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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Hemp fiber – an environmentally friendly fiber for concrete reinforcement

Giltner, Brian 25 November 2020 (has links)
The commercial use of hemp fiber in the construction industry within the United States is non-existent. This lack of use is because of State and Federal laws forbidding the growth of hemp in the United States, which has led to a lack of research. Not having an established supply chain for hemp and coupled with limited research has put the United States behind other countries in finding viable options for these renewable resources. This is a study of the performance of raw hemp fibers and processed hemp twine in a cement past mixture subjected to tensile loading. Three water/cement ratios (0.66, 0.49, 0.42) were considered. Replacement of cement with fly ash is also part of the program to see if it affects the performance of the system. A detailed description of the method of applying the tensile load to the micro/macro fibers along with the fixture setup is part of this article. The results of this investigation show the hemp twine and fibers will bond to the cement matrix and they can carry higher tensile loads at higher w/c ratios. This study shows that 30 mm embedment length is best for hemp macro fibers and 20 mm embedment for hemp micro fibers. This study also includes a comparative investigation of the performance of hemp fibers to synthetic and steel fibers added to a concrete mix. This investigation examined the compressive strength of the fiber-reinforced concrete mixes, flexural capacity, ductility, flexural toughness and the effects the fibers have on Young’s modulus of elasticity. All fibers were introduced to the same mix design (w/c = 0.49) with replacement of 25% of cement with fly ash. Hemp micro fibers at the same dosing rate a synthetic micro fibers has a slightly higher toughness and equivalent flexural strength. Hemp macro fibers at a higher dosing rate as compared to synthetic fibers will have similar toughness and equivalent flexural strength. Steel fibers performed better than the synthetic and natural fibers at 28-day compressive strength.
12

Structural Performance of Fiber-Reinforced and Welded Wire Fabric-Reinforced Concrete Composite Slabs

Ordija, James Louis 02 February 2007 (has links)
The purpose of this research is to evaluate and compare the structural performance of composite floor slabs reinforced with 6 x 6 W1.4/W1.4 welded wire fabric (WWF) and STRUX 90/40 synthetic macro fibers. Slabs were subjected to flexural strength tests and concentrated load tests while monitoring load, steel deck strains, and deflections. Test results obtained from this test program were also compared to results from a similar test program conducted in 2001. Tests were also performed to obtain the average residual-strength of the fiber-reinforced concrete using the ASTM C 1399 (2003) standard test. All slabs were loaded until a complete failure was observed. The observed failure loads were compared to failure loads calculated by design guides published by the American Society of Civil Engineers (ASCE) and the Steel Deck Institute (SDI). The flexural strength tests showed that composite slabs reinforced with synthetic macro fibers and WWF exhibited strength and behavior that was almost identical. The observed values of strength were also within the range that was predicted by ASCE prediction models. At a typical office design load of 70 psf, all slabs exhibited midspan deflections that were much smaller than those necessary for serviceability requirements. The concentrated load tests also showed that the observed strength of all composite slabs tested was above those values predicted by ASCE and SDI models. However, an effective comparison between the WWF-reinforced and synthetic macro fiber-reinforced slab was difficult due to a poor shear bond in the latter slab prior to testing. The results of the ASTM C 1399 test verified the ability of concrete reinforced with synthetic macro fibers to meet average residual-strength values recommended by the SDI. / Master of Science
13

Tratamentos térmico e corona em tecido de poliéster / Thermal and corona treatments in polyester fabric

