Sulphur reaction

Accelerators are second in importance only to sulphur. Their function is to accelerate the normally slow rubber-sulphur reaction, increase the rate of vulcanization, and increase productivity. Accelerators are classified into two main classes by types, namely organic and inorganic. The inorganic accelerators such as lime, litharge and other lead compounds and magnesia were employed extensively before the introduction of organic accelerators. They are still used mainly to produce hard rubber or ebonite products. Litharge is used in rubberized fabrics, insulated wires and cables and shoe compounds as well as chemical resistant rubber products... 

W. A. Pryor, Mechanisms of Sulphur Reactions, McGraw-Hill, New York, 1962, p. 57. 

In particular iodine-sulphur reaction results quite attractive [68]. It consists of three steps at different operation temperatures, which involve the H2SO4 and HI dissociation and the re-production of both acids starting from I, SO2 and H2O. Particular interest is also focused on CeO2/Ce2O3 cycle, cerium-chlorine cycle (Ce-Cl), Zinc-zinc-oxide cycle (Zn/ZnO), but also on a Cu-Cl cycle, which is a cycle with an electrochemical step [69]. 

It is the sodium-vanadium-sulphur reactions that will contribute substantially to the deposition problems in heavy fuel oil combustion. The vanadium in the fuel oil is generally associated with the combustible organic material so that, as the combustion process proceeds, the vanadium is subject to extremely high temperatures in the flame. Under these extreme conditions the vanadium will be converted to vanadium pentoxide At least some of the sodium present will... 

V. Sulphur Reaction.—When a protein solution is warmed with a solution which contains sodium hydroxide and a lead salt, either a black precipitate or brown coloration is produced. The reaction depends on the splitting off of sulphur from cystine, and the subsequent formation of lead sulphide. 

Molten sodium and sulphur at 300-400 C are inherently reactive materials, especially when exposed to air or water. The uncontrolled sodixiin/sulphur reaction itself, which would take place in the event of electrolyte fracture, is rapid and highly exothermic. It is therefore necessary to design cells which are intrinsically safe under normal operati j conditions and can withstand likely accident situations ... 

Thiophens may also be obtained from aldehydes in like manner. The kinetics and mechanism of these sulphurization reactions, and especially of the industrially important reverse reactions (hydrodesulphurization), have been examined in some detail thiols may be intermediates. 

If a study of vulcanization chemistry is to become part of a routine technological investigation it is necessary for a technique to be developed that will give very rapidly information on the distribution of rubber-sulphur reaction products for a specified set of vulcanization conditions (e.g. sulphur level, accelerator level, cure time, cure temperature). A most useful contribution in this direction has been made by Lautenschlaeger (1977). The model compound 2-methyl-2-pentene was heated with typical curing systems in Pyrex tubes from 10 to 100 minutes over a range of temperatures from 100 C to 150 C. The reaction products were then subjected to gas... 

Abend, Block, Cocke, Time-of-Right] Abend, Gunter/Jochen H. Block/David L Cocke The Field Ionization Time-of-Flight Mass Spectrometer. A Tool for Chemical Kinetic Investigations as Shown by Elemental Sulphur Reactions, Advances in Mass Spectrometry 7 (1979), p. 703-705. 

Further studies have been reported of the use of boron and silicon sulphides in sulphurization reactions. One of the products obtained in the pyrano-pyrone series has been converted into the l,6-dioxa-6a-thiapentalene (28). 

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