Polysulfides density

Polysulfides are the key reactants in the high-density sodium-sulfur and Hthium-sulfur batteries [4] which are based on the following reversible redox reaction taking place in the polysulfide melt ... 

The molecular structures of the isolated polysulfide monoanions 8 with n=2-9 have been studied by density functional calculations and those of the smaller ions also by ab initio MO calculations. Compared to the neutral 8 molecules the extra electron occupies an antibonding orbital resulting in longer 88 bonds. The species 83 is bent and of C2V symmetry (a=115°) [140, 141]. 84 was calculated to be a planar ion of C2V symmetry (similar to the neutral molecule 84) but the planar C2h structure is only slightly less stable [140, 141]. The most stable isomer of 85 is a chain of Q symmetry sim-... 

The influence of ZnCFO concentration (3,0 5,0 7,0 phr) on formation of properties complex of the unfilled rubber mixes and their vulcanizates on the basis of isoprene rubber of the following recipe, phr isoprene rubber - 100,0 sulfur - 1,0 di - (2-benzothiazolyl) -disulfide - 0,6 N, N -diphenylguanidine - 3,0 stearic acid - 1,0, was carried out in comparison with the known activator - zinc oxide (5,0 phr). The analysis of Rheometer data of sulfur vulcanization process of elastomeric compositions at 155°C (fig. 5) shows, that on crosslink density and cure rate, about what the constants of speed in the main period (k2) testify, they surpass the control composition with 5,0 phr of zinc oxide. Improvement of the complex of elastic - strong parameters of rubbers with ZnCFO as at normal test conditions, and after thermal air aging (tab. 1), probably, is caused by influence of the new activator on vulcanization network character. So, the percent part of polysulfide bonds (C-Sx-C) and amount of sulfur atoms appropriating to one crosslink (S atoms/crosslink) in vulcanizates with ZnCFO are decreased, the percent part of disulfide bonds (C-S2-C) is increased (fig. 62). 

Scission of Polysulfide Crosslinks in Scrap Rubber Particles. Throughout this study, we used a single lot of scrap rubber peelings having the average composition described in the Experimental Section. We began our studies with Aliquat 336 as the phase transfer catalyst because of its proven effectiveness in simple systems and its commercial availability. When devulcanization is performed in a refluxing benzene/aqueous NaOH mixture, the chemical crosslink density (M... 

Colorless crystals or white crystalline mass rapidly deliquesces converts to a yellow rhomhohedral crystalline mass upon exposure to air, forming polysulfides and H2S density 1.68g/cm3 the hemdiydrate loses water at about 175°C melts at 455°C to a dark red hquid decomposes in water soluble in alcohol. 

Bojkova et al. (4) prepared high-impact poly(urethane-urea) polysulfides having a refractive index of at least 1.57, an Abbe number of at least 32, and a density >1.3g/cm2 3, which consisted of the reaction product of... 

Another combination is to use any sepia or polysulfide toner, then Kodak T-26 Blue Toner. To use this combination, wash the print thoroughly after using sepia or polysulfide toner then use T-26 as per directions. The red tone should appear after approximately 15 to 30 minutes in this solution at 90F/32C. This technique usually produces a density loss in the shadows. Start with a print that has higher-than-normal contrast. Cold-tone papers will produce a truer red warm-tone papers will produce an orange hue. 

