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Artykuły w czasopismach na temat "Vegetal-Composite"
STEPINA, I. V., i M. SODOMON. "BIOSTABLE VEGETAL COMPOSITE FOR THERMAL INSULATION". Building and reconstruction 103, nr 5 (2022): 115–23. http://dx.doi.org/10.33979/2073-7416-2022-103-5-115-123.
Pełny tekst źródłaGavrilescu, Dan, Bogdan Marian Tofanica, Adrian Catalin Puitel i Puiu Petrea. "SUSTAINABLE USE OF VEGETAL FIBERS IN COMPOSITE MATERIALS. SOURCES OF VEGETAL FIBERS". Environmental Engineering and Management Journal 8, nr 3 (2009): 429–38. http://dx.doi.org/10.30638/eemj.2009.058.
Pełny tekst źródłaKageura, H., i K. Yamana. "Pattern formation in 8-cell composite embryos of Xenopus laevis". Development 91, nr 1 (1.02.1986): 79–100. http://dx.doi.org/10.1242/dev.91.1.79.
Pełny tekst źródłaMiraoui, Imed, i Hedi Hassis. "Mechanical Model for Vegetal Fibers-Reinforced Composite Materials". Physics Procedia 25 (2012): 130–36. http://dx.doi.org/10.1016/j.phpro.2012.03.061.
Pełny tekst źródłaMintova, Svetlana, Valentin Valtchev, Brian Schoeman i Johan Sterte. "Preparation of zeolite Y-vegetal fiber composite materials". Journal of Porous Materials 3, nr 3 (1996): 143–50. http://dx.doi.org/10.1007/bf01134025.
Pełny tekst źródłaGil, Lluís, Luis Mercedes, Virginia Mendizabal i Ernest Bernat-Maso. "Shear Performance of the Interface of Sandwich Specimens with Fabric-Reinforced Cementitious Matrix Vegetal Fabric Skins". Applied Sciences 14, nr 2 (19.01.2024): 883. http://dx.doi.org/10.3390/app14020883.
Pełny tekst źródłaOrnaghi Júnior, Heitor L., Matheus Poletto, Felipe G. Ornaghi, Ademir J. Zattera i Sandro C. Amico. "Dynamic mechanical properties and the dynamic fragility concept applied to vegetal fiber on vegetal composite materials". Journal of Composite Materials 50, nr 18 (4.09.2015): 2469–75. http://dx.doi.org/10.1177/0021998315604208.
Pełny tekst źródłaSederholm, Helena. "Slow Life of Vegetal, Animal, and Some Composite Organisms". Research in Arts and Education 2022, nr 1 (27.05.2022): 1–3. http://dx.doi.org/10.54916/rae.119452.
Pełny tekst źródłaGrădinaru, Cătălina Mihaela, Adrian Alexandru Șerbănoiu, Radu Muntean i Bogdan Vasile Șerbănoiu. "The Synergy between Bio-Aggregates and Industrial Waste in a Sustainable Cement Based Composite". Materials 14, nr 20 (17.10.2021): 6158. http://dx.doi.org/10.3390/ma14206158.
Pełny tekst źródłaSantos, Paulo A., Marcia A. S. Spinacé, Karen K. G. Fermoselli i Marco-A. De Paoli. "Polyamide-6/vegetal fiber composite prepared by extrusion and injection molding". Composites Part A: Applied Science and Manufacturing 38, nr 12 (grudzień 2007): 2404–11. http://dx.doi.org/10.1016/j.compositesa.2007.08.011.
Pełny tekst źródłaRozprawy doktorskie na temat "Vegetal-Composite"
Marques, Maria Gorett dos Santos. "Estudo das propriedades físicas e mecânicas e da durabilidade de compósitos cimentícios reforçados com fibra amazônica". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-15022016-091455/.