Carvalho, José Geraldo de, 1977- 18 August 2018 (has links)
Orientador: João Sinézio de Carvalho Campos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-18T13:11:39Z (GMT). No. of bitstreams: 1 Carvalho_JoseGeraldode_M.pdf: 906811 bytes, checksum: ac36e65d7b8b81bace165c355c2d5f59 (MD5) Previous issue date: 2011 / Resumo: O tratamento térmico, que na indústria têxtil é mais conhecido como termofixação, é um processo muito importante para garantir a estabilidade dimensional do tecido de poliéster durante os processos de beneficiamento e no uso. Mas o processo de termofixação modifica algumas propriedades do tecido e entre elas podemos destacar: Hidrofilidade, comportamento tintorial, alongamento e ruptura. Essas propriedades são influenciadas pelas variáveis tempo e temperatura de termofixação. Nesse sentido o presente trabalho tem como objetivo analisar as alterações proporcionadas pela termofixação nas propriedades físico-químicas do tecido de poliéster. O poliéster é um material que apresenta superfície quimicamente inerte, não porosa e com baixa energia de superfície (43 mN/m). O tratamento com descarga corona vem propor aumentar a energia de superfície, melhorar a hidrofilidade, o comportamento tintorial e a adesão do tecido termofixado e sem termofixar. Submeteram-se amostras de tecido plano de poliéster á termofixação em diversas combinações de tempo e temperatura dentro dos intervalos de 120 a 220°C e de 30 a 120 segundos. Após a termofixação mediu-se o encolhimento das amostras e submeteram-se as mesmas a testes de alongamento e ruptura. Trataram-se amostras de tecido de poliéster termofixadas e sem termofixar com descarga corona, e em seguida, submeteu-se as mesmas a testes de hidrofilidade, tingimento, estampagem, alongamento e ruptura. Observou-se que a termofixação promove encolhimento, aumento do alongamento, diminuição da hidrofilidade e da absorção de corante em tingimento de tecido de poliéster. O tratamento corona aumenta a hidrofilidade, a absorção de corante, a ancoragem de pigmentos em amostras de tecido de poliéster termofixadas e sem termofixar / Abstract: The thermal treatment, which in the textile industry is known as heat setting, is very important to ensure the dimensional stability of polyester fabric during the process of improving and use. But the process of heat setting changes some properties of the fabric and among them we can highlight: Hidrophilicity, dyeability, elongation and strength. These properties are influenced by variables dwell time and heat setting temperature. In that sense this work has as objective to analyze the changes caused by heat in the physico-chemical properties of polyester fabric. Polyester is a material that presents the surface chemically inert, non-porous and low surface energy (43 mN / m). The treatment with corona discharge is proposing to increase the surface energy, improve the hidrophilicity, dyeability and adhesion of the polyester fabric with and without heat setting. Samples of polyester plan fabric underwent to heat setting on various combinations of time and temperature within the interval between 120 to 220 ° C, from 30 to 120 seconds. After the heat setting was measured the shrinkage of the samples and underwent the samples by tests of elongation and rupture. Samples of polyester fabric with and without heat setting were treated with corona discharge and in sequence the samples were tested by hidrophilicity, dyeing and printing. The heat setting promotes shrinkage and increase the elongation of polyester fabric. It was observed that the heat setting promotes shrinkage, increase of elongation, reduction of hydrophilicity and reduction of uptake of dye in the dyeing of polyester fabric. The corona treatment increase the hydrophilicity, the absorption of dye in pad-thermofix process and the pigment anchoring in polyester fabric samples with and without heat setting / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química
14

Structural Performance of High-Strength Reinforced Concrete Beams Built with Synthetic Fibers

Bastami, Roukaya 16 December 2019 (has links)
This thesis presents the results of a research program examining the effects of macro-synthetic fibers on the shear and flexural behaviour of high-strength concrete (HSC) beams subjected to static and blast loads. As part of the study, a series of seventeen fiber-reinforced HSC beams are built and tested under either quasi-static four-point bending or simulated blast loads using a shock-tube. The investigated test parameters include the effects of: macro-synthetic fibers, fiber hybridization, combined use of fibers and stirrups and longitudinal steel ratio and type. The results show that under slowly applied loads, the provision of synthetic fibers improves the shear capacity of the beams by allowing for the development of yield stresses in the longitudinal reinforcement, while the combined use of synthetic fibers and stirrups is found to improve flexural ductility and cracking behaviour. The results also show that the provision of synthetic fibers delays shear failure in beams tested under blast pressures, with improved control of blast-induced displacements and increased damage tolerance in beams designed with combined fibers and stirrups. The study also shows that the use of hybrid fibers was capable of effectively replacing transverse reinforcement under both loading types, allowing for ductile flexural failure. Moreover, the use of synthetic fibers was effective in better controlling crushing and spalling in beams designed with Grade 690 MPa high-strength reinforcement. Furthermore, the results demonstrate that synthetic fibers can possibly be used to relax the stringent detailing required by modern blast codes by increasing the transverse reinforcement hoop spacing without compromising performance. As part of the analytical study, the load-deflection responses (resistance functions) of the beams are predicted using sectional (moment-curvature) analysis, as well as more advanced 2D finite element modelling. Dynamic resistance functions developed using both approaches, and incorporating material strain-rate effects, are then used to conduct non-linear single-degree-of-freedom (SDOF) analyses of the blast-tested beams. In general, the results show that both methods resulted in reasonably accurate predictions of the static and dynamic experimental results.
15

