Les effets du caoutchouc nitrile (NBR), du traitement de la surface des fibres et du noir de carbone sur les propriétés des composites à base de caoutchouc naturel renforcé par des fibres d'ananas (NR / PALF) ont été étudiés. L'incorporation de NBR et le traitement de surface de la fibre ont été utilisés pour améliorer les propriétés mécaniques des composites à faible déformation, alors que le noir de carbone a été utilisé pour améliorer ces propriétés à forte déformation. La teneur en fibres a été fixée à 10 phr. Les matériaux composites ont été préparés à l'aide d'un mélangeur à cylindres et ont été réticulés sous presse permettant ainsi le maintien de l'orientation des fibres. Ces composites ont été caractérisés à l’aide du rhéomètre à matrice mobile (MDR), par analyse thermique mécanique dynamique (DMTA) et par tests de traction. La morphologie après fracture cryogénique a été observée à l'aide de la microscopie électronique à balayage (MEB). L'effet du NBR dont la teneur varie de 0 à 20 phr par rapport à la teneur totale en caoutchouc, a été également étudié. Le NBR est utilisé afin d’encapsuler totalement les fibres d’ananas (PALF) ; ceci conduisant à un meilleur transfert de contraintes entre la matrice et les fibres. La méthode de mélange a également été étudiée. Plusieurs types de silanes tels que le propylsilane, l'allylsilane et le silane-69 ont été utilisés pour traiter les fibres pré-nettoyées à l’aide d’un traitement alcalin. Les fibres silanisées ont été caractérisées par spectroscopie infrarouge à transformée de Fourier (FTIR), par spectroscopie de photoélectrons aux rayons X (XPS) et par MEB. Le traitement de la fibre par le silane-69 a permis d’augmenter fortement le module du matériau composite à faible déformation. Ce traitement a été plus efficace que l'incorporation de NBR dans les composites NR / PALF. Ceci peut s’expliquer par une possible réticulation chimique entre le caoutchouc et la fibre traitée au silane-69 plutôt qu’une simple interaction physique du NR, du NBR et de la fibre. Cependant, le renforcement par fibre réduit la déformation à la rupture. Par conséquent, du noir de carbone a également été incorporé dans les composites NR/NBR/PALF et NR/ PALF traitée, afin d’améliorer leurs propriétés ultimes. En incorporant du noir de carbone à un taux de 30 phr dans les deux composites, les propriétés mécaniques des composites ont été améliorées et peuvent être contrôlées à la fois à des déformations faibles et hautes. / The effects of nitrile rubber (NBR), fiber surface treatment and carbon black on properties of pineapple leaf fiber-reinforced natural rubber composites (NR/PALF) were studied. The incorporation of NBR and surface treatment of fiber were used to improve the mechanical properties of composites at low deformation, whereas carbon black was used to improve these properties at high deformation. The fiber content was fixed at 10 phr. The composites were prepared using two-roll mill and were cured using compression moulding with keeping the fiber orientation. These composites were characterized using moving die rheometer (MDR), dynamic mechanical thermal analysis (DMTA) and tensile testing. The morphology after cryogenic fracture was observed using scanning electron microscopy (SEM). The effect of NBR from 0 to 20 phr of total rubber content was investigated. NBR is proposed to encase PALF leading to higher stress transfer between matrix and PALF. The method of mixing was also studied. For the fiber surface treatment, propylsilane, allylsilane and silane-69 were treated on the alkali-treated fiber. Treated fibers were characterized using Fourier-Transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) and SEM. Silane-69 treatment of fiber increased the modulus at low deformation more than the incorporation of NBR of NR/PALF composites due to the chemical crosslinking between rubber and fiber from silane-69 treatment rather than the physical interaction of NR, NBR and fiber. However, reinforcement by fiber reduced the deformation at break. Hence, carbon black was also incorporated into NR/NBR/PALF and NR/surface-treated PALF composites to improve the ultimate properties. By incorporation of carbon black 30 phr in both composites, the mechanical properties of composites were improved and can be controlled at both low and high deformations.

