Continuous Fiber Coating with Grafted Fluoropolymer for Stronger Adhesion
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Solution Overview
Problem
Existing methods for impregnating continuous fibers with polymer matrices face challenges such as high costs, difficulty in melting thermoplastic polymers below 200°C, and issues with compatibility and cohesion between fluorinated polymers and fibers, leading to weak spots and reduced tensile strength.
Innovation Solution
A method involving a polymer matrix composed of a fluorinated polymer grafted with carboxylic polar functions, optionally mixed with nongrafted fluorinated polymers and carbon nanotubes, is used to coat continuous fibers, enhancing mechanical properties and cohesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fluorinated polymer is used to coat continuous fibers, then production cost is reduced and processing temperature is lowered, but compatibility and cohesion between polymer and fibers deteriorate, leading to weak spots and reduced tensile strength
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of the fluorinated polymer through grafting carboxylic polar functions. This changes the surface properties and chemical reactivity of the polymer, enabling better adhesion to fibers while maintaining the base fluorinated polymer's low cost and low processing temperature advantages.
Solution Approach 2:
The patent creates a composite polymer system by combining grafted fluorinated polymer with carbon nanotubes. This composite structure leverages the strong adhesion properties of the grafted polymer and the reinforcing properties of carbon nanotubes to achieve both cost-effectiveness and high mechanical strength.
2Strength
If carbon nanotubes are added to fluorinated polymer matrix, then mechanical strength is enhanced, but tensile strength at ambient temperature deteriorates due to poor compatibility
Solution Approach 1:
The grafted fluorinated polymer acts as an intermediary between the carbon nanotubes and the fiber substrate. The carboxylic polar groups on the grafted polymer improve interfacial adhesion and dispersion of carbon nanotubes, preventing aggregation and ensuring effective stress transfer, thereby maintaining high tensile strength at ambient temperature.
3Ease of operation
If thermoplastic polymers are used for coating fibers, then ease of thermoforming and shape diversity are improved, but melting difficulty below 200°C and energy input requirements worsen
Solution Approach 1:
The patent selects fluorinated polymers with specific glass transition temperatures below 100°C, which allows thermoforming at lower temperatures. This parameter selection (Tg < 100°C) enables ease of thermoforming while avoiding the high melting point requirements of conventional thermoplastics like PEEK, thereby reducing energy input.
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 approach results in composite fibers with improved hot creep strength and tensile strength, suitable for aeronautical and motor vehicle applications, while reducing production costs and energy input.
Implementation Method 1
a fluorinated polymer grafted with at least one carboxylic polar function
Implementation Method 2
coating said fibers with a polymer matrix
Data Source
AI summary
The invention relates to a method for the impregnation of continuous fibers that comprises coating said fibers with a polymer matrix containing: (a) at least one fluorinated polymer grafted with at least one carboxylic polar function and (b) optionally at least one fluorinated nongrafted polymer. The invention also relates to the composite fibers that can be obtained by said method and to the use thereof.