Made available in DSpace on 2014-12-17T14:58:07Z (GMT). No. of bitstreams: 1 SistanleyJLB_DISSERT.pdf: 3362424 bytes, checksum: 30d67bc0b13dba47c7002133ab1bb63d (MD5) Previous issue date: 2011-06-20 / This research presents an approach to the addition of curau? fibers and licuri fibers in a polypropylene resin matrix, such as an alternative proposal to reinforce the polymeric composites. Fiber content of 0 %, 5 %, 10 %, and 20% were analyzed for verification of their mechanical properties comparing them, inclusive with the properties of polypropylene. The grainulated biocomposites had been prepared in an extrusora. The test bodies had been molded by injection and submitted to the mechanical essays uniaxial traction, flexion on three points, impact, in addition to thermal tests (HDT). These biocomposites had been also subjected the essay physicist-chemistry index of fluidity (IF). It was observed that the biocomposites of PP with 20% curau?, obtained bigger increase in the modulus of elasticity and a bigger reduction in the resistance to the impact. In the mechanical behavior, for all the biocomposites, these were increases in values of the limit of drainage and tension of rupture, when tested by uniaxial traction, as they added the fibers. Another important point was the increase of the resistance the flexion. It was also noted that the addition of fibers reduced the thermal degradation of the mixture natural fibers / polypropylene. / Esta pesquisa apresenta uma abordagem da adi??o de fibras de licuri e curau? em uma matriz de resina de polipropileno, essa como uma proposta alternativa de refor?o aos comp?sitos polim?ricos. Teores de fibras de 0 %, 5 %, 10 %, e 20 % foram analisados para verifica??o de suas propriedades mec?nicas comparando-as, inclusive com as propriedades do polipropileno. Os biocomp?sitos granulados foram preparados em uma extrusora. Os corpos de prova foram moldados por inje??o e submetidos aos ensaios mec?nicos de tra??o uniaxial, flex?o em tr?s pontos, impacto, al?m de ensaios t?rmicos (HDT). Estes biocomp?sitos tamb?m foram submetidos a ensaio f?sico-qu?mico de ?ndice de fluidez (IF). Observou-se que os biocomp?sitos de PP com 20% curau? obteve maior aumento no m?dulo de elasticidade, e uma maior diminui??o na resist?ncia ao impacto. No comportamento mec?nico, para todos os biocomp?sitos, houve acr?scimos nos valores do limite de escoamento e tens?o de ruptura quando ensaiados por tra??o uniaxial, ? medida que se adicionavam as fibras. Outro ponto importante foi o aumento da resist?ncia ? flex?o. Verificou-se tamb?m que a adi??o de fibras reduziu a degrada??o t?rmica da mistura fibras naturais / polipropileno.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-30T23:20:44Z No. of bitstreams: 1 LucemaideBatistaMirandaFerreira_TESE.pdf: 4494748 bytes, checksum: f35753b1191ecb306cd0973efb042a35 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-01T23:33:29Z (GMT) No. of bitstreams: 1 LucemaideBatistaMirandaFerreira_TESE.pdf: 4494748 bytes, checksum: f35753b1191ecb306cd0973efb042a35 (MD5) / Made available in DSpace on 2016-06-01T23:33:29Z (GMT). No. of bitstreams: 1 LucemaideBatistaMirandaFerreira_TESE.pdf: 4494748 bytes, checksum: f35753b1191ecb306cd0973efb042a35 (MD5) Previous issue date: 2015-08-06 / O presente trabalho tem como objetivo fazer uma an?lise das propriedades mec?nicas e do comportamento mec?nico de duas l?minas refor?adas com tecido unidirecional de fibra de curau? com diferentes fra??es volum?tricas, baseado em crit?rios de falha definidos em literatura. Os comp?sitos, que apresentam matriz polim?rica e refor?o com tecido unidirecional de fibra de curau?, foram submetidos a ensaios de tra??o e cisalhamento em uma s?rie de corpos de provas normatizados cuja orienta??o das fibras direcionadas em ?ngulos de 0?, 10?, 20?, 75? e 90? para a l?mina com fra??o volum?trica de 30% e 0?, 30?, 45?, 60?, e 90? para a l?mina com fra??o volum?trica de 22%, para ensaios de tra??o e para ensaio de cisalhamento a orienta??o do ?ngulo do refor?o foi de 90?. Os ensaios foram executados em uma m?quina universal de tra??o e coletados os dados das propriedades mec?nicas dos corpos de prova dos comp?sitos. Estes dados experimentais foram inseridos nas equa??es te?ricas que definem os crit?rios de falha, como tamb?m, tratados graficamente para an?lise dos resultados e compara??o entre os ?ngulos de orienta??o do refor?o. Constatou-se uma grande dispers?o entre os dados experimentais do m?dulo de Elasticidade e do Coeficiente de