Recyclable Epoxy Composite via Degradable Curing Agent
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Solution Overview
Problem
Current fiber reinforced epoxy composites are not recyclable due to their irreversible cross-linked networks, making them difficult to recycle and rework, contributing to environmental waste and economic inefficiencies, particularly in industries like wind energy where material wastage is significant.
Innovation Solution
Development of a recyclable composite material using a cross-linked epoxy resin matrix derived from a degradable curing agent, which can be degraded using an acid and solvent under mild conditions, allowing for the separation and recovery of both the epoxy resin and reinforcement fibers through a filtration and precipitation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional cross-linked epoxy formulations are used, then mechanical strength and thermal stability are improved, but recyclability and reworkability deteriorate
Solution Approach 1:
The patent changes the chemical parameters of the curing agent from conventional polyamine to a degradable curing agent containing hydrolyzable groups (acetals, orthoesters, carbamates). This parameter change allows the cross-linked network to be degraded under mild conditions while maintaining the mechanical strength and thermal stability of the cured epoxy composite.
Solution Approach 2:
The patent creates a composite material system combining epoxy resin with a specially designed degradable curing agent. This composite approach allows the material to exhibit both the desirable mechanical properties of cross-linked epoxies and the recyclability enabled by the hydrolyzable cross-linking groups.
2Reliability
If irreversible cross-linking reactions are used, then post-cure adhesion and mechanical strength are improved, but reworkability and re-shaping capability deteriorate
Solution Approach 1:
The patent introduces dynamic reversibility to the cross-linking system. The cross-links are formed irreversibly under curing conditions to provide strength, but can be reversibly broken under mild hydrolytic conditions (acid or base catalysis) to enable reworkability. This dynamic behavior allows the material to switch between a rigid, strong state and a processable, recyclable state.
Solution Approach 2:
The patent changes the chemical nature of the cross-linking bonds from irreversible covalent bonds to dynamically reversible bonds that can be broken under specific conditions. The degradable curing agent creates cross-links that are stable during service but can be hydrolyzed under mild conditions, enabling reworkability while maintaining reliability during use.
3Loss of substance
If standard recycling practices are applied, then material recovery is attempted, but separation of epoxy matrix and fibers is difficult
Solution Approach 1:
The patent enables selective extraction of the epoxy matrix from the composite by degrading the cross-linked network through hydrolysis of the degradable curing agent. This extraction process releases the fibers from the matrix, allowing easy separation and recovery of both components. The matrix can be recovered as soluble degradation products while fibers are liberated for reuse.
4Loss of energy
If incineration is used for disposal, then energy recovery is achieved, but environmental harm and complete destruction of materials occur
Solution Approach 1:
The patent converts the previously harmful aspect of epoxy composites (their persistence and difficulty to recycle) into a beneficial property by designing a degradable curing agent. The cross-linked network that once made recycling impossible now enables controlled degradation under mild conditions, allowing complete material recovery without incineration and eliminating environmental harm while maintaining energy efficiency.
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
Enables the creation of fully recyclable fiber reinforced epoxy composites with high mass recovery of both components, exceeding 96%, under economically controlled and mild reaction conditions, addressing the environmental and economic challenges of waste management in industries relying on these materials.
Implementation Method 1
the cross-linked polymer comprises a cross-linking group derived from a curing agent... which can be degraded using an acid and solvent under mild conditions
Data Source
AI summary
The present invention relates to a reinforced composite and method for recycling the same. The reinforced composite comprises a reinforcement material in a cross-linked polymer matrix, wherein the cross-linked polymer comprises a cross-linking group derived from a curing agent represented by formula (I), Wherein R1 is hydrogen, alkyl, cycloalkyl, heterocycloalkyl, alkenyl, cycloalkenyl, aryl, heteroaryl, alkoxy alkyl or alkynyl; A is alkyl, alkenyl, alkenene, alkylene-hetero-alkylene, alkylene-heterocyclo-alkylene, alkylene, alkylene-oxy-alkylene, 1,4-alkyl substituted piperazine, carbonyl, thiocarbonyl; B is alkyl, alkenyl, alkenene, alkylene-hetero-alkylene, alkylene-heterocyclo-alkylene, alkylene, alkylene-oxy-alkylene, 1,4-alkyl substituted piperazine, carbonyl, thiocarbonyl; R2 is hydrogen, alkyl, aminoalkyl, alkyl-amino-alkyl, cycloalkyl, heterocycloalkyl, alkenyl, aryl, or heteroaryl; and R3 is hydrogen, alkyl, aminoalkyl, alkyl-amino-alkyl, cycloalkyl, heterocycloalkyl, alkenyl, aryl, or heteroaryl.