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Antioxidants vulcanizing

Parallel to the process of chemical and biological degradation, components of the abraded material may also be washed out by precipitation water. The elutive behavior of tires and abraded tire material has already been investigated in a number of studies, in particular the possibility of contamination of the environment with components of rubber during utilization [19] and as the result of waste deposition [20]. These studies concluded that the environment can, in principle, be contaminated due to elutimi of antioxidants, vulcanization accelerators and the conversion products resulting from vulcanization [1]. [Pg.381]

Rubber is a popular closure component, and additives such as vulcanizers, pigments (qv), or antioxidants may leach into the product. In cases where mbber closures are penetrated by needles in dosing, bits of the closure (coring) could enter the product. Thus, such closure components must be sufficiendy tested before use. [Pg.234]

Rubber. The mbber industry consumes finely ground metallic selenium and Selenac (selenium diethyl dithiocarbamate, R. T. Vanderbilt). Both are used with natural mbber and styrene—butadiene mbber (SBR) to increase the rate of vulcanization and improve the aging and mechanical properties of sulfudess and low sulfur stocks. Selenac is also used as an accelerator in butyl mbber and as an activator for other types of accelerators, eg, thiazoles (see Rubber chemicals). Selenium compounds are useflil as antioxidants (qv), uv stabilizers, (qv), bonding agents, carbon black activators, and polymerization additives. Selenac improves the adhesion of polyester fibers to mbber. [Pg.337]

Rubber Chemicals. Sodium nitrite is an important raw material in the manufacture of mbber processing chemicals. Accelerators, retarders, antioxidants (qv), and antiozonants (qv) are the types of compounds made using sodium nitrite. Accelerators, eg, thiuram [137-26-8J, greatly increase the rate of vulcaniza tion and lead to marked improvement in mbber quaUty. Retarders, on the other hand (eg, /V-nitrosodiphenylamine [156-10-5]) delay the onset of vulcanization but do not inhibit the subsequent process rate. Antioxidants and antiozonants, sometimes referred to as antidegradants, serve to slow the rate of oxidation by acting as chain stoppers, transfer agents, and peroxide decomposers. A commonly used antioxidant is A/,AT-disubstituted Nphenylenediamine which can employ sodium nitrite in its manufacture (see Rubber chemicals). [Pg.200]

A similar reaction with phenols is employed to make commercial vulcanizing agents and antioxidants (see Antioxidants Antiozonants). [Pg.138]

Sulfuiized and sulfurchlorinated unsaturated compounds and meicaptans are used as lubricant additives (antiwear, friction modification, load-carrying, extreme pressure and temperature, corrosion inhibition, and antioxidants), refinery catalyst regeneration compounds, steel processing (annealing) aids, and vulcanization catalysts (see Lubrication and lubricants). [Pg.207]

This combination of monomers is unique in that the two are very different chemically, and in thek character in a polymer. Polybutadiene homopolymer has a low glass-transition temperature, remaining mbbery as low as —85° C, and is a very nonpolar substance with Htde resistance to hydrocarbon fluids such as oil or gasoline. Polyacrylonitrile, on the other hand, has a glass temperature of about 110°C, and is very polar and resistant to hydrocarbon fluids (see Acrylonitrile polymers). As a result, copolymerization of the two monomers at different ratios provides a wide choice of combinations of properties. In addition to providing the mbbery nature to the copolymer, butadiene also provides residual unsaturation, both in the main chain in the case of 1,4, or in a side chain in the case of 1,2 polymerization. This residual unsaturation is useful as a cure site for vulcanization by sulfur or by peroxides, but is also a weak point for chemical attack, such as oxidation, especially at elevated temperatures. As a result, all commercial NBR products contain small amounts ( 0.5-2.5%) of antioxidant to protect the polymer during its manufacture, storage, and use. [Pg.516]

There is also a large number of synthetic heterocyclic compounds with other important practical applications, as dyestuffs, copolymers, solvents, photographic sensitizers and developers, as antioxidants and vulcanization accelerators in the rubber industry, and many are valuable intermediates in synthesis. [Pg.47]

Brittleness with age. Degradative oxidation can be produced, even after vulcanization, due to oxygen and ozone attack to the carbon-carbon double bonds. Adequate antioxidants must be added if ageing is a key factor in performance. [Pg.647]

