Considerando o grande interesse na produção de materiais provenientes de fontes renováveis, biocompatíveis e que combinem as propriedades de dois ou mais componentes em um único material, buscou-se contribuir para com estudos sobre a incorporação de nanopartículas (NPs) de magnetita (Fe3O4) em filmes preparados a partir de polpa celulósica de sisal e de acetatos obtidos usando esta polpa. Pretendeu-se obter filmes compósitos com boas propriedades magnéticas e com propriedades mecânicas similares ou melhores que aquelas dos filmes puros. Optou-se por polpa celulósica de sisal pelo fato de a planta ser largamente produzida no país, além de ter rápido crescimento e fibras com alto teor de celulose. A magnetita foi escolhida devido a sua baixa toxicidade quando comparada as NPs metálicas e pelo seu potencial de aplicação em diversas áreas, incluindo a médica. A magnetita foi obtida por decomposição térmica (método do poliol) e caracterizada via microscopia eletrônica de transmissão (MET), difração de raios X (DRX) e por magnetometria via SQUID (superconducting quantum interference device). Os resultados indicaram que as NPs preparadas corresponderam a um sistema de partículas esféricas e monodispersas, com diâmetro médio de 5,1 ± 0,5 nm e comportamento superparamagnético a temperatura ambiente. Os filmes foram preparados a partir da dissolução da polpa celulósica (2 g) em dimetilacetamida/cloreto de lítio (DMAc/LiCl), a 160 °C, com ou sem NPs (0,5; 1,4 e 3,0 g L-1) e caracterizados quanto a microscopia eletrônica de varredura (MEV), espectroscopia de energia dispersiva de raios X (EDX), DRX, propriedades de tração e magnetometria de amostra vibrante (VSM, Vibrating Sample Magnetometry). Resultados de absorção atômica (Li) e análise elementar (N) mostraram que LiCl e DMAc foram praticamente eliminados dos filmes. O aumento da concentração das NPs de magnetita nos filmes compósitos tornou-os menos rígidos, com maior resistência à tração e maior alongamento quando comparado ao filme de celulose. A magnetização de saturação dos filmes compósitos (23; 31; 37 emu g-1) se correlacionou positivamente com o aumento da concentração de NPs. A ausência de histerese e coercividade indicaram que a temperatura ambiente os filmes compósitos são superparamagnéticos. Posteriormente, a celulose foi acetilada em DMAc/LiCl, a 110 °C por 4 h, e acetatos com diferentes graus de substituição (GS) foram obtidos.Filmes compósitos a partir destes acetatos foram obtidos em DMAc/LiCl (condições similares aquelas dos filmes de celulose), na ausência e na presença de NPs (3,0 g L-1). A caracterização destes filmes foi feita por DRX, MEV, EDX, TG e DSC, ensaio de tração e VSM. As imagens MEV mostraram que os filmes de acetatos com diferentes GS apresentaram morfologias distintas e que a introdução das NPs nas matrizes dos diferentes acetatos não teve efeito sobre a morfologia dos filmes. Filmes a partir de acetatos de GS maior ou igual a 2,0 apresentaram microesferas em sua superfície. Filmes de acetatos mais substituídos foram menos resistentes à tração que os filmes de acetatos mais substituídos e a inserção de NPs nessas matrizes levou a filmes menos rígidos. No geral, filmes compósitos apresentaram menores índices de cristalinidades e decomposição térmica com início a temperaturas inferiores (entre 220 e 270 °C) em relação ao respectivo filme de acetato (controle, entre 280-300 °C), mas sem comprometer as possibilidades de aplicação. Os filmes compósitos baseados nos acetatos de celulose apresentaram comportamento superparamagnético a temperatura ambiente, com temperatura de bloqueio de 14 K e boa magnetização de saturação (27-46 emu.g-1). Não foi observado correlação entre GS e propriedades magnéticas dos filmes, as quais mostraram certa dependência da presença ou não de microesferas. A associação das NPs de magnetita nas matrizes poliméricas, tanto de celulose como de acetato de celulose, levou a filmes poliméricos com boas propriedades magnéticas e mecânicas. / Considering the great interest in the production of materials from renewable sources and biocompatible ,and that combining the properties of two or more components in a single material, the aim was to contribute to studies on the incorporation of magnetite nanoparticles (NPs) (Fe3O4) in films produced from sisal pulp or acetates from this pulp. To obtain composite films with good magnetic properties, as well as mechanical properties similar or better than those of the pure films was also intended. The sisal pulp was chosen due to the fact that the plant is widely produced, not to mention its rapid growth and fibers with a high cellulose concentration. Magnetite was chosen due to its low toxicity when compared with metallic NPs and its potential application in several areas, including the medical area. The magnetite was obtained by thermal decomposition (polyol method) and characterized by transmission and scanning electron microscopy (TEM), X-ray diffraction (XRD) and by SQUID magnetometry (superconducting quantum interference device).The results showed that the prepared NPs correspond to a system of spherical and monodisperse particles with a mean diameter of 5.1 ± 0.5nm and superparamagnetic behavior at room temperature. The films were prepared by dissolving cellulosic pulp (2 g) in dimethylacetamide/lithiumchloride (DMAc/LiCl) to 160°C, with or without NPs (0.5, 1.4 and 3.0 g g L-1) and characterized by electron microscopy (SEM), energy dispersive X-ray spectrum (EDX), XRD, tensile properties and vibrating sample magnetometry (VSM). Results of atomic absorption (Li) and elemental analysis (N) showed that LiCl and DMAc were practically eliminated from the films. Increasing the concentration of magnetite NPs in the composite films made them less rigid, with higher tensile strength and elongation when compared to the cellulose film. The saturation magnetization of the composite films (23, 31, and 37 emu g-1) was positively correlated with the concentration of NPs. The lack of hysteresis and coercivity indicated that the composite films are superparamagnetic at room temperature. Subsequently, cellulose was acetylated in DMAc/LiCl, at 110°C for 4h, and acetates with different degrees of substitution (DS) were obtained. Composite films from these acetates were obtained in DMAc/LiCl (conditions similar to those of the cellulose films) in the absence and presence of NPs (3.0 g L-1).The characterization of these films was performed by XRD, SEM, EDX, TG and DSC, tensile testing and VSM. SEM images showed that acetate films with different DS exhibited different morphologies and that the introduction of NPs in the matrices of different acetates had no effect on the morphology of the films. Films from acetates of DS greater than or equal to 2.0 showed microspheres on its surface. Acetate films more substituted were less resistant to traction than acetate films less substituted and the inclusion of NPs in these matrices led to less rigid films. Overall, composite films exhibited lower levels of crystallinity and thermal decomposition starting at lower temperatures (between 220-270°C) compared to the corresponding acetate film (control) (between 280-300°C), but without compromising the ability of application. The composite films based on cellulose acetate showed superparamagnetic behavior at room temperature with blocking temperature of 14 K and good saturation magnetization (27-46 emu.g-1). No correlation between DS and the magnetic properties of the films was observed, which showed some dependence on the presence or absence of microspheres. The association of the NPs in the polymeric matrices of both cellulose and cellulose acetate led to polymeric films with good magnetic and mechanical properties.

Considerando o grande interesse na produção de materiais provenientes de fontes renováveis, biocompatíveis e que combinem as propriedades de dois ou mais componentes em um único material, buscou-se contribuir para com estudos sobre a incorporação de nanopartículas (NPs) de magnetita (Fe3O4) em filmes preparados a partir de polpa celulósica de sisal e de acetatos obtidos usando esta polpa. Pretendeu-se obter filmes compósitos com boas propriedades magnéticas e com propriedades mecânicas similares ou melhores que aquelas dos filmes puros. Optou-se por polpa celulósica de sisal pelo fato de a planta ser largamente produzida no país, além de ter rápido crescimento e fibras com alto teor de celulose. A magnetita foi escolhida devido a sua baixa toxicidade quando comparada as NPs metálicas e pelo