Branched Polyethylene Rubber Composite for Foamed Seal Strips
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing foamed rubber materials face challenges in achieving both good heat and aging resistance while maintaining mechanical properties, particularly with the peroxide vulcanization system, which compromises tensile strength and tear strength.
Innovation Solution
A rubber composition incorporating branched polyethylene with a degree of branching of not less than 50 branches/1000 carbon atoms, combined with EPM and EPDM, and utilizing a peroxide-based crosslinking system, along with a low-temperature radiation pre-vulcanization process, to enhance crosslinking efficiency and foaming performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a peroxide vulcanization system is used to achieve excellent heat and aging resistance, then heat resistance and aging resistance are improved, but tensile strength and tear strength are lowered
Solution Approach 1:
The patent combines peroxide vulcanization system with sulfur vulcanization system to create a hybrid crosslinking network. The peroxide provides C-C crosslinks for heat and aging resistance, while sulfur contributes polysulfide bonds for enhanced tensile and tear strength, thus merging the advantages of both systems.
Solution Approach 2:
The invention uses a composite crosslinking structure where peroxide-crosslinked polyethylene forms the base network and sulfur-crosslinked ethylene-propylene rubber segments are integrated into it. This composite material approach allows simultaneous achievement of thermal stability and mechanical strength.
2Reliability
If EPM is used to improve aging resistance, then aging resistance is improved, but mechanical strength is lowered
Solution Approach 1:
The patent creates a composite rubber composition where EPM segments provide aging resistance through their saturated structure, while EPDM segments contribute to mechanical strength. The peroxide vulcanization system crosslinks both segments into a unified network that exhibits both properties.
Solution Approach 2:
Different regions of the rubber molecule are optimized for different functions: EPM segments with higher saturation are positioned to provide aging resistance, while EPDM segments with pendant groups are optimized for crosslinking and mechanical strength, creating local quality differentiation within the material.
3Reliability
If degree of branching is increased to improve aging resistance, then aging resistance is improved, but process difficulty and raw material cost increase
Solution Approach 1:
The patent optimizes the degree of branching parameter to a specific range (50-200 branches per 1000 carbon atoms) that balances aging resistance with processability. This parameter optimization ensures sufficient tertiary carbon atoms for crosslinking while avoiding excessive branching that would complicate processing and increase costs.
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 achieves improved aging resistance, mechanical strength, and compression set resistance, while allowing for effective pre-crosslinking control and reduced radiation processing energy, resulting in a foamed rubber product with enhanced performance and productivity.
Implementation Method 1
When a peroxide vulcanization system is used, the foamed material is formed to have single carbon-carbon crosslink bonds
Implementation Method 2
When a sulfur vulcanization system is used, the foamed material is formed to have a crosslinked structure mainly composed of polysulfide bonds
Implementation Method 3
low-temperature radiation pre-vulcanization process, to enhance crosslinking efficiency
Data Source
AI summary
The present invention discloses a rubber composition, a processing method thereof, and a foamed rubber product produced by the rubber composition and a production method thereof. The rubber composition comprises a rubber matrix and essential components, wherein, based on 100 parts by weight of the rubber matrix, the rubber matrix comprises a branched polyethylene with a content represented as A, in which 0<A≤100 parts; and an EPM and an EPDM with a total content represented as B, in which 0≤B<100 parts, and the essential components comprises 0.5-10 parts of a crosslinking agent, and 1.5-25 parts of a foaming agent. The rubber composition is useful in the production of sponge seal strip, foamed rubber compound of high expansion ratio, shock absorbing foamed rubber sheet, light-colored high-strength foamed sheet, foam-solid composite seal strip, and solid cycle tires internally filled with foamed elastomer. The branched polyethylene replaces a part or all of the ethylene-propylene rubber in the foaming rubber composition, which can increase the melt strength, the foamability and particularly the pre-foamability of the rubber composition, and make the rubber product has a lower compression set.