Pełny tekst źródłaThis present study aims to develop a cementation composite reinforced with arumã fiber. The aim is to aggregate value to a typical plant of the Amazon region, called arumã, belonging to species of the genus Ischnosiphon arouma (Aubl) Korn and originally from Maranthaceae family, so that, it can be obtained a New Material. In the first stage of the study was performed the characterization the vegetable fiber arumã and all components of the cementicious matrix, which comprised chemical, physical and mechanical tests for research and evaluation of their properties. In the next stage, it was adopted the procedure of working the physical and mechanical characteristics of the fibers with the cementitious matrix comprising a study of the surface of the fiber modification by chemical treatments using sodium hydroxide solution or employing procedures with hot water and hornification. In the third step, the reinforced plates were produced without and with treatment, which, part of were subjected to cure for 28 days and the remaining subjected to the accelerated aging test. The results obtained in the characterization of arumã fibers indicate its potential use as a reinforcement element for cementicious composites. On the other hand, the composites produced with arumã fiber fabrics without and with a treatment (hornification and alkaline) showed slightly ductile behavior and low strength as a result of degradation of fibers in the cementitious matrix. This was confirmed through accelerated aging tests with wetting and drying cycles.
SOUSA, Iradenia da Silva. "Herança do comprimento do pedúnculo ramificado em feijão - caupi e sua relação com a produção e seus componentes". Universidade Federal Rural de Pernambuco, 2008. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6410.
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The cowpea is a main source of vegetable protein for the people of lower purchasing power of Asia, Africa, Europe and North America, Central and South. In the North and Northeast of Brazil, represent one the most important leguminous food of the diet. Most of the genotypes grown in the world have simple inflorescence. However, cultivars with composite inflorescence were find in cowpea. The aim this work was to study the inherintance of the characters related to production and to inflorescence in crosses between genotypes with simple inflorescence and composite inflorescence. The work was realized at Embrapa Meio-Norte, in Teresina, PI, in the years from 2006 to 2007. It was been made crosses between TVx 5058-09C (P2) x Cacheadoroxo (P1) and Cacheado-roxo (P1) x AU94-MOB-816 (P3). The genitor Cacheadoroxo with composite inflorescence and the other two genitors presenting simple inflorescence. The parents, the generations F1's, F2's and the backcrosses were evaluated in complete randomized blocks design with six repetitions. The parents and F1's consisted of a plot per block, the F2 generations and the backcrosses consisted of five and two rows per block, respectively. The plots were represented per one row with 7,0 m of length, the spacing between rows was 1,0 m and between hole in rows of 0,70 m. The genetic studies were realized with based on the means and variances, with help of the Program Genes. The comparison of means between the populations with simple inflorescence and with composite inflorescence was made using the “t” test with the degrees of freedom obtained by the approach of Satterthwaite. The complete model was enough to explain the observed variation in the characters related to production and peduncle. The additive effect was the more important in the genetic control for most of the characters, suggests are useful in the selection for increased of the production. The heritabilities were low and average magnitudes, recommending that the selection is made in generations more advanced. Statisticaly were differences significant between the mean of the population with simple inflorescence and the averages of populations with composite inflorescence for the characters under study.
