Carbon Fiber Prepreg Surface Oxygen Concentration
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Solution Overview
Problem
Current methods for enhancing the interlaminar toughness of carbon fiber reinforced materials, particularly in Mode I and Mode II, are insufficient, and existing techniques do not adequately address the surface element ratio and interface adhesion properties between the carbon fibers and matrix resin.
Innovation Solution
A prepreg comprising carbon fibers treated with an alkaline electrochemical oxidation process and an epoxy resin system with a hardener, where the surface oxygen concentration is 0.10 or more and the cured product exhibits molecular anisotropy visible in polarizing microscope observation, improving interlaminar toughness and tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional thermosetting resin is used as matrix resin, then excellent adhesiveness to carbon fiber and mechanical properties are achieved, but interlaminar toughness and resistance to peeling stress are insufficient
Solution Approach 1:
The patent applies parameter changes by controlling the surface oxygen concentration of carbon fibers to 0.10 or more through alkaline electrochemical oxidation treatment. This specific parameter control modifies the fiber surface properties to enhance both adhesion and interlaminar toughness, resolving the contradiction between strength and reliability
Solution Approach 2:
The patent creates a composite system combining carbon fibers with specific surface treatment (surface oxygen concentration ≥0.10) and epoxy resin matrix. This composite approach integrates the high strength of carbon fiber with the improved interlaminar toughness achieved through surface modification, addressing both adhesion and peeling resistance requirements
2Strength
If carbon fiber surface is treated to improve adhesion, then interface adhesion property is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent replaces complex mechanical surface treatment methods with electrochemical oxidation. This substitution achieves the required surface oxygen concentration through electrochemical reactions in an alkaline medium, simplifying the manufacturing process while maintaining effective adhesion enhancement
Solution Approach 2:
The patent controls the surface oxygen concentration as a key parameter (≥0.10) through electrochemical treatment. By focusing on this specific parameter rather than complex multi-step surface treatments, the manufacturing process becomes more manageable and controllable
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 solution achieves excellent Mode I and Mode II interlaminar toughness and tensile strength by optimizing the surface treatment of carbon fibers and the epoxy resin system, enhancing the adhesion properties and structural integrity of the carbon fiber reinforced material.
Implementation Method 1
carbon fibers treated with an alkaline electrochemical oxidation process
Implementation Method 2
alkaline electrochemical oxidation process
Implementation Method 3
a cured product obtained by curing [B] and [C] includes a resin region having molecular anisotropy exhibiting interference fringes in polarizing microscope observation
Implementation Method 4
resin region having molecular anisotropy exhibiting interference fringes in polarizing microscope observation
Data Source
AI summary
A prepreg, which includes a carbon fiber reinforced material, has excellent Mode I interlaminar toughness, Mode II interlaminar toughness, and tensile strength. The prepreg includes the following constituents [A] to [C] and satisfies the following conditions (I) and (II):[A]: a carbon fiber;[B]: an epoxy resin; and[C]: a hardener for [B], and(I) a surface oxygen concentration O/C of [A] measured by X-ray photoelectron spectroscopy is 0.10 or more; and(II) a cured product obtained by curing [B] and [C] includes a resin region having molecular anisotropy exhibiting interference fringes in polarizing microscope observation in a crossed Nicol state.