Urethane-Modified Rubber Composition to Minimize Payne Effect
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Solution Overview
Problem
Existing rubber compositions used in mechanical organs with dynamic functions, such as antivibratory supports and elastic joints, suffer from insufficient dynamic properties due to the Payne effect, which is exacerbated by the use of reinforcing loads like carbon black and silica.
Innovation Solution
A rubber composition is developed by reacting an elastomer with a reinforcing load, precursors of a polymer with urethane groups, and a chain elongator through thermomechanical mixing, followed by reticulation. This process achieves a fine and homogeneous dispersion of the urethane group polymer within the elastomer matrix, minimizing the Payne effect while preserving static properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If reinforcing fillers such as carbon black and silica are added to improve mechanical properties, then strength and rigidity are improved, but the Payne effect is generated causing non-linearity and stiffening at low temperatures
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating polyurethane segments with specific hard segment content (20-40 mass%) and using isocyanate index values of 80-120. These parameter adjustments modify the molecular structure to reduce filler-elastomer interactions while maintaining mechanical strength, thereby minimizing the Payne effect without sacrificing reinforcement benefits
Solution Approach 2:
The patent creates a composite material system combining polyurethane elastomer with reinforcing fillers (carbon black and/or silica) in a controlled manner. The composite structure leverages the phase-separated morphology where hard segments provide reinforcement compatibility and soft segments provide elasticity, achieving both strength improvement and Payne effect reduction through synergistic material combination
2Object-affected harmful factors
If the ratio of storage moduli G'0.5% / G'20% is reduced to minimize Payne effect, then dynamic properties are improved, but static properties such as secant moduli and rigidity may be compromised
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: polyol molecular weight (1000-5000 g/mol), isocyanate index (80-120), hard segment content (20-40 mass%), and filler loading (20-60 phr). This multi-parameter optimization enables the composition to achieve G'0.5% / G'20% ratio ≤ 1.50 while maintaining adequate static properties through the balanced molecular architecture and crosslinking density
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 resulting rubber composition exhibits significantly reduced Payne effect across a wide temperature range, as indicated by a G'0.5% / G'20% ratio that is closer to 1.00, thereby enhancing dynamic properties without compromising static properties.
Implementation Method 1
reacting an elastomer with a reinforcing load, precursors of a polymer with urethane groups, and a chain elongator through thermomechanical mixing
Implementation Method 2
polyurethanes (PU) are obtained by reaction between isocyanate (NCO) and alcohol (OH) functional groups to obtain the urethane (NHCOO) function
Implementation Method 3
followed by reticulation
Data Source
Figure 1~2
Figure 2a~5
Figure 3~4
AI summary
The invention relates to a rubber composition for a mechanical member with a dynamic function, a method for producing said composition, such a member, and the use of a polymer with urethane function. The composition is based on at least one elastomer and comprises a reinforcing filler and the aforementioned polymer dispersed in the elastomer, the composition comprising the product of an in-situ reaction involving thermomechanical mixing of the elastomer with the filler, precursors of the polymer and a chain extender. According to the invention, the composition has a ratio G' 0.5% / G' 20% of storage modulus G' relative to complex shear modulus G* that satisfies at least one of the conditions (i) to (v) below, G' 0.5% and G' 20% being measured according to ISO standard 4664 at respective dynamic strain amplitudes of 0.5% and 20% on double-shear test pieces subjected to shear strain of between 0.02% and 50% at the same frequency of 5 Hz and at the same temperature T: (i) G' 0.5% / G' 20% ≤ 1.15 for T = 100° C, (ii) G' 0.5% / G' 20% ≤ 1.40 for T = 65° C, (iii) G' 0.5% / G' 20% ≤ 1.50 for T = 25° C, (iv) G' 0.5% / G' 20% ≤ 1.60 for T = 0° C, (v) G' 0.5% / G' 20% ≤ 2.50 for T = -30° C.