Studies of synergism between carbon black and stabilisers in LDPE photodegradation

Peña, José Martínez; Allen, Norman S.; Edge, Michèle; Liauw, Christopher M.; Valange, B.

doi:10.1016/s0141-3910(01)00033-7

Cited by 48 publications

(24 citation statements)

References 13 publications

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“…The commercial samples, beyond carbon black, contain primary and secondary additives to prevent thermo-oxidation whereas our CBTS sample is free of these additives. Therefore, as pointed out by Peña et al 12,13 , the nature of the CB plays an important role in controlling its performance as a stabilizing agent alone, as well as its interactions with light stabilizers and antioxidants, via adsorption-desorption processes as well as other chemical interactions. Thus, if there is a synergistic interaction between the additives and carbon black, it can improve the thermal behaviour of the LDPE matrix during the OIT measurements.…”

Section: Resultsmentioning

confidence: 99%

Correlation among volumetric conductivity, electrical threshold field and compensation plots by oxidation induction time on LDPE/CB composites

2008

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The thermodynamic compensation effect plot derived from Eyring rate process theory was applied to the thermal and UV ageing of LDPE/Carbon Black composites containing commercial carbon black (CB) and carbon black surface oxidized with nitric acid. Correlations were tested among compensation effect, electrical threshold field and volumetric electrical conductivity. Compensation plots from OIT measurements correlate with thermal and UV ageing effect on activation ∆S and ∆H values, giving a good linear correlation for all samples studied. The relative changes in dc conductivity and electrical threshold field are consistent with the OIT compensation plot, demonstrating that this analysis can be used to monitor LDPE/CB composite degradation under thermal or UV ageing. It can also be used to evaluate, quite accurately, the effect of oxidizing the surface of the CB on the electrical properties (dc conductivity and electrical threshold field) of the LDPE/CB composites.

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Section: Resultsmentioning

confidence: 99%

Correlation among volumetric conductivity, electrical threshold field and compensation plots by oxidation induction time on LDPE/CB composites

2008

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“…Primary antioxidants break the degradation by donating H atoms to free radicals, thus preventing those radicals from the chain reaction. Secondary antioxidants rely on a mechanism involving the decomposition of hydroperoxides, which make them relatively stable so that they can't contribute to further polymer oxidation [7,8]. In particular, physical mixtures of these two types of antioxidants often show remarkable synergistic effects [7,[9][10][11]; however, either additive or antagonistic effects may also result as a consequence of using mixtures of stabilizers [9,11].…”

Section: Introductionmentioning

confidence: 99%

“…In particular, physical mixtures of these two types of antioxidants often show remarkable synergistic effects [7,[9][10][11]; however, either additive or antagonistic effects may also result as a consequence of using mixtures of stabilizers [9,11]. It is presumed that synergism of formulations can be attributed to the following reasons: (1) the synergism effect is attributed to their different and complementary anti-oxidative mechanisms [7,8] which have been discussed above. The reactions listed below are used to explain the synergism effect between hindered phenol and sulfuring containing antioxidant:…”

Section: Introductionmentioning

confidence: 99%

Performance and synergistic effect of phenolic and thio antioxidants in ABS graft copolymers

Guo

Wang

et al. 2010

Front. Chem. Sci. Eng.

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The synergistic effect of phenolic and thio antioxidants on the stabilization of acrylonitrile-butadienestyrene (ABS) graft copolymers has been studied. Three commercial antioxidants Irganox245, Irganox1076 and dilauryl thiodipropionate (DLTP) were selected. Formulations based on hindered phenols and secondary antioxidant DLTP were prepared. Stabilization was monitored in terms of changes in the functional groups (oxidation products), tensile properties and yellowness index. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were also used to assess the stability. The results indicated that the combination of Irganox245 and DLTP showed much better stabilization effect than the individual components due to the strong synergistic effect. Only weak synergism could be observed in the formulation that contained Irganox1076 and DLTP. Irganox1076 and Irgnox1076/DLTP exhibited similar behaviors between antioxidants with the highest and lowest efficiencies.

