Unmodified and Modified Surface Sisal Fibers as Reinforcement of Phenolic and Lignophenolic Matrices Composites: Thermal Analyses of Fibers and Composites

Paiva, Jane Maria Faulstich de; Frollini, Elisabete

doi:10.1002/mame.200500334

Cited by 148 publications

(59 citation statements)

References 54 publications

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“…Devido à característica fenólica, a lignina torna-se interessante para incorporação em resinas poliméricas [20] . Os anéis fenólicos presentes na estrutura complexa da lignina permitem também a sua utilização como substituinte parcial do fenol, o qual pode ser empregado em sínteses de alguns tipos polímeros, principalmente, resinas fenólicas, pois a lignina reage com o formaldeído [21][22][23][24] . No entanto, apesar da lignina possuir essas vantagens químicas, sua composição exata ainda é de difícil determinação, devido à presença de inúmeras ligações complexas, além de muitos grupos químicos [25] .…”

Section: Introductionunclassified

Filmes poliméricos baseados em amido e lignossulfonatos: preparação, propriedades e avaliação da biodegradação

et al. 2014

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Resumo: Este trabalho envolveu a obtenção de filmes poliméricos a partir de amido de milho e incorporação de lignina na forma de lignossulfonato. A motivação deste trabalho está relacionada à utilização do amido na obtenção de filmes devido ao seu potencial de biodegradação, além do aproveitamento de resíduos de lignossulfonatos provenientes da indústria de celulose e papel. Para a obtenção dos filmes foram utilizados lignossulfonatos em pó e foram realizadas diversas moldagens com variação do tipo e da proporção (1% a 4%) de lignossulfonato utilizado. Algumas análises foram realizadas nos filmes poliméricos para comparar propriedades térmicas por DSC (Calorimetria Exploratória Diferencial), e propriedades de tração, em equipamento de DMTA (Análise Térmica Dinâmico-Mecânica). Neste estudo são destacadas as análises da biodegradação e da emissão dos gases liberados utilizando a técnica de Cromatografia Gasosa. De acordo com os resultados de DMTA, a maioria dos filmes poliméricos contendo lignossulfonatos apresentou resistência à tração inferior quando comparados aos filmes poliméricos sem lignossulfonatos (1,024 MPa). Porém, os filmes contendo lignossulfonato modificado com sódio (Vixil S) apresentaram maiores valores de resistência à tração quando comparado aos outros filmes contendo os lignossulfonatos utilizados (Vixil I e Vixil Tan). Nas análises térmicas foram notadas semelhanças entre os dois tipos principais de filmes poliméricos (amido; e amido com lignossulfonato), com alguns deslocamentos das temperaturas dos principais picos máximos dos filmes contendo lignossulfonato (4%, Vixil S). Na análise de biodegradabilidade foi verificado que os materiais são biodegradáveis e houve uma emissão maior de CO 2 e N 2 O das amostras dos filmes contendo 4% lignossulfonato do tipo Vixil S, em comparação com as amostras sem lignossulfonato. Palavras-chave: Filme polimérico, amido, lignossulfonato, DMTA, DSC, biodegradação. Polymeric Films Based on Starch and lignosulfonates: Preparation, Properties and Evaluation of BiodegradationAbstract: We obtained polymer films from corn starch with lignin incorporation as lignosulfonate. The motivation is the use of starch in obtaining films, due to their potential for biodegradation, and the use of lignosulfonate waste from the pulp and paper industry. To obtain films of lignosulfonates various powders of lignosulfonate were used, varying type and proportion (1% to 4%). Analyses were performed on polymer films to compare thermal properties by Differential Scanning Calorimetry, and tensile properties in Dynamic Mechanical Thermal Analysis, DMTA. We emphasize analyses of biodegradation and gas emission using gas chromatography. According to the results of DMTA, most polymeric films containing lignosulfonates showed lower tensile strength when compared to polymer films without lignosulfonates (1.024 MPa). However, the films containing lignosulfonate modified with sodium (Vixil S) showed higher tensile strength when compared to other films containing lignosulfonates (Vixil I and Vixi...

