Branched Polyethylene EPDM Rubber Composition for Aging Resistance
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Solution Overview
Problem
Ethylene-propylene rubber products face challenges with aging resistance and mechanical strength, particularly due to lower mechanical strength in peroxide-vulcanized ethylene-propylene rubber compared to sulfur-vulcanized versions, and difficulties in crosslinking of ethylene/1-octene copolymers which affect processing efficiency and product performance.
Innovation Solution
A rubber composition comprising a branched polyethylene with a degree of branching of at least 50 branches/1000 carbon atoms, combined with ethylene-propylene rubber, and incorporating specific crosslinking agents, reinforcing fillers, and plasticizers, which enhances aging resistance and crosslinking performance through peroxide crosslinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If peroxide crosslinking is used for ethylene-propylene rubber, then aging resistance is improved, but mechanical strength decreases
Solution Approach 1:
The patent combines peroxide crosslinking and sulfur crosslinking systems into a dual crosslinking system. The peroxide provides C-C crosslinks for aging resistance while sulfur provides additional crosslinks to maintain mechanical strength. This merging of two crosslinking mechanisms resolves the contradiction by allowing both aging resistance and mechanical strength to be achieved simultaneously.
Solution Approach 2:
The patent creates a composite crosslinked network structure where peroxide-crosslinked segments and sulfur-crosslinked segments coexist within the same rubber matrix. This composite structure allows the material to benefit from both crosslinking types: the peroxide crosslinks provide thermal and oxidative stability while the sulfur crosslinks contribute to tensile strength and elongation properties.
2Ease of manufacture
If EPDM is used instead of EPM, then processing is easier, but aging resistance decreases
Solution Approach 1:
The patent uses a heterogeneous blend where EPM domains provide superior aging resistance while EPDM domains provide easier processing characteristics. The local quality principle is applied by allowing different regions of the rubber compound to have different monomer compositions, with EPM-rich regions contributing to aging resistance and EPDM-rich regions contributing to processing ease.
Solution Approach 2:
The patent creates a composite rubber system blending EPM and EPDM in specific ratios. This composite approach allows the material to exhibit properties intermediate between the two homopolymers, achieving a balance between processing ease (from EPDM) and aging resistance (from EPM) that neither component could provide alone.
3Reliability
If degree of branching is increased in ethylene/α-olefin copolymer, then aging resistance is improved, but crosslinking difficulty increases
Solution Approach 1:
The patent introduces sulfur as an intermediary crosslinking agent that facilitates crosslinking in highly branched EPM structures. The sulfur system acts as a mediator that can effectively crosslink the tertiary carbon atoms in branched EPM, overcoming the steric hindrance that makes peroxide crosslinking difficult. This intermediary approach enables crosslinking of high-branching polymers that would otherwise be resistant to conventional peroxide crosslinking.
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 and mechanical strength, including better compression set resistance and tear strength, while maintaining efficient crosslinking performance, thereby addressing the limitations of existing ethylene-propylene rubber technologies.
Implementation Method 1
incorporating specific crosslinking agents, reinforcing fillers, and plasticizers, which enhances aging resistance and crosslinking performance through peroxide crosslinking
Data Source
AI summary
The present invention discloses a rubber composition, a processing method thereof, and an aging resistant rubber product using the rubber composition. 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 content represented as B, in which 0≤B<100 parts; and the essential components comprise 1.5-10 parts of a crosslinking agent, 30-200 parts of a reinforcing filler, and 5-250 parts of a plasticizer. The rubber composition provided by present invention has good processability and can be used for producing rubber products with high aging resistance and compression set resistance.