Kidney-Shaped Polyimide Fiber Preparation via Circular Spinneret
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Solution Overview
Problem
The existing methods for producing polyimide fibers with non-circular cross-sections, such as kidney-shaped fibers, are complex and costly due to the need for non-circular spinneret orifices, which complicates the manufacturing process and increases production costs.
Innovation Solution
A method for producing polyimide fibers with kidney-shaped cross-sections using a spinneret with circular orifices, involving the reaction of aromatic dianhydrides with aromatic diamines to form polyamic acid, followed by coagulation in a bath with controlled temperature and depth, and subsequent thermal curing and stretching to achieve the desired shape without the need for non-circular spinneret orifices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If non-circular spinneret orifices are used to produce fibers with non-circular cross-sections, then the desired fiber shape and surface area are achieved, but the manufacturing complexity and production cost increase significantly
Solution Approach 1:
The invention uses asymmetric flow distribution within circular spinneret orifices to create asymmetric fiber cross-sections. By controlling the position and configuration of coagulation holes relative to the spinneret wall, the patent generates non-circular fiber shapes (including kidney-shaped, triangular, and other asymmetric cross-sections) from symmetric circular orifices, thereby achieving the desired fiber asymmetry without complex spinneret geometry
Solution Approach 2:
The invention introduces coagulation holes as an intermediary element between the spinneret and the fiber formation process. These holes act as mediators that transform the circular orifice geometry into non-circular fiber cross-sections by controlling the coagulation flow pattern. The coagulation holes serve as the intermediate structure that enables shape transformation without modifying the spinneret orifice geometry
2Shape
If non-circular spinneret orifices are used to produce fibers with non-circular cross-sections, then the fiber shape and surface area are improved, but the production efficiency decreases due to difficult and costly machining
Solution Approach 1:
The patent achieves asymmetric fiber cross-sections through asymmetric flow control rather than asymmetric orifice geometry, allowing the use of simple circular spinneret orifices that are easy to manufacture. This maintains high production efficiency while achieving the desired non-circular fiber shapes through process control
Solution Approach 2:
The invention changes process parameters (coagulation hole position, size, and configuration) to achieve shape transformation. By adjusting these parameters, the patent can produce different fiber cross-section shapes using identical circular spinneret orifices, thereby maintaining production efficiency while achieving shape diversity
3Productivity
If circular spinneret orifices are used, then the manufacturing process is simplified and production efficiency is improved, but the fiber surface area and cohesion are reduced compared to non-circular sections
Solution Approach 1:
The patent uses asymmetric flow distribution within circular orifices to create asymmetric fiber cross-sections that have larger surface areas than circular fibers of equivalent diameter. The non-circular shapes (kidney-shaped, triangular, etc.) inherently provide greater surface area for the same material volume, thus improving surface area while maintaining circular orifices for high productivity
Solution Approach 2:
The invention transforms the fiber cross-section from a two-dimensional circular shape to non-circular shapes (kidney-shaped, triangular, etc.) through flow control. This dimensional transformation increases the surface area and perimeter of the fiber cross-section, thereby improving surface area and cohesion without changing the spinneret orifice geometry
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 simplifies the manufacturing process, reduces costs, and enables high-efficiency production of fibers with increased specific surface area, cohesion, and improved drapability, making them suitable for high-temperature resistant applications.
Implementation Method 1
converting the polyamic acid to the corresponding polyimide
Implementation Method 2
entering as-spun polyamic acid fibers into at least one coagulation bath to form polyamic acid nascent fibers with kidney-shaped cross-sections
Data Source
AI summary
The present disclosure provides polyimide fibers with kidney-shaped cross-section and their preparation methods thereof, falling within the technical field of polyimide fiber. Polyimide fibers with kidney-shaped cross-sections are prepared by a continuous, integrated approach, starting from a polyamic acid solution prepared by reacting an aromatic dianhydride with an aromatic diamine. PAA nascent fibers with kidney-shaped cross-sections are obtained by adopting a spinneret having circular orifices under wet spinning process. The kidney-shaped cross-sections are obtained by varying the processing condition, including spinning speed, coagulation bath composition, coagulation temperature, and depth of coagulation bath. After washing and drying, polyamic acid nascent fibers are converted to polyimide fibers with kidney-shaped cross-sections under thermal curing. The integrated preparation methods are suitable for mass industrial production.