O feijão-caupi é uma das principais fontes de proteína vegetal, para as populações de menor poder aquisitivo da Ásia, África, Europa e Américas do Norte, Central e do Sul. Nas regiões Norte e Nordeste do Brasil, representa uma das leguminosas mais importantes da dieta alimentar. A maioria dos genótipos cultivados em todo o mundo possui inflorescência simples. Contudo, foram encontradas cultivares com inflorescência composta. O objetivo deste trabalho foi estudar a herança dos caracteres relacionados à produção e à inflorescência em cruzamentos entre genótipos com inflorescência simples e inflorescência composta. O trabalho foi realizado na Embrapa Meio-Norte, em Teresina, PI, nos anos de 2006 a 2007. Foram feitos dois cruzamentos entre TVx 5058-09C (P2) x Cacheado-roxo (P1) e Cacheado-roxo (P1) x AU94-MOB-816 (P3). O genitor Cacheado-roxo com inflorescência composta e os outros dois genitores apresentam inflorescência simples. Os genitores, as gerações F1’s, F2’s e os respectivos retrocruzamentos foram avaliados quanto aos caracteres relacionados à produção e à inflorescência em um experimento em blocos casualizados com seis repetições. Os genitores e as F1’s constaram de uma parcela por bloco; as gerações F2’s e os retrocruzamentos constaram de cinco e duas fileiras por bloco,respectivamente. As parcelas foram representadas por uma fileira com 7,0 m de comprimento, o espaçamento entre fileiras foi de 1,0 m e entre covas dentro da fileira de 0,70 m. Os estudos genéticos foram realizados com base nas médias e variâncias com auxilio do Programa Genes. A comparação de médias entre as populações com inflorescência simples e composta foi feito utilizando-se o teste ‘’t’’ com o grau de liberdade obtido pela aproximação de Satterthwaite. O modelo completo foi suficiente para explicar a variação observada nos caracteres relacionados à produção e ao pedúnculo. O efeito aditivo foi o mais importante no controle genético para a maioria dos caracteres, sendo úteis na seleção para aumento da produção. As herdabilidades foram de baixa e média magnitudes, recomendando-se que a seleção seja feita em gerações mais avançadas. Estatisticamente, houve diferenças significativas entre as médias das populações com inflorescência simples e as das populações com inflorescência composta para os caracteres em estudo.
Sadeghsa, Shohre. "Prédiction, réseau de neurones et optimisation : applications aux domaines des agro-matériaux et de la télécommunication". Electronic Thesis or Diss., Amiens, 2021. http://www.theses.fr/2021AMIE0091.
Pełny tekst źródłaIn the context of global changes in the world, the use of vegetal resources in composite materials is an alternative solution to the exploitation of fossil resources. However, the development of the vegetal composite requires taking into account the time and space availability of bio-sourced raw materials, their interchangeability, and their consequences on resulting functional characteristics. Optimization of the vegetal composite faces a variety of available data, the complexity to establish cause and effect relationships, and the mandatory handling of unexpected events (such as disaster, crises, break down, etc, ...). Thus, a reliable and sustainable system is required in order to produce the vegetal composite with constant efficiency. Artificial intelligence methods should allow improving the understanding and control of the production related to the concerned materials. Considering the uncertainty and changeability of the data related to the vegetal materials, we applied machine learning and artificial intelligence methods to predict the parameters of the experiments dynamically. A model can adapt itself based on the training data. Predictions are dynamic, and the results are data-oriented.Herein, the vegetal composite is studied with three aspects: to predict the compressive strength of the composite, to predict the flexural strength of the composite, and a simulation model to predict the parameters of the compressive composite strength test. To overcome the mentioned problems, artificial intelligence and machine learning methods are suggested as a solution that learns from the old data in order to converge towards better local optima. The development of the vegetal composite requires taking into account the specific parameters of the bio-sourced raw materials such as temporal availability, interchangeability, and the consequences on the resulting functional properties. Optimization of the vegetal composites can be viewed as a complex problem related to different domains such as biology, physico-chemistry, and process engineering. The sustainable optimization and production of the vegetal materials also require the localization, centralization, and consolidation of the supply chain sites. The supply chain problems consist of localizing the production sites, routing, and scheduling, and storage of raw materials, and final distribution and marketing. Regrouping, consolidating or clustering are referred to the act of merging two or more sites. It is the act of reducing the number of existing centers. In order to keep the continuous efficiency in the supply and production chains, each site has to provide the whole services that used to be served by the replaced sites. The regrouping problem can be seen in any part of this chain. The k-clustering problem can be defined in any of the two parts of the supply chain that are in direct relations. This thesis aims to deal with the complexity encountered to optimize the vegetal composite and to ensure the sustainability of the supply, production, and marketing sites. The former is achieved, in the first part, by optimizing the characteristics of the composite material using artificial intelligence methods. The latter is presented in the second part of this study. The proposed method merges the supply chain site(s) using the K-clustering problem. Different optimization solution methods are proposed. The applied transversal approach allowing the coupling of skills is presented within the research unit EPROAD. The proposed methods are from the field of artificial intelligence, combinatorial optimization, discrete modeling resulting from applied mathematics, sensitivity analysis, and the field of process engineering for the development of intelligent cooperative methods
CRUZ, Valério Carlos de Almeida. "Compósitos de matriz poliéster com fibras de macambira (Bromélia laciniosa): modelagem, simulação e experimentação". Universidade Federal de Campina Grande, 2013. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1799.