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“…Estes aditivos são empregados em larga escala em materiais poliméricos para melhorar características, principalmente estéticas, exigidas em diversas aplicações comerciais. Porém, a presença destes aditivos pode afetar de maneira drástica a estabilidade térmica ou fotoquímica do material, retardando ou acelerando a degradação do polímero [4][5][6][7][8][9].…”

Section: Introductionunclassified

“…Alguns mecanismos são propostos para explicar a ação dos colorantes nos processos degradativos [4][5][6][7][8]. Estes mecanismos prevêem que o oxigênio e a água podem participar diretamente da degradação, por meio da formação de espécies oxidantes com a participação do colorante ou participar de reações subsequentes de oxidação após o colorante ter sensibilizado a formação de espécies reativas no polímero [4][5][6][7][8].…”

Section: Introductionunclassified

Influência de colorantes na degradação termo-oxidativa do policarbonato

Saron¹,

Felisberti

2009

Matéria (Rio J.)

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RESUMOCorantes e pigmentos são incorporados aos polímeros principalmente para melhorar suas propriedades estéticas. Porém, estes aditivos podem afetar a estabilidade térmica e fotoquímica do material. Este trabalho teve como objetivo estudar a influência de diferentes classes de colorantes sobre a estabilidade termo-oxidativa do policarbonato (PC), empregando os pigmentos à base de diazo de condensação e vanadato de bismuto e os corantes do tipo antraquinona e ftalocianina de cobre. Para tanto, foram realizados ensaios termogravimétricos no modo dinâmico em diferentes taxas de aquecimento e avaliadas as taxas de conversão, determinadas pela derivação das curvas termogravimétricas, e as energias de ativação, determinadas segundo o método de FLYNN e WALL. A análise da taxa de conversão revelou que a decomposição do PC contendo ou não colorantes ocorre em três etapas principais, porém a velocidade nestas etapas para o PC com colorantes é, na maioria dos casos estudados, superior à taxa de decomposição do PC puro. Isto indica que os colorantes estudados aceleram a degradação do PC. Entretanto, a energia de ativação calculada segundo o método de FLYNN e WALL não apresentou a mesma tendência observada nos resultados obtidos a partir das taxas de decomposição, sugerindo que a decomposição do PC não deve ser regida por uma cinética de primeira ordem, conforme se baseia o modelo de FLYNN e WALL.Palavras-chaves: policarbonato, decomposição térmica, colorantes, energia de ativação. Influence of colorants on thermo-oxidative degradation of polycarbonate ABSTRACTDyes and pigments are additives used in polymer systems to change the original coloration of the material. However, the thermal and photochemical stability of the polymer is frequently affected with the incorporation of these additives. The aim of this work was to study the influence of different colorant types (bismuth vanadate pigment, condensation diazo pigment, Cu-phthalocyanine dye and anthraquinone dye) on the thermo-oxidative stability of polycarbonate. Dynamic thermogravimetric analysis at different heating rate were carried out to evaluate the decomposition behavior of the material and to calculate the activation energy related to the decomposition process according to the FLYNN and WALL method. The curves of conversion rate showed that the polycarbonate with or without colorants present three steps of thermal decomposition, however the decomposition rate in theses steps for polycarbonate containing colorants is almost always higher than in polycarbonate without colorants. This indicates that the colorants accelerate the polycarbonate decomposition. On the other hand, the activation energy did not present the same behavior found to curves of conversion rate, suggesting that the decomposition reaction of polycarbonate does not follow a first order kinetic such as is based the FLYNN and WALL method.Keywords: polycarbonate, thermal decomposition, colorants, activation energy. INTRODUÇÃODurante todo o ciclo de vida útil os polímeros são submetidos a diversas con...

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Studies of synergism between carbon black and stabilisers in LDPE photodegradation

Cited by 48 publications

References 13 publications

Correlation among volumetric conductivity, electrical threshold field and compensation plots by oxidation induction time on LDPE/CB composites

Correlation among volumetric conductivity, electrical threshold field and compensation plots by oxidation induction time on LDPE/CB composites

Performance and synergistic effect of phenolic and thio antioxidants in ABS graft copolymers

Influência de colorantes na degradação termo-oxidativa do policarbonato

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