Branched Polyethylene Rubber Composition for Heat Aging
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Solution Overview
Problem
Ethylene-propylene rubber products face challenges in achieving both high mechanical strength and heat aging resistance, particularly in high-temperature applications, due to the inferior mechanical strength of peroxide-vulcanized ethylene-propylene rubber and the low mechanical strength of ethylene-propylene rubber when used in areas requiring higher mechanical properties.
Innovation Solution
A rubber composition incorporating branched polyethylene with a degree of branching of not less than 50 branches/1000 carbon atoms is used to enhance the mechanical properties and heat aging resistance, combined with EPM and EPDM, which acts as an intrinsic auxiliary crosslinking agent, reducing the need for additional crosslinking agents and improving processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If peroxide vulcanization is used to improve heat aging resistance of ethylene-propylene rubber, then heat aging resistance is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent uses a composite rubber matrix consisting of ethylene-propylene rubber (EPDM or EPM) combined with butadiene rubber (BR) or styrene-butadiene rubber (SBR). This composite structure allows the ethylene-propylene rubber to provide heat aging resistance while the butadiene or styrene-butadiene rubber components contribute to mechanical strength, thereby resolving the contradiction between heat aging resistance and mechanical strength in peroxide-vulcanized rubber products
Solution Approach 2:
The patent modifies the vulcanization system by using a combination of peroxide and sulfur vulcanization, or by optimizing the peroxide vulcanization process parameters. This allows achieving both heat aging resistance and adequate mechanical strength by controlling the vulcanization conditions and crosslinking density, rather than relying on peroxide vulcanization alone
2Reliability
If EPM is used to improve aging resistance, then aging resistance is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent creates a composite rubber system by combining EPM (which provides excellent aging resistance) with EPDM and butadiene rubber or styrene-butadiene rubber (which provide mechanical strength). This composite approach allows the final rubber product to achieve both improved aging resistance from the EPM component and adequate mechanical strength from the butadiene/SBR component
Solution Approach 2:
The patent applies different rubber types to different functional requirements within the same product. The EPM provides the aging resistance property where needed, while the butadiene or styrene-butadiene rubber provides mechanical strength in regions requiring higher strength, achieving local optimization of different properties within the rubber matrix
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 rubber composition maintains or exceeds heat aging resistance while significantly improving mechanical strength, addressing the limitations of ethylene-propylene rubber in high-temperature applications such as power transmission belts and rubber rollers.
Implementation Method 1
EPM and EPDM, which acts as an intrinsic auxiliary crosslinking agent, reducing the need for additional crosslinking agents
Implementation Method 2
EPM and EPDM, which acts as an intrinsic auxiliary crosslinking agent, reducing the need for additional crosslinking agents and improving processing efficiency
Data Source
AI summary
A rubber composition is disclosed and comprises a rubber matrix and essential components. The rubber matrix comprises, based on 100 parts by weight of the rubber matrix, A parts of a branched polyethylene, wherein 0<A<100 parts, and B parts of an EPM and an EPDM, wherein 0<B<100 parts. The essential components comprise, based on 100 parts by weight of the rubber matrix, 1.5-9 parts of a crosslinking agent, and 5-60 parts of a staple fiber. The branched polyethylene comprises an ethylene homopolymer having a degree of branching of from 60 to 105 branches/1000 carbon atoms, a weight average molecular weight of from 268,000 to 518,000, and a Mooney viscosity ML (1+4) at 125° C. of from 42 to 102.