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Capes
O presente trabalho tem como objetivo o estudo teórico/experimental da sorção de água em compósitos poliméricos reforçados com fibras de macambira (Bromélia Laciniosa). Foi utilizado como matriz polimérica uma resina de poliéster insaturado e fibras de Macambira originárias do cariri paraibano. Os compósitos foram confeccionados com 70% de poliéster e 30% de fibras cortadas em tamanhos de aproximadamente 3 cm. Os ensaios de sorção de água foram realizados com amostras de 3 mm e 6 mm de espessura nas temperaturas de 25, 50 e 70°C. Uma modelagem matemática tridimensional transiente foi usada para predizer a transferência de massa durante a sorção de água destes compósitos. A cinética de sorção de água nos compósitos mostrou ser influenciada pela sua relação área/volume. Verificou-se que em tempos curtos, aproximadamente 50 horas, e temperatura de processo mais elevadas, os corpos com maior relação área/volume apresentam uma maior velocidade de sorção. Em tempos longos, os compósitos com maior relação área/volume e maior temperatura de processo apresentam maiores teores de água sorvida. O teor de umidade de equilíbrio dos compósitos com 30% de fibras de Macambira apresentaram valores de 16,8%, a 25°C, 17,00% a 50°C e 19,10% a 70ºC, para as espessuras de 3 mm, e de 12,5% a 25°C, 15,8% a 50°C e 14,8% a 70ºC, para a espessura de 6 mm. Resultados teóricos do teor de umidade médio dos compósitos foram comparados com dados experimentais e um bom ajuste foi obtido. Desta comparação, os coeficientes de difusão de massa foram obtidos para cada condição experimental.
This reseach aims to study theoretically and experimentally water absorption in polymer composites reinforced with macambira fiber (BromeliaLaciniosa). As polymer matrix was used unsaturated polyester resin and macambira fiber from cariri region of the Paraiba state. The composite samples were manufactured with 70% polyester resin and 30% macambira fiber (3cm length). Experiments were carried out in samples with 3 and 6 mm thickness at the temperatures 25, 50 and 70ºC. A transient 3D mathematical model was used to predict mass transfer during water sorption of the composites. It was verified that the water sorption kinetic is affected by area /volume relationships. For short time, approximately 50 h, the sample with lower area/volume relationships and higherprocess temperature presents a larger water absorption velocity, and for long times, these samples presents higher equilibrium water content. Equilibrium moisture content of the samples were 16.8% at 25ºC, 17.00%. at 50ºC and 19.10% at 70ºC, for 3 mm thickness, and 12.5% at 25ºC, 15.8% at 50ºC and 14.8% at 70 ºC, for 6 mm thickness. Predicted results of the moisture content of the composites were compared with experimental data, and a good agreement was verified. From this comparison diffusion coefficients were obtained for different experimental conditions.
Pereira, Camila Lúcio. "Aproveitamento do resíduo do coco verde para produção de compósitos destinados à construção rural". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/74/74131/tde-04072012-105220/.
