Elastomeric Sealant Low Temperature Sealing Force
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Solution Overview
Problem
Cured elastomeric sealants often exhibit a significant decrease in sealing force at temperatures below their glass transition temperature, making them unsuitable for applications in harsh ambient conditions where low temperature sealing is required.
Innovation Solution
A curable elastomeric sealant composition is developed, comprising a cross-linkable elastomeric oligomer, a monomer with a higher glass transition temperature, and a cross-linking agent, which upon curing retains a higher sealing force at temperatures above the glass transition temperature, ensuring effective sealing even at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cured elastomeric sealant is used, then it provides good sealing force at high temperatures, but it exhibits significant decrease in sealing force at temperatures below glass transition temperature
Solution Approach 1:
The patent modifies the chemical composition parameters of the elastomeric sealant by incorporating specific ratios of rubbery oligomers, glassy monomers, and rubbery monomers. This compositional parameter change adjusts the glass transition temperature and maintains molecular chain mobility at low temperatures, thereby preserving sealing force below the original glass transition temperature while maintaining high-temperature performance
Solution Approach 2:
The patent creates a composite elastomeric system combining three distinct components: crosslinkable rubbery oligomers (providing low-temperature flexibility), glassy monomers (providing high-temperature stability), and rubbery monomers (enhancing elasticity). This composite structure synergistically maintains sealing force across both high and low temperature ranges, resolving the contradiction between temperature-dependent sealing performance
2Temperature
If the glass transition temperature is lowered to improve low temperature sealing, then sealing force is maintained at lower temperatures, but the material loses elasticity and retractive stress
Solution Approach 1:
The patent applies local quality by assigning different functional roles to different components within the elastomeric system. The rubbery oligomer component specifically addresses low-temperature flexibility needs, while the glassy monomer component maintains high-temperature elasticity and retractive force. This functional differentiation allows the material to exhibit appropriate mechanical properties at different temperature ranges without compromising overall performance
Solution Approach 2:
By combining glassy monomers with rubbery components in specific ratios, the patent creates a composite where the glassy phase provides structural integrity and elasticity at high temperatures, while the rubbery phase ensures flexibility at low temperatures. This composite approach maintains elastic retractive force across the temperature range without requiring a uniform reduction in glass transition temperature
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 composition maintains a higher sealing force at temperatures above the glass transition temperature, enhancing the sealant's performance in applications where low temperature sealing is critical, such as in automotive and aerospace industries.
Implementation Method 1
The cross linkable sealant composition can be cured by exposure to conditions and for a time sufficient to at least partially cross-link and cure that composition
Implementation Method 2
The theory of rubber elasticity, derived from the second law of thermodynamics, states that the retractive stress of an elastomer arises as a result of the reduction in entropy upon extension
Data Source
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AI summary
Curable sealant compositions having low temperature sealing ability improved over convention curable sealing compositions. The composition is flowable and can be cured to a cross linked form to provide cured reaction products that exhibit elastomeric properties. The curable elastomeric sealant composition can include a cross linkable elastomeric oligomer; an initiator or cross-linking agent; a glassy monomer and/or a rubbery monomer; and optionally one or more of a catalyst; a filler; a coloring agent; an antioxidant; and an optional reaction modifier. The cross linkable elastomeric sealant composition can be prepared by reacting a cross linkable elastomeric oligomer having a Tg with at least one of a glassy monomer and a rubbery monomer. Cured reaction products of the composition have a single Tg and retain a higher sealing force at low temperatures (but above the cured product Tg) as compared to a curable composition made from the same cross linkable elastomeric oligomer but without the glassy and/or rubbery monomer.