A phenolic antioxidant trapping both alkyl and peroxy radicals

Ohkatsu, Yasukazu; Matsuura, Takanori; Yamato, Mitsugu

doi:10.1016/s0141-3910(03)00084-3

Cited by 30 publications

(14 citation statements)

References 6 publications

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“…21 The higher antioxidant activity of cardanol (higher τ i and smaller k) compared with Hcardanol, both added at 5% concentration (Table 1) indicates that the unsaturation on the long side chain could be an important factor. Recently, Ohkatsu et al 22 proposed that some phenols with allyl substituents could trap both alkyl and peroxy radicals, and increase antioxidant activity, taking into account that autoxidation includes these two radicals as chain carriers. The mechanism of trapping rubber radicals (R • ) is suggested in Figure 4, similar to that proposed by the authors.…”

Section: Effect Of Cnsl Derivative Structurementioning

confidence: 99%

“…The mechanism of trapping rubber radicals (R • ) is suggested in Figure 4, similar to that proposed by the authors. 22 To assure a better understanding of those mechanism, the long side chain of cardanol (R = C 15 H 31-2n ) was considered as having only one unsaturation (n = 1). Steps II and IV are probably difficult to occur considering the high molar mass of the rubber radical.…”

Section: Effect Of Cnsl Derivative Structurementioning

confidence: 99%

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Antioxidant activity of cashew nut shell liquid (CNSL) derivatives on the thermal oxidation of synthetic cis-1,4-polyisoprene

Rodrigues¹,

Feitosa²,

Ricardo³

et al. 2006

J. Braz. Chem. Soc.

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LCC (Líquido da Castanha de Caju), ou CNSL (Cashew Nut Shell Liquid), é uma mistura de meta-alquilfenóis, que variam no grau de insaturação do grupo ligado ao núcleo benzênico. A degradação térmica do poli(1,4-cis-isopreno) sintético a 140 °C foi estudada na presença do LCC técnico e de alguns derivados (cardanol, cardanol hidrogenado e cardanol hidrogenado e alquilado), através de FTIR. A quantidade de grupamentos OH/OOH e C=O formados e de C=C consumidos foi determinada durante a degradação. Todos os materiais aumentaram o tempo de indução e diminuíram as constantes aparentes de velocidade. Com base nos parâmetros cinéticos, a ordem de atividade antioxidante é: LCC >> cardanol ≅ cardanol hidrogenado e alquilado > cardanol hidrogenado. O efeito do LCC pode ser atribuído à contribuição extra de seus outros componentes, além do cardanol, e à insaturação na longa cadeia lateral. Essa maior atividade é importante, considerando que o LCC tem mais baixo custo do que seus derivados.CNSL is a mixture of meta-alkylphenols with variable degree of unsaturation attached to the benzene ring. The kinetic study of the thermal degradation at 140 °C of synthetic cis-1,4-polyisoprene film, in the presence of technical CNSL and some derivatives (cardanol, hydrogenated cardanol and alkylated hydrogenated cardanol) was carried out by FTIR. The amount of OH/OOH and C=O formed and also of C=C consumed during the degradation was determined. All materials increase the induction period and decrease the apparent rate constants of thermal-oxidation. Based on kinetic parameters, the order of antioxidant activity was: CNSL >> cardanol ≅ hydrogenated and alkylated cardanol > hydrogenated cardanol. The effect of CNSL could be attributed to the extra contribution of the other components besides cardanol and to the unsaturation on the long side chain. This greater activity is important because CNSL is much more cost effective than its derivatives.

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Section: Effect Of Cnsl Derivative Structurementioning

confidence: 99%

Section: Effect Of Cnsl Derivative Structurementioning

confidence: 99%

Antioxidant activity of cashew nut shell liquid (CNSL) derivatives on the thermal oxidation of synthetic cis-1,4-polyisoprene

Rodrigues¹,

Feitosa²,

Ricardo³

et al. 2006

J. Braz. Chem. Soc.

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“…The radicals generated during the irradiation process should be quickly scavenged by the antioxidants in the layers where these additives are present [14]. The presence of oxygen-containing organic molecules results from the competition between the free-radical scavenging by antioxidants and the reaction of O 2 with the hydrocarbon chains [15]. This competition may depend on the g-irradiation dose rate and on the direct availability of oxygen and antioxidants [15].…”

Section: Introductionmentioning

confidence: 99%

Degradation of γ-irradiated polyethylene-ethylene vinyl alcohol-polyethylene multilayer films: An ESR study

Audran

Dorey²,

Dupuy

et al. 2015

Polymer Degradation and Stability

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International audienceThe present work aims to investigate by ESR the effects of gamma-irradiation on antioxidants and on solid multilayer films used in biomedical applications. The multilayer films analyzed here are mainly composed of polyethylene and ethylene vinyl alcohol. Radical species are monitored over time after gamma-irradiation at several doses (30, 50,115 and 270 kGy) using ESR to assess the impact of the dose-value on the formation of the radicals

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“…Hindered phenols terminate autoxidation by trapping alkylperoxy, alkoxy and alkyl radicals [11][12][13][14]. The efficiency of the phenolic antioxidant depends on the number of hydroxyl groups and the nature of substituents at the orto and para positions to the phenolic OH group [15,16]. The synergistic effect of phenol/phosphorous antioxidant combinations compared to single antioxidants can be partly attributed to the reduced rate of consumption of each type of stabiliser during the processing of polyethylene [10].…”

Section: Introductionmentioning

confidence: 99%

Study of the effect of natural antioxidants in polyethylene: Performance of β-carotene

Tátraaljai

Major

Földes

et al. 2014

Polymer Degradation and Stability

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The effect of β-carotene on the behaviour of polyethylene stabilized with α-tocopherol and a phosphonite antioxidant was studied under processing and storage conditions. The amount of β-carotene ranged between 0 and 2000 ppm. The polymer was characterised by different methods after processing then during and after storage at ambient temperature in light and dark. β-Carotene hinders the oxidation of polyethylene and does not increase the chain extension reactions during processing, though more vinyl groups and phosphonite molecules react. β-Carotene colours polyethylene strongly already at low concentrations. The reactions of the polymer and β-carotene are affected strongly by the storage conditions. The presence of β-carotene does not influence the stabilizing efficiency of the primary and secondary antioxidants. In dark the molecular structure of the polymer does not change appreciably, while the reactions of β-carotene lead to an increase in the yellowness index. In light the molecular characteristics of polyethylene undergo significant changes indicating long chain branching. The polymer fades rapidly after an induction period. The length of the induction period is not influenced by light. The rate of the degradation reactions of β-carotene during storage is controlled by its concentration and film thickness. Visible autoaccelerated decomposition in light renders β-carotene candidate as an indicator in active packaging materials.

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A phenolic antioxidant trapping both alkyl and peroxy radicals

Cited by 30 publications

References 6 publications

Antioxidant activity of cashew nut shell liquid (CNSL) derivatives on the thermal oxidation of synthetic cis-1,4-polyisoprene

Antioxidant activity of cashew nut shell liquid (CNSL) derivatives on the thermal oxidation of synthetic cis-1,4-polyisoprene

Degradation of γ-irradiated polyethylene-ethylene vinyl alcohol-polyethylene multilayer films: An ESR study

Study of the effect of natural antioxidants in polyethylene: Performance of β-carotene

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