Pełny tekst źródłaThis thesis studies the use of green coconut fiber as a reinforcer in the matrix cement for the production of fibre-cement. Besides being an organic material, the green coconut residues are not easily degradable, but can reduce the landfills lifespan. To evaluate the possibility of use of coconut residue fiber, as reinforcer in composites, physical-chemical treatments were carried out on the fibers, and partially replacing Portland cement with pozzolanic materials for high reactivity (rice husk ash (RHA)) was also added to decrease the alkaline attack matrix on the plant fiber. The experiment was divided into two stages: the first assessed the green coconut fiber with and without treatment and the composites produced with them. The second stage examined the influence reinforcer high reactivity to allow the use of coconut fiber as reinforcement in cementitious matrix. In the preparation of the composites, the technique of dispersing the materials in aqueous solution was used, followed by draining and pressing, as a simplified simulation Hatschek process of industrial manufacture. The composites were analyzed after 28 days and after an aging process, with 100 cycles of immersion-drying or heating in water for 28 days at 65°C). Physical and mechanical tests were used to e valuated the performance, traction resistance and ductility of the composites. A thermogravimetry test allowed the observation of the use of portlandita and the alkalinity reduction of the matrix with the addition of RHA, without affecting the resistance of the material. The results obtained indicate that the green coconut fiber has great potential to be used as a fibre-cement reinforcer, as long it is included in a matrix with reduced alkalinity.
Pimentel, Lia Lorena. "Durabilidade de argamassas modificadas por polimeros e reforçadas com fibras vegetais". [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257233.
Pełny tekst źródłaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola
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Resumo: A grande quantidade de resíduos agro-industriais, aliada à proibição do uso do amianto e à necessidade de solucionar problemas ambientais decorrentes do depósito e/ou queima destes resíduos, impulsionam a pesquisa para o desenvolvimento de compósitos fibro-vegetais-cimento. A durabilidade desses compósitos é um dos fatores mais importantes para a colocação deste material no mercado consumidor. Existem várias pesquisas desenvolvidas ou em andamento, algumas propondo o tratamento químico das fibras vegetais, outras fazendo uso de produtos que alterem a composição da matriz cimentícia. A utilização de polímeros em concreto e argamassa, com o objetivo de melhorar sua durabilidade é cada vez mais freqüente e a característica de certos polímeros de melhorar a aderência entre fibra e matriz, além de reduzir a capacidade de absorção de água, pode vir a melhorar a durabilidade desses compósitos. Este estudo visou a caracterização de propriedades físicas e mecânicas de compósito biomassa vegetal-cimento modificado com polímeros e a análise da durabilidade desse compósito. Foi testado um polímero de base acrílica em dois tipos de compósitos: um executado com polpas celulósicas (de Eucalipto e da reciclagem de papel jornal) e outro executado com resíduo de Pinus caribaea. Foram realizados ensaios de envelhecimento acelerado por meio de ciclos de imersão em água e secagem, e por imersão em água quente, além do processo de envelhecimento natural, por exposição dos corpos-de-prova às intempéries. As propriedades físicas do compósito avaliadas foram: a massa específica, a absorção total de água por imersão e o índice de vazios. As propriedades mecânicas avaliadas foram determinadas por meio de ensaios de resistência à tração na flexão analisando-se a tensão e a energia de ruptura; também foi determinado o módulo de deformação dinâmico, com auxílio de ultra-som. O microscópio eletrônico de varredura permitiu constatar a modificação da característica morfológica do compósito com a adição do polímero e o estado das fibras dentro do compósito ao longo do tempo. O uso do polímero melhorou o desempenho mecânico do compósito nas primeiras idades, além de promover uma significativa redução da capacidade de absorção de água, denotando sua adequação para aumentar a durabilidade do compósito
