Thermoreversible Urethane Adhesive via Diels-Alder Bonds
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Solution Overview
Problem
Traditional thermoreversible adhesives, particularly epoxy-based ones, face challenges due to the difficulty and expense of sourcing furfuryl glycidyl ether, a critical component, limiting their widespread adoption in aerospace applications where temporary bonding is necessary.
Innovation Solution
Development of thermoreversible urethane-based adhesive compositions using a reaction product of multifunctional maleimide species and furan-endcapped prepolymers, which incorporate Diels-Alder thermoreversible bonds, allowing for temperature-dependent adhesion properties similar to epoxy-based adhesives but with potentially more accessible and cost-effective materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epoxy-based thermoreversible adhesives are used, then temperature-dependent reversible bonding is achieved, but the cost and sourcing difficulty increase significantly
Solution Approach 1:
The patent replaces expensive epoxy-based thermoreversible adhesives with a more economical urethane-based adhesive system. The urethane adhesive achieves the same temporary bonding function at lower cost, making the adhesive itself a more accessible consumable material for temporary aircraft part securing applications.
Solution Approach 2:
The patent modifies the chemical composition parameters of the adhesive system by substituting epoxy chemistry with urethane chemistry while maintaining the thermoreversible functionality. This parameter change in the adhesive base chemistry enables cost reduction while preserving the essential temperature-dependent bonding behavior needed for temporary aerospace applications.
2Reliability
If furfuryl glycidyl ether is used in epoxy-based adhesives, then thermoreversible bonding is achieved, but the adhesive loses effectiveness at elevated temperatures
Solution Approach 1:
The patent changes the chemical parameters of the adhesive system by using urethane-based chemistry with different curing mechanisms compared to epoxy systems. This allows the adhesive to maintain its thermoreversible properties while potentially offering improved temperature stability, as the urethane linkage and its reaction products exhibit different thermal behavior than epoxy networks.
Solution Approach 2:
The patent creates a composite adhesive formulation combining urethane polymers with thermoreversible crosslinking chemistry. This composite material structure integrates the beneficial properties of urethane adhesives (temperature resistance, flexibility) with the reversible bonding mechanism, achieving both temporary bonding capability and improved temperature tolerance.
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 urethane-based adhesives exhibit maximum bond strength at lower temperatures and can be softened at elevated temperatures, offering a cost-effective and efficient solution for temporary bonding in aerospace applications, such as in aircraft manufacturing and maintenance, with improved sourcing and reduced material costs.
Implementation Method 1
the unique properties of thermoreversible adhesives make them particularly attractive when parts are only temporarily secured or installed on an aircraft... at certain lower temperatures, thermoreversible adhesives present their maximum bond strength, while at certain elevated temperatures, thermoreversible adhesives lose their adhesiveness
Data Source
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AI summary
A thermoreversible urethane-based adhesive composition comprising the reaction product of a multifunctional maleimide species and a furan-endcapped prepolymer, wherein the furan-endcapped prepolymer comprises the reaction product of a monofunctional furan species and an isocyanate-terminated prepolymer, wherein the isocyanate-terminated prepolymer comprises the reaction product of a diisocyanate and a difunctional oligomer that is terminated at a first end with an alpha moiety, wherein the alpha moiety is a hydroxyl group or an amine group, and that is terminated at a second end, opposed from the first end, with an omega moiety, wherein the omega moiety is a hydroxyl group or an amine group. (Fig. 1)