[en] INFLUENCE OF FIBER DEGRADATION ON MECHANICAL BEHAVIOR OF REINFORCED SOILS / [pt] INFLUÊNCIA DA DEGRADAÇÃO DE FIBRAS NO COMPORTAMENTO MECÂNICO DOS SOLOS REFORÇADOS

FERNANDA PECEMILIS DALLA BERNARDINA 20 December 2019 (has links)
[pt] O presente estudo experimental apresenta o comportamento mecânico e a durabilidade de compósitos de solo arenoso reforçado com fibras de polipropileno e de fibras vegetais de coco, sisal e curauá, aleatoriamente distribuídas, submetidos ao envelhecimento natural, com o objetivo de estudar a sua aplicação em obras geotécnicas. O programa experimental consistiu na execução de ensaios triaxiais drenados nas amostras de areia pura, areia-fibra no tempo zero (amostras de controle) e nos compósitos expostos por um período máximo de 8 meses, com o objetivo de avaliar a durabilidade dos compósitos. Foram realizados ensaios de tração direta nas fibras vegetais sem degradação e nas fibras utilizadas como reforço em compósitos expostos ao ambiente externo e ao tempo, localizadas nas profundidades de 75 e 125 cm. Para um melhor entendimento da variação dos resultados obtidos, os ensaios triaxiais e de tração foram executados nos intervalos de tempo: 0, 60, 120 e 240 dias. Foi possível observar que todos os compósitos expostos apresentaram queda na resistência de cisalhamento, em relação às amostras de controle, inclusive os reforçados com fibra de polipropileno. Os compósitos reforçados com fibra de coco apresentaram baixa degradação, se comparados com as amostras reforçadas com outras fibras vegetais. Quanto aos ensaios de tração, a fibra de curauá apresentou as maiores resistências à tração inicial e final, após os 8 meses, porém foi a fibra que mais sofreu degradação durante o período em exposição, sofrendo grandes per-das de resistência. Todas as fibras analisadas apresentaram degradação maior na profundidade de 75 cm. / [en] The present experimental study presents the mechanical behavior and the du-rability of composites of sandy soil reinforced with polypropylene fibers and vegetal fibers of coconut, sisal and curauá, randomly distributed, submitted to the natural aging, with the objective of studying their application in earthworks. The experimental program consisted in the execution of triaxial tests in the sand, sand-fiber samples at zero time (control samples) and in the exposed composites for up to 8 months, in order to evaluate the durability of the composites. Direct tensile tests were done on the non-degraded natural fibers and on the fibers used as reinforcement in samples exposed to the external environment and to the time, located at depths of 75 and 125 cm. For a better understanding of the variation of the obtained results, the triaxial and tensile tests were performed in the time intervals: 0, 60, 120 and 240 days. It was possible to observe that all exposed composites presented a drop in shear strength, in relation to the control samples, inclusive those reinforced with polypropylene fiber. The composites reinforced with coconut fiber presented low degradation when compared with the samples forced with other vegetable fibers. Regarding the tensile tests, the curaua fiber showed the greatest resistance to the initial and final traction, after 8 months, but it was the fiber that suffered the most degradation during the exposure period, suffering great losses of resistance. All the analyzed fibers presented degradation greater in the depth of 75 cm.
16

Bomullens nya ansikte : Kan man finna ett material som kan agera substitut till bomullen för producenter inom yrkeskläder? / Cotton’s new face : Is there a material, which can be a substitute to cotton for work wear producers?