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Section: Introductionunclassified

Filmes poliméricos baseados em amido e lignossulfonatos: preparação, propriedades e avaliação da biodegradação

et al. 2014

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“…Physical interactions, such as hydrogen bonding can occur, affecting kinetic parameters. The literature cites that the interface of polymer matrix composites with untreated sisal fibers is poorer when compared with the treated ones 43 . Figure 5.…”

Section: Discussionmentioning

confidence: 99%

Influence of glass and sisal fibers on the cure kinetics of unsaturated polyester resin

et al. 2012

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The effect of grinded glass and sisal fibers (25 vol%) on the cure kinetics of composites of unsaturated polyester resin (UPR) was investigated by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The DSC analysis was carried out at four different heating rates (5, 10, 20 and 40 °C/min), and the cure enthalpy and activation energy (E a ) were determined according to the Flynn-Wall-Ozawa (FWO) method. The results showed that increasing heating rates promoted reduced reaction times. The sisal fiber-containing composites exhibit higher activation energy values for the cure process in comparison with the neat polyester resin and the glass fiber composites. This can be due to the presence of polar groups in the sisal components, which physically interact with the polyester resin and retard the cure reaction. Hence, as sisal fiber retarded the cure reaction of the UPR resin, it is suggested that the use of natural fibers in polymer matrix composites can affect the cure kinetics of the polyester resin.

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“…In this type of ionizer, both positive and negative ions are generated in the air by applying a high voltage (7.5 kV) waveform to the series of electrodes at 5 mA. The fibers were then treated with a flow of ionized air blown the surface for 1, 3 and 5 h and immediately used to prepare the composite [2,5] . Fiber characterization: The untreated and treated fibers were characterized by determining the crystallinity index of the cellulose and subjecting them to inverse gas chromatography (IGC), as described elsewhere [1,12] .…”

Section: Ionized Air Treatmentmentioning

confidence: 99%

“…Aggregation involving fiber bundles can also be related to electrostatic interactions, which can be manipulated by specific treatments, such as the ionization of the surrounding air molecules. In the present study, the surface of jute fibers was treated with ionized air [2,5,8,9] . Both of the treatments investigated here, namely mercerization and ionized air, can change the energy and the acid-base properties of the fiber surface, which in turn can affect the interactions at the fiber-matrix interface.…”

Section: Introductionmentioning

confidence: 99%

“…Treatment of natural fibers with an alkaline solution (mercerization) is widely used. This treatment can increase the fiber surface roughness, separate the fiber bundles and remove cell wall components [1][2][3][4][5][6] . Usually, the wettability of the mercerized fibers is greater than that of unmodified fibers, thus improving strength of bonding between the fibers and the matrix [7] .…”

Section: Introductionmentioning

confidence: 99%

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Treatments of jute fibers aiming at improvement of fiber-phenolic matrix adhesion

2014

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Abstract:Composites based on a thermoset phenolic matrix and jute fibers were prepared and characterized. The fibers were alternatively treated with ionized air or aqueous alkaline solution (mercerization) with the aim of introducing changes in the morphology, dispersive component of surface free energy, g S D (estimated by Inverse Gas Chromatography, IGC) and the acid/base character of their surfaces, shown by their AN s /DN s ratio (estimated by IGC), and their degree of crystallinity. The final objective was to investigate the influence of these modifications on the adhesion at the jute fiber/phenolic matrix interface in the composites. The untreated jute fiber showed 50% crystallinity, g S D =18 mJ m -2 and AN s /DN s = 0.9 (amphoteric surface), tensile strength = 460 MPa and maximum elongation = 0.7%, while the respective composite had an impact strength of 72.6 J m -1 . The treatments positively modified the fibers and the adhesion at the interface was better in the composites reinforced with treated fibers than with untreated fibers. The best set of results was exhibited by the fiber treated with 10% NaOH [46% crystallinity, , AN s /DN s = 2.1 (acidic surface)] for further use as reinforcement of a phenolic matrix, but their partial degradation during the treatment decreased their tensile properties (395 MPa and 0.5% for tensile strength and maximum elongation, respectively) and their action as reinforcement (impact strength of the respective composite approximately 73 J m -1 ).

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Unmodified and Modified Surface Sisal Fibers as Reinforcement of Phenolic and Lignophenolic Matrices Composites: Thermal Analyses of Fibers and Composites

Cited by 148 publications

References 54 publications

Filmes poliméricos baseados em amido e lignossulfonatos: preparação, propriedades e avaliação da biodegradação

Filmes poliméricos baseados em amido e lignossulfonatos: preparação, propriedades e avaliação da biodegradação

Influence of glass and sisal fibers on the cure kinetics of unsaturated polyester resin

Treatments of jute fibers aiming at improvement of fiber-phenolic matrix adhesion

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