EPDM Rubber Composition with ENB-VNB Diene for High Loading
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Solution Overview
Problem
Highly filled EPDM rubber vulcanizates face challenges in achieving both good mechanical properties and elasticity, particularly in automotive applications, where high filler and plasticizer levels lead to deteriorated tensile strength, elongation at break, tear strength, and increased compression sets at various temperatures.
Innovation Solution
A rubber composition comprising an ethylene-α-olefin-non-conjugated-diene copolymer with specific Mooney viscosity, ethylene content, and molecular weight, combined with a controlled amount of extender oil, which allows for high total loading while maintaining excellent mechanical and elastic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the total loading of EPDM compound is increased with very high levels of filler(s) and plasticizer(s), then the cost is reduced and processing is improved, but the mechanical properties deteriorate (tensile strength, elongation at break, and tear strength decrease)
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ethylene content (50-65 wt%) and diene content (3-8 wt%) of the EPDM copolymer, along with specifying Mooney viscosity ranges (70-120 MU at 100°C). These parameter optimizations enable the rubber compound to maintain excellent mechanical properties even at very high total loadings of 500-700 phr, resolving the contradiction between high filler loading and mechanical strength.
2Quantity of substance
If the total loading of EPDM compound is increased with very high levels of filler(s) and plasticizer(s), then the cost is reduced, but the elastic properties deteriorate (compression sets increase at various temperatures)
Solution Approach 1:
The patent optimizes specific parameters including Mooney viscosity (70-120 MU at 100°C) and molecular weight distribution (Mw/Mn = 2.0-5.0) of the EPDM copolymer. These parameter changes enable the compound to maintain outstanding elastic properties with compression sets of less than 30% at 70°C and less than 50% at 100°C, even at very high total loadings of 500-700 phr.
3Strength
If high molecular weight EPDM rubber is used to improve mechanical properties, then the viscosity increases resulting in low extrusion and moulding productivity
Solution Approach 1:
The patent applies parameter changes by controlling the Mooney viscosity to specific ranges (70-120 MU at 100°C, and alternatively 40-80 MU at 100°C) while maintaining high molecular weight (Mw ≥ 200,000 g/mol). This optimization balances mechanical strength with processing efficiency, achieving both high tensile strength (>15 MPa) and good extrusion/moulding productivity.
Data Source
Figure 1
AI summary
A rubber composition, comprising i) an ethylene-α-olefin-non-conjugated-diene copolymer having - a Mooney viscosity ML (1 +8) at 150 °C ≥ 85 MU and - an ethylene content ≤ 63 wt.% - the diene content is 4 to 8 % by weight of the ethylene-a-olefin-non-conjugated- diene copolymer i), - the non-conjugated diene is a combination of 5-ethylidene-2-norbornene (ENB) and 5-vinylnorbornene (VNB), - the ethylene-α-olefin-non-conjugated-diene copolymer i) has an amount of VNB between 0.05 and 1 wt.%, and has a Mw of at least 400,000 g/mol and, ii) an extender oil of 10 to 40 phr based on the copolymer i) with the sum of the EPDM copolymer i) and the oil ii) amounting to at least 95 wt.% of the composition.