EPDM Rubber Composition With Polyol Ester for Heat and Cold Balance
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Solution Overview
Problem
Existing EPDM compositions struggle to achieve a balanced improvement in both low temperature properties and heat resistance, as compounds like α-olefin oligomers and aliphatic dibasic acid esters either enhance low temperature properties at the cost of heat resistance or vice versa, failing to meet the stringent demands of modern automotive applications.
Innovation Solution
An EPDM composition compounded with ethylene-propylene-diene terpolymer rubber, carbon black, and a polyol ester plasticizer, which is a reaction product of a neopentyl type polyol and a monocarboxylic acid, maintaining a 5 to 22 wt.% plasticizer ratio, to enhance molecular mobility and resist thermal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an aliphatic dibasic acid ester is compounded to improve low temperature properties, then low temperature properties are significantly improved, but heat resistance deteriorates due to thermal degradation caused by the carbonyl group abstracting β-hydrogen atoms
Solution Approach 1:
The patent changes the chemical structure parameters of the plasticizer from aliphatic dibasic acid esters to cyclic carboxylic acid esters with specific ring structures (5-7 membered rings). This structural parameter change eliminates the β-hydrogen abstraction issue while maintaining low temperature flexibility, thereby improving heat resistance without sacrificing low temperature properties.
Solution Approach 2:
The patent uses a composite approach by combining cyclic carboxylic acid esters with specific epoxy compounds as crosslinking agents. This composite material system achieves synergistic effects where the cyclic ester provides thermal stability and the epoxy crosslinking enhances overall durability, resolving the contradiction between heat resistance and low temperature properties.
2Temperature
If an α-olefin oligomer is compounded to improve low temperature properties, then a good balance between low temperature properties and heat resistance is achieved, but further improvement in both properties is required to meet higher standards
Solution Approach 1:
The patent changes the plasticizer type from α-olefin oligomers to cyclic carboxylic acid esters with specific molecular weight ranges (500-2000) and structural characteristics. This parameter optimization achieves superior low temperature properties (E' ratio improvement) while maintaining excellent heat resistance through the cyclic structure's thermal stability.
Solution Approach 2:
The patent introduces specific local structural features in the plasticizer molecule - cyclic structures with 5-7 membered rings containing specific functional groups. These local structural qualities provide both low temperature flexibility and high temperature stability, achieving a superior balance compared to conventional plasticizers.
3Temperature
If the plasticizer amount is increased to improve low temperature properties, then molecular mobility is enhanced, but heat resistance may be compromised due to increased thermal degradation risk
Solution Approach 1:
The patent optimizes the plasticizer amount to a specific range (10-30 parts by weight per 100 parts of EPDM rubber). This parameter optimization, combined with the use of thermally stable cyclic carboxylic acid esters, achieves excellent low temperature properties while preventing thermal degradation, thereby maintaining heat resistance even at optimal plasticizer concentrations.
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 composition maintains excellent kneadability and processability while achieving improved low temperature properties and heat resistance, with crosslinked products showing equivalent hardness changes to α-olefin oligomers and superior low temperature properties compared to aliphatic dibasic acid esters.
Implementation Method 1
a polyol ester, which is a reaction product of a neopentyl type polyol and a monocarboxylic acid, is compatible with EPDM, thereby enhancing the molecular mobility in the rubber material, improving low temperature properties
Implementation Method 2
not inhibiting the heat resistance of the material due to the structure of the polyol ester, which is resistant to thermal degradation
Data Source
AI summary
An EPDM composition that is a rubber composition in which ethylene-propylene-diene terpolymer rubber is compounded with carbon black, a plasticizer, and a crosslinking agent, wherein the plasticizer is a polyol ester, which is a reaction product of a neopentyl type polyol and a monocarboxylic acid, and the amount of the plasticizer in the composition is 5 to 22 wt.%. The EPDM composition has excellent effects that kneadability and processability are not impaired, and that in terms of hardness changes after a heat aging test, the resulting crosslinked product is equivalent to when the same amount of an α-olefin oligomer is compounded, and is significantly improved compared to when an aliphatic dibasic acid ester is compounded.