Abstract: Several researches on vegetal-fiber-cement composites have been developed aiming to solve problems related to the banishment of asbestos and environmental damages due to deposition or burnirng of agro-industry residues. The durability of the cellulose-cement composites is a key factor to introduce such material in the market. Several researches have been developed aiming to avoid the degradation of vegetable fiber-cement, some of them using chemically treated fibers and others modifying the matrix. Polymers have been used in concrete and mortar production to increase the durability. Composite degradation can be controled by polymers that modify the fiber-matrix bond and the amount of water absorption. The goal of this work was to characterize the physical and the mechanical properties of cellulose-cement composites modified by a polymer and to evaluate the subsequent durability of these materials. The dispersion of an acrylic based polymer was evaluated with two types of composites: one with cellulose pulps (Eucalyptus and wastepaper) and another with Pinus caribaea particles. The physical properties under observation were water absorption by immersion, apparent void volume and bulk density. The mechanical properties of toughness and modulus of rupture were determined by flexural test. The dynamic elasticity modulus was obtained by ultrasonic method. Samples were subjected to natural aging tests and to accelerated-aging tests by repeated soak and dry cycles and warm-water immersion. By the range of composites analyzed, the use of the polymer improves the initial mechanical properties of composites and promotes a significant decrease of the water absorption. The scanning electron microscopy (SEM) allowed to verify the modification of the morphologic characteristic of the composite with the polymeric addition and the preservation of the fibers along the time. The use of the polymer improved the mechanical performance of the composite in the first ages, besides promoting a significant reduction of the capacity of absorption of water, denoting its adaptation to increase the durability of the composite
Doutorado
Construções Rurais e Ambiencia
Doutor em Engenharia Agrícola
Mota, Rui Carlos de Sousa. "An?lise de viabilidade t?cnica de utiliza??o da Fibra de bananeira com resina sint?tica em Comp?sitos". Universidade Federal do Rio Grande do Norte, 2010. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15617.
Pełny tekst źródłaThis paper aims to present the feasibility of using a composite using discarded material from the cultivation of banana tree (pseudostem), which is fibrillated together with synthetic resin replacing glass fiber to be used in structural elements that do not demand large mechanical stress such as reservoirs, troughs, domes, sewage pipes etc.. For this, there were studies about the mechanical properties of a composite made with polyester resin and fiber of banana tree (Musa sp, musac), in which the splints were removed from the pseudostem, being made fibrillation by hand, with the aid of a brush steel, followed by natural drying. After treatment for cleaning and removal of wax, the fiber was cut into pieces of approximately 60 mm to 100 mm, for, together with synthetic resin, make cards of a features fiber composite with random orientation relative to the weight of the resin. We used three different percentages of fiber (3%, 6% and 9%), in order to make a comparative study between them and what would be the one with the best performance. Were manufactured specimens of each material and then subjected to uniaxial tensile tests, three point bending, moisture absorption and thermal characteristics. The results show that, in general, the use of banana tree fiber is feasible simply by an improvement in the production process (machining of the procedure) and greater care in the manufacture of parts
Este trabalho tem como objetivo apresentar a viabilidade de um comp?sito utilizando material descartado da lavoura da bananeira (pseudocaule), o qual ? fibrilado juntamente com resina sint?tica em substitui??o ? fibra de vidro, a ser utilizado em elementos estruturais que n?o demandem grandes esfor?os mec?nicos, tais como reservat?rios, calhas, domos, tubula??es de esgotamento etc. Para isso foram efetuados estudos sobre as propriedades mec?nicas de um comp?sito de resina poli?ster e fibra de bananeira (musa s.p., mus?cea), nos quais foram retiradas as talas do pseudocaule, sendo feita a fibriliza??o de forma manual, com o aux?lio de uma escova de a?o, seguido de secagem ao natural. Ap?s tratamento para limpeza e retirada de cera, a fibra foi cortada em peda?os de aproximadamente 60 mm a 100 mm para, juntamente com a resina sint?tica, fabricar placas de um comp?sito de caracter?sticas fibrosas com orienta??o aleat?ria em rela??o ao peso da resina. Foram utilizadas tr?s percentagens distintas de fibras (3%, 6% e 9%), a fim de se efetuar um estudo comparativo entre elas e determinar qual seria aquela com o melhor desempenho mec?nico. Foram fabricados corpos de prova de cada material, sendo ent?o submetida aos ensaios de tra??o uniaxial, flex?o em tr?s pontos, absor??o de umidade e caracter?sticas t?rmicas. Os resultados demonstram que, de forma geral, o uso de fibra de bananeira ? vi?vel, bastando uma melhoria no seu processo de obten??o (mecaniza??o do procedimento) e um maior cuidado durante a fabrica??o das pe?as
Sauvageon, Thibaud. "Caractérisation et valorisation de fibres de chanvre issues de sols et de matériels délaissés : cas du traitement par explosion à la vapeur". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0211/document.