PB PBI PBMA PBO PBT(H) PBTP PC PCHMA PCTFE PDAP PDMS PE PEHD PELD PEMD PEC PEEK PEG PEI PEK PEN PEO PES PET PF PI PIB PMA PMMA PMI PMP POB POM PP PPE PPP PPPE PPQ PPS PPSU PS PSU PTFE PTMT PU PUR Poly(n.butylene) Poly(benzimidazole) Poly(n.butyl methacrylate) Poly(benzoxazole) Poly(benzthiazole) Poly(butylene glycol terephthalate) Polycarbonate Poly(cyclohexyl methacrylate) Poly(chloro-trifluoro ethylene) Poly(diallyl phthalate) Poly(dimethyl siloxane) Polyethylene High density polyethylene Low density polyethylene Medium density polyethylene Chlorinated polyethylene Poly-ether-ether ketone poly(ethylene glycol) Poly-ether-imide Poly-ether ketone Poly(ethylene-2,6-naphthalene dicarboxylate) Poly(ethylene oxide) Poly-ether sulfone Poly(ethylene terephthalate) Phenol formaldehyde resin Polyimide Polyisobutylene Poly(methyl acrylate) Poly(methyl methacrylate) Poly(methacryl imide) Poly(methylpentene) Poly(hydroxy-benzoate) Polyoxymethylene = polyacetal = polyformaldehyde Polypropylene Poly (2,6-dimethyl-l,4-phenylene ether) = Poly(phenylene oxide) Polyp araphenylene Poly(2,6-diphenyl-l,4-phenylene ether) Poly(phenyl quinoxaline) Polyphenylene sulfide, polysulfide Polyphenylene sulfone Polystyrene Polysulfone Poly(tetrafluoroethylene) Poly(tetramethylene terephthalate) Polyurethane Polyurethane rubber... 

At the end of the polymerization process, the polymers are washed free of sodium chloride, excess sodium polysulfide and solubihzed hydroxy-containing terminals. The molecular mass of the resultant polymer is thought to be at least 5 x 10 10 the yield is 80%. The polymer forms as small dispersed spheres approximately 5 15 lm in diameter, which have a higher density than the aqueous phase in which they are produced, and therefore settle to the bottom of the reactor. The polymer is washed with hot water, followed by decantation, coagulation by acidification, and drying with heat, resulting in a sohd, rubbery mass. 

Another factor in M-S bonding stability is the presence of S-S bonds. Calculations and fragmentary spectral studies indicate that the cr orbitals of S-S bonds are even lower in energy than those of S-H bonds (i.e., ct energies are lower in HjSj than in HjS). Thus disulfide ligands, and probably polysulfides in general, are better electron acceptors than sulfur itself. It is well known that transition metals form numerous compounds with polysulfides (Draganjac and Rauchfuss, 1985 Muller and Diemann, 1987). In many polysulfides (e.g., S/ ) there are also empty tt orbitals in addition to the empty ct orbitals, and these may also accept electron density from the metal. 

Vj, = polysulfidic link density V2 = disulfidic link density monosulfidic and C-C link density = pj (s. Experimental). 

This situation is reversed in the case of ENB-EPDM (Table 17) since, after high vulcanization times, relevant fractions of polysulfidic and disulfidic links are still present, while the overall cross-link density is rather low in relation with the unsaturation content. 

The feedstocks (straight-mn naphtha (SRN) and a blend of SRN and hydrocracked naphtha) and hydrotreated products were analysed by ASTM methods for density, carbon, hydrogen, hydrocarbon and boiling point distribution. Total sulfur was determined by ASTM D-4045 method, mercaptan sulfur by the potentiometric method (ASTM D-3227 and UOP-212), disulfides by the UOP-202 method, polysulfides by polarography [1], and elemental sulfur by the UOP-286 method. The Perkin-Elmer gas chromatograph (Model 8700), equipped with a flame photometric detector (GC/FPD) and a DB-1 fused silica capillary column (30 m x 0.53 mm), was used for identification of individual sulfur compounds [2-6]. The sensitivity of the GC/FPD technique was maximized by optimizing the gas flow rates and temperature programming as presented elsewhere [1]. 

Other physical properties of the sulfur-polysulfide melt influence cell performance and have been studied. Density is perhaps foremost among these since density variation during discharge will dictate cathode void volume requirements. Furthermore since the sulfur-polysulfide melt is a two-phase system (see Figure 2) over much of the discharge range, density in conjunction with viscosity and surface tension establish the nature of the phase separation. Measurements of density (19, 23) demonstrate that the reaction proceeds at 360°C according to ... 

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