Multi-component copolymer rubber composition crack growth resistance
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Solution Overview
Problem
Conventional rubber compositions, such as those based on diene rubbers, lack sufficient crack growth resistance and wear resistance due to increased crystallinity, particularly when polymerizing conjugated diene and non-conjugated olefin compounds, which affects the durability of rubber articles like tires and conveyor belts.
Innovation Solution
A multi-component copolymer comprising conjugated diene units, non-conjugated olefin units, and aromatic vinyl units, with a peak top molecular weight of non-conjugated olefin parts between 500 and 40,000, is developed to enhance crack growth resistance and wear resistance, achieved through a one-pot synthesis process that includes specific monomers and catalysts to control the molecular structure and properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional diene based rubbers (BR, SBR) are used to achieve excellent wear resistance, then wear resistance is improved, but crack growth resistance deteriorates due to insufficient resistance against ozone and time degradation
Solution Approach 1:
The patent uses a composite rubber composition comprising multiple rubber components including polybutadiene rubber (BR), styrene-butadiene rubber (SBR), and epoxidized natural rubber (ENR) in specific weight ratios. This composite approach combines the wear resistance of diene rubbers with the crack growth resistance of ENR, achieving both required properties simultaneously. The synergistic effect of the composite materials resolves the contradiction between wear resistance and crack growth resistance.
2Reliability
If a copolymer of conjugated diene compound and non-conjugated olefin is used to improve crack growth resistance, then crack growth resistance is improved, but crystallinity increases which deteriorates wear resistance
Solution Approach 1:
The patent precisely controls the molecular weight parameters of the non-conjugated olefin parts, specifically setting the peak top molecular weight between 500 and 40,000. This parameter control optimizes the balance between crack growth resistance and wear resistance by preventing excessive crystallinity while maintaining sufficient molecular weight for mechanical properties. The controlled molecular weight distribution resolves the contradiction by finding the optimal parameter range.
Solution Approach 2:
The patent employs a multi-component copolymer system combining conjugated diene units, non-conjugated olefin units, and aromatic vinyl units. This composite polymer structure allows the non-conjugated olefin parts to provide crack growth resistance while the conjugated diene and aromatic vinyl components maintain wear resistance, preventing the deterioration that would result from high crystallinity alone.
3Reliability
If the peak top molecular weight of non-conjugated olefin parts is increased to improve crack growth resistance, then crack growth resistance is improved, but crystallinity increases which affects durability
Solution Approach 1:
The patent establishes a specific range for the peak top molecular weight of non-conjugated olefin parts (500-40,000) to optimize both crack growth resistance and durability. This parameter control prevents excessive crystallinity formation that would harm durability while maintaining sufficient molecular weight for crack growth resistance. The defined molecular weight range resolves the contradiction between these two durability aspects.
Data Source
AI summary
Provided is a multi-component copolymer having excellent crack growth resistance and wear resistance. The multi-component copolymer comprises conjugated diene units, non-conjugated olefin units and aromatic vinyl units, wherein: a peak top molecular weight of non-conjugated olefin parts linking only the non-conjugated olefin units is 500 or more and less than 40,000.