mechanistic action of phenolic antioxidants in polymers
Mechanistic action of phenolic antioxidants in polymers—A
Mechanistic action of phenolic antioxidants in polymers 191 MECHANISM OF ANTIOXIDANT ACTION OF PHENOLIC ANTIOXIDANTS: CHEMISTRY OF TRANSFORMATIONS Phenoxyls are the first detectable radical species formed from phenolic antioxidants as a consequence of H-transfer to RO2 (RO') radicals.4'6 They are also formed to some extent by oxidation with molecular oxygen at temperatures above 150, in sensitised photo-oxidation27 and during the radiolysis of phenols.7 The chemistry of phenoxyls is decisive ...
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Polymer Degradation and Stability | Polymer Additives
Read the latest articles of Polymer Degradation and Stability at ScienceDirect.com, Elsevier’s leading platform of peer-reviewed scholarly literature. ... Mechanistic action of phenolic antioxidants in polymers—A review. Jan Pospíšil. Pages 181-202 Download PDF. Article preview.
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Phenolic Antioxidant - an overview | ScienceDirect Topics
Research findings. In food contact and medical grade PVC, good stabilization was obtained by a combination of zinc carboxylate, alkyl ester of thiodipropionic acid, and phenolic antioxidant.312 A halogen containing polymer in the form of an aqueous suspension or emulsion contains a partially hindered phenolic antioxidant...
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Secondary Antioxidant - an overview | ScienceDirect Topics
It is well known that polymerization catalyst residues can induce the degradation of polymers, which can result in a faster conversion of present phenolic antioxidants and thus to discoloration. A possible mechanism of action of phosphites is that they form a complex with these metal ions and reduce their negative influence.
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Color Inhibition of Phenolic Antioxidants in Ziegler-Natta
clic phenolic antioxidants that are substituted in positions 2 or 4 to a hydroxyl group with methyl, methylene or methine groups. However, it is well-established that QM also exhibit a stabilizing effect when present in combina-tion with phenolic antioxidants [7, 8] due to the formation of a stillbenequinone.
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Phenolic Antioxidants
Phenolic antioxidants inhibit autooxidation of organic polymers by reducing the amount of peroxyl radicals during processing, storage and service. They are strong hydrogen / electron donors and, in addition, their radical intermediates are relatively stable due to aromatic resonance stabilization of the unpaired electron.
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Antioxidants: Mechanisms of Action and Effectiveness
Antioxidants: Mechanisms of Action and Effectiveness. Those antioxidants capable of interrupting the free radical chain reaction are usually the most effective. 4 They are characterized by aromatic or phenolic rings and act by donating a hydrogen atom to free radicals formed during oxidation.
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Polymer stabilizers
Light stabilizers. Light stabilizer are used to inhibit polymer photo-oxidation, which is the combined result of the action of light and oxygen. Like autoxidation this is a free radical process, hence the antioxidants described above are effective inhibiting agents, however additional classes of additives are also beneficial,...
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Chemical and photochemical behaviour of phenolic
Polymer Degradation and Stability 39 (1993) 103-115 Chemical and photochemical behaviour of phenolic antioxidants in polymer stabilization: a state of the art report, part II Jan Pospi~il Institute of Macromolecular Chemistry, Czechoslovak Academy of Sciences, 162 06 Prague 6, Czechoslovakia (Received 8 October 1991; accepted 8 October 1991) In practical stabilization of polymers, phenols are ...
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Chemical and molecular mechanisms of antioxidants
The antioxidant may directly react with initiator radicals or lipid peroxides, and it may also inhibit the formation of active radicals. These mechanisms of action of any antioxidant are critical and warrant for further investigations with radical scavenging assays and ion chelating tests.
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Two phenolic antioxidants in Suoyang enhance viability of
Then, two phenolic antioxidant references, epicatechin and luteolin-7-O-β-D-glucoside, along with LAS, were investigated for their effects on the viability ofThe comparison and mechanistic chemistry of epicatechin and luteolin-7-O-β-D-glucoside were further explored using various antioxidant assays
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Mechanistic aspects of hydrogen abstraction for phenolic antioxidants
Isolation and Characterization of Phenolic Antioxidants - CiteSeerX. Mechanistic Aspects of Photoinduced Rearrangement.For example, the phenol a-tocopherol (vitamin E) is the most important lipid-soluble, chain breaking natural antioxidant in human blood plasma and low-density
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Phenolic Antioxidant - an overview | ScienceDirect Topics
Use of phenolic antioxidants, in spite of a large number of commercial products available, is quite limited in PVC.A halogen containing polymer in the form of an aqueous suspension or emulsion contains a partially hindered phenolic antioxidant andMechanism of action of benzofuranones.
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Phenolic Antioxidants | Polymer Chemistry
Phenolic antioxidants inhibit autooxidation of organic polymers by reducing the amount of peroxyl radicals during processing, storage and service. They are strong hydrogen / electron donors and, in addition, their radical intermediates are relatively stable due to aromatic resonance stabilization of the
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Two phenolic antioxidants in Suoyang enhance viability
can act as phenolic antioxidants because of the presence. of phenolic –OH in their molecules.tive effect of phenolic antioxidants in Suoyang towards. •OH-mediated MSCs based on MTT assayaction of LAS. When comparing epicatechin and luteolin-7-O-β-. D-glucoside, however, the former
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Two phenolic antioxidants in Suoyang enhance viability
The comparison and mechanistic chemistry of epicatechin and luteolin-7-O-β-D-glucoside were further explored using various antioxidant assays, includingThe present study attempted to investigate the protective effect of phenolic antioxidants in Suoyang towards •OH-mediated MSCs and then further
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Antioxidant Interactions Between Major Phenolic Compounds
biological action of phenolic antioxidants. In Figure 2 are shown the chemical structures of the four phenolictype of phenolic compound or other kind of antioxidants contained in the product, such as vitaminMore studies with combinations are required in a more mechanistic way, including infrared
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In all probability it can be assumed that the high potential of the stabilising action of BP is connected withThe index used in evaluating the stabilising properties of antioxidants in SKI-3, characterising theIt is known that the basic reaction of inhibition of the oxidation of carbon-chain polymers is the
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Mechanistic aspects of hydrogen abstraction for phenolic antioxidants.
Density functional calculations using the B3LYP functional are used to provide insight into the hydrogen abstraction mechanism of phenolic antioxidants. The energy profiles for 13 ortho, meta, para and di-methyl substituted phenols with hydroperoxyl radical have been determined.
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Antioxidant and Antiradical Properties of Selected Flavonoids
Phenolic compounds and flavonoids are known by their antioxidant properties and one of the most important sources for humans is the diet.Many methods have been developed to determine the antioxidant capacities of synthetic or naturally sourced compounds, plant extracts, and other samples.
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