Poisson em rela??o ao comportamento te?rico principalmente para a l?mina com menor fra??o volum?trica. O comp?sito com orienta??o de refor?o a 0? apresentou a maior resist?ncia ? tra??o em rela??o ?s demais inclina??es para as duas l?minas. No entanto, em rela??o aos crit?rios de falha as l?minas tiveram comportamentos diferentes. Para a l?mina com fra??o volum?trica 30%, os quatro crit?rios estudados nesta Tese apresentaram boa concord?ncia em termos de resist?ncia, mas para a l?mina com fra??o volum?trica de 22%, apenas o crit?rio de Tsai-Will e Hashin apresentaram boa concord?ncia. . / This study aims to analyze the mechanical properties and the mechanical behavior of two laminas reinforced with unidirectional fabric curau? with different fiber volume fractions, based on failure criteria defined in the literature. The composites which have polymeric matrix and reinforcement with unidirectional fabric curaua fiber, were submitted to tensile and shear tests at a series of specimens standardized whose fiber orientation directed at angles of 0?, 10?, 20?, 75? and 90? to the lamina with volume fraction of 30% and 0?, 30 ?, 45 ?, 60 ?, and 90 ? to the lamina with volume fraction of 22% to tensile tests and shear tests the direction of strengthening the angle was 90 ? to the x axis (direction of the applied load). The tests were performed in a universal machine traction and collected the data of mechanical properties of the composite specimens. These experimental data were entered in the theoretical equations that define the failure criteria, as well as graphically treated to analyze the results and compare the enhanced orientation angles. It found major disparities between the experimental data of elastic modulus and Poisson's ratio in relation to the theoretical behavior primarily to the lamina with a lower volume fraction. The composite reinforcement orientation at 0 ? showed the highest tensile strength compared to other inclinations for the two laminas. However, regarding the failure criteria laminas have different behaviors. To the lamina with volume fraction 30%, the four criteria studied in this thesis showed equivalent results in terms of resistance and to the blade with volume fraction of 22%, only the maximum stress criterion was not satisfactory in representing experiemtais data.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-06-03T23:57:10Z No. of bitstreams: 1 ItailzaGomesDaRocha_DISSERT.pdf: 3542376 bytes, checksum: feceaf0a2a5196b154b6fcc7af590782 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-07T21:10:55Z (GMT) No. of bitstreams: 1 ItailzaGomesDaRocha_DISSERT.pdf: 3542376 bytes, checksum: feceaf0a2a5196b154b6fcc7af590782 (MD5) / Made available in DSpace on 2016-06-07T21:10:55Z (GMT). No. of bitstreams: 1 ItailzaGomesDaRocha_DISSERT.pdf: 3542376 bytes, checksum: feceaf0a2a5196b154b6fcc7af590782 (MD5) Previous issue date: 2015-09-08 / Atualmente se observa uma grande busca por materiais originados de fontes renov?veis. As fibras vegetais como refor?o para matrizes polim?ricas, tem sido uma alternativa para substituir fibras sint?ticas, por serem biodegrad?veis e de baixo custo. Este trabalho objetiva desenvolver um material comp?sito de resina ep?xi refor?ado com fibra de curau? e aditivo retardante de chama de alumina trihidratada (hidr?xido de alum?nio - Al(OH)3), que foi utilizado em propor??es de 10%, 20% e 30% do volume total do comp?sito. As fibras de curau? passaram por um processo de limpeza com um banho alcalino de hidr?xido de s?dio (NaOH), paralelizadas atrav?s de cardagem manual e cortadas de acordo com o comprimento predefinido. Foram moldados comp?sitos com fibras de 30cm e com fra??o volum?trica de 20% de fibra no Lossy Mould. Os comp?sitos foram preparados no Laborat?rio de Engenharia T?xtil da UFRN. Os testes de resist?ncia ao fogo foram realizados no laborat?rio de engenharia de materiais da UFRN. Para medir o desempenho do material, foram realizados ensaios de resist?ncia ? tra??o e flex?o, com as amostras que foram posteriormente analisadas no aparelho de Microscopia Eletr?nico de Varredura (MEV). Os comp?sitos apresentaram bom desempenho mec?nico, e foi observado que a adi??o do agente retardante de chama influenciou nas propriedades mec?nicas, e em alguns casos, deixando o comp?sito mais fr?geis a ruptura. Esses resultados mec?nicos foram submetidos ao teste estat?stico Qui-Quadrado ao n?vel de signific?ncia de 5% para verificar poss?veis diferen?as entre ao grupos de comp?sitos. O teste de flamabilidade