EPDM Rubber Track Pad Composition Viscosity Elasticity Trade-off
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Solution Overview
Problem
The productivity of railroad rail track pads is hindered by the need to lower the viscosity of EPDM-based rubber compositions for injection molding, which compromises rubber elasticity.
Innovation Solution
A composition comprising an ethylene/α-olefin/non-conjugated polyene random copolymer, surface-treated clay, and a sulfur atom-containing silane coupling agent is used, optimizing viscosity and rubber elasticity for injection molding while maintaining crosslinked product properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the viscosity of EPDM-based rubber composition is lowered to make it suitable for injection molding, then the fluidity and processability are improved, but the rubber elasticity of the crosslinked product deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the rubber system by introducing a specific copolymer with controlled diene content (1-6 mole %) and using silane coupling agents with sulfur atoms. This compositional parameter change allows the uncrosslinked rubber to have low viscosity for injection molding while the crosslinked product maintains high elasticity through optimized crosslinking density
Solution Approach 2:
The invention creates a composite rubber system combining EPDM copolymer with silane coupling agents (such as bis(3-triethoxysilylpropyl) tetrasulfide). This composite approach allows the silane groups to participate in crosslinking reactions, forming a network structure that preserves rubber elasticity while the base copolymer provides low viscosity for injection molding
2Ease of manufacture
If the amount of filler blended is reduced to increase the fluidity of uncrosslinked rubber composition, then the injection molding processability is improved, but the tensile strength and mechanical properties deteriorate
Solution Approach 1:
The invention changes the filler composition parameters by using silane-treated clay instead of traditional carbon black or silica fillers. The silane treatment on clay surface provides reactive groups that participate in crosslinking, allowing reduced filler content while maintaining mechanical strength through chemical bonding rather than physical reinforcement alone
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 solution achieves low viscosity suitable for injection molding without compromising the rubber elasticity of the crosslinked and molded product, enhancing the productivity and performance of railroad rail track pads.
Implementation Method 1
clay (B) surface-treated with a silane coupling agent
Implementation Method 2
a sulfur atom-containing silane coupling agent (C)... a crosslinked product of the composition of the invention
Data Source
Figure 1
AI summary
A railroad rail track pad composition including a particular ethylene·α-olefin·non-conjugated polyene random copolymer (A), clay (B), and a sulfur atom-containing silane coupling agent (C) is used in order to lower the viscosity of a rubber composition that is a raw material for molding while suppressing lowering of the rubber elasticity of a crosslinked and molded product to be obtained. In addition, a molded product obtained by crosslinking the composition, particularly a molded product obtained by crosslinking and foam-molding the composition, is provided with rubber elasticity that is suitable as a railroad rail track pad.