seu potencial de aplicação em diversas áreas, incluindo a médica. A magnetita foi obtida por decomposição térmica (método do poliol) e caracterizada via microscopia eletrônica de transmissão (MET), difração de raios X (DRX) e por magnetometria via SQUID (superconducting quantum interference device). Os resultados indicaram que as NPs preparadas corresponderam a um sistema de partículas esféricas e monodispersas, com diâmetro médio de 5,1 ± 0,5 nm e comportamento superparamagnético a temperatura ambiente. Os filmes foram preparados a partir da dissolução da polpa celulósica (2 g) em dimetilacetamida/cloreto de lítio (DMAc/LiCl), a 160 °C, com ou sem NPs (0,5; 1,4 e 3,0 g L-1) e caracterizados quanto a microscopia eletrônica de varredura (MEV), espectroscopia de energia dispersiva de raios X (EDX), DRX, propriedades de tração e magnetometria de amostra vibrante (VSM, Vibrating Sample Magnetometry). Resultados de absorção atômica (Li) e análise elementar (N) mostraram que LiCl e DMAc foram praticamente eliminados dos filmes. O aumento da concentração das NPs de magnetita nos filmes compósitos tornou-os menos rígidos, com maior resistência à tração e maior alongamento quando comparado ao filme de celulose. A magnetização de saturação dos filmes compósitos (23; 31; 37 emu g-1) se correlacionou positivamente com o aumento da concentração de NPs. A ausência de histerese e coercividade indicaram que a temperatura ambiente os filmes compósitos são superparamagnéticos. Posteriormente, a celulose foi acetilada em DMAc/LiCl, a 110 °C por 4 h, e acetatos com diferentes graus de substituição (GS) foram obtidos.Filmes compósitos a partir destes acetatos foram obtidos em DMAc/LiCl (condições similares aquelas dos filmes de celulose), na ausência e na presença de NPs (3,0 g L-1). A caracterização destes filmes foi feita por DRX, MEV, EDX, TG e DSC, ensaio de tração e VSM. As imagens MEV mostraram que os filmes de acetatos com diferentes GS apresentaram morfologias distintas e que a introdução das NPs nas matrizes dos diferentes acetatos não teve efeito sobre a morfologia dos filmes. Filmes a partir de acetatos de GS maior ou igual a 2,0 apresentaram microesferas em sua superfície. Filmes de acetatos mais substituídos foram menos resistentes à tração que os filmes de acetatos mais substituídos e a inserção de NPs nessas matrizes levou a filmes menos rígidos. No geral, filmes compósitos apresentaram menores índices de cristalinidades e decomposição térmica com início a temperaturas inferiores (entre 220 e 270 °C) em relação ao respectivo filme de acetato (controle, entre 280-300 °C), mas sem comprometer as possibilidades de aplicação. Os filmes compósitos baseados nos acetatos de celulose apresentaram comportamento superparamagnético a temperatura ambiente, com temperatura de bloqueio de 14 K e boa magnetização de saturação (27-46 emu.g-1). Não foi observado correlação entre GS e propriedades magnéticas dos filmes, as quais mostraram certa dependência da presença ou não de microesferas. A associação das NPs de magnetita nas matrizes poliméricas, tanto de celulose como de acetato de celulose, levou a filmes poliméricos com boas propriedades magnéticas e mecânicas. / Considering the great interest in the production of materials from renewable sources and biocompatible ,and that combining the properties of two or more components in a single material, the aim was to contribute to studies on the incorporation of magnetite nanoparticles (NPs) (Fe3O4) in films produced from sisal pulp or acetates from this pulp. To obtain composite films with good magnetic properties, as well as mechanical properties similar or better than those of the pure films was also intended. The sisal pulp was chosen due to the fact that the plant is widely produced, not to mention its rapid growth and fibers with a high cellulose concentration. Magnetite was chosen due to its low toxicity when compared with metallic NPs and its potential application in several areas, including the medical area. The magnetite was obtained by thermal decomposition (polyol method) and characterized by transmission and scanning electron microscopy (TEM), X-ray diffraction (XRD) and by SQUID magnetometry (superconducting quantum interference device).The results showed that the