An antiozonant, also known as anti-ozonant, is an organic compound that prevents or retards the degradation of material caused by ozone (ozone cracking). Antiozonants are used as additives to plastics and rubber, especially in tire manufacturing.
In chemistry, an organic compound is generally any chemical compound that contains carbon. Due to carbon's ability to catenate, millions of organic compounds are known. Study of the properties and synthesis of organic compounds is the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds, along with a handful of other exceptions, are not classified as organic compounds and are considered inorganic. No consensus exists among chemists on precisely which carbon-containing compounds are excluded, making the definition of an organic compound elusive. Although organic compounds make up only a small percentage of the Earth's crust, they are of central importance because all known life is based on organic compounds. Most synthetically produced organic compounds are ultimately derived from petrochemicals consisting mainly of hydrocarbons.
Ozone, or trioxygen, is an inorganic molecule with the chemical formula O
3. It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope O
2, breaking down in the lower atmosphere to O
2 (dioxygen). Ozone is formed from dioxygen by the action of ultraviolet light (UV) and electrical discharges within the Earth's atmosphere. It is present in very low concentrations throughout the latter, with its highest concentration high in the ozone layer of the stratosphere, which absorbs most of the Sun's ultraviolet (UV) radiation.
Cracks can be formed in many different elastomers by ozone attack, and the characteristic form of attack of vulnerable rubbers is known as ozone cracking. The problem was formerly very common, especially in tires, but is now rarely seen in those products owing to preventive measures.
Common antiozonants include:
p-Phenylenediamine (PPD) is an organic compound with the formula C6H4(NH2)2. This derivative of aniline is a white solid, but samples can darken due to air oxidation. It is mainly used as a component of engineering polymers and composites like kevlar. It is also an ingredient in hair dyes and is occasionally used as a substitute for henna.
N-Isopropyl-N′-phenyl-1,4-phenylenediamine is a chemical compound commonly used as an antiozonant in rubbers, particularly those used for tires. Like other p-phenylenediamine based antiozonants it works by virtue of its low ionization energy which allows it to react with ozone faster than ozone will react with rubber. This reaction converts it to the corresponding aminoxyl radical (R2N–O•), with the ozone being converted to a hydroperoxyl radical (HOO•), these species can then be scavenged by other antioxidant polymer stabilizers.
Ethylene diurea (EDU) is a chemical compound with the formula C4H10N4O2. It has been analyzed by several groups to determine whether it is a successful antiozonant. If so, this substance would help crops by preventing the harmful effects on crops by ozone. In an experiment run in 2002 by a group called Alberta Environment (now known as Alberta Environment and Sustainable Resource Development, they determined that EDU did one of two things. The substance either prevented the harmful effects of ozone or it stimulated plant growth.
In industrial chemistry, a stabilizer is a chemical that is used to prevent degradation. Heat and light stabilizers are added to plastics and elastomers because they ensure safe processing and protect products against aging and weathering. The trend is towards fluid systems, pellets, and increased use of masterbatches. There are monofunctional, bifunctional, and polyfunctional stabilizers. In economic terms the most important product groups on the market for stabilizers are compounds based on calcium, lead, and tin stabilizers as well as liquid and light stabilizers. Cadmium-based stabilizers largely vanished in the last years due to health and environmental concerns.
Antioxidants are compounds that inhibit oxidation. Oxidation is a chemical reaction that can produce free radicals, thereby leading to chain reactions that may damage the cells of organisms. Antioxidants such as thiols or ascorbic acid terminate these chain reactions. To balance the oxidative state, plants and animals maintain complex systems of overlapping antioxidants, such as glutathione and enzymes, produced internally, or the dietary antioxidants vitamin C, and vitamin E.
Aniline is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the prototypical aromatic amine. Its main use is in the manufacture of precursors to polyurethane and other industrial chemicals. Like most volatile amines, it has the odor of rotten fish. It ignites readily, burning with a smoky flame characteristic of aromatic compounds.
Ozonolysis is an organic reaction where the unsaturated bonds of alkenes, alkynes, or azo compounds are cleaved with ozone. Alkenes and alkynes form organic compounds in which the multiple carbon–carbon bond has been replaced by a carbonyl group while azo compounds form nitrosamines. The outcome of the reaction depends on the type of multiple bond being oxidized and the work-up conditions.
Methyl isobutyl ketone (MIBK) is the organic compound with the formula (CH3)2CHCH2C(O)CH3. This colourless liquid, a ketone, is used as a solvent for gums, resins, paints, varnishes, lacquers, and nitrocellulose.
o-Phenylenediamine (OPD) is an organic compound with the formula C6H4(NH2)2. This aromatic diamine is an important precursor to many heterocyclic compounds. It is isomeric with m-phenylenediamine and p-phenylenediamine.
2-Nitrodiphenylamine, also called NDPA, 2-NDPA, 2NO2DPA, Sudan Yellow 1339, C.I. 10335, CI 10335, phenyl 2-nitrophenylamine, 2-nitro-N-phenylaniline, or N-phenyl-o-nitroaniline, is an organic chemical, a nitrated aromatic amine, a derivate of diphenylamine. Its chemical formula is C12H10N2O2, or C6H5NHC6H4NO2. It is a red crystalline solid, usually in form of flakes or powder, with melting point of 74-76 °C and boiling point of 346 °C. It is polar but hydrophobic.
Thiocarbanilide is an organic chemical compound with the formula (C6H5NH)2CS. This white solid is a derivative of thiourea. It is prepared by the reaction of aniline and carbon disulfide.
A diamine is an organic compound with two amino groups. Diamines are used as monomers to prepare polyamides, polyimides, and polyureas. In terms of quantities produced, 1,6-diaminohexane, a precursor to Nylon 6-6, is most important, followed by ethylenediamine. Vicinal diamines (1,2-diamines) are a structural motif in many biological compounds and are used as ligands in coordination chemistry.
Stabilizers are a class of chemical additives commonly added to polymeric materials, such as plastics, to inhibit or retard their degradation. Polymers can be subject to various degradation processes, including oxidation, UV-damage, thermal degradation, ozonolysis, or combinations thereof like photo-oxidation. These processes all degrade the polymer on a chemical level, leading to chain scission that can adversely affect its mechanical properties such as strength and malleability, as well as its appearance and colour.
Dimethyl-4-phenylenediamine is an amine. It has been used as an accelerator for the vulcanization of rubber. It can be used in oxidase tests.
Pentylone is a stimulant developed in the 1960s. It is a substituted cathinone. It has been identified in some samples of powders sold as "NRG-1", along with varying blends of other cathinone derivatives including flephedrone, MDPBP, MDPV and 4-MePPP. It was also found in combination with 4-MePPP being sold as "NRG-3". Reports indicate side effects include feelings of paranoia, agitation and inability to sleep, with effects lasting for several days at high doses.
Joseph A. Kuczkowski is a Goodyear scientist, noted for successfully explaining the mechanisms of antioxidant and antiozonant function, and for commercial development of new antiozonant systems and improvement of the stability of polymeric materials.
Aminoxyl radicals are chemical species containing the R2N–O• functional group. They are also known as nitroxyl radicals and nitroxides, however IUPAC discourages the use of these terms, as they erroneously suggest the presence of a nitro group. They are radicals and are structurally related to oximes (hydroxylamines) and N-oxoammonium salts, with which they can interconvert via a series of redox steps.
In polymer chemistry, materials science, and food science, bloom refers to the migration of one component of a solid mixture to the surface of an article. The process is an example of phase separation or phase aggregation.
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