Antimony-stabilized

Commercial Stabilizers. The performance of the antimony stabilizers is significantly enhanced by adding polyhydroxybenzene compounds, eg, catechol, to the PVC (36). In commercial practice, about 5—10% catechol is formulated with the antimony mercaptide stabilizer products. The antimony mercaptides are normally prepared by heating antimony oxide with the appropriate mercaptan, normally isooctyl thioglycolate, under conditions to remove water. 

Health and Safety Aspects. The U.S. EPA has significantly reduced the allowed levels of antimony compounds in drinking water, causing a toxicity cloud over the viability of this class of stabilizers. Presently, antimony products are no longer allowed for use as potable water pipe stabilizers under NSF International s current Standard 61(28). For these reasons, antimony stabilizer technology is no longer commercial in the United States. 

Kaiser B, Bernhardt T M, Kinne M, Rademann K and Fleidenreich A 1999 Formation, stability, and structures of antimony oxide cluster ions J. Chem. Phys. 110 1437... 

Antimony(V) oxide can be prepared by treating antimony with concentrated nitric acid. It is an oxidising agent and when gently heated loses oxygen to form the trioxide. (The change in oxidation state stability shown by antimony should be noted since it corresponds to increasing metallic character.)... 

Powdered antimony pentoxide is used primarily in plastics. Stabilizers used to prevent the particles from growing are caustic, and can react with the halogen in the formulation. This can result in color formation and a lower flame-retarding efficiency of the system. 

Cblorina.ted Pa.ra.ffins, The term chlotinated paraffins covers a variety of compositions. The prime variables are molecular weight of the starting paraffin and the chlorine content of the final product. Typical products contain from 12—24 carbons and from 40—70 wt % chlorine. Liquid chlotinated paraffins are used as plasticizers (qv) and flame retardants ia paint (qv) and PVC formulations. The soHd materials are used as additive flame retardants ia a variety of thermoplastics. In this use, they are combiaed with antimony oxide which acts as a synergist. Thermal stabilizers, such as those used ia PVC (see vinyl polymers), must be used to overcome the inherent thermal iastabiUty. 

Current manufacturers of these products are the Polymer Additives Group of Witco Corp. (New York), with the trade name Mark, and Synthetic Products Co. (Cleveland), with the trade name Synpron. The antimony-based stabilizers are typicaHy used for rigid PVC extmsion appHcations at about 0.4 to about 0.8 phr, priced at about 3.80— 4.50/kg. 

Selenium acts as a grain refiner in lead antimony alloys (114,115). The addition of 0.02% Se to a 2.5% antimonial lead alloy yields a sound casting having a fine-grain stmcture. Battery grids produced from this alloy permit the manufacture of low maintenance and maintenance-free lead—acid batteries with an insignificant loss of electrolyte and good performance stability. 

Antimony tris(isooctylthioglycolate) has found use in pipe formulations at low levels. Its disadvantage is that it cross-stains with sulfide-based tin stabilizers (122). Barium—zinc stabilizers have found use in plasticized compounds, replacing barium—cadmium stabilizers. These are used in mol dings, profiles, and wire coatings. Cadmium use has decreased because of environmental concerns surrounding certain heavy metals. 

Antimony may be added to copper-base alloys such as naval brass. Admiralty Metal, and leaded Muntz metal in amounts of 0.02—0.10% to prevent dezincification. Additions of antimony to ductile iron in an amount of 50 ppm, preferably with some cerium, can make the graphite fliUy nodular to the center of thick castings and when added to gray cast iron in the amount of 0.05%, antimony acts as a powerflil carbide stabilizer with an improvement in both the wear resistance and thermal cycling properties (26) (see Carbides). 

Antimony trioxide has numerous practical applications (1). Its principal use is as a flame retardant in textiles and plastics (see Flame RETARDANTS Flame retardants in textiles). It is also used as a stabilizer for plastics, as a catalyst, and as an opacifier in glass (qv), ceramics (qv), and vitreous enamels... 

Brown combinations usually contain iron with chromium, zinc, titanium, or aluminum. There are a few without iron that contain chromium, antimony, tin, zinc, manganese, or aluminum. They range from tight tans to dark chocolate. The shades ate not as red as ferric oxide, but the browns are far superior to hydrated iron oxide in brightness and thermal stability. 

Radical cations can be derived from aromatic hydrocarbons or alkenes by one-electron oxidation. Antimony trichloride and pentachloride are among the chemical oxidants that have been used. Photodissociation or y-radiation can generate radical cations from aromatic hydrocarbons. Most radical cations derived from hydrocarbons have limited stability, but EPR spectral parameters have permitted structural characterization. The radical cations can be generated electrochemically, and some oxidation potentials are included in Table 12.1. The potentials correlate with the HOMO levels of the hydrocarbons. The higher the HOMO, the more easily oxidized is the hydrocarbon. 

The stabilized fluorinated allylic cation, generated from cis- or trans-l-(p-methoxyphenyl)pentafluoropropene and antimony pentafluoride in sulfur dioxide, is solvolyzed by methanol to methyl 2-(p-methoxyphenyl)difluoroacrylate [36] (equation 37)... 

Apparent indicator constant 264, 267 Apparent stability constant 59 Aqua regia 111 Arc alternating current, 764 direct current, 763, 771 sensitivities of elements, (T), 766 Aromatic hydrocarbons analysis of binary mixtures, 715 Arsenates, D. of (ti) 357 Arsenic, D. of as silver arsenate, (ti) 357 as trisulphide, (g) 448 by iodine, (am) 634, (ti) 397 by molybdenum blue method, (s) 681 by potassium bromate, (ti) 406 by potassium iodate, (ti) 401 in presence of antimony, (s) 724 Arsenic(III) oxide as primary standard, 261... 

A PEIT of 50/50 (molar ratio) composition is synthesized by a two-step reaction sequence as follows. In the first step, 97.10 g (0.5 mol) dimethyl terephthalate (DMT), 97.10 g (0.5 mol) dimethyl isophthalate (DMI), 136.55 g (2.2 mol) 1,2-ethanediol, and zinc acetate dihydrate ester interchange catalyst (2.7 x 10 4% mass of the total amount of DMI and DMT mixture) are weighed into a threenecked flask fitted with a mechanical stirrer, a nitrogen inlet, and a condenser. The medium is stirred for 2.0-2.5 h at 180-210°C under nitrogen. Ninety-two percent of the theoretical amount of methanol is removed by distillation. In the second step, antimony acetate polycondensation catalyst and trimethyl phosphate thermal stabilizer (9.9 x 10-4 and 1.5 x 10 3% mass of the total amount of DMI... 

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