and filter clogging, which are unsuitable for industrial-scale continuous processes.
Innovation Solution
A process involving direct combination of polyacrylonitrile-based polymer powder with a solvent free of non-solvents at ambient temperature, followed by shearing with a rotor-stator to create a uniform dispersion, and subsequent heating to dissolve the polymer completely, forming a homogeneous solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If polyacrylonitrile-based polymer powder is combined with a strong solvent like DMSO at ambient temperature, then the polymer dissolves effectively, but the polymer particles adhere to one another forming agglomerates and gels, increasing viscosity and causing filter clogging
Solution Approach 1:
The patent applies preliminary action by pre-dispersing the polymer powder in a non-solvent (water or alcohol) before adding the strong solvent (DMSO). This preliminary dispersion step prevents polymer particles from directly adhering to each other upon contact with the strong solvent, thereby avoiding agglomerate and gel formation while still achieving complete dissolution in the final solution.
2Object-generated harmful factors
If water is added to DMSO to reduce its solubilizing capacity, then agglomerate formation is reduced, but the dissolution time increases significantly and requires heating under vacuum
Solution Approach 1:
The patent uses preliminary action by pre-dispersing polymer powder in a non-solvent before adding DMSO. This approach reduces agglomerate formation without requiring water addition, thereby avoiding the need for extended heating under vacuum and significantly reducing dissolution time while maintaining complete polymer dissolution.
Solution Approach 2:
The patent employs a non-solvent (water or alcohol) as an intermediary medium. This intermediary allows polymer particles to be pre-dispersed in a controlled manner before the strong solvent is introduced, preventing direct particle-to-particle adhesion and reducing agglomerate formation without requiring water-DMSO mixtures and their associated long processing times.
3Object-generated harmful factors
If low temperature (−5° C. to 10° C.) is used during mixing, then dissolution is limited and particles remain free-flowing, but no homogeneous solution is formed and the process is unsuitable for industrial scale
Solution Approach 1:
The patent applies preliminary action by performing the dispersion step at low temperature (−5° C. to 10° C.) to prevent particle adhesion and maintain free-flowing particles, then subsequently raising the temperature to complete dissolution and form a homogeneous solution. This two-stage temperature approach achieves both particle separation and complete dissolution suitable for industrial scale.
Solution Approach 2:
The patent uses periodic action by changing the temperature in stages: first maintaining low temperature during the critical dispersion phase to prevent agglomeration, then raising the temperature in a second phase to achieve complete dissolution. This periodic temperature control enables both particle separation and homogeneous solution formation.
4Productivity
If high concentration of polymer is targeted in the solution, then productivity increases, but the solution becomes more prone to gel formation and filter clogging
Solution Approach 1:
The patent applies preliminary action by pre-dispersing high concentrations of polymer powder in a non-solvent before adding the strong solvent. This preliminary step prevents particle adhesion even at high concentrations, enabling the production of high-concentration homogeneous solutions without gel formation or filter clogging, thereby maintaining high productivity.
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 process produces stable, gel-free and agglomerate-free solutions with high solids concentrations, suitable for continuous industrial processes, maintaining solution stability over time and reducing filter clogging issues.
Implementation Method 1
subjecting the combination obtained in step a) to the shearing action of at least one rotor-stator
Implementation Method 2
heating the dispersion obtained in step b) at a temperature and for a time sufficient to completely dissolve the polyacrylonitrile-based polymer
Data Source
AI summary
The present disclosure relates to a process for producing homogeneous solutions comprising dissolved polyacrylonitrile-based polymer, and a system suitable therefor. The homogeneous polymer solutions produced by the process described herein may be used for producing carbon fiber, typically carbon fiber used in manufacturing composite materials.