Functionalized Renewed Rubber for Low Hysteresis Tires
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Solution Overview
Problem
Current devulcanization techniques for recycled rubber are not commercially viable at high loadings, leading to compromised properties in rubber compounds, particularly in high-performance applications like vehicle tires, due to challenges such as short cure times, poor processability, and unacceptable cure characteristics.
Innovation Solution
A chemically functionalized renewed rubber composition is developed by blending micronized rubber powder with processing aids and functionalizing agents, then processed under high shear and low temperature, followed by addition of stabilizers to achieve properties similar to virgin rubber, allowing for use in high-performance applications without the limitations of conventional recycled rubber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional devulcanization techniques are used to recycle cured rubber, then the rubber can be reprocessed, but the properties of the new rubber article are diminished and it is unsuitable for high-performance applications
Solution Approach 1:
The patent applies parameter changes by carefully controlling devulcanization conditions (temperature, time, chemical agents) to selectively break sulfur crosslinks while preserving the rubber polymer structure. This allows the recycled rubber to maintain high molecular weight and elastic properties, making it suitable for high-performance applications like vehicle tires rather than just low-performance filler uses
Solution Approach 2:
The patent creates composite materials by combining devulcanized rubber with virgin rubber or other elastomers in specific ratios. This composite approach allows the recycled rubber to contribute to volume and basic elastomeric properties while virgin rubber provides the high-performance characteristics needed for critical applications, resolving the contradiction between recyclability and performance
2Productivity
If high loadings of devulcanized rubber are used in rubber compounds, then recycling efficiency increases, but processing challenges arise including short cure times, too little tack, too high viscosity, and poor mill handling
Solution Approach 1:
The patent uses parameter changes to modify the physical and chemical properties of devulcanized rubber through controlled devulcanization processes. By adjusting devulcanization intensity, the patent optimizes the balance between crosslink density and polymer chain integrity, resulting in material that maintains acceptable viscosity and tack at high loadings while remaining processable
Solution Approach 2:
The patent introduces intermediary substances such as processing aids, plasticizers, or coupling agents that mediate between the devulcanized rubber and the rubber compound matrix. These intermediaries improve compatibility, reduce viscosity, enhance tack, and facilitate mill handling, allowing high loadings of recycled rubber to be processed effectively without sacrificing ease of operation
3Loss of substance
If recycled rubber is used as a filler in rubber formulations, then waste rubber is utilized, but it does not bond to virgin rubber and compound processing becomes more viscous with higher loadings
Solution Approach 1:
The patent transforms recycled rubber from an inert filler state to an active elastomeric component through controlled devulcanization. By adjusting devulcanization parameters to partially reverse crosslinking while preserving polymer structure, the recycled rubber regains bonding capability and can chemically or physically interact with virgin rubber, creating a homogeneous compound rather than a filler-dispersed system
Solution Approach 2:
The patent employs intermediary agents such as silane coupling agents, zinc oxide, or other compatibilizers that facilitate bonding between devulcanized rubber particles and virgin rubber matrix. These intermediaries create chemical bridges or strong physical interactions at the interface, ensuring effective stress transfer and preventing the recycled rubber from acting as a non-bonding filler
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 formulation exhibits improved processability and cure characteristics, enabling its use in demanding applications like tires and conveyor belts with reduced hysteresis, leading to energy efficiency and cost-effectiveness.
Implementation Method 1
blending micronized rubber powder with a processing aid and functionalizing agent(s) to produce a blended mixture; processing the blended mixture under conditions of high shear and low temperature to produce a reacted mixture
Implementation Method 2
processing the blended mixture under conditions of high shear and low temperature to produce a reacted mixture
Implementation Method 3
adding a stabilizer to the reacted mixture to produce the renewed rubber composition
Data Source
AI summary
This invention relates to certain rubber formulations which exhibit a low level of hysteresis which are comprised of a chemically functionalized renewed rubber and virgin solution styrene-butadiene rubber. These rubber formulations are loaded with a reinforcing silica. The rubber formulations of this invention can be utilized in making rubber products such as, tires, tracks, and conveyor belts which will promote energy savings by virtue of their low hysteretic properties. The present invention more specifically discloses a rubber composition which is comprised of (1) a solution styrene-butadiene rubber; (2) a functionalized renewed rubber composition which is comprised of an elastomeric polymer and a stabilizer; wherein the rubber composition has a crosslink density which is within the range of 0.05 to 2.0×10−5 mole/g, and wherein the rubber composition has a solubility fraction of less than 90 percent; and (3) a reinforcing filler including reinforcing silica.