Anti-ozonants

3-dimethylbutyl)-n -phenyl-p-phenylenediamine is a very powerful agent against the effects of flex cracking and ozone. Experience has shown that it is best used in conjunction with a microcrystalline wax having a melting range of 50 C to 54 C. Although a number of suppliers offer these materials it should be noted that there are minor variations, in the form of impurities that can affect performance. 

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Ozone degradation is a surface phenomenon and hence a physical anti-ozonant must form a protective barrier. A chemical anti-ozonant can be added during polymer fabrication, but again it must diffuse to the surface. It must also provide a defence over the lifetime of the article. 

Other Uses for Aniline. Aniline currently is used as a raw material in most of the major groups of rubber-processing chemicals accelerators, antioxidants and stabilizers, and anti-ozonants. The most important of these are the thiazole derivatives and substituted para-phenylenediamines. The demand for aniline in these rubber-processing uses is expected to grow at less than 1 percent/year. In agricultural chemicals, the major use for aniline is as a raw material in the manufacture of amide herbicides for controlling annual... 

Although equipped with several antioxidants, land-bound organisms have practically no protection against ground-level ozone, as the antioxidant do not protect against ozone itself but only its degradation products. A specific anti-ozonant is as yet unknown. In any case, it has not yet been necessary, as the organisms antioxidants were able to cope with the prior ozone concentrations. 

Uses Pigment for printing inks, thermoplastics, rubber compds., paints, soaps and iaundry blues, cosmetics, textile printing colorant for foods in food-contact textiies Features Strong anti-ozone chars. 

Features Strong anti-ozone chars. exc. light reist. very good weatherability good alkali resist. good... 

Acrylonitrile butadiene rubber is susceptible to ozone attack, and therefore suitable anti-ozonants and/or waxes need to be added. Acrylonitrile butadiene rubber /EPDM blends (at 70/30 or 80/20 ratio) bave a better ozone resistance than NBR alone. 

For most sealing applications, attack by ozone is only likely during storage, and this can be reduced by packing the seals properly. With exterior seals, ozone attack is possible, and ozone-resistant rubbers should be selected. If this is not possible, anti-ozonants should be added to the compound. 

Antiozone softener Effective cationic anti-ozone softness to treat premature yellowing of indigo denim garments. This imparts protective colloids over indigo dyes and softness to fibres. 

In the case of the purified rubber the trisulphide retarded oxidation but with the smoked sheet (which because of the natural antioxidants present oxidized at a lower rate) the trisulphide was a pro-oxidant. A similar pro-oxidant effect was obtained with a peroxide-cured vulcanizate from purified natural rubber but this contained both a trisulphide and a fairly conventional amine antioxidant (N-isopropyl N -phenyl-p-phenylene diamine—actually better known as an anti-ozonant). Monosulphides (e.g. AiSAi) were less antagonistic in their effect. 

The term antioxidant refers only to oxygen and in some cases temperature influence the designation antiozonant refers only to ozone influence. The term antifatigue agent is also used, because there are products with antioxidant function that also protect against dynamically induced crack formation without being anti-ozonants [229]. 

Also, nitrobenzene is used to produce 4-aminodiphenylamine to produce 6PPD anti-ozonant more efficiently than other synthesis routes. 

Compounds are pervasive in the polymer industry. Indeed, even presumably neat polymers are compounds containing antidegradents, which are antioxidants and/or anti-ozonants. These additives are small polar molecules. In more complex compounds there are in addition other polymers, reinforcing fillers, oils, curatives, and accelerators, which are intended to crosslink polymers. These are also small, usually polar, molecules. This chapter is about the philosophy of the polymer compound and the characteristics of their various ingredients. 

Polymer compoimds invariably contain antidegradents. These are generally further divided into antioxidants and anti-ozonants. The major group of antidegradents used in elastomers is composed of phenylene diamines, which have the structure ... 

Until recently, there were no effective, nonstaining, chemical antiozonants, since most chemical antiozonants were based upon p-phenylenediamine which severely stains rubber compounds. However, recent developments in the rubber chemicals industry have resulted in the production of a nonstaining, slightly discoloring anti-ozonant based upon triazine chemistry. This antiozonant is 2,4,6-tris-(Af-1,4-dimethyl-pentyl-p-phenylenediamino)-l,3,5-triazine (TAPDT), and the molecular stmcture is shown below. 

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