Crosslinked Rubber Composition with Thermoplastic Nodules
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Solution Overview
Problem
Conventional rubber compositions reinforced with carbon black or silica exhibit high hysteretic losses due to filler-elastomer and filler-filler interactions, leading to unsatisfactory dynamic properties, particularly at low temperatures, resulting in stiffening and non-linear behavior under dynamic stresses.
Innovation Solution
A crosslinkable rubber composition is developed by thermomechanically processing a mixture of elastomer and thermoplastic polymer in the molten state, where the thermoplastic polymer is dispersed as nanometric or micrometric nodules, and crosslinked using a specific crosslinking system, such as sulfur or peroxide, to achieve improved mechanical properties and reduced hysteretic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon black or silica fillers are added to reinforce elastomers, then mechanical properties are improved, but hysteretic losses increase and dynamic properties deteriorate
Solution Approach 1:
The invention changes the fundamental parameter of reinforcement mechanism from filler-based (carbon black/silica) to polymer-based (thermoplastic domains). This parameter change eliminates the filler-elastomer interactions that cause hysteretic losses while maintaining reinforcement through thermoplastic elastomer phase separation and domain formation, resolving the contradiction between strength improvement and energy loss reduction.
Solution Approach 2:
The invention creates a composite material system consisting of crosslinked elastomer matrix with dispersed thermoplastic polymer domains. This composite structure provides reinforcement through the thermoplastic phase (analogous to filler function) while avoiding the harmful interactions associated with traditional mineral fillers, thus improving mechanical properties without increasing hysteretic losses.
2Strength
If reinforcing fillers are added to rubber compositions, then mechanical strength is improved, but dynamic behavior becomes non-linear and stiffening occurs at low temperatures
Solution Approach 1:
The invention changes the reinforcement approach from using inorganic fillers that create rigid networks to using thermoplastic polymer domains that maintain flexibility. This parameter change preserves the linear dynamic behavior and prevents low-temperature stiffening while still providing mechanical strength through the thermoplastic elastomer phase separation mechanism.
Solution Approach 2:
The invention replaces permanent, rigid filler structures with thermoplastic domains that can reversibly soften and adapt to thermal and mechanical conditions. These thermoplastic domains act as dynamic, adaptable reinforcement elements that maintain linearity across temperature ranges, unlike fixed filler networks that cause stiffening.
3Strength
If traditional filler reinforcement is used, then mechanical properties are enhanced, but the composition requires complex mixing processes at controlled temperatures
Solution Approach 1:
The invention utilizes the melting phase transition of thermoplastic polymers during mixing to achieve homogeneous dispersion. By heating above the thermoplastic melting point, the polymer becomes molten and easily disperses in the elastomer matrix, then solidifies upon cooling to form the reinforcing domains. This phase transition-based approach simplifies processing compared to traditional filler mixing that requires precise temperature control to prevent premature vulcanization.
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 crosslinked rubber composition exhibits improved mechanical properties, reduced density, and minimized hysteretic losses, maintaining performance under static and dynamic stresses, as well as resistance to thermo-oxidative aging and UV radiation, while being free or low in carbon black and silica.
Implementation Method 1
thermomechanically processing a mixture of elastomer and thermoplastic polymer in the molten state
Implementation Method 2
the thermoplastic polymer is dispersed as nanometric or micrometric nodules
Implementation Method 3
crosslinked using a specific crosslinking system, such as sulfur or peroxide
Implementation Method 4
these filler-elastomer and filler-filler interactions generate an undesirable phenomenon linked to hysteretic losses
Implementation Method 5
G' characterizing the rigidity or viscoelastic behavior of the composition
Data Source
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AI summary
The invention relates particularly to a crosslinkable rubber composition and a process for preparing it. The composition is based on an elastomer, comprises a crosslinking system and a thermoplastic phase which at melting temperature Tm is dispersed as nodules, and comprises the product: a) of a reaction in the melt by thermomechanical work of the elastomer and other ingredients apart from the system, then b) of mechanical work with prior addition of the system. According to the invention: - the size of the nodules is between 10 nm and 10 pm, - a) comprises heating the mixture to a temperature > Tm, which is maintained for a hold time, and - the system comprises sulfur when the elastomer is unsaturated and the said phase comprises saturated chains, and a peroxide when the elastomer is saturated.