Made available in DSpace on 2014-12-17T14:58:12Z (GMT). No. of bitstreams: 1 MarcosSA.pdf: 1402858 bytes, checksum: aafed934486c8c9ba68e0133cc239956 (MD5) Previous issue date: 2006-05-19 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In 1998 the first decorticator was developed in the Textile Engineering Laboratory and patented for the purpose of extracting fibres from pineapple leaves, with the financial help from CNPq and BNB. The objective of the present work was to develop an automatic decorticator different from the first one with a semiautomatic system of decortication with automatic feeding of the leaves and collection of the extracted fibres. The system is started through a command system that passes information to two engines, one for starting the beater cylinder and the other for the feeding of the leaves as well as the extraction of the decorticated fibres automatically. This in turn introduces the leaves between a knife and a beater cylinder with twenty blades (the previous one had only 8 blades). These blades are supported by equidistant flanges with a central transmission axis that would help in increasing the number of beatings of the leaves. In the present system the operator has to place the leaves on the rotating endless feeding belt and collect the extracted leaves that are being carried out through another endless belt. The pulp resulted form the extraction is collected in a tray through a collector. The feeding of the leaves as well as the extraction of the fibres is controlled automatically by varying the velocity of the cylinders. The semi-automatic decorticator basically composed of a chassis made out of iron bars (profile L) with 200cm length, 91 cm of height 68 cm of width. The decorticator weighs around 300Kg. It was observed that the increase in the number of blades from 8 to twenty in the beater cylinder reduced the turbulence inside the decorticator, which helped to improve the removal of the fibres without any problems as well as the quality of the fibres. From the studies carried out, from each leaf 2,8 to 4,5% of fibres can be extracted. This gives around 4 to 5 tons of fibres per hectare, which is more than that of cotton production per hectare. This quantity with no doubt could generate jobs to the people not only on the production of the fibres but also on their application in different areas / No ano de 1998 foi patenteada uma desfibradeira que foi desenvolvida no laborat?rio de Engenharia T?xtil da UFRN, com objetivo de desfibrar a folha do abacaxi, com apoio do CNPq e BNB. O presente trabalho objetiva desenvolver uma desfibradeira automatizada com a mesma finalidade e se buscou a fabrica??o de uma nova desfibradeira com sistema semi-autom?tico. A desfibradeira ? acionada atrav?s de um quadro de comando, que passa informa??es para dois motores, um para acionamento do cilindro batedor e outro para os movimentos de alimenta??o das folhas e sa?da das fibras. A desfibradeira ? composta de um sistema de alimenta??o autom?tico, atrav?s de uma esteira sem fim, que desloca as folhas at? os cilindros alimentadores, que introduz as mesmas, entre uma espera (faca) e um batedor rotativo de vinte palhetas (desfibradeira anterior s? tinha 8 palhetas). Estas palhetas s?o apoiadas em tr?s flanges eq?idistantes com um eixo central de transmiss?o possibilitando um maior numero de batidas na folha. Portanto o operador tem a fun??o de colocar as folhas na esteira de alimenta??o e retirar as fibras que foram desfibradas, que est?o na esteira de sa?da. A qualidade das fibras extra?das pode ser melhorada atrav?s do controle da velocidade de entrada das folhas bem como a velocidade de cilindro batedor. Al?m disso, h? sistema de remo??o de polpa numa bandeja separadamente. A desfibradeira foi confeccionada com um chassi em cantoneiras (perfis L ) tendo com dimens?es b?sicas de comprimento de 200 cm, a altura de 91 cm e a largura de 68 cm. O peso total da desfibradeira ? de 250 kg. A caracter?stica mais importante da m?quina ? um maior numero de batida e uma menor turbul?ncia de ar dentro da m?quina. Isso facilitou a melhoria da qualidade das fibras. Os estudos mostram que de cada folha pode ser extra?do cerca de 2,8 a 4,5 % de fibras Assim sendo pode ser retirada cerca de 4 a 5 toneladas de fibras por hectare. Esta quantidade ? bem maior do que a produ??o de algod?o por hectare. Quando as fibras sendo empregadas no mercado podem gerar postos de trabalho e renda para popula??o do campo bem como das suas aplica??es