foi realizado baseado na norma Underwriter's Laboratory 94 e o material apresentou um resultado satisfat?rio, tendo a sua taxa m?dia de queima (mm/min) diminuindo com o aumento da adi??o do retardante de chamas nos comp?sitos. / Currently, there is a great search for materials derived from renewable sources. The vegetable fibers as reinforcement for polymer matrixes, has been used as an alternative to replace synthetic fibres, being biodegradable and of low cost. The present work aims to develop a composite material with epoxy resin reinforced with curau? fibre with the addition of alumina trihydrate (aluminum hydroxide, Al(OH)3) as a flame retardant, which was used in proportions of 10 %, 20% and 30% of the total volume of the composite. The curau? fibers have gone through a cleaning process with an alkaline bath of sodium hydroxide (NaOH ), parallelized by hand and cut carding according to the default length . They were molded composites with fibers 30cm. Composites were molded in a Lossy Mold with unidirectional fibres in the proportion of 20% of the total volume of the composite. The composites were prepared in the Chemical Processing Laboratory of the Textile Engineering Department at UFRN. To measure the performance of the material, tests for the resistance to traction and flexion were carried out. with samples that were later analyzed in the Electronic Microscopy Apparatus (SEM ). The composites showed good mechanical properties by the addition of flame retardant and in some cases, leaving the composite more vulnerable to breakage. These mechanical results were analyzed by chi-square statistical test at the 5% significance level to check for possible differences between the composite groups. Flammability testing was conducted based on the standard Underwriters Laboratory 94 and the material showed a satisfactory result taking their average burn rate (mm / min) decreasing with increasing addition of the flame retardant composite.

Made available in DSpace on 2014-12-17T14:58:04Z (GMT). No. of bitstreams: 1 JoseAMN_DISSERT.pdf: 2578831 bytes, checksum: 78ca7925672b7876fad1b54e774b3827 (MD5) Previous issue date: 2010-12-30 / With the objective to promote sustainable development, the fibres found in nature in abundance, which are biodegradable, of low cost in comparison to synthetic fibres are being used in the manufacture of composites. The mechanical behavior of the curau? and pineapple leaf fibre (PALF) composites in different proportions, 25% x 75% (P1), 50% x 50% (P2) e 75% x 25% (P3) were respectively studied, being initially treated with a 2% aqueous solution of sodium hydroxide. Mechanical analyses indicated that with respect to studies of traction, for the combination of P1 and P3, better results of 22.17 MPa and 16.98 MPa, were obtained respectively, which are higher than that of the combination P2. The results of the same pattern were obtained for analysis of bending resistance where P1 is 1.21% and P3 represents 0.96%. In the case of resistance to bending, best results were obtained for the combination P1 at 49.07 MPa. However, when Young's modulus values were calculated, the values were different to the pattern of the results of other tests, where the combination P2 with the value of 4.06 GPa is greater than the other combinations. This shows that the PALF had a greater influence in relation to curau? fibre. The analysis of the results generally shows that in combinations of two vegetable fibers of cellulosic origin, the fiber which shows higher percentage (75%) is the best option than to the composition of 50%/50%. In the meantime, according to the results obtained in this study, in the case where the application should withstand bending loads, the better composition would be 50%/50% / Com o objetivo de promover o desenvolvimento sustent?vel, as fibras encontradas em abund?ncia na natureza, que s?o biodegrad?veis e de baixo custo quando comparado com as fibras sint?ticas, vem sendo utilizadas na aplica??o de produ??o de comp?sitos. Neste trabalho foi analisado o comportamento mec?nico ? partir do ensaio de tra??o e flex?o, em um comp?sito h?brido tendo como matriz uma resina sint?tica ortoft?lica refor?ada com fibras de curau? e fibras da folha de abacaxizeiro (PALF), nas propor??es de 25% x 75% (P1), 50% x 50% (P2) e 75% x 25% (P3), respectivamente, com as fibras de curau? e as fibras da folha do abacaxizeiro sendo tratadas quimicamente por uma solu??o aquosa de hidr?xido de s?dio (NaOH) com 8% de concentra??o. As an?lises mec?nicas indicaram que com rela??o aos estudos de tra??o, para a combina??o P1 e P3, foram obtidas melhores resultados de 22,17 MPa e 16,98 MPa, respectivamente, que ? maior que da outra combina??o de P2. Os resultados do mesmo padr?o foram obtidos para an?lise de flex?o onde P1 ? 