Antioxidant properties of lignin in polypropylene

Pouteau, Charlyse; Dole, Patrice; Cathala, Bernard; Avérous, Luc; Boquillon, Nicolas

doi:10.1016/s0141-3910(03)00057-0

Cited by 370 publications

(221 citation statements)

References 28 publications

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“…Todas essas observações são estatisticamente válidas e apresentaram um grau de confiança (p) muito inferiores ao limite imposto, igual a 0,005. Assim, a causa do fenômeno da diminuição da resistividade com o aumento da concentração de anilina e de APS parece ser relacionada com o caráter antioxidante da lignina presente nas fibras [12] , levando a necessidade de maiores quantidades de oxidante para a formação de polianilina de menor resistividade. Além disso, este conjunto de resultados permite, em comparação com estudos anteriores, prever as propriedades elétricas Os resultados morfológicos estão possivelmente relacionados à quantidade de polímero necessária para a modificação das fibras.…”

Section: Caracterizaçãounclassified

Estudo das propriedades mecânicas e elétricas de fibras de curauá modificada com polianilina

Picciani

Rocha

et al. 2010

Polímeros

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Resumo: Fibras naturais têm sido empregadas em diversos compósitos, principalmente na indústria automobilística. Dentre as diversas fibras naturais, a fibra de curauá é atraente por apresentar elevada propriedade mecânica associada a baixos valores de densidade. Neste trabalho a fibra de curauá é modificada quimicamente pelo recobrimento de uma camada condutora de polianilina, PAni. O material obtido foi caracterizado pelas técnicas espectrometria de infravermelho por transformada de Fourier (FTIR), análise termogravimétrica (TG) e microscopia ótica. As técnicas de caracterização utilizadas demonstraram que a metodologia empregada foi eficiente para formar um recobrimento parcial, porém efetivo, uma vez que o recobrimento permitiu a formação de caminhos condutores ao longo de toda a fibra. As propriedades eletro-mecânicas das fibras também foram avaliadas e os compósitos apresentaram um grande potencial para a construção de sensores de pressão a baixos custos. Palavras-chave: Fibra de curauá, polianilina, condutividade elétrica, degradabilidade. Study on Mechanical and Electrical Properties of Curaua Fibers Modified with PolianilineAbstract: Natural fibers have been employed as reinforcement filler in composite materials for the automobile industry. Among the natural fibers, the curauá fiber is promising due to its high mechanical resistance associated with low density values. In this work curauá fibers are chemically modified by a conducting polyaniline coating, with the aim of using this new conductive composite as pressure sensors. The composite material obtained was characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG) and optical microscopy. The results demonstrated that the methodology adopted was efficient in forming a partial, but effective, coating of the fiber, thus leading to conducting paths along the whole fiber. The electro-mechanical properties of the fibers were also evaluated and the composites have potential for low cost pressure sensors. Furthermore, the modified fibers had good thermal stability and the partial coating allows the composite to be naturally degraded as an environmentally-friendly material. Keywords: Curaua fiber, polyaniline, electrical conductivity, degradability. IntroduçãoO aproveitamento dos recursos naturais é uma opção para alguns setores produtivos devido à possibilidade de substituição, total ou parcial, dos materiais sintéticos por outros ecologicamente amigáveis, também capazes de agregar valor ao produto final. Dentre os materiais que apresentam grande potencial para a aplicação industrial encontram-se as fibras vegetais. Muitas destas fibras já estão presentes na natureza em quantidades apropriadas para serem utilizadas pela indústria, enquanto outras apresentam fácil adaptação de cultivo visando o aumento da produção. O curauá (Ananás erectifo) é uma planta nativa da floresta amazônica e integrante da família do abacaxi [1] , sua fibra é um material atrativo do ponto de vista econômico e tecnológico devido às facilidade...

