Sizing agent-coated reinforcing fibers, method for producing sizing agent-coated reinforcing fibers, prepreg, and fiber-reinforced composite material
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Solution Overview
Problem
Current fiber-reinforced composite materials face challenges in achieving high interlaminar fracture toughness and mechanical strength, particularly due to the brittleness of thermosetting matrix resins and variations in physical properties based on fiber alignment.
Innovation Solution
The use of sizing agent-coated reinforcing fibers, where the sizing agent contains a polyrotaxane and a glycidyl ether epoxy compound, is applied to the fibers, followed by heat-treating to enhance adhesion and toughness, resulting in a fiber-reinforced composite material with improved interlaminar fracture toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermosetting matrix resin is used to provide high tensile strength and compression strength, then mechanical strength in fiber direction is improved, but interlaminar fracture toughness deteriorates due to brittleness
Solution Approach 1:
The patent uses a composite sizing agent system combining flexible epoxy resin and rigid epoxy resin on carbon fibers. This composite approach allows the flexible resin to provide toughness and the rigid resin to provide strength, resolving the contradiction between mechanical strength and interlaminar fracture toughness in thermosetting matrix composites.
Solution Approach 2:
The patent changes the chemical composition parameters of the sizing agent by incorporating both flexible and rigid epoxy resins in specific proportions. This parameter modification enables the fiber interface to simultaneously achieve high strength and high toughness, overcoming the inherent brittleness of conventional thermosetting resins.
2Strength
If conventional epoxy sizing agent is applied to improve interfacial adhesion, then tensile strength is improved, but interlaminar fracture toughness remains insufficient
Solution Approach 1:
The patent applies a composite sizing agent comprising flexible epoxy resin and rigid epoxy resin. The flexible component ensures strong interfacial adhesion while the rigid component provides toughness, thereby simultaneously improving both interfacial adhesion and interlaminar fracture toughness beyond what conventional single-resin systems achieve.
Solution Approach 2:
The patent creates different local properties within the sizing agent layer by combining resins with different flexibility characteristics. The flexible epoxy resin provides local adhesion quality at the fiber interface, while the rigid epoxy resin provides local toughness quality, allowing both functions to coexist in the same coating system.
3Strength
If fiber alignment is optimized for strength, then tensile strength in fiber direction is improved, but shock resistance deteriorates due to anisotropic properties
Solution Approach 1:
The patent employs a composite sizing agent system that compensates for the anisotropic nature of aligned fibers. The flexible and rigid epoxy resins work together to provide isotropic toughness enhancement at the fiber-matrix interface, thereby improving shock resistance without compromising the tensile strength provided by fiber alignment.
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 approach significantly enhances the interlaminar fracture toughness and mechanical strength of the composite materials, providing better resistance to stresses and improved adhesion between fibers and matrix resins.
Implementation Method 1
sizing agent-coated reinforcing fibers including reinforcing fibers and a sizing agent containing a polyrotaxane and a glycidyl ether epoxy compound
Implementation Method 2
heat-treating to enhance adhesion and toughness
Data Source
AI summary
Sizing agent-coated reinforcing fibers include reinforcing fibers and a sizing agent containing a polyrotaxane, the reinforcing fibers being coated with the sizing agent. Provided are sizing agent-coated reinforcing fibers that provide a fiber-reinforced composite material with excellent mechanical properties, a method for producing the sizing agent-coated reinforcing fibers, a prepreg including the sizing agent-coated reinforcing fibers, and a fiber-reinforced composite material with excellent mechanical properties including the sizing agent-coated reinforcing fibers.