Sulfur Vulcanization of Simple Model Olefins, Part II: Characterization and Reactivity of Intermediate Vulcanization Products of 2,3-Dimethyl-2-Butene

Abstract In a study of the mechanism of the sulfur vulcanization of unsaturated rubber, 2,3-dimethyl-2-butene (C6H12) was used as a simple, low-molecular model alkene. Only equivalent allylic positions are present in this alkene. Treating C6H12 with a mixture of ZnO, S8 and the accelerator tetramethylthiuramdisulflde at 140°C for 20 minutes yields a mixture of addition products (C6H11—Sn—C6H11) and also intermediate products (C6H11—Sn—S(S)CN(CH3)2). The formation of C6H11—Sn—C6H11 from these intermediate products only proceeds in the presence of the zinc dimethyldithiocarbamate complex and free alkene.

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Sulfur Vulcanization of Simple Model Olefins, Part IV: Vulcanizations of 2,3-Dimethyl-2-Butene with TMTD and Activated Zinc Dithiocarbamate/Xanthate Accelerators at Different Temperatures

Rubber Chemistry and Technology ◽

10.5254/1.3538757 ◽

1995 ◽

Vol 68 (4) ◽

pp. 563-572 ◽

Cited By ~ 12

Author(s):

P. Versloot ◽

J. G. Haasnoot ◽

J. Reedijk ◽

M. van Duin ◽

J. Put

Keyword(s):

Simple Model ◽

Room Temperature ◽

Molecular Model ◽

Secondary Amines ◽

Temperature Range ◽

Intermediate Products ◽

Sulfur Vulcanization ◽

Different Temperatures

Abstract The mechanism of the accelerated sulfur vulcanization of rubber was studied by the use of 2,3-dimethyl-2-butene (C6H12, TME) as a simple, low-molecular model alkene. Treatment of TME with a mixture of ZnO, S8 and the classical accelerator TMTD at temperatures above 100°C yields a mixture of addition products ((C6H11—Sn—C6H11) ). In the temperature range of 50 up to 100 °C only intermediate products, C6H11—Sn—S(S)CN(CH3)2 are obtained. Room temperature vulcanization is feasible using highly reactive accelerators, such as xanthate derivatives. These derivatives result in formation of the crosslink precursors which are converted to the actual crosslink in the presence of zinc dithiocarbamates. The addition of (secondary) amines enhances the solubility of the dithiocarbamates, and therefore the reactivity of the xanthate/zinc dithiocarbamate combination.

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Sulfur Vulcanization of Simple Model Olefins Part III: Vulcanization of 2,3-Dimethyl-2-Butene in the Presence of Different Metal Complexes

Rubber Chemistry and Technology ◽

10.5254/1.3538673 ◽

1994 ◽

Vol 67 (2) ◽

pp. 263-279 ◽

Cited By ~ 9

Author(s):

P. Versloot ◽

J. G. Haasnoot ◽

J. Reedijk ◽

M. van Duin ◽

J. Put

Keyword(s):

Zinc Oxide ◽

Simple Model ◽

Metal Complexes ◽

Metal Oxides ◽

Molecular Model ◽

Sulfur Vulcanization

Abstract The mechanism of the sulfur vulcanization of rubber was studied by using 2,3-dimethyl-2-butene (C6H12) as a simple, low-molecular model alkene. Only equivalent allylic positions are present in this alkene. Treating C6H12 with a mixture of ZnO, S8 and the accelerator tetramethylthiuramdisulfide at 140°C yields a mixture of addition products (C6H11—Sn—C6H11). Similar reactions in the presence of various metal oxides instead of zinc oxide show poor vulcanization results. Experiments with various metal dithiocarbamate complexes show a reactivity towards vulcanization in the following sequence: Zn(detc)2>Cd(detc)2>Cu(detc)2>Pb(detc)2>Zn(dmtc)2>Ni(detc)2>Cu(dmtc)2.