prepared NPs correspond to a system of spherical and monodisperse particles with a mean diameter of 5.1 ± 0.5nm and superparamagnetic behavior at room temperature. The films were prepared by dissolving cellulosic pulp (2 g) in dimethylacetamide/lithiumchloride (DMAc/LiCl) to 160°C, with or without NPs (0.5, 1.4 and 3.0 g g L-1) and characterized by electron microscopy (SEM), energy dispersive X-ray spectrum (EDX), XRD, tensile properties and vibrating sample magnetometry (VSM). Results of atomic absorption (Li) and elemental analysis (N) showed that LiCl and DMAc were practically eliminated from the films. Increasing the concentration of magnetite NPs in the composite films made them less rigid, with higher tensile strength and elongation when compared to the cellulose film. The saturation magnetization of the composite films (23, 31, and 37 emu g-1) was positively correlated with the concentration of NPs. The lack of hysteresis and coercivity indicated that the composite films are superparamagnetic at room temperature. Subsequently, cellulose was acetylated in DMAc/LiCl, at 110°C for 4h, and acetates with different degrees of substitution (DS) were obtained. Composite films from these acetates were obtained in DMAc/LiCl (conditions similar to those of the cellulose films) in the absence and presence of NPs (3.0 g L-1).The characterization of these films was performed by XRD, SEM, EDX, TG and DSC, tensile testing and VSM. SEM images showed that acetate films with different DS exhibited different morphologies and that the introduction of NPs in the matrices of different acetates had no effect on the morphology of the films. Films from acetates of DS greater than or equal to 2.0 showed microspheres on its surface. Acetate films more substituted were less resistant to traction than acetate films less substituted and the inclusion of NPs in these matrices led to less rigid films. Overall, composite films exhibited lower levels of crystallinity and thermal decomposition starting at lower temperatures (between 220-270°C) compared to the corresponding acetate film (control) (between 280-300°C), but without compromising the ability of application. The composite films based on cellulose acetate showed superparamagnetic behavior at room temperature with blocking temperature of 14 K and good saturation magnetization (27-46 emu.g-1). No correlation between DS and the magnetic properties of the films was observed, which showed some dependence on the presence or absence of microspheres. The association of the NPs in the polymeric matrices of both cellulose and cellulose acetate led to polymeric films with good magnetic and mechanical properties.

This work investigates the compositional and nanostructural variability of celluloses isolated from plants and the impact of the variability in the production of cellulose nanocrystals. A variable set of cellulose isolated from plants were generated starting with a range of feedstocks (coconut fiber, sisal fiber, eucalyptus sawdust, pine sawdust, sugarcane rind and sugarcane pith), applying a range of cellulose isolation processes (acetossolv, liquid hot water, alkaline, and liquid hot water + alkaline) and adding commercial cellulose (eucalyptus kraft pulp, dissolving pulp, and microcrystalline cellulose) as reference materials. The nanostructural characteristics were evaluated by calorimetric thermoporometry, X-ray diffraction, and moisture sorption isotherms. Composition was evaluated by standard wet chemical analysis and insights on functional groups were obtained by infrared spectroscopy. The cellulose nanocrystals were produced by acid hydrolysis with sulfuric acid and characterized by atomic force microscopy and X-ray diffraction. The measured parameters of the isolated celluloses were spread, showing we could achieve a highly diverse set of substrates. Significant correlations between measured variables across the sample set, indicating possible unforeseen multivariate relations among cellulose features. For example, we could show that cellulose monolayer hydration is determined by both hemicelluloses content (compositional parameter) as well as cellulose crystal width (structural parameter). Cellulose nanocrystals were successfully produced, although in some cases such