Polysulphides chemistry

Sulphur dyes in the insoluble disulphide form and the Cl Solubilised Sulphur brands are reduced by the dyer as part of the application procedure. In the case of the Cl Leuco Sulphur brands reduction has already been carried out by the manufacturer, so that they are substantially in a form suitable for immediate application (section 1.6.2) The chemistry of the reduction of sulphur dyes is complex, as is the chemistry of the dyes themselves it has been well described elsewhere [204]. It is possible to describe the state of a reduced sulphur dye in alkaline sulphide or polysulphide solution by the general formula 12.42, but there are certain complications. In many cases the chromogen is not itself reduced, but in others, notably reddish browns, blues and navy blues based on indophenols, the chromogenic... 

Figure 2.2 Chemistry of sodium polysulphide (after Mortimer, 1975)...

Those patents are also listed in the references at the end of this book. Innogy selected the positive and negative electrolytes of sodium bromide ( anolyte ) and sodium polysulphide ( catholyte ). Sodium polysulphide is shown in Figure 2.2, as a Lewis structure, as in the textbook of chemistry (Mortimer, 1975). Further reading on polysulphides is available in Porterfield (1993), Lessner (1986 1988) and Murray (1983). 

Except in ozone, the alkali-metal ozonates, the unstable O4F2, and a number of organic peroxides and trioxides (e.g. F3C, 000. CF3), the covalent linking of 0 to 0 does not proceed beyond 0=0 or -0—0—. Sulphur, on the other hand, presents a very different picture, a feature of its chemistry being the easy formation of chains of S atoms—in the element itself, in halides S ,X2, polysulphides, and polythionates. 

PAN 14] Pang Q., KUNDU D., Cuisinier M., et al, Surface-enhanced redox chemistry of polysulphides on a metallic and polar host for lithium-sulphur batteries , Nature Communications, vol. 5, p. 4759, 2014. 

E. R. Bertozzi, Chemistry and technology of elastomeric polysulphide polymers. Rubber Chem. Technol. 41, 114 (1968). 

Schematic diagram of the most conventional Li/S batteries and its t5 cal discharge voltage profile. The circled areas correspond to the progressive formation of the polysulphides during discharge. (Adapted from B. Scrosati, J. Hassoun and Y.-K. Sun, Lithium-ion batteries. A look into the future. Energy Environ. Set. 4, 2011, 3287-3295. Reproduced by permission of The Royal Society of Chemistry.)...

A study was conducted to differentiate between the crosslinking reactions of bismaleimides and biscitraconimides in squalene as well as in NR. Bismaleimides were found to participate in the crosslinking reaction in the absence of curing compounds such as accelerators and sulphur. Biscitraconimides took part in the crosslinking reaction when polysulphidic crosslinks were under the process of degradation. Sulphur and accelerator were required for the formation of polysulphidic crosslinks and hence the presence of sulphur and accelerator were essential for biscitraconimide crosslinking. The differences in the reactivity and the chemistry of crosslinking are studied and discussed. Some application data are provided in order to elaborate on the differences. 17 refs. 

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