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Sulfur Vulcanization of Simple Model Olefins, Part I: Characterization of Vulcanization Products of 2,3-Dimethyl-2-Butene

Rubber Chemistry and Technology ◽

10.5254/1.3538616 ◽

1992 ◽

Vol 65 (2) ◽

pp. 343-349 ◽

Cited By ~ 23

Author(s):

P. Versloot ◽

J. G. Haasnoot ◽

J. Reedijk ◽

M. van Duin ◽

E. F. J. Duynstee ◽

...

Keyword(s):

Molecular Weight ◽

Double Bond ◽

Simple Model ◽

1H Nmr ◽

Low Molecular Weight ◽

Rp Hplc ◽

Sulfur Vulcanization ◽

Weight Model

Abstract To study the mechanism of the sulfur vulcanization of rubber, 2,3-dimethyl-2-butene (C6H12) was used as a simple, low-molecular-weight model alkene. Only equivalent allylic positions are present in this alkene. Treating C6H12 with a mixture of ZnO, S8, and the accelerator tetramethylthiuramdisulfide at 140°C yields a mixture of addition products (C6H11—Sn—C6H11). RP-HPLC in combination with MS and 1H-NMR shows that the products differ only in the length of the sulfur bridge. Small quantities of isomerized products have been found, in which a 1,3-shift of the double bond has occurred.

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Toward an alignment of the actin molecule within the actin filament

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075981 ◽

1983 ◽

Vol 41 ◽

pp. 450-451

Author(s):

P.R. Smith ◽

W.E. Fowler ◽

U. Aebi

Keyword(s):

Actin Filament ◽

Diffraction Data ◽

Quantitative Estimate ◽

Molecular Model ◽

Quantitative Comparison ◽

Regulatory Proteins ◽

Essential Information ◽

X Ray ◽

Maximum Resolution ◽

Lack Of Information

An understanding of the specific interactions of actin with regulatory proteins has been limited by the lack of information about the structure of the actin filament. Molecular actin has been studied in actin-DNase I complexes by single crystal X-ray analysis, to a resolution of about 0.6nm, and in the electron microscope where two dimensional actin sheets have been reconstructed to a maximum resolution of 1.5nm. While these studies have shown something of the structure of individual actin molecules, essential information about the orientation of actin in the filament is still unavailable.The work of Egelman & DeRosier has, however, suggested a method which could be used to provide an initial quantitative estimate of the orientation of actin within the filament. This method involves the quantitative comparison of computed diffraction data from single actin filaments with diffraction data derived from synthetic filaments constructed using the molecular model of actin as a building block. Their preliminary work was conducted using a model consisting of two juxtaposed spheres of equal size.

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Exploration of cell wall architecture with the rapid-freeze deep-etch technique

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100146485 ◽

1993 ◽

Vol 51 ◽

pp. 128-129

Author(s):

Béatrice Satiat-Jeunemaitre ◽

Chris Hawes

Keyword(s):

Plant Cell ◽

Cell Walls ◽

Cell Biology ◽

Molecular Model ◽

Three Dimensional ◽

Secretory Activity ◽

Wall Structure ◽

Specimen Preparation ◽

Molecular Architecture ◽

Plant Cell Walls

The comprehension of the molecular architecture of plant cell walls is one of the best examples in cell biology which illustrates how developments in microscopy have extended the frontiers of a topic. Indeed from the first electron microscope observation of cell walls it has become apparent that our understanding of wall structure has advanced hand in hand with improvements in the technology of specimen preparation for electron microscopy. Cell walls are sub-cellular compartments outside the peripheral plasma membrane, the construction of which depends on a complex cellular biosynthetic and secretory activity (1). They are composed of interwoven polymers, synthesised independently, which together perform a number of varied functions. Biochemical studies have provided us with much data on the varied molecular composition of plant cell walls. However, the detailed intermolecular relationships and the three dimensional arrangement of the polymers in situ remains a mystery. The difficulty in establishing a general molecular model for plant cell walls is also complicated by the vast diversity in wall composition among plant species.

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