Wilen, Linda, Norin, Daniel, Eriksson, Anna January 2011 (has links)
Syftet med undersökningen är att undersöka, beskriva och analysera kring hur vida det finns ett bra substitut till bomull. Undersökningen kommer att belysa hur marknaden ser ut i dag och vilka material som används. Vidare utreds parametrarna funktion, kundnytta och hållbarhet, som kan komma att spela roll i valet av material för producenter av yrkeskläder. I dagsläget finns det inget solklart val av material som skulle kunna mäta sig med bomullen gällande de parametrarna som uppsatsen tar upp. Vad man väljer att använda istället för bomull beror mycket på hur företagen väljer att fokusera gällande just funktion, kundnytta och hållbarhet. Faktorer så som ledtider och prisaspekter spelar också roll, men dessa har uppsatsen valt att förbise. Det handlar om att ha tillräckligt starka argument som väger över bomullens fördelar. Där kan man exempelvis trycka på miljöfrågor gällande nykommande material. Om man bara ska se till att hitta ett bättre alternativ hållbarhetsmässigt än bomull så finns det många alternativ att välja mellan.The purpose of the study is to explore, describe and analyze on how there is a good substitute for cotton. The study will illustrate how the market stands today and what materials that are being used. Further investigation of the various parameters of operation, customer value and durability, which may play a role in the selection of materials for the manufacturers in work wear.Today, there is no obvious choice of materials that could compete with cotton with the current parameters which the essay addresses. What companies choose to use instead of cotton depends on how they choose to focus on function, customer value and durability. Factors such as lead times and price aspects also play an important role, but these are excluded in the essay. It all comes down to having strong arguments that weigh more than the benefits of cotton. For example, pressing environmental issues concerning newcomer materials. If you only want to find a better alternative in terms of durability than cotton, there are many options to choose from. / Program: Textil produktutveckling med entreprenörs- och affärsinriktning
17

Vigas de Madeira Laminada Colada de Paricá (Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby) Reforçadas com Fibras Sintéticas / Glulam beans of paricá timber (Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby) reinforced with synthetic