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Section: Caracterizaçãounclassified

Estudo das propriedades mecânicas e elétricas de fibras de curauá modificada com polianilina

Picciani

Rocha

et al. 2010

Polímeros

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“…Lignins are bound phenolic substances [4]; therefore, hydrolysis is needed to free soluble phenolic compounds from its bound form [5]. Released phenols showed high antioxidant activity [6,7], and they might be utilized in food and pharmaceutical industry as antioxidant compounds [8,9].…”

Section: Introductionmentioning

confidence: 99%

Phenolic Compounds and Antioxidant Activity of Rice Straw Extract

Elzaawely

Maswada

El-Sayed

et al. 2017

ILNS

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Abstract. Agricultural wastes cause a serious environmental problem in Egypt. Utilization of these wastes by an environmentally friendly way is a very important issue. The objective of this study was to utilize rice straw into high-value products. Antioxidant activity, total soluble phenols, and flavonoids were evaluated in ethyl acetate extract prepared from rice straw after alkaline hydrolysis. Total phenols were found to be 221.6 mg gallic acid equivalents (GAE), while total flavonoids were 4.9 mg rutin equivalents (RE). The extract exhibited strong antioxidant activity measured by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method and its IC 50 value was 0.4 mg/ml. Furthermore, the ethyl acetate extract possessed high antioxidant activity assayed by β-carotene bleaching method and its value of lipid peroxidation inhibition (LPI) was 75.4%. It also exhibited high reducing power and its IC 50 value was equal to 0.06 mg/ml. HPLC analysis indicated that this extract contained seven phenolic acids including; protocatechuic, caffeic, syringic, p-coumaric, ferulic, rosmarinic and cinnamic, in addition to two flavonoids; qurecetin and kaempferol. Results indicated that ferulic and p-coumaric acids were the major soluble phenolic acids in rice straw, and their concentrations were 3.9 and 2.9 mg/g DW. It can be summarized that the strong antioxidant activity of ethyl acetate extract, prepared from rice straw, was highly correlated with its high level of phenolic compounds.

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“…Pure lignin is basically an amorphous form consisted of aromatic ether backbone that can be potential substrates for the production of aromatic chemicals (Chakar & Ragauskas, 2004). Lignin can be isolated in large quantity from lignocellulosic materials by a strong dilute acid, alkaline treatment, organosolve isolation or sulphite pulping process (Pouteaua, et al, 2003;Fernandez-Bolanos, et al, 1999). However, the drawbacks in the case of the above processes are toxicity, high cost, difficulties in recovery, severe side-reaction, and instability in processing.…”

Section: Introductionmentioning

confidence: 99%

Isolation and Characterization of Lignin from Rubber Wood in Ionic Liquid Medium

Shamsuri¹,

Abdullah²

2010

MAS

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In this study, lignin was isolated from rubber wood by means of ionic liquid (1,3-dimethylimidazolium methylsulfate). The optimum parameters to isolate lignin were investigated which include the concentrations of ionic liquid (0.1, 0.2, 0.3, 0.4, 0.5 moles), isolation durations (30, 60, 90, 120, 150 minutes), and isolation temperatures (25, 40, 60, 80, 100°C). The optimum parameters for lignin isolation are 0.5 moles concentration, 120 minutes and 100ºC. Lignin could be isolated from rubber wood up to 13.03wt.% by ionic liquid however, in comparison with acid and alkaline isolation, they give better yields than ionic liquid which 22.15wt.% and 18.56wt.% of lignin, respectively. Lignin preliminary structures isolated by ionic liquid have been confirmed based on Fourier transform infrared (FTIR) results. From these results, isolated lignin by ionic liquid provides lignin without other related isolative. Apart from that, ionic liquid also could be recycled up to three times compared to acid and alkaline isolation methods.

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Antioxidant properties of lignin in polypropylene

Cited by 370 publications

References 28 publications

Estudo das propriedades mecânicas e elétricas de fibras de curauá modificada com polianilina

Estudo das propriedades mecânicas e elétricas de fibras de curauá modificada com polianilina

Phenolic Compounds and Antioxidant Activity of Rice Straw Extract

Isolation and Characterization of Lignin from Rubber Wood in Ionic Liquid Medium

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