Tetroxide Sb

Antimony Tetrasulphide, Sb S. —This was obtained by Berzelius by passing hydrogen sulphide gas into a solution of the tetroxide. Hose was able to obtain it from the decomposition of an aqueous solution of the fusion-product of the trisulphide and bisulphate of potassium by tartaric acid. It is a reddish-yellow powder. 

A part of the trioiide is further oxidised to the pentoxide, SbjOj, which, combining with some of the trioxide, forms the tetroxide, Sb,0. When oxides of metals are present, antimoniates are formed. If the ore contains a large quantity-of sulphides of foreign metals, which would, under ordinary circumstances, form sulphates, if they alone were calcined, antimoniates of the foreign metals are formed. 

The segregation phenomena in V-Sb-0 catalyst for selective propylene oxidation to acrolein were studied by means of X-ray photoelectron spectroscopy, scanning electron microscopy with EDS, as well as electron and X-ray diffraction. The vanadium antimonate crystals were found to be a main component of the catalyst. It was stated that epitaxial layers of antimony tetroxide on the base faces of vanadium antimonate crystals, exposing (010) plane, were responsible for high catalyst selectivity. 

Figure 4.15. Transmission electron micrograph illustrating the first stage in the deformation process of SBS block copolymers (Beecher et aL 1969) the formation of rows of spherical domains. Films were solvent-cast to a thickness of 500-800 A, subjected to tensile stretch, and stained with osmium tetroxide ( — = 1000 A).

Fig. 3. Example of electron micrograph of a hexagonal structure. Copolymer polystyrene-poly-butadiene SB. 32 containing 30,5% of polybutadiene, swollen with 29% of MMA and post-polymerized. Main figure section along the plane perpendicular to the direction of the axis of the insoluble poly butadiene cylinders insert section by a plane parallel to the axis of the cylinders. Polybutadiene stained by osmium tetroxide in dark

Many of the studies of multiphase polymers are conducted on unsaturated rubbers which are adequately stained by osmium tetroxide, which reveals the nature of the dispersed phase domains. Polymers with activated aromatic groups have been selectively stained by reaction with mercuric trifluoroacetate (Section 4.4.8). Hobbs [262] has successfully used this technique to provide contrast in blends of poIy(2,6-dimethyl-l,4-phenylene oxide) and Kraton G (SBS block copolymer). Although this stain is effective in enhancing contrast, a drawback of the method is that the material is not hardened or fixed by the stain. 

Temperature and air feed is carefully controlled in the process to suppress any formation of antimony tetroxide (86204). Antimony trioxide is separated from any arsenic trioxide (AS2O3) that may be present as an impurity by volatilization, as the latter is much more volatile than the former. It may be also prepared by alkaline hydrolysis of antimony trichloride and subsequent dehydration of hydrous oxide under controlled heating (rapid or vigorous heating may partially oxidize 8b(III) to Sb(V). 

Early results with cryomicrotomes were described by Cobbold and Mendelson [61]. Polyurethane elastomer, a blend of crystalline and noncrystalline polymers, showed spherulitic textures after sectioning at about -70°C. Injection molded polypropylene (PP) was also sectioned at about -70 °C, while polytetrafluorethylene (PTFE) was sectioned at much lower temperatures. The authors concluded that the technique, though difficult, had potential. Extruded styrene-butadiene-styrene (SBS) copolymer was prepared by cryosectioning with a diamond knife in liquid air at -85 to -115°C, followed by osmium tetroxide vapor staining for one hour [62]. This method revealed the alternating sequence of the 

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