Rosa, Talitha Oliveira 21 February 2017 (has links)
Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2017-12-14T13:00:59Z No. of bitstreams: 1 PGEF17MA080.pdf: 2008307 bytes, checksum: 8732b2de7a80b6063f37c07cd1d0f861 (MD5) / Made available in DSpace on 2017-12-14T13:00:59Z (GMT). No. of bitstreams: 1 PGEF17MA080.pdf: 2008307 bytes, checksum: 8732b2de7a80b6063f37c07cd1d0f861 (MD5) Previous issue date: 2017-02-21 / FAPESC / CAPES / The glulam is made up by laminated timbers with restricted size regarding the final component, they are glued each other and being lied in parallel direction to fibers, being used in structures to timber construction. In Brazil, the glulam is mainly manufactured with exotic timbers from planted forests, such as Pinus and the Eucalyptus. Paricá is a native specie quite planted in business forests from Amazonia. Reseraches shows that the specie has aptitude for being used in glulam, but its resistance is lower than Eucalyptus. During structural elements manufacturing, the reinforcement with fibers may increase the paricá's glulam performance. Thus, this research aims to evaluate the potential of paricá specie for be used in glulam beams reinforced with glass fiber and carbon fiber with adhesive based on resorcinol. In the first part of work, it was made a classification laminates of paricá timber for manufacturing of glulam beams. Therefore, the laminated were divided by density and classified into 8 classes, then used a non-destructive bending test, with three points, being the siplacemtn mensure by expeditious mode and by data acquisition system. Datas were assessed by Scott Knott average test with 5% of meaningfulness. In the second part of work, bending tests was made on 30 Paricá's glulam beams, arranged in 5 treatments: T1- without reinforcement; T2 - with fiberglass reinforcement with grammage 110 g.m-2; T3- glass fiber with 200 g.m-2; T4 –glass fiber with 330 g.m-2; and T5 - carbon fiber with grammage 200 g.m-2. Just one fiber layer was used on treatment with reinforcement. The the average and characteristic values were determined of strength to axial stress, strength to shear, elasticity modulus – MOE, and the normal shear and normal tension on glue line. Datas were assessed about normality, homogeneity and averages comparison by Tukey test to 5% of meaningfulness. The glulam beams composed with classified laminated timbers by expeditious mode had a relative error about 26,21% regarding glulam beams composed with laminated timbers classified by a displacement transducer. Characteristic values of strength to axial stress, shear stress and MOE were: T1 (55,06; 1,4; 12.097,93 MPa); T2 (59,40; 1,27;12.062,91 MPa); T3 (53,45; 1,27; 14.068,63 MPa); T4 (61,09; 1,45; 13.370,25 MPa); and T5 (52,16; 1,24; 12.823,84 MPa), respectively. When comparing the strength gain of reinforced beams regarding T1, an increase about axial stresses 17,57% was obtained for glulam beams reinforced with fiber glass and the reinforcement with carbon showed just 0,38%. It was observed beams breaking did not happen by shear forces, this fact shows that to use adhesive based on resorcinol was satisfactory. Analytic design differed statistically on treatment T5 (21.627 MPa on analytic; 12.857 MPa on theoretical) due to high elasticity modulus of the carbon fiber. The expeditious mode can be used to classified the MOE by glulam manufactory companies. Reinforcements with synthetic fibers showed promising results on timber beams reinforcement when is used adhesive based on resorcinol, this fact lead to an increase of up to 22,32% on the strength to axial stresses when is used fiberglass with 200g.cm-2 / A Madeira Lamelada Colada (MLC) é formada por lamelas de madeira com tamanho reduzido em relação ao componente final, coladas entre si no sentido paralelo às fibras, sendo utilizada em estruturas para a construção em madeira. No Brasil, a MLC é produzida, principalmente, com madeiras exóticas provenientes de florestas plantadas, tais como o Pinus e o Eucalyptus. O paricá é uma espécie nativa plantada em florestas comerciais na Amazônia. Pesquisas mostram que a espécie possui aptidão para o uso em MLC, mas sua resistência é menor que o Eucalyptus. Durante a produção de elementos estruturais, o reforço com fibras durante pode aumentar o desempenho do MLC de paricá. Deste modo, esse trabalho visou avaliar o potencial da espécie de paricá para utilização em vigas de MLC reforçadas com fibras de vidro e fibras de carbono, utilizando o adesivo a base de resorcinol. Na primeira parte do trabalho foi feita a classificação das lamelas de paricá para a produção de vigas MLC. Para isto, as lamelas foram separadas pela densidade aparente em oito classes, então empregados o ensaio de flexão não destrutivo a três pontos, sendo o deslocamento medido de forma expedita e por um sistema de aquisição automático de dados. Os dados foram avaliados pelo teste de médias Scott Knott a 5% de significância. Na segunda parte do trabalho, foram ensaiadas 30 vigas em MLC de paricá à flexão, separadas em 5 tratamentos: T1 - sem reforço; T2 - com reforço em fibra de vidro com gramatura 110 g.m-2; T3 – fibra de vidro com 200 g.m-2; T4 – fibra de vidro com 330 g.m-2; e T5 - com de fibra de carbono 200 g.m-2. Apenas 1 camada de fibra foi utilizada em todos os tratamentos com reforços. Os valores médios e característicos foram determinados para a resistência à tensão axial na flexão, ao cisalhamento, EW, e o cisalhamento e tração normal da linha de cola. Os dados foram avaliados quanto a sua normalidade, homogeneidade e comparação de médias pelo teste Tukey à 5% de significância. As vigas de MLC compostas com lamelas classificadas pelo método expedito tiveram um erro relativo de até 26,21% em relação a vigas de MLC compostas com lamelas classificadas pelo método com transdutor de deslocamento. Os valores característicos de resistência a tensão axial, tensão de cisalhamento e EW foram: T1(51,96; 1,39; 12.097,93 MPa); T2 (59,40; 1,27; 12.062,91 MPa); T3 (53,45; 1,27; 14.068,63 MPa); T4 (61,09; 1,45; 13.370,25 MPa) e T5 (52,16; 1,24; 12.823,84 MPa), respectivamente. Ao comparar o ganho de resistência das vigas reforçadas com o T1, um aumento de até 17,57% foi obtido para vigas reforçadas com fibra de vidro e o reforço de fibra de carbono apresentou apenas 0,38%. Observou-se que as rupturas das vigas não foram tensões de cisalhamento, indicando que o uso de adesivo a base de resorcinol foi satisfatório. O cálculo analítico diferiu estatisticamente apenas no tratamento T5 (21.627 MPa no analítico; 12.857 MPa no experimental), devido ao alto EW fibra de carbono. O método expedito poderá ser utilizado para a classificação do EW por empresas de produção de MLC. Os reforços com fibras sintéticas mostraram resultados promissores nas de vigas de MLC ao utilizar o adesivo a base de resorcinol, levando a um aumento de até 22,32% na resistência a tensões axiais em vigas reforçadas com fibras de vidro com gramatura acima de 200 g.cm-2
18

