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Mémoire de Maîtrise
DOI
10.11606/D.100.2014.tde-22042014-230234
Document
Auteur
Nom complet
Barbara Maria Gama Guimarães
Adresse Mail
Unité de l'USP
Domain de Connaissance
Date de Soutenance
Editeur
São Paulo, 2014
Directeur
Jury
Baruque Ramos, Júlia (Président)
Mantovani, Waldir
Savastano Junior, Holmer
Titre en portugais
Estudos das caracterísitcas físico-químicas de fibras vegetais têxteis de espécies de Malvaceae
Mots-clés en portugais
Caracterização físico-química
Fibras naturais
Fibras têxteis vegetais
Malvaceae
Têxtil
Resumé en portugais
As fibras vegetais podem ser utilizadas nao somente para tecidos, mas tambem para fabricacao de fios, cordames, naotecidos, compositos em substituicao aos fabricados em madeira ou materiais sinteticos, sendo que o Brasil possui uma grande variedade de fibras naturais. O presente estudo teve como principal objetivo a caracterizacao fisico-quimica de seis fibras texteis vegetais de especies da familia Malvaceae: Sida rhombifolia L.; Sida carpinifolia L. f.; Sida cordifolia L.; Sidastrum paniculatum (L.) Fryxell; Malvastrum coromandelianum (L.) Gurck e Wissadula subpeltata (Kuntze) R. E. Fries. Foram realizados testes fisicos tenseis (resistencia e alongamento); microscopia optica (sem e com solucao de iodo); teores de regain e umidade; testes quimicos de combustao, determinacao do pH do extrato aquoso, efeitos de solvente organico, alcali e acido. Em adicao, foram feitos testes de DSC, TGA, SEM, FTIR, microscopia de luz polarizada, grau de polimerizacao e densidade. Os valores de tenacidade (21-33 cN/tex), alongamento (2-3%) e modulo de Young (10-20 N/tex) sao compativeis com as de fibras naturais de reconhecida empregabilidade textil, com excecao de Sida rhombifolia L. (12 cN/tex). Os resultados obtidos de microscopias opticas e SEM, combustao e regain (10-18%) sao compativeis com os de outras fibras celulosicas. Os testes de FTIR confirmaram presenca de celulose, hemicelulose e lignina, sendo que os testes de DSC e TGA indicaram as temperaturas de picos endotermicos e composicao de hemicelulose (285-337oC; 10-15%), -celulose (360- 365oC; 55-60%) e lignina (420-425oC, 11-27%), valores esses coerentes com os reportados em literatura para outras fibras lignocelulosicas. Em funcao dessas temperaturas, a possibilidade de emprego das fibras estudadas em compositos termoplasticos e bastante restrita. No entanto, por nao haver alteracao significativa de massa apos tratamento com solvente organico, ha indicacao que as fibras do presente estudo poderiam ser empregadas em compositos plasticos termorrigidos.
Titre en anglais
Study of physicochemical characteristics of textile vegetal fibers from Malvaceae species.
Mots-clés en anglais
Malvaceae
Natural fibers
Physicochemical characterization
Textile
Textile vegetal fibers
Resumé en anglais
Vegetal fibers can be employed not only for fabrics, but also for the production of yarns, ropes, nonwovens and composites substituting those ones manufactured from wood or synthetic materials whereas Brazil has a great variety of natural fibers. The present study had as main objective the physicochemical characterization of six textile vegetal fibers of species from Malvaceae family: Sida rhombifolia L.; Sida carpinifolia L. f.; Sida cordifolia L.; Sidastrum paniculatum (L.) Fryxell; Malvastrum coromandelianum (L.) Gurck and Wissadula subpeltata (Kuntze) R. E. Fries. Tensile physical tests (resistance and elongation); optical microscopy (with and without iodine solution); moisture and regain contents; chemical combustion tests; aqueous extract pH; the effects of organic solvent, alkali, acid were carried out. In addition DSC, TGA, SEM, FTIR tests, polarized light microscopy, density and degree of polymerization tests were performed. The values of tenacity (21-33 cN/tex), elongation (2-3%) and Young s modulus (10-20 N/tex) are compatible with those ones from natural fibers of recognized textile employability, exception Sida rhombifolia L. (12 cN/tex). The results of optical and SEM microscopies, combustion and regain (10-18 %) are consistent with those of other cellulosic fibers. The FTIR tests confirmed the presence of cellulose, hemicellulose and lignin, whereas DSC and TGA tests showed endothermic peak temperatures and composition values of hemicellulose (285-337oC ; 10-15%) , -cellulose (360-365oC ; 55-60%) and lignin (420-425oC , 11- 27%), which are consistent with those reported in the literature for other lignocellulosic fibers. Taking in account these temperatures, the possibility of employing the studied fibers in thermoplastic composites is very limited. However, because no significant mass change after treatment with organic solvent, there is indication that the fibers of the present study could be employed in thermoset plastic composites.
 
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Date de Publication
2014-12-10
 
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