Pełny tekst źródłaHemp plants have been cultivated for their usable fibers for thousands of years. The fibers are long and resistant and can be utilized for creation of textile and composite materials, relevant to burgeoning industrial sectors. However, due to their lack of homogeneity and the complexity of their refining, hemp fibers are unable to compete with synthetic and cotton fibers. But fine hemp fibers could be successfully produced from technical fibers using a steam explosion treatment at a low cost, a low energy consumption and with a low environmental impact. To optimize the parameters of this process, a morphological, chemical, and mechanical characterization was performed before and after steam explosion using a design of experiments methodology. These experiments showed that this process can be used to produce hemp fibers with the standards defined by the textile and composite materials industries. Some features have also suggested some prospects in the industrialization of steam explosion for fibers production. These results showed that this process could be industrially competitive in terms of costs, water and energy consumption and yield. Finally, phytoremediation-borne hemp fibers were produced from soils contaminated with trace elements. The metals concentrations in plant components and in the fibers were measured before and after steam explosion treatment. The results offer new insights and prospects for a sustainable use of Technosols (in particular brownfield sites) by the production of hemp fibers
NÓBREGA, Múcio Marcos Silva. "Compósitos de matriz poliéster com fibras de caroá Neoglaziovia variegata: caracterização mecânica e sorção de água". Universidade Federal de Campina Grande, 2007. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1813.
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O presente trabalho tem como objetivo o desenvolvimento de compósitos poliméricos reforçados com fibras de Caroá Neoglaziovia variegata para avaliação de seu desempenho mecânico, bem como suas características de sorção de água. Foi utilizado como matriz polimérica uma resina de poliéster insaturado e fibras de Caroá originárias do cariri paraibano. Os compósitos foram confeccionados com diferentes teores de fibras, cortadas em tamanhos de aproximadamente 3 cm, e moldados por compressão em molde metálico para avaliação das propriedades mecânicas. A composição de amostras de melhor desempenho mecânico foi escolhida para os ensaios de sorção de água, com amostras de 20x20mm² com 3cm e 6cm de espessura na temperatura de 25°C, 50°C e 70°C. Uma modelagem matemática tridimensional transiente foi usada para predizer a transferência de massa durante a sorção de água destes compósitos. Os resultados indicam que as propriedades mecânicas em tração dos compósitos estudados aumentam com o teor de fibras acima de 24% em massa até um volume crítico, em torno de 30%.Resistência ao impacto aumentou para todas as composições em virtude da eficiência de transferência de tensão para as fibras. Os resultados obtidos para o módulo de elasticidade dos compósitos evidenciam que estes são superiores ao da matriz, para todos os teores abaixo de 45% de fibras, o que é associado às características das fibras. A cinética de sorção de água nos compósitos mostrou ser influenciada pela relação área/volume. Pôde-se observar que em tempos curtos, aproximadamente 100 horas, os corpos com menor relação apresentam uma maior velocidade de sorção. Em tempos longos os compósitos com maior relação área/volume apresentam maiores teores de água sorvida. O teor de umidade de equilíbrio dos compósitos com 30% de fibras de caroá apresentaram valores de 14,48% à 25ºC e 16,52% à 70ºC, para as espessuras de 3 e 6 mm, respectivamente. A modelagem matemática utilizada para a obtenção da solução numérica de sorção de água nos compósitos reforçados por fibras de caroá foi adequada e satisfatória e a técnica de volumes finitos mostrou-se eficiente para discretizar a equação de difusão no sistema de coordenadas cartesianas para um sólido paralelepípedo, possibilitando a análise de fenômenos difusivos transientes nestes sólidos.
