Inhibition of Autoxidation by Hindered Amine Light Stabilizers and Their Derivatives.

Ohkatsu, Yasukazu; Yamaguchi, Kazuo; Kubo, Kenji; Sengoku, Tadashi

doi:10.1627/jpi1958.37.395

Cited by 6 publications

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“…HALS and derivatives undergo changes in chemical structures during action as antioxidants and do not show any clear induction period, so the n value cannot be calculated. Therefore, the nkinh values are used as the total antioxidant index to com- pare the activities of antioxidants used in this study 6) . The index, nkinh, shows that antioxidant activities decrease in the order of linear dialkyl hydroxylamines BHTHALS NOH.…”

Section: Radical Scavenging Potential Of Distearylmentioning

confidence: 99%

Radical Scaveging Mechanism of Distearyl Hydroxylamine Antioxidant

Ohkatsu

Baba

Watanabe

2011

J. Jpn. Petrol. Inst.

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Section: Radical Scavenging Potential Of Distearylmentioning

confidence: 99%

Radical Scaveging Mechanism of Distearyl Hydroxylamine Antioxidant

Ohkatsu

Baba

Watanabe

2011

J. Jpn. Petrol. Inst.

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Interactions of stabilizers during oxidation processes

Habicher

Бауер

Scheim

et al. 1997

Macromolecular Symposia

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The antioxidative action of mixtures of phenols, phosphites, HALS, and some of their transformation products in various compositions has been studied in the thermo-and photooxidation of hydrocarbons and polypropylene under different conditions. In the AIBN-initiated oxidation of hydrocarbons at low temperatures (< 8OoC), hindered phenols, hindered aryl phosphites and the nitroxyl derivatives of HALS act antioxidatively when used individually in appropriate concentrations. Secondary HALS do not show any induction period, but a certain retardation of the oxidation process after some reaction time. The inhibiting efficiency of nitroxyls observed cannot be explained completely by the currently accepted action mechanisms of HALS, but is also related to the reaction of the nitroxyls with alkylperoxyl radicals.In mixtures with hindered phenols, HALS have almost no influence on the rate of thermooxidation at low temperatures. Their nitroxyl derivatives, however, always exhibit synergism, most pronounced when both stabilizers are used in equimolar ratios. During the photooxidation phenols lower the efficiency of HALS.The influence of mixtures of stabilizers on the oxidative stability of polypropylene is rather different and depends on the oxidation conditions, the structure, the concentration and the ratio of the stabilizers. Synergistic as well as antagonistic effects are observed. Both aliphatic and aromatic phosphites studied act synergistically when used together and with phenols. This demonstrates that for acting as synergist for phenols, the hydrogen peroxide decomposing capability of the phosphites, but not their chain breaking activity is important. HALS-phosphites and phosphonites, containing amine and phosphorus units in one molecule, are highly effective inhibitors of photo-and thermwxidation and exhibit lower critical antioxidant concentrations and longer induction periods than phosphites alone. They even exceed the efficiency of phenols in many cases.Transformation products of phenolic antioxidants investigated act differently and in many cases contrarily under photo-and thermooxidative conditions. Therefore, they influence the efficiency of stabilizer mixtures also in a different way. a) HALS: Hindered Arnine Light Stabilizers

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Influence of Ultraviolet Absorbers on Decomposition of Hydroperoxide by Hindered Amine Light Stabilizers

Mizokawa

Ohkatsu

2007

J. Jpn. Petrol. Inst.

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The interaction between hindered amine light stabilizers (HALS), and ultraviolet absorbers (UVA) was investigated, in order to clarify the reason why they generally show synergism, although UVA belong to kinds of phenols. A homolytic decomposition of cumene hydroperoxide (CHP) by amine-type HALS (HALS NH) in the presence of UVA is the antagonism bringing about autoxidation. This antagonism is found considerably weaker for UVA than that of 3,5-di-t-butyl-4-hydroxytoluene. This is based on a weak proton-donating ability of UVA to HALS due to their intramolecular hydrogen bond. Furthermore, a good relationship was found between the inhibition of photo-oxidation by UVA and the initial rate of homolytic decomposition of CHP by HALS in the presence of UVA, and a strong synergism of UVA with HALS was observed. As a result, UVA are able to exhibit an apparent synergism in a combination with HALS, because of no or little acceleration (antagonism) of homolytic hydroperoxide decomposition caused by the interaction with HALS, as well as the estimated regeneration (synergism) of new UVA from the corresponding quinoide-type compounds, even if formed, by the action of HALS or the derivatives.

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Inhibition of Autoxidation by Hindered Amine Light Stabilizers and Their Derivatives.

Cited by 6 publications

References 0 publications

Radical Scaveging Mechanism of Distearyl Hydroxylamine Antioxidant

Radical Scaveging Mechanism of Distearyl Hydroxylamine Antioxidant

Interactions of stabilizers during oxidation processes

Influence of Ultraviolet Absorbers on Decomposition of Hydroperoxide by Hindered Amine Light Stabilizers

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