The pineapple leaf (PL) is an agricultural waste with annual output and available in abundance, whereas in 2011 were produced about three million tons, being rarely used and currently has a low commercial value. Therefore, this agro-waste deserves to be better and/or properly used. The aim of this study was to explore PL as a source of raw material for the production of cellulose nanocrystals (CN). The CN were extracted by acid hydrolysis at 45°C for 5, 30 and 60 minutes, using 20 mL of H2SO4 (9.17 M) for each gram of material. The resulting CN were characterized by crystallinity index, morphology (shape and size) and thermal stability. Among the hydrolysis conditions carried out, the best extraction time was 30 minutes, with yield of 65%. At this extraction time, the CN presented a needle-shaped nature, high thermal stability (225 °C) when compared to the thermoplastic processing temperature (about 200 °C), high crystallinity (87.3%) relative to other sources CN cellulosic derived from agricultural residues (e.g., soy hull 73.5%), an average length of 249.7 ± 51.5 nm and a diameter of 4.45 ±1.41 nm, giving an aspect ratio (L/D) of around 60. Therefore, CN obtained from PL has great potential as reinforcement in the manufacture of nanocomposites. The production of CN from this underutilized agro-waste has commercial application potential that can add value to the pineapple cultivation, generate extra income for farmers and also help in agribusiness diversification. In addition, the reuse of these residues allows a significant reduction in both the volume of waste accumulated in the environment and in the extraction of raw materials, which is against the concept of sustainable development. / A folha do abacaxi (PL) é um resíduo agrícola com produção anual e disponível em abundância, visto que em 2011 foram produzidas aproximadamente três milhões de toneladas, sendo utilizado muito raramente, tem atualmente um baixo valor comercial. Portanto, este resíduo agrícola merece ser melhor e/ou usado corretamente. O objetivo deste estudo foi o de explorar a PL, como fonte de matéria prima para a produção de nanocristais de celulose (CN). Os CN foram extraídos por meio de hidrólise ácida, a 45 °C durante 5, 30 e 60 minutos, utilizando-se 20 mL de H2SO4 (9,17 M) para cada grama de fibra de celulose purificada obtida da PL. Os CN resultantes foram caracterizados por índice de cristalinidade, morfologia (forma e tamanho), e estabilidade térmica. Entre as condições de hidrólise realizadas, o melhor tempo de extração foi de 30 minutos, com rendimento de 65%. Neste tempo de extração, os CN apresentaram-se em forma de agulha, estabilidade térmica elevada (225 °C) quando comparada a temperatura de processamento dos termoplásticos (cerca de 200 °C), elevada cristalinidade (87,3%) em relação à NC de outras fontes celulósicas oriunda de resíduos agrícolas (por exemplo, a casca de soja 73,5%), um comprimento médio (L) de 249,7 ± 51,5 nm e um diâmetro (D) de 4,45 ± 1,41 nm, dando um razão de aspecto (L/D) de cerca de 60. Por conseguinte, os CN obtidos a partir da PL têm um grande potencial como reforço na produção de nanocompósitos. A produção dos CN a partir deste resíduo agrícola subutilizado tem potencial para aplicação comercial que pode agregar valor ao cultivo de abacaxi, gerar renda extra para os agricultores e também ajudar na diversificação do agronegócio. Além disso, a reutilização desses resíduos permite uma redução significativa, tanto no volume de resíduos acumulados no meio ambiente como na extração de matérias-primas, o que vem de encontro com o conceito de desenvolvimento sustentável. / Mestre em Química

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%