Mechanism of Rubber Vulcanization with Sulfur

Lewis, W. K.; Squires, Lombard; Nutting, Robert D.

doi:10.1021/ie50334a011

“…It is difficult to understand why such a reaction should occur differently in Hevea than it does in GIt-S. For a long time there has been a hypothesis that a thermal depolymerization of Hevea takes place during cure which increases its reactivity. Lewis, Squires, and Nutting (19) discount this theory but nevertheless it remains the most attractive explanation of the results obtained here. From this viewpoint, it would be considered that the high pressure retards this depolymerization of Hevea to a sufficient extent to make it the controlling reaction for the rate of vulcanization.…”

Section: Discussionsupporting

confidence: 50%

Vulcanization at High Pressures

Wilkinson¹,

Gehman²

1949

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“…It is difficult to understand why such a reaction should occur differently in Hevea than it does in GIt-S. For a long time there has been a hypothesis that a thermal depolymerization of Hevea takes place during cure which increases its reactivity. Lewis, Squires, and Nutting (19) discount this theory but nevertheless it remains the most attractive explanation of the results obtained here. From this viewpoint, it would be considered that the high pressure retards this depolymerization of Hevea to a sufficient extent to make it the controlling reaction for the rate of vulcanization.…”

supporting

confidence: 50%

Nitrosoguanidine: Stability in Aqueous Pastes and Solutions

Henry¹,

Skolnik²,

Makosky³

et al. 1949

Ind. Eng. Chem.

0

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“…However, since we observed differences in the products between OAm and HDA, it is of particular importance to understand the interaction mechanism between S and unsaturated monomers, as in OAm. The relevant process is known as vulcanization, which is preceded by the formation of linear diradicals from the homolytic breakup of labile S–S bonds. , These sulfur radicals are known for having a high affinity toward double bonds, and because oleylamine possesses a long alkyl chain with an unsaturated double bond, the oleylamine and S species can undergo a radical polymerization. This results in the sulfur diradicals establishing bridges between oleylamine molecules and cross-linking them, forming what is called a poly(oleylamine-random-sulfur) copolymer, or poly-OLA-r-S, as shown in Scheme Reaction 3 .…”

Section: Resultsmentioning

confidence: 99%

Crystallinity and Size Control of Colloidal Germanium Nanoparticles from Organogermanium Halide Reagents

Pescara

¹

,

Mazzio

²

,

Lips

³

et al. 2019

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Germanium (Ge) nanoparticles are gaining increasing interest due to their properties that arise in the quantum confinement regime, such as the development of the band structure with changing size. While promising materials, significant challenges still exist related to the development of synthetic schemes allowing for good control over size and morphology in a single step. Herein, we investigate a synthetic method that combines sulfur and primary amines to promote the reduction of organometallic Ge(IV) precursors to form Ge nanoparticles at relatively low temperatures (300 °C). We propose a reaction mechanism and examine the effects of solvents, sulfur concentration, and organogermanium halide precursors. Hydrosulfuric acid (H2S) produced in situ acts as the primary reducing species, and we were able to increase the particle size more than 2-fold by tuning both the reaction time and quantity of sulfur added during the synthesis. We found that we are able to control the crystalline or amorphous nature of the resulting nanoparticles by choosing different solvents and propose a mechanism for this interaction. The reaction mechanism presented provides insight into how one can control the resulting particle size, crystallinity, and reaction kinetics. While we demonstrated the synthesis of Ge nanoparticles, this method can potentially be extended to other members of the group IV family.

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Mechanism of Rubber Vulcanization with Sulfur

Cited by 6 publications

References 2 publications

Vulcanization at High Pressures

Vulcanization at High Pressures

Nitrosoguanidine: Stability in Aqueous Pastes and Solutions

Crystallinity and Size Control of Colloidal Germanium Nanoparticles from Organogermanium Halide Reagents

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