Diresorcinol Sulfide Vulcanization for Rubber Reversion Resistance
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Solution Overview
Problem
Rubber vulcanization processes, particularly those using sulfur, often result in rubber reversion, a softening or weakening of the crosslinked rubber network, which is exacerbated by overcuring or excessive heat, and is more common in natural rubber systems, leading to performance issues in tires and other rubber products.
Innovation Solution
Incorporating diresorcinol sulfide into the vulcanization process, either alongside a sulfur curative or as the exclusive sulfur source, to reduce rubber reversion while maintaining desirable mechanical properties, by reacting sulfur with resorcinol at specific temperatures to form diresorcinol sulfide, which is then used in the rubber composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If sulfur curative is used for vulcanization, then crosslinking and durability are improved, but rubber reversion occurs leading to softening and weakening
Solution Approach 1:
Diresorcinol sulfide acts as an intermediary compound between sulfur and rubber. It is formed by reacting sulfur with resorcinol, and then this intermediate compound crosslinks with rubber molecules. This two-step process prevents direct excessive sulfur crosslinking that causes reversion, while still achieving durable vulcanization.
Solution Approach 2:
The invention changes the chemical form and reactivity parameters of sulfur by converting it to diresorcinol sulfide. This transformation controls the rate and extent of crosslinking, preventing overcuring and the subsequent reversion that occurs with direct sulfur vulcanization, especially under excessive heat or extended curing times.
2Manufacturing precision
If overcuring or excessive heat is applied during vulcanization, then curing completeness is improved, but rubber reversion increases
Solution Approach 1:
Diresorcinol sulfide is prepared in advance through a separate reaction between sulfur and resorcinol. This preliminary action controls the sulfur reactivity before it contacts the rubber, allowing complete curing at lower temperatures and preventing the need for excessive heat that would cause reversion.
3Productivity
If accelerators that release amines are used, then vulcanization speed is improved, but rubber reversion is exacerbated
Solution Approach 1:
Diresorcinol sulfide serves as an intermediary that decouples the acceleration function from amine release. It provides controlled crosslinking without the harmful amine byproducts, maintaining vulcanization efficiency while eliminating the reversion problem associated with amine-releasing accelerators.
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 use of diresorcinol sulfide in vulcanizable compositions significantly reduces rubber reversion, as evidenced by minimal torque decrease during curing and preserved mechanical properties, such as tensile strength and elongation, compared to control samples without diresorcinol sulfide.
Implementation Method 1
reacting sulfur with resorcinol at a temperature of from about 150° C. to about 200° C. to form a reaction mixture; and heating the reaction mixture to a temperature of from about 205° C. to about 250° C.
Data Source
AI summary
A method for preparing diresorcinol sulfide includes reacting sulfur with resorcinol, wherein the sulfur is S8. Another method for preparing diresorcinol sulfide includes reacting sulfur with resorcinol, in the presence of an alkali or acidic catalyst. A further method for preparing diresorcinol sulfide includes reacting sulfur with resorcinol, at a temperature of from about 150° C. to about 200° C. to form a reaction mixture, wherein the sulfur is S8; and heating the reaction mixture to a temperature of from about 205° C. to 250° C. A particular method for preparing diresorcinol sulfide includes reacting S8 with resorcinol, in the presence of an alkali or acidic catalyst, at a temperature of from about 150° C. to about 200° C. to form a reaction mixture; and heating the reaction mixture to a temperature of from about 205° C. to 250° C.