Radiation-Curable Polythioether Sealants for Fuel Resistance
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Solution Overview
Problem
Current radiation-curable polythioether sealants lack efficient low-temperature flexibility and fuel resistance, particularly in high-solvent and high-fuel environments, and require lengthy curing processes.
Innovation Solution
A radiation-curable composition comprising dithiol, diene, and polyyne or diyne monomers, along with a photoinitiator, which can include epoxy resin and nanoparticle fillers, that cures quickly under actinic light sources, such as UV or blue light, forming a polythioether polymer with low glass transition temperature and high fuel resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polythioether sealants are used, then basic sealing function is provided, but low-temperature flexibility and fuel resistance are insufficient
Solution Approach 1:
The patent employs a composite formulation combining polythioether polymers with specific diene monomers (divinyl ether or polyallyl compound) and polyene compounds. This composite material system achieves superior fuel resistance (volume swell <30% per SAE AS5127/1) and solvent resistance simultaneously, resolving the contradiction between these two performance requirements.
2Productivity
If conventional curing methods are used, then complete curing is achieved, but curing time is lengthy
Solution Approach 1:
The patent replaces conventional thermal or extended chemical curing mechanisms with radiation-curable technology. The composition includes photoinitiators that enable curing through exposure to actinic radiation (UV or visible light), dramatically reducing curing time from hours to minutes or seconds while achieving complete cure and maintaining low Tg (<-55°C).
Solution Approach 2:
The patent utilizes photoinitiators that absorb actinic radiation and convert it to chemical energy, initiating rapid polymerization. By changing the curing mechanism from thermal/chemical to photochemical, the curing speed parameter is dramatically improved while maintaining complete cure quality.
3Temperature
If polythioether polymers with low Tg are formulated, then low-temperature flexibility is improved, but fuel resistance deteriorates
Solution Approach 1:
The patent creates a composite polymer system where polythioether chains provide low Tg (<-55°C) for flexibility, while crosslinked networks formed by diene and polyene components provide fuel resistance. The synergistic combination maintains both low-temperature flexibility and high fuel resistance simultaneously.
Solution Approach 2:
The patent introduces crosslinked regions through diene and polyene components within the polythioether matrix. These localized crosslinked structures provide fuel resistance without significantly affecting the overall low Tg of the polymer, enabling both flexibility and fuel resistance.
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 enables rapid curing of polythioether polymers with low glass transition temperatures and high resistance to jet fuel, providing accelerated manufacturing and improved solvent and thermal resistance properties, suitable for aerospace applications.
Implementation Method 1
a radiation curable composition... comprising: a) at least one dithiol monomer; b) at least one diene monomer; c) at least one polyyne monomer comprising at least two ethyne groups; and d) at least one photoinitiator
Data Source
AI summary
Certain polythioether polymers are presented, as well as compositions which are radiation curable to polythioether polymers and seals and sealants comprising same. The compositions radiation curable to polythioether polymers include those comprising: a) at least one dithiol monomer; b) at least one diene monomer; c) at least one polyyne monomer comprising at least two ethyne groups; and d) at least one photoinitiator. In some embodiments, the polyyne monomer is a diyne monomer. In some embodiments, the composition also comprises at least one epoxy resin. In another aspect, the compositions radiation curable to polythioether polymers include those comprising: f) at least one thiol terminated polythioether polymer; g) at least one diyne monomer; and h) at least one photoinitiator. In some embodiments the thiol terminated polythioether polymer comprises pendent hydroxide groups.