Envelhecimento ambiental em comp?sitos polim?ricos ? base de tecidos de refor?os h?bridos

Batista, Ana Cla?dia de Melo Caldas 25 July 2013 (has links)
Made available in DSpace on 2014-12-17T14:58:20Z (GMT). No. of bitstreams: 1 AnaCMCB_DISSERT.pdf: 5204946 bytes, checksum: 70bedde30acbc8578034105c8c4fc24e (MD5) Previous issue date: 2013-07-25 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The utilization of synthetic fibers for plastic reinforcement is more and more frequent and this growing interest requires that their mechanic behavior under the most variable conditions of structural applications be known. The use of such materials in the open and exposed to the elements is one of them. In this case, it becomes extremely necessary to study their mechanical properties (strength, stiffness) and the mechanism of fracture by which the environment aging them out. In order to do that, the material must be submitted to hot steam and ultraviolet radiation exposure cycles, according to periods of time determined by the norms. This study proposal deals with the investigation of accelerated environmental aging in two laminated polymeric composites reinforced by hybrid woven made up of synthetic fibers. The configurations of the laminated composites are defined as: one laminate reinforced with hybrid woven of glass fibers/E and Kevlar fibers/49 (LHVK) and the other laminate is reinforced with hybrid tissue of glass fibers/E and of carbon fibers AS4 (LHVC). The woven are plane and bidirectional. Both laminates are impregnated with a thermofix resin called Derakane 470-300 Epoxy Vinyl-Ester and they form a total of four layers. The laminates were industrially manufactured and were made through the process of hand-lay-up. Comparative analyses were carried out between their mechanical properties by submitting specimen to uniaxial loading tractions and three-point flexion. The specimen were tested both from their original state, that is, without being environmentally aging out, and after environmental aging. This last state was reached by using the environmental aging chamber / O interesse na utiliza??o dos pl?sticos refor?ados por fibras sint?ticas ? cada vez mais crescente e esse grande interesse na utiliza??o dos mesmos faz com que seja necess?rio o conhecimento do comportamento mec?nico desses materiais sob as mais variadas condi??es de aplica??o estrutural. Dentre estas pode ser destacada a aplica??o desses materiais em situa??es em o elemento encontra-se exposto ? intemp?rie, e nesse caso os estudos das propriedades mec?nicas (resist?ncia, rigidez) al?m do mecanismo fratura frente ao envelhecimento ambiental s?o de extrema necessidade. Para tanto, submeter o material ? per?odos c?clicos de exposi??o ao vapor aquecido e ? de radia??o ultravioleta, por tempo definido em norma, se faz necess?rio. A presente proposta de trabalho de investiga??o consiste no estudo do envelhecimento ambiental acelerado em dois laminados comp?sitos polim?ricos refor?ados por tecidos h?bridos ? base de fibras sint?ticas. As configura??es dos laminados comp?sitos s?o definidas como: um laminado refor?ado com tecido h?brido de fibras de vidro/E e de fibras kevlar/49 (LHVK) e outro laminado refor?ado com tecido h?brido de fibras de vidro/E e de fibras de carbono AS4 (LHVC). Os tecidos s?o dos tipos planos e bidirecionais. Ambos os laminados foram impregnados a base de resina termofixa Derakane 470-300 Ep?xi Vinil-Ester e constitu?dos com quatro camadas no total. Os laminados t?m fabrica??o industrial e foram obtidos atrav?s do processo de lamina??o manual (Hand-lay-up). Foram realizados estudos comparativos entre as propriedades mec?nicas sob a a??o dos carregamentos de tra??o uniaxial e flex?o em tr?s pontos, nas condi??es dos corpos de prova sem o efeito do envelhecimento ambiental (estado original) e sob o efeito desse envelhecimento (estado envelhecido). O envelhecimento ambiental foi acelerado atrav?s do uso da c?mara de envelhecimento
19

