Efeito de Aditivos Desaerantes nas Características de Compósitos de Epóxi/Fibras de Vidro

Oliveira, Alexsandro; Becker, Cristiane Miotto; Amico, Sandro Campos

doi:10.4322/polimeros.2014.059

Cited by 5 publications

(3 citation statements)

References 12 publications

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“…The mixture was then sonicated for 30 min at 188 W using Sonics VCX 750 high energy sonication equipment. After cooling to room temperature, 0.3 wt% of degassing agent BYK A500 and 0.5 wt% of BYK A560 were added, following previous results of the group 21 . The resulting mixture was magnetically stirred for 40 min at room temperature, under vacuum, in order to remove entrapped air.…”

Section: Methodsmentioning

confidence: 99%

Glass fiber hybrid composites molded by RTM using a dispersion of carbon nanotubes/clay in epoxy

et al. 2013

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Nanocomposites based on epoxy and a mixture of clays and multi-walled carbon nanotubes (MWCNT) were produced by casting, and also molded by RTM using glass fibers as reinforcement, yielding a hybrid multi-scale micro/nanocomposite material. Two types of montmorillonite clays were used, natural (MMT-Na) and organophilic (MMT-30B). Higher viscosity was obtained for the mixture with MMT-30B and it was observed that this clay did not perform as well as the MMT-Na in helping the dispersion of the carbon nanotubes (CNT). The glass transition temperature (T g) of the nanocomposites increased in up to 6 °C with the addition of MWCNT and up to 10 °C with the addition of MMT-30B, differently from the MMT-Na which did not alter the T g of the material. By transmission electron microscopy, it was verified that more homogeneous dispersions and more intercalated structures were obtained with the MMT-30B than with the MMT-Na. Finally, the low clay content used and, especially, the very low MWCNT content, did not significantly alter the studied flexural properties.

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Section: Methodsmentioning

confidence: 99%

Glass fiber hybrid composites molded by RTM using a dispersion of carbon nanotubes/clay in epoxy

et al. 2013

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“…The composite LF was the treatment that presented the lowest density value with 1.01 g cm À3 . The higher basic density value presented by the composite FG compared to LF may be due to the higher density of the fiberglass, which has a value of 2.54 g cm À3 , 24 while the Luffa fibers have a density of 0.92 g cm À3 . 15 Nevertheless, the low density of the Luffa fibers compared to the synthetic ones is one of the most advantageous properties of that material, because when employed in the manufacture of composites, besides allowing a decrease in weight, the material is partially biodegradable.…”

Section: Basic Density and Moisture Contentmentioning

confidence: 99%

Characterization of polyester composites reinforced with natural fibers from Luffa cylindrica

Paula

Melo

Silva

et al. 2022

Journal of Composite Materials

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Concerns about global warming, environmental preservation, overexploitation of raw materials, and the development of new technologies are increasing. This has been attracting increasing interest in composites reinforced with natural fibers, mainly to replace synthetic materials. In this context, the present research work aimed to demonstrate the technical feasibility of the production of polyester-polymeric-matrix composites reinforced with fibers of Luffa cylindrica and a hybrid with fiberglass. The composites' physical properties (density, moisture content, water absorption, and thickness swelling) and mechanical properties (tensile, bending strength, and Rockwell hardness (RH)) were assessed. The composites were produced through cold pressing in a closed mold. The experiment was performed according to an entirely randomized design with two replicates per treatment and the means were compared by the Tukey test at 95% probability. The results demonstrated that the reinforcement with the Luffa fibers promoted a decrease in the density of the composites, with a minimum value of 1.01 g cm−3. In the assays of tensile strength, the reinforced composite presented a value of 10.20 MPa for this property, while for the bending strength, the value was 18.04 MPa. When the Luffa fibers were employed in the hybrid composite, the bending strength reached 105.12 MPa. In general, the composites reinforced with the plant fibers and the hybrid had physical and mechanical properties permitting their employment for several end-uses, according to the characteristics of each one. The new composites are partially biodegradable, sustainable, and light.

