Branched Polyethylene Rubber Composition Aging Resistance
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Solution Overview
Problem
Ethylene-propylene rubbers reinforced with silica face challenges in achieving better aging resistance, resilience, mechanical strength, and compression set resistance, particularly under peroxide-based vulcanization systems, while maintaining good crosslinking performances.
Innovation Solution
A rubber composition comprising a rubber matrix with branched polyethylene, silica, and specific crosslinking agents, where the branched polyethylene has a degree of branching of not less than 50 branches/1000 carbon atoms and a weight average molecular weight of at least 50,000, enhancing heat resistance, mechanical strength, and compression set resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If peroxide vulcanization is used to improve heat resistance, aging resistance, resilience and compression set resistance, then these properties are enhanced, but mechanical strength becomes weaker compared to sulfur vulcanized rubber
Solution Approach 1:
The patent changes the chemical structure parameter of the polyethylene by controlling the degree of branching (introducing tertiary carbon atoms) to enable peroxide crosslinking. This structural modification allows the rubber to achieve both good aging resistance and acceptable mechanical strength under peroxide vulcanization system.
Solution Approach 2:
The patent creates a composite vulcanization system by combining peroxide crosslinking agents with specific polyethylene rubber containing tertiary carbon atoms, along with silica filler and other additives. This composite formulation optimizes both aging resistance and mechanical strength properties.
2Reliability
If EPDM is used to improve aging resistance through the third monomer with double bond, then aging resistance is enhanced, but the mechanical strength decreases compared to EPM
Solution Approach 1:
The patent modifies the polyethylene structure by introducing a specific degree of branching (50-200 branches per 1000 carbon atoms) to create tertiary carbon atoms. This structural parameter change enables the saturated polyethylene to achieve crosslinking capability similar to unsaturated rubbers, while maintaining good mechanical strength and aging resistance.
3Reliability
If the degree of branching of ethylene/α-olefin copolymer is increased to improve aging resistance, then aging resistance is enhanced, 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). This optimized parameter level provides sufficient tertiary carbon atoms for crosslinking while avoiding excessive branching that would cause processing difficulties and high costs. The patent specifies that polyethylene with 0.5-2.0% tertiary carbon atoms meets this optimization.
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 achieves improved aging resistance, mechanical properties, and crosslinking performances, effectively addressing the limitations of ethylene-propylene rubbers in silica-reinforced products.
Implementation Method 1
Sulfur vulcanization and peroxide vulcanization are the two most commonly used vulcanization systems for ethylene-propylene rubber
Implementation Method 2
Ethylene-propylene rubber reinforced with silica often has the characteristics of good tear resistance, high adhesion strength
Data Source
AI summary
The present invention discloses a rubber composition, a processing method thereof, and rubber product reinforced with silica using the same. 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, and an EPM and an EPDM with a total content represented as B, in which 0≤B<100; and the essential components comprise 1-10 parts of a crosslinking agent and 15-80 parts of silica. The rubber composition can be used for producing high-voltage insulating sheath rubber, high-temperature resistant conveyor belt, waterproof coil, rubber particles for plastic track surface layer, rubber plug, rubber roller, inner tube, tire tread, tire sidewall, and inner rubber layer of air-conditioner hose.