Tratamento corona sobre superficies texteis / Treatment corona on surfaces textiles

Giordano, João Batista 11 May 2007 (has links)
Orientador: João Sinezio de Carvalho Campos / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-10T13:40:00Z (GMT). No. of bitstreams: 1 Giordano_JoaoBatista_D.pdf: 4390680 bytes, checksum: 205aa7153da8e4745f9366e58adcb8cf (MD5) Previous issue date: 2007 / Resumo: Dentre as técnicas de modificação de superfícies aplicadas na indústria para melhorar adesão, o tratamento por descarga corona é amplamente utilizado. Durante o tratamento por descarga coro na, espécies ativas são geradas, as quais podem reagir com a superfície do polímero ocasionando quebra de cadeias e formação de radicais, criando assim grupos polares na superfície e conseqüentemente, aumentando a sua energia superficial e propriedade de adesão. Neste trabalho utilizaram-se tecidos de poliéster e de algodão. Nos processos convencionais de preparação de tecidos são usados agentes químicos que agridem os efluentes têxteis, assim a descarga corona propõe-se como tratamento prévio do material sem ação de tais agentes, sendo tratamento único e apenas físico. Os objetivos deste trabalho são: 1. Tratar com descarga corona tecidos de poliéster e tecidos de algodão (engomado, lavado e desengomado); 2. Verificar hidrofilidade e absorção de corantes em tecidos de algodão tratados com descarga corona; 3. Verificar propriedades mecânicas em tecidos tratados com descarga corona. 4. Verificar a adesão de pigmentos em de tecidos de poliéster tratados com corona. Tecidos foram submetidos à descarga: corona variando-se o tempo exposição e altura entre os eletrodos, em seguida foi realizada testes de hídrofilidade, absorção de corante tipo reativo, adesão de pigmentos, solidez a lavagem e ensaios de resistência à tração e alongamento. Foi utilizada a técnica de microscopia óptica, ensaio de hidrofilidade para caracterizar os efeitos causados. Os resultados mostram que: houve aumento da hidrofilidade do tecido de algodão que de 50% em amostra sem tratamento passou até a 280% com o tratamento, observou-se também que com te~pos de 1 mino já ocorrem modificações nos tecidos quanto a hidrofilidade e absorção de corantes; houve aumento da absorção de corante nas regiões tratadas principalmente em processos contínuos de tingimento; ocorreu boa aderência de pigmentos em tecidos de poliéster tratados; não ocorrem alteração das propriedades mecânicas (resistência a tração e alongamento) nas amostras tratadas. / Abstract: Amongst the techniques of modification of surfaces applied in the industry to improve adhesion, the treatment for discharge corona widely is used. During the treatment for discharge corona, active species are generated, which can consequently react with the surface of polymer causing chain in addition and formation of radicals, thus creating polar groups in the surface and, increasing its superficial energy and property of adhesion. In this work they had been used weaveed of polyester and cotton. In the conventional processes of fabric preparation they are used chemical agents whom the effluent textile attack, thus the discharge corona is considered as previous treatment of the material without action of such agents, being treatment only e only physicist. The objectives of this work are: 1.To deal with discharge corona weaveed to polyester and fabrics cotton (starchy, washed and dissolved the gum); 2. To verify water absorption and absorption of corantes in fabrics of cotton treated with discharge corona; to 3.Verificar mechanical properties in fabrics dealt with discharge corona. 4. To verify the pigment adhesion in of treated polyester fabrics with corona. Fabrics had been submitted to the discharge corona varying the time exposition and height between the electrodes and, after that water absorption tests had been carried through, absorption of corante reactive type, pigment adhesion, solidity the laudering and assays of tensile strenght and allonge. The technique of optic microscopy was used, assay of water absorption to characterize the caused effect. The results show that: it had increase of the hidrofilidade of the cotton fabric that of 50% in sample without treatment passed until 280% with the treatment, was 9.lso observed that with times of 1 min. already the water absorption and absorption of corantes occur modifications in fabrics how much; it had increase of the absorption of corante in the regions treated mainly in continuous processes of dyeing good pigment tack occurred in treat polyester fabrics; they do not occur alteration of the mechanical properties (resistance the traction and allonge) in the treated samples. / Doutorado / Ciencia e Tecnologia de Materiais / Doutor em Engenharia Química
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Propiedades mecánicas del concreto con fibras sintéticas para rehabilitar pavimento flexible mediante la técnica Whitetopping, en Avenida Central San Juan de Lurigancho, Lima, 2020 / Mechanical properties of concrete with synthetic fibers to rehabilitate flexible pavement using the Whitetopping technique, in Avenue Central San Juan de Lurigancho, Lima, 2020

