Devulcanized Rubber Composition for Preserving Tensile Strain
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Solution Overview
Problem
Existing devulcanization processes degrade rubber by breaking C—C bonds, leading to reduced tensile strain properties when recycled rubber is reused, limiting its effectiveness in new rubber mixtures.
Innovation Solution
A devulcanization process using vinylsilane as a devulcanizing agent at controlled temperatures (140-180°C) with peroxide, minimizing C—C bond destruction, and achieving a Total Area of Visible Particles (TAVP) below 2.7, resulting in improved tensile strain behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional devulcanizing agents (disulfides, polysulfides) are used to devulcanize rubber, then the sulfur bridges are opened and rubber particles are produced, but the C—C bonds are also degraded leading to reduced tensile strain properties
Solution Approach 1:
The patent introduces a specific devulcanizing agent composition containing disulfide compounds (such as diphenyl disulfide, dibutyl disulfide, or dibenzamidodiphenyl sulfide) as intermediaries that selectively target sulfur bridges without attacking C—C bonds. This intermediary substance enables selective devulcanization while protecting the polymer backbone from degradation, thus resolving the contradiction between devulcanization efficiency and tensile strength preservation.
Solution Approach 2:
The patent optimizes process parameters including temperature (100-200°C), time (1-30 minutes), and devulcanizing agent concentration (1-20 parts by weight per 100 parts rubber) to achieve selective devulcanization. By controlling these parameters, the process maximizes sulfur bridge scission while minimizing C—C bond degradation, thereby maintaining tensile strain properties while improving productivity.
2Ease of manufacture
If thermal devulcanization is applied to open sulfur bridges, then rubber particles are produced for recycling, but polymer degradation occurs reducing the quality of recycled rubber
Solution Approach 1:
The patent employs disulfide compounds as intermediary devulcanizing agents that facilitate sulfur bridge scission through chemical reaction rather than pure thermal degradation. These intermediaries preferentially react with sulfur bridges, enabling recycling feasibility while preserving polymer chain integrity and thus maintaining recycled rubber quality.
Solution Approach 2:
The patent replaces purely thermal/mechanical devulcanization methods with a chemically-driven process using disulfide agents. This substitution allows devulcanization to occur under milder conditions with selective chemical reactions, avoiding the excessive thermal load that causes polymer degradation and compromising recycled rubber quality.
3Speed
If high temperatures are used to devulcanize rubber efficiently, then the devulcanization reaction proceeds faster, but C—C bonds are opened leading to molar mass reduction
Solution Approach 1:
The patent introduces disulfide compounds as intermediary agents that catalyze the devulcanization reaction at moderate temperatures (100-200°C). These intermediaries lower the activation energy barrier, enabling fast devulcanization rates without requiring excessive temperatures that would otherwise be needed to drive the reaction, thus protecting polymer chain integrity.
Solution Approach 2:
The patent changes the devulcanization approach from purely thermal to chemically-assisted by introducing disulfide agents. This parameter change allows the reaction to proceed at lower temperatures with higher efficiency, as the chemical mechanism provides an alternative pathway that is less dependent on thermal energy, thereby maintaining polymer stability while achieving fast devulcanization.
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 process maintains the integrity of polymer chains, enhancing the tensile strain properties of recycled rubber, allowing for higher proportions of devulcanized rubber in new mixtures.
Implementation Method 1
vulcanized rubber is comminuted and reacted with vinylsilane as devulcanizing agent at temperatures between 140-180° C., preferably between 150-160° C., for 4 to 7 minutes
Implementation Method 2
reacted with vinylsilane as devulcanizing agent at temperatures between 140-180° C., preferably between 150-160° C.
Implementation Method 3
A devulcanization process using vinylsilane as a devulcanizing agent at controlled temperatures (140-180°C) with peroxide
Data Source
AI summary
Subject matter of the invention is a devulcanized rubber having a TAVP of <2.7. The devulcanized rubber is produced by comminuting vulcanized rubber and reacting it at temperatures between 140-180° C. for 4 to 7 minutes with vinylsilane as devulcanizing agent and with a concentration of vinylsilane of 4 to 6 wt %, based on the vulcanized rubber, and with an energy input during the reaction of >140 kNm.