as for the acetossolv pulps the acid conditions were too aggressive and oxidized the substrates. Finally, some quantitative correlations were seen between the parameters of cellulose substrates and the resulting cellulose nanocrystals. These results supply the first hints about how the nanostructural variability of isolated cellulose can influence the cellulose nanocrystals produced from them. / Este trabalho investiga a variabilidade composicional e nanoestrutural de celuloses isoladas de plantas e o seu impacto na variabilidade na produção de nanocristais de celulose. Um conjunto variável de celuloses isoladas de plantas foi gerado a partir de uma série de matérias-primas (fibra de coco, sisal, serragem de eucalipto, serragem de pinheiro, casca de cana e miolo de cana), aplicando uma série de processos de isolamento de celulose (hidrotérmico, alcalino, hidrotérmico + alcalino e acetosolve) e adicionando celuloses comerciais (polpa kraft de eucalipto, polpa para dissolução e celulose microcristalina) como materiais de referência. As características nanoestruturais foram avaliadas por termoporometria calorimétrica, difração de raios X e isotermas de sorção de umidade. A composição foi avaliada por análise química húmida padrão e os conhecimentos sobre grupos funcionais foram obtidos por espectroscopia de infravermelhos. Os nanocristais de celulose foram produzidos por hidrólise ácida com ácido sulfúrico e caracterizados por microscopia de força atômica e difração de raios-X. Os parâmetros medidos das celuloses isoladas foram distribuídos, demonstrando que poderíamos alcançar um conjunto altamente diversificado de substratos. Correlações significativas entre as variáveis medidas foram observadas em todo o conjunto amostral, indicando possíveis relações multivariadas imprevistas entre as características da celulose. Por exemplo, poderíamos demonstrar que a monocamada de hidratação de celulose é determinada tanto pelo conteúdo de hemiceluloses (parâmetro de composição) quanto pela largura do cristal de celulose (parâmetro estrutural). Os nanocristais de celulose foram produzidos com sucesso, embora em alguns casos, como nas polpas acetosolve, as condições ácidas fossem muito agressivas e oxidassem os substratos. Finalmente, algumas correlações quantitativas foram observadas entre os parâmetros dos substratos de celulose e os nanocristais de celulose resultantes. Estes resultados fornecem as primeiras dicas sobre como a variabilidade nanoestrutural da celulose isolada pode influenciar os nanocristais de celulose produzidos a partir deles.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / Tese (Doutorado) / Abstract: Since this thesis presents two independent studies on cellulose nanocrystals (CNCs), the abstract was divided in two sections referring to chapters II and III, respectively. Comprehensive morphological and structural investigation of cellulose I and II nanocrystals prepared by sulfuric acid hydrolysis Cellulose has several polymorphs. These polymorphs differ by crystal packing (i.e. unit cell parameters), polarity of the constituting chains and hydrogen bond patterns established between them. Most of cellulose polymorphs result from chemical treatments of the native polymorph, the so-called cellulose I (Cel-I) (Wada et al., 2008). In Cel-I, the chains are parallel and can be packed into two allomorphs, namely Iα and Iβ. Among the cellulose polymorphs, cellulose II (Cel-II), in which the chains are antiparallel, can be prepared from Cel-I by two distinct processes: Mercerization or Regeneration. Mercerization is an essentially solid-state process during which cellulose fibers are swollen in concentrated alkali media and recrystallized into cellulose II upon washing and drying (removal of the swelling agent). Unlike the mercerization process, in process known as regeneration, cellulose is first dissolved in an appropriated solvent and subsequent reprecipitated by adding a non-solvent, leading the chains to recrystallize into into Cel-II polymorph. The Cel-I to Cel-II transition is irreversible, which suggests that Cel-II is thermodynamically more stable (Habibi et al., 2010). Cell-II is the second most extensively studied polymorph due to its technical relevance. Nevertheless, so far, most of