The largest user of phenol in the form of thermosetting resins is the plastics industry. Phenol is also used as a solvent and in the manufacture of intermediates for pesticides, pharmaceuticals, and dyestuffs. Styrene is used in the manufacture of synthetic rubber and polystyrene resins. Phthalic anhydride is used in the manufacture of DMT, alkyd resins, and plasticizers such as phthalates. Maleic anhydride is used in the manufacture of polyesters and, to some extent, for alkyd resins. Minor uses include the manufacture of malathion and soil conditioners. Nitrobenzene is used in the manufacture of aniline, benzidine, and dyestuffs and as a solvent in polishes. Aniline is used in the manufacture of dyes, including azo dyes, and rubber chemicals such as vulcanization accelerators and antioxidants. [Pg.55]

Styrene-butadiene-styrene (SBS) block copolymers are adequate raw materials to produce thermoplastic mbbers (TRs). SBS contains butadiene—soft and elastic—and styrene— hard and tough—domains. Because the styrene domains act as cross-links, vulcanization is not necessary to provide dimensional stability. TRs generally contain polystyrene (to impart hardness), plasticizers, fillers, and antioxidants processing oils can also be added. Due to their nature, TR soles show low surface energy, and to reach proper adhesion a surface modification is always needed. [Pg.762]

In order to support and meet this demand, an all-around development has taken place on the material front too, be it an elastomer new-generation nanofiller, surface-modified or plasma-treated filler reinforcing materials like aramid, polyethylene naphthenate (PEN), and carbonfiber nitrosoamine-free vulcanization and vulcanizing agents antioxidants and antiozonents series of post-vulcanization stabUizers environment-friendly process oil, etc. [Pg.920]

Rubber chemicals (accelerator, antioxidant, retarder, peptizer, blowing and vulcanizing agents)... [Pg.1037]

ASTM Standard D 3156-81, Thin-layer Chromatographic Analysis of Antidegradants (Stabilizers, Antioxidants and Antiozonants) in Raw and Vulcanized Rubbers, Annual Book of ASTM Standards, ASTM, Philadelphia, PA (1990). [Pg.289]

Zinc dithiocarbamates have been used for many years as antioxidants/antiabrasives in motor oils and as vulcanization accelerators in rubber. The crystal structure of bis[A, A-di- -propyldithio-carbamato]zinc shows identical coordination of the two zinc atoms by five sulfur donors in a trigonal-bipyramidal environment with a zinc-zinc distance of 3.786 A.5 5 The electrochemistry of a range of dialkylthiocarbamate zinc complexes was studied at platinum and mercury electrodes. An exchange reaction was observed with mercury of the electrode.556 Different structural types have been identified by variation of the nitrogen donor in the pyridine and N,N,N, N -tetra-methylenediamine adducts of bis[7V,7V-di- .vo-propyldithiocarbamato]zinc. The pyridine shows a 1 1 complex and the TMEDA gives an unusual bridging coordination mode.557 The anionic complexes of zinc tris( V, V-dialkyldithiocarbamates) can be synthesized and have been spectroscopically characterized.558... [Pg.1196]

Modern life and civilization opened the way to other important practical applications of heterocycles, for example dyestuffs, copolymers, solvents, photographic sensitizers and developers, and in the rubber industry antioxidants and vulcanization accelerators. Some of the sturdiest polymers, such as Kevlar, have aromatic rings. Melamines (2,4,6-triamino-substituted s-triazines) are monomers with numerous applications as both homopolymers and copolymers. Scheme 9 shows a few examples of compounds with various applications in our daily life, having in common the same building block, the aromatic s-triazine. [Pg.4]

A more practical synthesis of 88 has been described involving chlorination and ring closure of bis(p-chlorophenyl) sulfide with a mixture of chlorine, sulfur, and aluminum chloride at 60° (82%). The octachloro compound (88) is reported to be very stable, showing little fragmentation in the mass spectrometer,and to be useful as a plasticizer, flame-proofing agent, antioxidant, and vulcanization accelerator. ... [Pg.251]

Type IV reactions are due to chemicals added during manufacture of NRL, which include accelerators, antioxidants, antiozo-nants, emulsifiers, stabilizers, extenders, colorants, retarders, stiffeners, and biocides. Accelerators primarily control the rate, uniformity, and completeness of vulcanization. The most common accelerators include thiurams, carbamates, and mercaptobenzothiazoles. These chemicals are covered in detail in their specific monographs in this volume. [Pg.622]


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See also in sourсe #XX -- [ Pg.123 , Pg.130 ]




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