The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances VI. Factors Influencing Cyclic Sulfide Formation in the Reaction of Sulfur with Polyisoprenes

1950 ◽  
Vol 23 (2) ◽  
pp. 326-331
Author(s):  
George F. Bloomfield
Keyword(s):  
Reaction Times ◽  
Sulfur Compounds ◽  
Cross Linking ◽  
Secondary Products ◽  
Factors Influencing ◽  
The Cross ◽  
Time Of Reaction ◽  
Cyclic Sulfide

Abstract Cyclic Sulfides are to a large extent secondary products of the reaction of primarily formed intermolecular polysulfides with polyisoprene hydrocarbon, and undue prolongation of the time of reaction of sulfur with polyisoprenes favors cyclic sulfide formation and so reduces the cross-linking efficiency of the sulfur. Various accelerating substances markedly increase the cross-linking efficiency, either by permitting shorter reaction times to be employed, or by promoting a cross-linking rather than a cyclizing reaction of the sulfur. Thiuram disulfide accelerators in the absence of sulfur bring about cross-linking, the linkages being of C—S—C type rather than C—C.

The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances. VI. Factors Influencing Cyclic Sulfide Formation in the Reaction of Sulfur with Polyisoprenes

1949 ◽  
Vol 22 (4) ◽  
pp. 982-987
Author(s):  
George F. Bloomfield
Keyword(s):  
Reaction Times ◽  
Sulfur Compounds ◽  
Cross Linking ◽  
Secondary Products ◽  
Factors Influencing ◽  
The Cross ◽  
Time Of Reaction ◽  
Cyclic Sulfide

Abstract Cyclic sulfides are to a large extent secondary products of the reaction of primarily formed intermolecular polysulfides with polyisoprene hydrocarbon, and undue prolongation of the time of reaction of sulfur with polyisoprenes favors cyclic sulfide formation and so reduces the cross-linking efficiency of the sulfur. Various accelerating substances markedly increase the cross-linking efficiency, either by permitting shorter reaction times, or by promoting a cross-linking rather than a cyclizing reaction of the sulfur. Thiuram disulfide accelerators in the absence of sulfur bring about cross-linking, the linkages being of —C—S—C type rather than C—C.

The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances. Part IX. The Reaction of Sulfur with 2,6-Dimethylocta-2,6-Diene

1958 ◽  
Vol 31 (5) ◽  
pp. 1065-1077
Author(s):  
L. Bateman ◽  
R. W. Glazebrook ◽  
C. G. Moore
Keyword(s):  
Infrared Spectrum ◽  
Sulfur Compounds ◽  
Formed Part ◽  
Time Of Reaction ◽  
Cyclic Sulfide

Abstract Farmer and Shipley showed that reaction of sulfur with 2,6-dimethylocta-2,6-diene (I) at 140° yields a cyclic monosulfide and a crosslinked polysulfide. No detailed investigation of the structures of these cyclic monosulfide or polysulfide products was undertaken, but it was deduced that the former contained 6-ethyl-2,2,6-trimethylthiaeyclohex-3-ene (VIII) and a compound having vinylidene unsaturation, CH2:CRR′, as apparently revealed by the infrared spectrum, and this has formed part of the evidence on which broad mechanistic conclusions have been based. This reaction has now been re-examined in greater detail; the compositions of the cyclic sulfide and crosslinked polysulfide fractions and their variation with time of reaction have been determined. Results and conclusions differing in important respects from those advanced by the earlier workers have been reached, as reported preliminarily elsewhere.

scholarly journals Investigation of the functional network modifier loading on the stoichiometric ratio of epoxy resins and their dielectric properties

2021 ◽  
Author(s):  
Istebreq A. Saeedi ◽  
Sunny Chaudhary ◽  
Thomas Andritsch ◽  
Alun S. Vaughan
Keyword(s):  
Glass Transition ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Epoxy Resins ◽  
Functional Network ◽  
Cross Linking ◽  
Network Modifier ◽  
Epoxy Resin System ◽  
The Cross ◽  
The Impact

AbstractReactive molecular additives have often been employed to tailor the mechanical properties of epoxy resins. In addition, several studies have reported improved electrical properties in such systems, where the network architecture and included function groups have been modified through the use of so-called functional network modifier (FNM) molecules. The study reported here set out to investigate the effect of a glycidyl polyhedral oligomeric silsesquioxane (GPOSS) FNM on the cross-linking reactions, glass transition, breakdown strength and dielectric properties of an amine-cured epoxy resin system. Since many previous studies have considered POSS to act as an inorganic filler, a key aim was to consider the impact of GPOSS addition on the stoichiometry of curing. Fourier transform infrared spectroscopy revealed significant changes in the cross-linking reactions that occur if appropriate stoichiometric compensation is not made for the additional epoxide groups present on the GPOSS. These changes, in concert with the direct effect of the GPOSS itself, influence the glass transition temperature, dielectric breakdown behaviour and dielectric response of the system. Specifically, the work shows that the inclusion of GPOSS can result in beneficial changes in electrical properties, but that these gains are easily lost if consequential changes in the matrix polymer are not appropriately counteracted. Nevertheless, if the system is appropriately optimized, materials with pronounced improvements in technologically important characteristics can be designed.

scholarly journals The Effect of Surfactant-Modified Montmorillonite on the Cross-Linking Efficiency of Polysiloxanes

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2623
Author(s):  
Monika Wójcik-Bania ◽  
Jakub Matusik
Keyword(s):  
Total Pore Volume ◽  
Cross Linking ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Cross ◽  
Chain Lengths ◽  
First Time ◽  
Substituent Influence ◽  
Benzyl Substituent

Polymer–clay mineral composites are an important class of materials with various applications in the industry. Despite interesting properties of polysiloxanes, such matrices were rarely used in combination with clay minerals. Thus, for the first time, a systematic study was designed to investigate the cross-linking efficiency of polysiloxane networks in the presence of 2 wt % of organo-montmorillonite. Montmorillonite (Mt) was intercalated with six quaternary ammonium salts of the cation structure [(CH3)2R’NR]+, where R = C12, C14, C16, and R’ = methyl or benzyl substituent. The intercalation efficiency was examined by X-ray diffraction, CHN elemental analysis, and Fourier transform infrared (FTIR) spectroscopy. Textural studies have shown that the application of freezing in liquid nitrogen and freeze-drying after the intercalation increases the specific surface area and the total pore volume of organo-Mt. The polymer matrix was a poly(methylhydrosiloxane) cross-linked with two linear vinylsiloxanes of different siloxane chain lengths between end functional groups. X-ray diffraction and transmission electron microscopy studies have shown that the increase in d-spacing of organo-Mt and the benzyl substituent influence the degree of nanofillers’ exfoliation in the nanocomposites. The increase in the degree of organo-Mt exfoliation reduces the efficiency of hydrosilylation reaction monitored by FTIR. This was due to physical hindrance induced by exfoliated Mt particles.

Effects of a crosslinking agent on a supramolecular gel to control lost circulation

2021 ◽  
Vol 45 (16) ◽  
pp. 7089-7095
Author(s):  
Bo Wang ◽  
Jinsheng Sun ◽  
Kaihe Lv ◽  
Feng Shen ◽  
Yingrui Bai
Keyword(s):  
Crosslinking Agent ◽  
Network Density ◽  
Cross Linking ◽  
Supramolecular Gel ◽  
Lost Circulation ◽  
The Cross

The Cr3+ can improve the cross-linking degree and network density of the GP-A gel, and enhance its strength and plugging ability to control lost circulation.

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