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“…Neste sentido, trabalhos anteriores do grupo de pesquisa avaliaram o efeito do uso de um aditivo desaerante nas propriedades de compósitos de resina epóxi utilizando mantas e tecidos de fibras de vidro como reforço. Os resultados mostraram que a utilização do aditivo desaerante minimiza a formação de vazios, contudo, o trabalho sugere que os efeitos positivos de sua utilização poderiam ser mais bem apreciados caso a avaliação das propriedades fosse feita diretamente na resina epóxi, sem a presença de fibras [11] . Assim, o objetivo deste trabalho foi avaliar o efeito da utilização de aditivos desaerantes diretamente nas propriedades de uma resina epóxi.…”

Section: Introductionunclassified

Avaliação das características da resina epóxi com diferentes aditivos desaerantes

2015

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ResumoEste trabalho tem por objetivo a busca por técnicas alternativas para diminuir a incidência de vazios em resinas poliméricas e, por consequência, em materiais compósitos. Foram produzidas formulações diferentes utilizando resina epóxi à base de éter diglicidílico do Bisfenol A, endurecedor de poliamina alifática com e sem a adição de diferentes aditivos desaerantes a base de éteres e ésteres modificados. As formulações produzidas foram submetidas a condições extremas de agitação e processamento, sendo posteriormente avaliadas quanto a incidência de bolhas e vazios, densidade, propriedades mecânicas, morfológicas e térmicas. Os resultados foram bastante positivos quanto à diminuição da quantidade e do tamanho de poros pela utilização de técnicas de desgaseificação a vácuo e pelo uso de aditivos desaerantes. Palavras-chave: resina epóxi, aditivos desaerantes, vazios. AbstractThis study aims alternative techniques to reduce the incidence of voids in polymeric resins and in composite materials. Different formulations were prepared using epoxy resin based on bisphenol A diglycidyl ether and an aliphatic polyamine hardener, with and without the addition of different degasing agents based on modified esters and ethers. The formulations produced were subjected to extreme agitation and processing conditions and we evaluated the incidence of bubbles and voids, density, mechanical, morphological and thermal properties. The results were very positive. We observed the decrease in number and size of pores by the use of vacuum degassing techniques and degasing agent additives.Keywords: epoxy resin, degassing agents, voids. IntroduçãoA presença de vazios afeta severamente as propriedades das resinas poliméricas e, por consequência, as propriedades dos materiais compósitos produzidos com estas resinas, principalmente as propriedades mecânicas [1][2][3][4] . Em compósitos, os vazios podem se apresentar em vários formatos e tamanhos, sendo diversas as causas para a sua formação, entre elas, o aprisionamento de gás (frequentemente gás úmido) durante o processo de impregnação dos reforços fibrosos com resina, os voláteis gerados durante a formulação da resina e bolhas de ar que podem ser aprisionadas durante a agitação de resinas de elevada viscosidade [5][6][7][8][9] . A quantidade de bolhas de ar aprisionadas, por vezes, pode ser reduzida se o sistema de resina é sujeito a um processo de desgaseificação a vácuo ou pelo próprio uso do vácuo durante o processo de moldagem [10] . A busca por técnicas alternativas para reduzir a incidência destes defeitos leva ao desenvolvimento de aditivos químicos especiais, o que consiste na inclusão de um aditivo desaerante no sistema polimérico que deslocará as bolhas de ar para a superfície da resina, trabalhando em conjunto com o polímero em uma relação de compatibilidade e solubilidade e alterando sua tensão superficial. Neste sentido, trabalhos anteriores do grupo de pesquisa avaliaram o efeito do uso de um aditivo desaerante nas propriedades de compósitos de resina epóxi utilizando man...

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Efeito de Aditivos Desaerantes nas Características de Compósitos de Epóxi/Fibras de Vidro

Cited by 5 publications

References 12 publications

Glass fiber hybrid composites molded by RTM using a dispersion of carbon nanotubes/clay in epoxy

Glass fiber hybrid composites molded by RTM using a dispersion of carbon nanotubes/clay in epoxy

Characterization of polyester composites reinforced with natural fibers from Luffa cylindrica

Avaliação das características da resina epóxi com diferentes aditivos desaerantes

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