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Previous issue date: 2017-08-21 / Superf?cies superhidrof?bicas t?m sido objeto de muitos estudos devido ao grande interesse cient?fico e tecnol?gico para aplica??es como autolimpeza, anticorros?o, separa??o ?gua/?leo, microflu?dica, dentre outras. A superhidrofobicidade depende das caracter?sticas qu?micas e topologia das superf?cies. Neste trabalho, foi desenvolvido um novo m?todo de produ??o de revestimento superhidrof?bico nanoestruturado em materiais fibrosos, utilizando o processo de deposi??o de espuma. Com base no m?todo desenvolvido, revestimentos nanocomp?sitos de politetrafluoretileno e nanopart?culas de ?xido de c?lcio foram depositados sobre fibras de Poli?cido l?ctico para avalia??o de superhidrofobicidade. A influ?ncia de par?metros de processo como, concentra??o de nanopart?culas de ?xido de c?lcio, concentra??o de politetrafluoretileno, temperatura de polimeriza??o e tempo de polimeriza??o, foi avaliada. O revestimento foi caracterizado por ?ngulo de contato, difra??o de raios-x, espectroscopia no infravermelho com transformada de Fourier e reflect?ncia total atenuada, microscopia eletr?nica de varredura, microscopia de for?a at?mica, microscopia eletr?nica de transmiss?o e espectroscopia de raios-x de dispers?o de el?trons, espectroscopia fotoeletr?nica por raios-x, ensaio de repel?ncia a l?quidos com v?rios valores de tens?o superficial, ensaio de verifica??o da autolimpeza e ensaio de resist?ncia a lavagem e abras?o. Os resultados de difra??o de raios-x e espectroscopia no infravermelho com transformada de Fourier indicaram a presen?a de politetrafluoretileno e nanopart?culas de ?xido de c?lcio sobre a superf?cie das fibras de Poli?cido l?ctico, confirmando a deposi??o do revestimento pelo processo desenvolvido. Dentre os par?metros de processo estudados, a condi??o de 0,6% sobre o peso do material (spm) de nanopart?culas de ?xido de c?lcio, 80 g/l de politetrafluoretileno, 140?C e 90 segundos de polimeriza??o resultou no maior valor de ?ngulo de contato para o revestimento de politetrafluoretileno/nanopart?culas de ?xido de c?lcio (159,67? ? 1,05?). As imagens de microscopia eletr?nica de varrimento, microscopia eletr?nica de transmiss?o e espectroscopia de raios-x de dispers?o de el?trons e microscopia de for?a at?mica mostraram nanopart?culas de ?xido de c?lcio com formas esf?rica e retangular e altera??es morfol?gicas e topogr?ficas na superf?cie das fibras de Poli?cido l?ctico com a deposi??o do recobrimento. A espectroscopia fotoeletr?nica por raios-x confirmou a exist?ncia da presen?a de elemento qu?mico fl?or na superf?cie do revestimento. Os resultados dos testes de repel?ncia aquosa realizados utilizando uma s?rie de solu??es de ?gua/?lcool isoprop?lico com diferentes tens?es superficiais indicaram repel?ncia da superf?cie revestida a todas as solu??es testadas. As fibras com o revestimento de politetrafluoretileno/ nanopart?culas de ?xido de c?lcio tamb?m apresentaram propriedade de autolimpeza fazendo com que uma gota de ?gua removesse a sujeira da superf?cie. O revestimento manteve a superhidrofobicidade mesmo ap?s 25 ciclos de lavagem e 100 ciclos de abras?o. Em resumo, o processo de fabrica??o apresentado nesta pesquisa utilizando a deposi??o de espuma mostrou-se simples e pr?tico para deposi??o de revestimentos superhidrof?bicos em fibras e tecidos. O revestimento de politetrafluoretileno/nanopart?culas de ?xido de c?lcio depositado em fibras de Poli?cido l?ctico via deposi??o de espuma apresentou propriedades superhidrof?bicas. / Superhydrophobic surfaces are of great scientific and technological interest for applications such as self-cleaning, anticorrosion, oil/water separation, microfluidics, among others. The superhydrophobicity depends on surface chemistry and topology. In this work, a new method for producing nanostructured superhydrophobic coatings on fibrous materials using foam deposition was developed. Based on the developed method, polytetrafluoroethylene/calcium oxide nanocomposite coating was deposited on polylactic acid fibers and the superhyphobicity was evaluated. The influence of processing parameters such as nanoparticle concentration, polytetrafluoroethylene concentration, polymerization temperature and polymerization time was evaluated. The nanocoating was analyzed by contact angle, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, transmission electron microscopy and electron-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, liquid repellency test with various surface tension values, self-cleaning check test and wash and abrasion resistance test. The results of X-ray diffraction and Fourier transform infrared spectroscopy indicated a presence of polytetrafluoroethylene and calcium oxide nanoparticles on the surface of the polylactic acid fibers, confirming the deposition of the coating by the process developed. Among the processing parameters studied, the condition of 0.6 wt.% of calcium oxide nanoparticles, 80 g/l polytetrafluoroethylene, 140 ?C and 90 seconds of polymerization resulted in the highest contact angle value for the nanocomposite coatings (159.67? ? 1.05?). Scanning electron microscopy images, transmission electron microscopy and electron-dispersive X-ray spectroscopy and atomic force microscopy showed calcium oxide nanoparticles with spherical and rectangular shapes and morphological and topographic changes on the surface of polylactic acid fibers with the deposition of the coating. X-ray photoelectron spectroscopy confirmed the presence of the chemical element fluorine on the surface of the coating. The results of the aqueous liquid repellency tests performed on the coated surface using a series of isopropyl alcohol/water solutions of different surface tensions indicated repellency to all tested solutions. The self-cleaning properties of the coated fibers were determined by the removal of dirt by water droplet flow. The nanocomposite coating maintained the superhydrophobicity even after 25 wash cycles and 100 abrasion cycles. In summary, the manufacturing process presented in this research using foam deposition, proved to be simple and practical for the deposition of superhydrophobic coatings in fibers and fabrics. The polytetrafluoroethylene/calcium oxide coating deposited on polylactic acid fibers by foam deposition showed superhydrophobic properties.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/24503 |
| Date | 21 August 2017 |
| Creators | Ara?jo, Rubens Capistrano de |
| Contributors | 46660640444, Steffens, Fernanda, 04100974973, Azeredo, Henriette Cordeiro Monteiro de, 54600561600, Nascimento, Jos? Heriberto Oliveira do, 02452573493, Delmonte, Mauricio Roberto Bomio, 27816279841, Melo, Jos? Daniel Diniz |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM ENGENHARIA MEC?NICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | Unknown |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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