Mechanisms of Antioxidant Action: Aromatic Nitroxyl Radicals and Their Derived Hydroxylamines as Antifatigue Agents for Natural Rubber

Abstract Diarylnitroxyl radicals and their reduction products, the diaryl hydroxylamines are effective anti-fatigue agents for rubber, confirming the previously proposed mechanism of action of the diaryamincs. The nitroxyls are reduced by sulfur species formed during the vulcanization reaction to a mixture of hydroxylamines and parent amines, and these species act as reservoirs for the nitroxyl radical during fatiguing. Removal of the reservoir of reduced species by solvent extraction removes the antifatigue activity.

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Mechanisms of Antioxidant Action: The Antioxidant Activity of “Spin-Traps” in Rubber

Rubber Chemistry and Technology ◽

10.5254/1.3536033 ◽

1984 ◽

Vol 57 (4) ◽

pp. 779-791 ◽

Cited By ~ 6

Author(s):

L. P. Nethsinghe ◽

G. Scott

Keyword(s):

Antioxidant Activity ◽

Mechanism Of Action ◽

Nitroxyl Radicals ◽

Antioxidant Action ◽

Spin Traps ◽

Phenolic Group ◽

Stable Phenoxyl ◽

High Level

Abstract A number of nitrones containing a partially hindered phenolic group are shown to be effective antidegradants for sulfur vulcanized rubbers. They exhibit a high level of antiozonant and antifatigue activity, but unlike commercial antiozonants they do not cause discoloration of light colored formulations. The new antidegradants are less effective than conventional additives as thermal antioxidants, but their performance as antifatigue agents and antioxidants is augmented by their use in combination with nonstaining antioxidants. The mechanism of action of the phenolic nitrones is believed to involve their oxidation to stable phenoxyl/nitroxyl radicals.

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The mechanism of action of N-acetylcysteine (NAC): The emerging role of H2S and sulfane sulfur species

Pharmacology & Therapeutics ◽

10.1016/j.pharmthera.2021.107916 ◽

2021 ◽

pp. 107916

Author(s):

Brandán Pedre ◽

Uladzimir Barayeu ◽

Daria Ezeriņa ◽

Tobias P. Dick

Keyword(s):

Mechanism Of Action ◽

Sulfur Species ◽

Sulfane Sulfur

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Mechanisms of antioxidant action: Radical addition reactions of the dialkyl dithiophosphoric acids and their derivatives to natural rubber

Polymer Degradation and Stability ◽

10.1016/0141-3910(86)90097-2 ◽

1986 ◽

Vol 16 (1) ◽

pp. 25-34 ◽

Cited By ~ 5

Author(s):

S. Al-Malaika ◽

S. Honggokusumo ◽

G. Scott

Keyword(s):

Natural Rubber ◽

Radical Addition ◽

Addition Reactions ◽

Antioxidant Action

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Mechanisms of Antioxidant Action: Rubber-Bound Antioxidants Based on Nitrones—I. Non-Sulphur Vulcanizates

Rubber Chemistry and Technology ◽

10.5254/1.3535257 ◽

1979 ◽

Vol 52 (5) ◽

pp. 949-961 ◽

Cited By ~ 2

Author(s):

G. Scott ◽

K. V. Smith

Keyword(s):

Solvent Extraction ◽

Antioxidant Activities ◽

Zinc Salt ◽

Antioxidant Action ◽

Before And After ◽

Hindered Phenol

Abstract The antioxidant activities of a number of N-phenyl nitrones containing phenolic functions were compared with N-methyl nitrones and conventional antioxidants in peroxide and TMTD sulphurless vulcanizates. The N-phenyl nitrones were found to be effectively bound during vulcanization; whereas, the N-methyl nitrones were not. Unhindered phenols reacted to a higher degree and were relatively more effective than the typical hindered phenol antioxidant structures. A conventional bisphenol was effective in the sulphurless vulcanizate after solvent extraction, but this is considered to be due to the formation of an insoluble zinc salt. Synergism was observed in the TMTD sulphurless vulcanizate both before and after extraction.

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Lanthanide Complexes with a Tripodal Nitroxyl Radical Showing Strong Magnetic Coupling

10.26434/chemrxiv.12801164 ◽

2020 ◽

Author(s):

Mauro Perfetti ◽

Andrea Caneschi ◽

Taisiya S. Sukhikh ◽

Kira E. Vostrikova

Keyword(s):

Single Molecule ◽

Nitroxyl Radical ◽

Magnetic Coupling ◽

Magnetic Behavior ◽

Nitroxyl Radicals ◽

Antiferromagnetic Coupling ◽

Zero Field ◽

Effective Barrier ◽

Mononuclear Complexes ◽

Tricapped Trigonal Prism

A series of isomorphous mononuclear complexes of Ln(III) ions comprising one stable tripoidal oxazolidine nitroxyl radical were obtained in acetonitrile media starting from nitrates. The compounds, [LnRad(NO3)3] (Ln = Gd, Tb, Dy, Tm, Y; Rad = 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl), have molecular structure. Their coordination polyhedron, LnO7N2, can be described as a tricapped trigonal prism with symmetry close to D3h. The value of 23 cm-1 for the antiferromagnetic coupling Gd-Rad established from the DC magnetic and EPR data is a record strength for the complexes of 4f-elements with nitroxyl radicals. The terbium derivative displays frequency-dependent out-of-phase signals in zero field indicating single-molecule magnetic behavior with an effective barrier of 57 cm-1.

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Mechanisms of antioxidant action. The role of nitroxyl radicals as chain-breaking acceptor antioxidants in the mechanodegradation of rubber

European Polymer Journal ◽

10.1016/0014-3057(84)90039-9 ◽

1984 ◽

Vol 20 (3) ◽

pp. 213-217 ◽

Cited By ~ 7

Author(s):

L.P. Nethsinghe ◽

G. Scott

Keyword(s):

Nitroxyl Radicals ◽

Antioxidant Action ◽

Chain Breaking

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Investigations on Metal Injection Molding of 316L SS Using Thermoplastic Natural Rubber (TPNR) Binder as a New System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.576.150 ◽

2012 ◽

Vol 576 ◽

pp. 150-153 ◽

Cited By ~ 1

Author(s):

Hassan Norita ◽

Noor Azlina Hassan ◽

Sahrim H. Ahmad ◽

N. Muhamad ◽

Mohd Afian Omar ◽

...

Keyword(s):

Solvent Extraction ◽

Injection Molding ◽

Natural Rubber ◽

Extraction Process ◽

Metal Injection Molding ◽

Binder System ◽

Outward Appearance ◽

Injection Parameter ◽

Near Net Shape ◽

Thermoplastic Natural Rubber

Metal injection molding (MIM) is a near net-shape manufacturing technology that is capable of mass production of complex parts cost-effectively. The unique features of the process make it an attractive route for the fabrication of the new binder system since the success of MIM process is dependent on the outward appearance of the resultant feedstock. Thermoplastic natural rubbers (TPNR) blends consist of thermoplastics, such as polyethylene (PE), alloyed with natural rubber (NR) with different thermoplastic to NR ratios. The soft grade TPNR is produced by blends with compositions richer in rubber while the harder grades can contain up to about 30 % NR. This study investigates the influence of new binder system consisting of TPNR on injection parameter, density of injected molded specimen and changes during solvent extraction. Results show that TPNR plays an important role as a good binder system and shortens the solvent extraction process.

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