This research has the objective of developing polymeric composites enhanced with Caroá fibers Neoglaziovia variegata, in order to evaluate its mechanical performance and water sorption. It was used as polymeric matrix an unsaturated polyester resin and Caroá fibers originated from Paraiba state. The composites were made with different fiber contents, cut approximately with 3cm length and molded by compression in a metallic mould in order to evaluate its mechanical properties. The better mechanical composition of the sample was chosen to water sorption test in sample with dimension 20x20mm² and 3cm and 6cm thickness in the temperature of 25°C, 50°C and 70°C. A tri-dimensional transient mathematical modeling was used to predict mass transfer during the water sorption by these composites. Results indicates enhancement of mechanical properties of composites with 24% of mass made of the fibers until a critical volume of 30%. For the impact resistance this increases occurred for all compositions because of the transference of tension for the fibers. The results for elasticity modulus of composite shows that are higher than to the matrix for all fiber contents lower than 45%, which is related with the fiber properties. The water sorption kinetic was related with the area/volume relationship. We can observe that in short period of time, 100 hours, that composites with lower area/volume relationship absorbs water faster. On the order hand, the ones with higher area/volume relationship show more sorption in longer periods of time. The equilibrium moisture content for 30% fiber composite show results of 14.48% in 25°C and 16.52% in 70°C, for 3mm and 6mm thickness respectively. Mathematical models used to obtain numerical solution of water sortion in composites enhanced with Caroá fibers were satisfactory and the finite volume techniques was adequated to discretize the diffusion equation in Cartesian coordinate system for a parallelepiped solids, permitting the analyze of transient diffusive phenomena in this solids.
Baldan, Victor José dos Santos. "Desenvolvimento e caracterização de placas poliméricas produzidas a partir da reciclagem do resíduo industrial de poliuretana termofixa". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/102/102131/tde-30062016-102309/.
Pełny tekst źródłaThis study proposes the development of a composite material in the form of polymer slabs. The material is created from the incorporation of recycled thermoset polyurethane to castor oil resin and glass fiber mats. Composite materials are formed by two phases with different chemical and physical properties. One phase is a matrix, and the other a reinforcement. These materials are highly stiff, light, have mechanical strength and present better responses to fatigue under cyclic loads. These properties make them a substitute for noble materials, being eligible for uses in aviation, sports, the arms industry and, specially, civil construction. Furthermore, composites may be obtained by the incorporation of residue, solving problems of waste disposal. In the procedures undertaken, the industrial waste of thermoset polyurethane is transformed into a recycled aggregate, achieved by the cutting, grinding, characterization and classification in compliance to the ABNT standards (NBR 10.004 to10.007). Afterwards, with the use of a thermal press, it was possible to produce the slabs and characterize them according to the following properties: mechanical (tensile strength, and puncture), physical (water absorption, swelling and stiffness), thermal (conductivity) and the potential durability (resistance to impact, abrasion, chemical attack. ultraviolet and weather exposure, electrical resistance, and flammability). The test results indicated that the composite behaves similarly to materials used in civil construction, which enables its use in the area.
Streszczenia konferencji na temat "Vegetal-Composite"
Trifan, Adrian, Ioan Calinescu, Mircea Vinatoru i Adina Ionuta Gavrila. "OPTIMIZATION OF MICROWAVE ASSISTED DELIGNIFICATION OF WOOD RESIDUES BY SURFACE RESPONSE METHODOLOGY". W Ampere 2019. Valencia: Universitat Politècnica de València, 2019. http://dx.doi.org/10.4995/ampere2019.2019.9861.
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