Copolyester-Stabilized Fiber Structure for Stronger Epoxy Composites
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Solution Overview
Problem
Existing fiber composite materials face challenges in achieving improved stability and adhesion between reinforcement fibers and polymer matrices, particularly in high-strength, low-weight applications such as aerospace and sports equipment, where corrosion resistance and handling simplicity are critical.
Innovation Solution
A statistical copolyester formed from terephthalic acid, isophthalic acid, butanediol, diethylene glycol, and triethylene glycol is used to stabilize and fix fibrous materials, enhancing the adhesion with a polymer matrix, particularly in epoxy resin composites, through specific synthesis and application methods like powder coating, paste coating, or sewing with copolyester threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fiber materials are used without stabilization agents, then the handling and processing is simpler, but the stability and adhesion between fibers and polymer matrix are insufficient
Solution Approach 1:
The patent introduces a thermoplastic copolyester as an intermediary substance between the reinforcement fibers and the thermosetting polymer matrix. This copolyester stabilization agent is applied to the fiber structure before embedding, creating an intermediate layer that enhances adhesion. The copolyester has specific compositional parameters (diol content: 10-40 mol%, trifunctional or higher alcohol content: 5-30 mol%) that enable it to bond effectively with both the fibers and the matrix, resolving the adhesion problem without requiring complex structural modifications to the fibers themselves.
Solution Approach 2:
The patent applies parameter changes by precisely controlling the compositional parameters of the thermoplastic copolyester stabilization agent. Specifically, the diol content is maintained at 10-40 mol% and trifunctional or higher alcohol content at 5-30 mol%, with the sum of these contents being 15-70 mol%. These parameter ranges optimize the copolyester's melting behavior, adhesion properties, and compatibility with both fibers and matrix, thereby improving reliability while keeping the stabilization process manageable.
2Strength
If fiber structures are stabilized with conventional agents, then handling is simplified, but the interlaminar shear strength and compression after impact are insufficient
Solution Approach 1:
The patent achieves enhanced strength properties through controlled parameter changes in the copolyester composition. The specific ranges for diol content (10-40 mol%), trifunctional or higher alcohol content (5-30 mol%), and their sum (15-70 mol%) create a stabilization agent that optimizes interlaminar shear strength and compression after impact. These parameter adjustments allow the agent to penetrate and bond effectively with the fiber structure, improving mechanical strength while maintaining ease of application through standard manufacturing processes.
Solution Approach 2:
The patent employs composite material principles by creating a tri-phase system consisting of reinforcement fibers, thermoplastic copolyester stabilization agent, and thermosetting polymer matrix. This composite approach leverages the complementary properties of each component: the fibers provide structural strength, the copolyester provides adhesion and stability, and the matrix provides structural continuity. The synergistic interaction between these components achieves high interlaminar shear strength and compression after impact values.
3Reliability
If thermoplastic fiber materials are used for fixing, then bonding properties are good, but the adhesion with thermosetting polymer matrix is insufficient
Solution Approach 1:
The patent resolves the adhesion issue by making precise parameter changes to the thermoplastic copolyester composition. The key parameters are: diol content (10-40 mol%), trifunctional or higher alcohol content (5-30 mol%), and their sum (15-70 mol%). These parameter ranges are optimized to ensure the copolyester can effectively bridge the interface between conventional reinforcement fibers and thermosetting polymer matrices. The specific composition enables the copolyester to exhibit compatible chemical and physical properties with both materials, achieving reliable adhesion despite the inherent incompatibility between thermoplastics and thermosetting matrices.
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 copolyester significantly improves the interlaminar shear strength and compression after impact of the fiber-resin composite materials, achieving adhesion values at least 3.7 times higher than conventional materials, with enhanced mechanical properties suitable for demanding industries like aerospace and sports equipment.
Implementation Method 1
The fibers in the form of filaments or meshes, woven fabrics or nonwovens have to be fixed and stabilized, which serves a simplified handling and allows the bonding of individual surface structures or of a plurality of these surface structures by the effect of temperature or pressure.
Data Source
AI summary
The invention relates to a fixed and/or stabilized fiber structure from a fibrous material as well as from an agent for its fixing and stabilizing. The agent for fixing and stabilizing is a statistical copolyester which is formed from the diacid components terephthalic acid and, optionally, isophthalic acid as well as the diol components butanediol, diethylene glycol and triethylene glycol. A method of manufacturing this fiber structure is also provided. The fiber structure is used as a reinforcement material for polymer matrices, in particular epoxy resins. A fiber composite material containing at least one thermosetting resin as well as the fiber structure in accordance with the invention is furthermore provided.