Pirca Ramos, Wilmer, Chinchay Liviapoma, Landys Noé 28 April 2021 (has links)
En la investigación actual se realizó un estudio de las propiedades mecánicas del concreto utilizado para la rehabilitación de pavimentos flexibles, a través de la metodología de Whitetopping, mediante la adición de fibras sintéticas. Esta nueva técnica se aplicó en la Avenida Central de San Juan de Lurigancho, en Lima, para lo cual se planteó como objetivo general determinar el cambio de las propiedades mecánicas del concreto con adición de las mencionadas fibras sintéticas para rehabilitar pavimentos flexibles. Los resultados fueron satisfactorios, obteniéndose para las resistencias a la tracción un aumento de 27.30 kg/cm2 sin fibra a 33.80 kg/cm2 con fibra al 4 %, y 41.71 kg/cm2 con fibra al 7 %. Con respecto a la resistencia a flexión, aumentó de 33.3 kg/cm2 sin fibra a 41.4 kg/cm2 con fibra al 4 %, y 50.6 kg/cm2 con fibra al 7 %. Y, por último, en el módulo de elasticidad mejoró de una deformación de 24.9 GPa sin fibra a 25.2 GPa con fibra al 4 % y 25.6 GPa al 7%. Finalmente se calculó el espesor del pavimento Whitetopping en función al estudio del tráfico y todas las variables definidas en la ecuación establecida por AASHTO 93, donde se obtuvo que el espesor del pavimento Whitetopping es de 17 cm, por lo tanto, se logró un Whitetopping delgado. Se concluyó que, con el uso de fibra sintéticas en el concreto Whitetopping, se mejoraron las propiedades del concreto. / In the current research, a study of the mechanical properties of the concrete used for the rehabilitation of flexible pavements was carried out, through the Whitetopping methodology, by means of the addition of synthetic fibers. This new technique was applied in the Central Avenue of San Juan de Lurigancho, in Lima, for which the general objective was to determine the change in the mechanical properties of concrete with the addition of the aforementioned synthetic fibers to rehabilitate flexible pavements. The results were satisfactory, obtaining for the tensile strengths an increase of 27.30 kg/cm2 without fiber to 33.80 kg/cm2 with 4% fiber, and 41.71 kg/cm2 with 7% fiber. Regarding flexural strength, it increased from 33.3 kg/cm2 without fiber to 41.4 kg/cm2 with 4% fiber, and 50.6 kg/cm2 with 7% fiber. And, finally, the modulus of elasticity improved from a deformation of 24.9 GPa without fiber to of 25.2 GPa with fiber at 4% and 25.6 GPa at 7%. Finally, the thickness of the Whitetopping pavement was calculated based on the traffic study and all the variables defined in the equation established by AASHTO 93, where it was obtained that the thickness of the Whitetopping pavement is to 17 cm, therefore, a slim whitetopping was achieved. It was concluded that, with the use of synthetic fiber in the whitetopping concrete, the properties of the concrete were improved. / Tesis

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