Paper-based electromagnetic shielding composite with flame retardant properties and its preparation method and application
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Solution Overview
Problem
Existing polyimide (PI) fibers used in paper-based electromagnetic shielding materials suffer from poor bonding strength, agglomeration of wave-absorbing fillers, and poor paper-forming performance, limiting their application in high-performance electromagnetic shielding composites.
Innovation Solution
A method involving the modification of PI fibers with polydopamine and grafting with carbon nanotubes, followed by in-situ synthesis of conductive MOFs and application of polyimide resin, using a wet papermaking process to create a paper-based electromagnetic shielding composite with flame retardant properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high-performance polyimide (PI) fibers are used as raw material for paper-based electromagnetic shielding materials, then temperature resistance and mechanical properties are improved, but bonding strength between fibers and pulp deteriorates due to smooth fiber surfaces
Solution Approach 1:
Polydopamine is introduced as an intermediary substance that coats the smooth PI fiber surfaces, providing anchoring sites for carbon nanotubes and improving bonding between fibers and pulp. The polydopamine layer acts as a mediator that bridges the gap between the hydrophobic PI fibers and the aqueous papermaking environment, enabling better integration while maintaining the inherent temperature resistance of PI fibers.
Solution Approach 2:
A composite structure is created by combining PI fibers with carbon nanotubes and polydopamine. This composite approach allows the PI fibers to provide temperature resistance while the carbon nanotubes and polydopamine coating enhance bonding strength and electromagnetic shielding performance, resolving the contradiction between maintaining high-temperature resistance and improving interfacial bonding.
2Reliability
If wave-absorbing fillers are added to PI fiber materials for electromagnetic shielding, then electromagnetic shielding performance is improved, but agglomeration of fillers occurs during papermaking process
Solution Approach 1:
Carbon nanotubes serve as an intermediary that disperses wave-absorbing fillers uniformly throughout the paper matrix. The nanotubes prevent filler agglomeration by creating a spatial network that distributes fillers evenly, while still allowing sufficient filler content to achieve effective electromagnetic shielding performance.
Solution Approach 2:
The porous and hierarchical structure formed by the carbon nanotube network provides spaces for filler particles to distribute uniformly without agglomerating. This porous architecture allows wave-absorbing fillers to be embedded within the three-dimensional network, maintaining compositional uniformity while achieving effective electromagnetic shielding.
3Ease of manufacture
If conventional papermaking process is used for PI fibers, then ease of manufacture is maintained, but paper-forming performance deteriorates due to poor bonding characteristics
Solution Approach 1:
The PI fibers undergo preliminary modification with polydopamine and carbon nanotube grafting before the papermaking process. This preliminary action enhances the bonding characteristics of the fibers, improving paper-forming performance while still using conventional papermaking equipment and processes, thus maintaining ease of manufacture.
Solution Approach 2:
The surface properties of PI fibers are modified by changing parameters such as surface chemistry through polydopamine coating and carbon nanotube grafting. These parameter changes improve bonding characteristics and paper-forming performance without fundamentally altering the papermaking process, allowing continued use of conventional manufacturing methods.
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 composite exhibits excellent mechanical properties, high heat resistance, flame retardancy, and effective electromagnetic shielding performance, suitable for industrial mass production.
Implementation Method 1
dispersing polyimide fibers (PI fibers) in water, adding dopamine hydrochloride and tris(hydroxymethyl) aminomethane to react
Implementation Method 2
adding carbon nanotubes to continue the reaction; after the reaction is finished, filtering and collecting solids
Implementation Method 3
dispersing the carbon nanotube-modified PI fibers and PPTA pulp in water, mixing well, and then using a wet papermaking process to make sheets
Implementation Method 4
dispersing a nickel source, a cobalt source and 2, 3, 6, 7, 10, 11-hexahydroxytriphenylene in water, then adding the obtained carbon nanotube/PI fiber paper, and carrying out a reaction at 70-100° C.
Implementation Method 5
spraying one side of the obtained NiCo-CAT/carbon nanotube/PI fiber paper with a pyrrole solution and making same stand still for a reaction
Implementation Method 6
spraying a polyimide resin solution onto the other side of the NiCo-CAT/carbon nanotube/PI fiber paper, and then performing hot-pressing treatment
Data Source
AI summary
Disclosed are a paper-based electromagnetic shielding composite with flame retardant properties and its preparation method and application, belonging to the technical field of electromagnetic shielding. In the present disclosure, PI fibers are modified by polydopamine and grafted with carbon nanotubes, polyimide fiber paper is prepared by a wet papermaking technology, an in-situ synthesis method is used to enable conductive MOFs and polymer PPy to grow on the fiber paper, and finally polyimide resin is sprayed onto the paper to prepare the paper-based electromagnetic shielding composite with flame retardant properties. The method is simple in process without complex synthesis equipment, and solves the problems that polyimide fiber paper is poor in paper forming property and paper mechanical property, and carbon nanotubes are easy to agglomerate in paper and limited in addition amount in the prior art. The paper-based composite has good mechanical property, heat resistance, flame retardancy and electromagnetic shielding performance.