Modified Diene Elastomer Rubber Composition for Tire Stiffness and Elongation Balance
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Solution Overview
Problem
Existing rubber compositions for tires face a challenge in achieving a balance between low hysteresis losses, high stiffness under moderate deformation, and high elongation at break, as increasing rubber/filler bond density improves stiffness but decreases elongation at break, and vice versa.
Innovation Solution
A rubber composition is developed by modifying diene elastomers through post-polymerization grafting with a specific modifier comprising a nitrogen-containing dipole and associative group, which improves hysteresis properties by optimizing the balance between stiffness and elongation, using a method that involves thermomechanical kneading and chemical crosslinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rubber/filler bond density is increased, then stiffness under average deformation is improved, but elongation at break decreases
Solution Approach 1:
The invention changes the chemical parameters of the coupling agent by introducing a nitrogen-containing associative group in addition to the nitrogen-containing dipole. This parameter change modifies the interaction mechanism between polymer and filler, enabling both strong bonding (for stiffness) and maintained chain mobility (for elongation).
Solution Approach 2:
The invention creates a composite interaction system where the coupling agent contains two distinct functional groups (dipole and associative group) that work together. The dipole provides strong chemical bonding to filler surfaces while the associative group maintains polymer chain flexibility, achieving a composite effect that resolves the contradiction between stiffness and elongation.
2Loss of energy
If hysteresis losses are reduced through improved filler dispersion, then rolling resistance is improved, but the balance between stiffness and elongation becomes difficult to maintain
Solution Approach 1:
The coupling agent acts as an intermediary between the polymer and filler, with its dual functional groups enabling it to mediate both the bonding interaction (for stiffness) and the dispersion quality (for hysteresis reduction). This intermediary role allows simultaneous achievement of low hysteresis and maintained stiffness.
3Strength
If crosslinking density is increased, then stiffness under average deformation is improved, but elongation at break decreases
Solution Approach 1:
The invention changes the crosslinking parameters by incorporating nitrogen-containing associative groups that provide reversible or dynamic crosslinking in addition to permanent crosslinks. This allows the material to exhibit high stiffness under service conditions while maintaining elongation capability through the reversible nature of some crosslink interactions.
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 modified rubber composition exhibits improved mechanical properties, including high stiffness under moderate deformation and high elongation at break, enhancing the balance between rolling resistance and resistance to large deformations, making it suitable for tire manufacturing.
Implementation Method 1
modifying the diene elastomer by grafting with a specific modifier comprising at least one nitrogen-containing dipole and at least one nitrogen-containing associative group
Implementation Method 2
These rings present in the polymer are capable of reacting in turn with surface functions of the fillers (such as carbon black or silica) with which the polymers are mixed. This reaction leads to the formation of covalent bonds between the polymer modified with the coupling agent and the filler, owing to the opening of the oxazoline or thiazoline ring.
Implementation Method 3
incorporating the reinforcing filler into the diene elastomer thus grafted with the modifier, by thermomechanically kneading the combined mixture
Implementation Method 4
a chemical crosslinker and at least one particular modifier
Data Source
AI summary
The invention relates to a rubber composition based on at least one diene elastomer, a reinforcing filler, a chemical crosslinker and a modifier selected from compounds comprising at least one group Q, and at least one group A, which are joined to one another by at least one and preferably one spacer group Sp, wherein:Q comprises a dipole containing at least one and preferably one nitrogen atom,A comprises an associative group comprising at least one nitrogen atom,Sp is an atom or group of atoms forming a bond between Q and A.This composition has an improved balance between stiffness under moderate deformations/elongation at break and improved hysteresis properties and is therefore especially suited to the manufacture of tires for enhancing the trade off between rolling resistance and resistance to large deformations.