1,21% e P3 de 0,96% que s?o maiores do que o resultado obtido da combina??o P2. No caso de resist?ncia ? flex?o, melhores resultados foram obtidos para a combina??o P1 de 49,07 MPa. Mas, quando foi calculado o m?dulo de Young, os valores foram diferentes do padr?o dos resultados dos outros testes realizados, com a combina??o P2 com o valor de 4,06 GPa que ? maior que das outras combina??es. Isto mostra que as fibras PALF tiveram uma influ?ncia maior com rela??o ? fibra de curau?. A an?lise dos resultados em geral demonstra que nas combina??es de duas fibras vegetais celul?sicas, uma ou a outra fibra com porcentagem maior (75%) ? a melhor op??o do que na composi??o de 50%/50%, entretanto no caso onde a aplica??o ser? para suportar cargas de flex?o, a melhor composi??o seria 50%/50%

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-10-11T20:53:57Z No. of bitstreams: 1 SistanleyJonesLimaBispo_TESE.pdf: 3279866 bytes, checksum: 4e4c98181eb5b9e3145660daab8debff (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-10-14T20:57:44Z (GMT) No. of bitstreams: 1 SistanleyJonesLimaBispo_TESE.pdf: 3279866 bytes, checksum: 4e4c98181eb5b9e3145660daab8debff (MD5) / Made available in DSpace on 2016-10-14T20:57:44Z (GMT). No. of bitstreams: 1 SistanleyJonesLimaBispo_TESE.pdf: 3279866 bytes, checksum: 4e4c98181eb5b9e3145660daab8debff (MD5) Previous issue date: 2016-06-03 / Esta pesquisa apresenta uma abordagem a cerca do processo de reciclagem do polipropileno refor?ado com fibras de curau? reprocessado. Sendo uma proposta alternativa de refor?o aos comp?sitos polim?ricos. Teores de fibras de 0%, 10%, 20% e 30% foram analisados para verifica??o de suas propriedades mec?nicas comparando-as, inclusive com as propriedades do polipropileno (PP). Os biocomp?sitos granulados foram preparados em uma extrusora. Os corpos de prova foram moldados por processo de inje??o e submetidos aos ensaios mec?nicos de tra??o uniaxial, flex?o em tr?s pontos e impacto. Para verifica??o de danos aos corpos de prova utilizou-se da an?lise por microscopia eletr?nica de varredura (MEV). Estes biocomp?sitos tamb?m foram submetidos a ensaios f?sico - qu?micos de ?ndice de fluidez (IF). Observou-se que os biocomp?sitos de polipropileno com 30% de fibras de curau? apresentaram maior m?dulo de elasticidade e menor resist?ncia ao impacto. Para todos os biocomp?sitos, os valores encontrados nos ensaios de tra??o para os limites de escoamento e tens?o de ruptura n?o sofreram altera??es ? medida que se adicionavam as fibras. Outros pontos relevantes foram o aumento da resist?ncia ? flex?o, a redu??o da degrada??o t?rmica das misturas polipropileno e fibras de curau?, e o n?o comprometimento de uma forma em geral, da fabrica??o dos biocomp?sitos, quando analisados por microscopia eletr?nica de varredura. / This research presents an approach about the polypropylene recycling process reinforced with curau? reprocessed fibers. As an alternative proposal reinforcement to polymeric composites. Levels of 10 %, 20 % and 30 % of fibers in the biocomposites were analyzed to check their mechanical properties comparing them, even with the properties of polypropylene (PP). Pellets biocomposites were prepared by the extrusion process, and the specimens were manufactured by injection process and subjected to mechanical tests of uniaxial tensile, three point bending and impact. To check for damage to the specimens was used to analysis by scanning electron microscopy (SEM). These biocomposites were also subjected to testing physical ? chemistry of index of fluidity (IF). It was observed that the polypropylene biocomposites with 30 % curau? fibers showed higher elastic modulus for both traction and to flexion and less resistance to impact. For all biocomposites, the values found in tensile tests to the limits of flow and maximum voltage have approximate values as they were added the curau? fibers. Another important point was increased resistance to bending in biocomposite as promoting the addition of curau? fibers and decrease as they were reprocessed also decreased thermal degradation of the polypropylene blends and curau? fibers, and no impairment of so in general, the production of biocomposites, when analyzed by scanning electron microscopy.