Sulfur-Free Elastomer Blend for Fuel Cell Sealing
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Solution Overview
Problem
Conventional crosslinking methods in fuel cell sealing materials, such as sulfur or peroxide crosslinking, result in high volatile components and compromised chemical properties due to poor mixing and insufficient covulcanization, while silicone-based materials exhibit poor compression set in humid environments and high temperatures.
Innovation Solution
A sulfur-free, low-emission elastomer blend comprising two chemically different rubbers that can be crosslinked via hydrosilylation, with a hydrosiloxane crosslinker and a hydrosilylation catalyst system, and minimal silicone content, optimized for improved mechanical properties and resistance to temperature and media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfur or peroxide crosslinking is used, then crosslinking efficiency is improved, but volatile components increase and chemical properties deteriorate
Solution Approach 1:
The patent changes the crosslinking chemistry from sulfur/peroxide-based to silane-based crosslinking. This parameter change in the chemical reaction mechanism eliminates the formation of volatile by-products while maintaining effective crosslinking, directly resolving the contradiction between crosslinking efficiency and harmful emissions.
Solution Approach 2:
The patent converts the previously harmful sulfur and peroxide crosslinking methods into a beneficial silane crosslinking system. By adopting silane chemistry, the harmful volatile components are eliminated entirely, transforming the crosslinking process into a clean, environmentally friendly method that maintains high crosslinking efficiency without generating harmful emissions.
2Reliability
If silicone-based materials are used, then sealing performance is improved, but compression set deteriorates in humid environments and high temperatures
Solution Approach 1:
The patent creates a composite elastomer system combining silane-crosslinked rubber with other compatible elastomers. This composite approach maintains the excellent sealing performance of silicone-like materials while the silane crosslinking network provides superior dimensional stability and reduced compression set in high-temperature humid environments, resolving the contradiction between sealing performance and compression set resistance.
3Device complexity
If single rubber compounds are used, then material simplicity is improved, but mechanical properties deteriorate
Solution Approach 1:
The patent employs composite elastomer formulations combining silane-crosslinked rubber with other elastomers. This composite approach achieves synergistic effects where the blend demonstrates superior mechanical properties including enhanced tensile strength, elongation, and compression set resistance compared to single rubber compounds, while maintaining reasonable formulation complexity through the use of compatible polymer systems.
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 elastomer blend exhibits significantly lower gas permeability, improved compression set, tensile strength, and elongation at break, with enhanced resistance to high temperatures and humid environments, outperforming individual compounds and conventional blends.
Implementation Method 1
a rubber (A) with at least two functional groups that can be crosslinked via hydrosilylation, at least one other rubber (B) with at least two functional groups that can be crosslinked via hydrosilylation, the rubber (B) chemically different from rubber (A), as crosslinker (C) a hydrosiloxane or hydrosiloxane derivative or a mixture of several hydrosiloxanes or derivatives which have on average at least two SiH groups per molecule, a hydrosilylation catalyst system (D)
Data Source
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AI summary
The invention relates to the use of a sulphur-free and low-emission elastomer blend which has properties of various rubbers, and the mechanical properties thereof are improved, in particular, in relation to the permanent set (DVR), elongation at rupture, tensile strength and/or gas permeability (permeation) in relation to the individual compounds, and it also has an improved temperature resistance and an improved resistance to media. Said elastomer blend comprises a rubber (A) having at least two functional groups which can be cross-linked by hydrosilylation, at least one other rubber (B) comprising at least two functional groups which can be cross-linked by hydrosilylation, and can be used as a material in the insertion area of the fuel cells, in particular, the direct-methanol-fuel cells. The rubber (B) is chemically different from the rubber (A), a cross-linking agent (C) comprises a hydrosiloxane or hydrosiloxane derivative or a mixture of several hydrosiloxanes or derivatives, which comprise at least two SiH groups per molecule in the centre, a hydrosilylation catalyst system (D) and at least one filling material (E).