Ensaios de Pullout em fibras lignocelulósicas: uma metodologia de análise

Monteiro, Sérgio Neves; d’Almeida, J.R.M.

doi:10.1590/s1517-70762006000300004

Cited by 21 publications

(15 citation statements)

References 10 publications

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“…First, that the average length of curaua, 846 mm, and piassava, 455 mm, are more than 15 times their criti- cal lengths, respectively, 10 mm and 15 mm. 34 This is considered a positive feature for optimum reinforcement of PMCs and assures effective strengthening for the composite. 35 Secondly, the statistical dispersion in dimensional values is quite accentuated, which, technically, is an undesirable feature.…”

Section: General Characteristicsmentioning

confidence: 99%

Natural-fiber polymer-matrix composites: Cheaper, tougher, and environmentally friendly

Monteiro¹,

Lopes²,

Ferreira³

et al. 2009

JOM

394

172

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Natural fi bers, especially lignocellulosic fi bers extracted from plants, are gaining attention as polymer-matrix composite (PMC) reinforcements due to their comparative advantages over synthetic fi bers. Natural fi bers are relatively low cost, renewable, and biodegradable. Their production systems are associated with low equipment wear and are energy effi cient. In addition, the incorporation of lignocellulosic fi bers into PMCs may signifi cantly improve some mechanical properties. This article presents an overview of the advantages and drawbacks of applying natural fi bers, some of them relatively unknown, as reinforcements of PMCs. The mechanical behavior of composites incorporated with selected fi bers is discussed in terms of the effect of surface micromorphology and the fi ber/matrix interaction.

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Section: General Characteristicsmentioning

confidence: 99%

Natural-fiber polymer-matrix composites: Cheaper, tougher, and environmentally friendly

Monteiro¹,

Lopes²,

Ferreira³

et al. 2009

JOM

394

172

View full text Add to dashboard Cite

show abstract

“…Therefore, there is a critical length that must be exceeded for the fiber to fracture without pullout. For values below the critical length, the failure usually occurs at the interface by fiber debonding 29 . Angelini et al 30 studied ramie fiber and obtained a critical length (lc) of 0.47 mm.…”

Section: Influence Of Fiber Length and Hybridizationmentioning

confidence: 99%

Preparation and characterization of ramie-glass fiber reinforced polymer matrix hybrid composites

et al. 2012

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The use of ramie fibers as reinforcement in hybrid composites is justified considering their satisfactory mechanical properties if compared with other natural fibers. This study aims to verify changes in chemical composition and thermal stability of the ramie fibers after washing with distilled water. One additional goal is to study glass fiber and washed ramie fiber composites focusing on the effect of varying both the fiber length (25, 35, 45 and 55 mm) and the fiber composition. The overall fiber loading was maintained constant (21 vol.%). Based on the results obtained, the washed ramie fiber may be considered as an alternative for the production of these composites. The higher flexural strength presented being observed for 45 mm fiber length composite, although this difference is not significant for lower glass fiber volume fractions: (0:100) and (25:75). Also, by increasing the relative volume fraction of glass fiber until an upper limit of 75%, higher flexural and impact properties were obtained.

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“…De todo modo, estas análises possuem relevante complexidade, uma vez que algumas fibras vegetais apresentam áreas irregulares e diferentes morfologias [6,14].…”

Section: Introductionunclassified

Influência de ciclos molhagem-secagem em fibras de sisal sobre a aderência com matrizes de cimento Portland

Ferreira¹,

Lima²,

Silva

et al. 2012

Matéria (Rio J.)

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RESUMOVisando a redução da capacidade de absorção de água de fibras ligno-celulósicas, ciclos de molhagem e secagem são usualmente utilizados na indústria de papel e celulose. Esse procedimento enrijece a estrutura polimérica das fibro-células (processo conhecido como hornificação) resultando assim em maior estabilidade dimensional da fibra. No presente estudo foi avaliada a influência da hornificação de fibras de sisal no seu comportamento físico (variações dimensionais e absorção de água), mecânico (comportamento sob cargas de tração direta) e microestrutural (modificações superficiais da fibra e da estrutura das fibro-células). Ensaios de arrancamento da fibra de sisal em matriz de cimento portland foram realizados, utilizando comprimentos de embebimento de 25 mm e 50 mm, com o objetivo de verificar se a possível estabilidade dimensional decorrente da hornificação aumentava a adesão fibra-matriz. Os resultados indicaram maior estabilidade dimensional, redução na capacidade de absorção de água, aumento na resistência à tração e capacidade de deformação e redução no módulo de elasticidade da fibra de sisal com a hornificação. Acréscimos na carga de arrancamento foram observados indicando uma maior aderência da fibra hornificada à matriz de cimento. Palavras-chave:Fibras naturais, Sisal, Interface, Resistência ao arrancamento, Hornificação ABSTRACT Aiming a reduction in the water absorption capacity of lingo-cellulosic fibers, wetting and drying cycles are usually performed in the industry of paper and cellulose. This procedure stiffens the polymeric structure of the fiber-cells (process known as hornification) resulting in a higher dimensional stability. In the present work it was investigated if the dimensional stability, obtained from the hornification process, can imporove the adhesion of the sisal fiber in a Portland cement matrix. In order to study the fiber-matrix bond adhesion pull-out tests were performed in embedment lengths of 25mm and 50mm. Furthermore, it was investigated the influence of the hornification in the physical behavior (dimensional variation and water absorption), mechanical (behavior under tensile loading) and microstructural (surface modifications of the fiber and changes in the fiber-cell structure). The results indicate a higher dimensional stability, reduction in the water absorption capacity, increase in the tensile strength and strain capacity and reduction in the modulus of elasticity with the hornification. The pull-out load increased which indicates a higher bond strength in the hornified fiber with the cementitious matrix.

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Ensaios de Pullout em fibras lignocelulósicas: uma metodologia de análise

Cited by 21 publications

References 10 publications

Natural-fiber polymer-matrix composites: Cheaper, tougher, and environmentally friendly

Natural-fiber polymer-matrix composites: Cheaper, tougher, and environmentally friendly

Preparation and characterization of ramie-glass fiber reinforced polymer matrix hybrid composites

Influência de ciclos molhagem-secagem em fibras de sisal sobre a aderência com matrizes de cimento Portland

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