Polysulfide Crosslinking Agent for Thermal Stability
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Solution Overview
Problem
Vulcanization with elemental sulfur leads to limited strength in vulcanizates due to thermal aging, causing reversion phenomena that adversely affect mechanical properties, particularly at high temperatures, constraining process conditions and elongation modulus in unsaturated polymers and diene elastomers.
Innovation Solution
A polysulfurized compound of formula (I) is used as a crosslinking agent, capable of forming stable sulfur bridges between polymer chains, acting as both a crosslinking agent and anti-reversion agent, allowing high-temperature crosslinking while maintaining or improving elongation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If elemental sulfur is used as vulcanizing agent, then crosslinking of polymer chains is achieved, but thermal aging causes reversion phenomenon that deteriorates mechanical properties
Solution Approach 1:
The patent changes the chemical structure of the vulcanizing agent from elemental sulfur to polysulfurized compounds with specific molecular structures (formula I), which fundamentally alters the crosslinking mechanism and eliminates thermal aging-induced reversion while maintaining effective crosslinking
Solution Approach 2:
The patent introduces a composite crosslinking system combining polysulfurized compounds (formula I) with traditional vulcanizing agents or accelerators, creating a synergistic effect that provides both crosslinking capability and thermal stability without the reversion phenomenon
2Productivity
If high crosslinking temperature is used to save time, then productivity increases, but reversion phenomenon worsens and mechanical properties deteriorate
Solution Approach 1:
The patent changes the chemical nature of the crosslinking agent to polysulfurized compounds that enable effective crosslinking at high temperatures without promoting reversion, thus allowing shortened processing times while maintaining mechanical integrity
Solution Approach 2:
The patent converts the harmful effect of high temperature (which normally accelerates reversion) into a beneficial condition by using polysulfurized compounds that are specifically designed to form stable crosslinks at elevated temperatures, turning the thermal stress into an advantage for faster processing
3Stability of the object's composition
If conventional crosslinking agents are used, then crosslinking is achieved, but elongation properties are limited and reversion occurs
Solution Approach 1:
The patent modifies the molecular structure of crosslinking agents to polysulfurized compounds with specific ring sizes and functional groups (formula I), which changes the crosslink topology to provide both stability and enhanced elongation properties
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 polysulfurized compound effectively prevents reversion phenomena, maintaining or enhancing mechanical properties even at high crosslinking temperatures, resulting in improved elongation and stress resistance in unsaturated polymer compositions.
Implementation Method 1
The principle of vulcanization, also called crosslinking by sulfur, lies in the creation of sulfur bridges between different chains of macromolecules by reaction on the double bonds of these chains of a vulcanization agent
Implementation Method 2
the use of specific additives called anti-reversion agents which make it possible to thermally stabilize the vulcanizates
Data Source
AI summary
The invention relates to the use, as a crosslinking agent for unsaturated polymers, of a polysulphide compound of formula (I) in which: n is a number greater than or equal to 2, Z represents an O atom or the group -N(H)-, and R and R2 each represent a linear or branched divalent hydrocarbon group having 1 to 18 carbon atoms. The invention also relates to specific compounds of formula (I).