Polythioether Sealant Low-Temperature Stability
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Solution Overview
Problem
Polythioether polymer-based sealants face challenges with spoilage and performance loss due to low temperature storage, particularly in aerospace applications where they require high flexibility, resistance to jet fuel, and low glass transition temperature.
Innovation Solution
Development of polythioether polymers and stabilizing diene monomers that form copolymers with polythiols and polyepoxides, incorporating specific divalent groups in the polymer backbone, which are synthesized using specific reaction methods to enhance stability and performance, including the use of stabilizing diene monomers and crosslinking agents like polyepoxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polythioether polymer-based sealants are stored at low temperatures, then flexibility and jet fuel resistance are improved, but spoilage and performance loss occur
Solution Approach 1:
The patent applies preliminary action by incorporating stabilizing diene monomers (specifically 4,5-epoxy-1,2,3-butadienyl monomers) into the polymer structure before storage. These monomers pre-establish protective functionality that prevents spoilage during low-temperature storage, eliminating the need for post-storage stabilization measures.
Solution Approach 2:
The patent creates composite materials by combining polythioether polymers with stabilizing diene monomers containing epoxy groups. This composite structure integrates the flexibility and jet fuel resistance of polythioether with the stabilizing properties of epoxy-functionalized dienes, achieving both low-temperature performance and storage stability simultaneously.
2Stability of the object's composition
If stabilizing diene monomers are incorporated into polythioether polymers, then storage stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges two functions into a single monomer component: the diene monomer simultaneously provides stabilization during storage and contributes to the polymer's flexibility and jet fuel resistance. This consolidation eliminates the need for separate stabilizer additives, simplifying the overall formulation despite the specialized nature of the monomer.
3Reliability
If glass transition temperature is reduced below -55°C, then flexibility at low temperature is improved, but polymer stability decreases
Solution Approach 1:
The patent applies local quality by introducing epoxy-functionalized diene monomers at specific locations within the polymer chain. These localized epoxy groups provide stability precisely where needed (preventing oxidation and degradation) while the overall polymer maintains its low glass transition temperature and flexibility through the polythioether backbone structure.
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 resulting sealants exhibit reduced risk of spoilage, high flexibility, and improved resistance to jet fuel at low temperatures, maintaining performance and preventing solids formation during storage, with a glass transition temperature typically below -55°C.
Implementation Method 1
a polythioether polymer which is a copolymer of one or more compounds according to the present disclosure (stabilizing diene monomers) with one or more polythiols and one or more polyepoxides
Data Source
AI summary
Polythioether polymers, sealants containing polythioether polymers, and compounds useful as stabilizing monomers in the manufacture of polythioether polymers are provided. In many embodiments the polymers and sealants demonstrate reduced risk of spoilage that may be caused by low temperature storage of the polymer or uncured sealant. Compounds useful as stabilizing monomers include compounds according to formula I: CH2=CR1-CHR2-S-R3-S-CHR4-CR5=CH2 [I] wherein R1, R2, R4 and R5 are independently selected from -H, -CH3 or -C2H5, and wherein R3 is selected from divalent groups comprising 2-12 carbon atoms, 0-5 ether oxygen atoms and 0-5 thioether sulfur atoms, which may be straight, branched or cyclic.