investigations involving Cel-II have focused on fibers and only a few recent studies have been carried out on CNCs. Cel-II nanocrystals have been prepared either by acid hydrolysis of mercerized fibers (Hirota et al., 2012; Kim et al., 2006; Yue et al., 2012), mercerization of Cel-I CNCs (Jin et al., 2016), or after recrystallization of fractions of short cellulose chains in solution (Dhar et al., 2015; Hirota et al., 2012; Hu et al., 2014; Sèbe et al., 2012). However, while these studies have generally combined the data from several imaging, diffraction and spectroscopic techniques, a complete structural picture of the nanocrystals has not been reported so far. In this context, the purpose of the research work presented in chapter II was to produce, characterize and compare CNCs obtained from eucalyptus wood pulp using three different methods: i) classical sulfuric acid hydrolysis (CN-I), ii) acid hydrolysis of cellulose previously mercerized by alkaline treatment (MCN-II), and iii) solubilization of cellulose in sulfuric acid and subsequent recrystallization in water (RCN-II). The morphology, crystal structure, crystallinity index, surface charge and degree of polymerization of these nanocrystals were characterized by complementary techniques, namely elemental analysis, zetametry, viscometry, transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier-transform infrared and solid-state nuclear magnetic resonance spectroscopies (FTIR and NMR, respectively). The three types of prepared CNC exhibit different morphologies and crystalline structures. When the acid hydrolysis conditions are set-up in such a way that the crystalline domains in the initial wood pulp and mercerized cellulose (WP and MWP, respectively) are preserved (60 wt% H2SO4, 45°C, 50 min), the resulting nanocrystals retain the fibrillar nature of the parent fibers (i.e., the chain axis is parallel to the long axis of the acicular particles) and their initial allomorphic type (I for WP and II for the MWP). In both cases, the particles are mostly composed of a few laterally-bound elementary crystallites, in agreement with what was shown for cotton CNCs by Elazzouzi-Hafraoui et al. (2008). The unit nanocrystals in CNCs from mercerized cellulose (MCN-II) are shorter but broader than those prepared from cellulose I fibers (CN-I). If harsher conditions are used (64 wt% H2SO4, 40°C, 20 min), resulting in the depolymerisation and dissolution of native cellulose, the short chains (with degree of polymerization DP ≈ 17) recrystallize into Cel-II ribbons upon regeneration in water at room temperature. In these somewhat tortuous ribbons, the chain axis would lie perpendicular to the long axis of the nanocrystal and parallel to its basal plane. In addition, these nanoribbons are very similar in shape and molecular orientation to mannan II nanocrystals prepared by recrystallization of mannan (Heux et al., 2005), a linear polymer of β-(1,4)-D-mannosyl residues, suggesting that this mode of crystallization may be a feature of short-chain linear β-(1,4)-linked polysaccharides. Although similar ribbons of recrystallized cellulose II have been reported by other authors, to our knowledge, it is the first time that a detailed morphological and structural description is proposed in terms of particle morphology, crystal structure and chain orientation. By comparison with the fibrillar nanocrystals prepared by acid hydrolysis of native or mercerized cellulose fibers, the unique molecular and crystal structure of the nanoribbons imply that a higher number of reducing chain ends are located at the particle surface, which may be important for subsequent chemical modification and specific potential applications such as biosensing and bioimaging agents. Therefore this study offers scope to a better understanding of crystalline structure and morphology of CNC obtained by regeneration process with sulfuric acid. Mechanical properties of natural rubber nanocomposites reinforced with high aspect ratio cellulose nanocrystals isolated from soy hulls At present, the most promising application of CNCs is as reinforcement material in the field of polymer nanocomposites.The incorporation of CNCs in polymer matrices generally leads to polymer-based nanocomposite materials with higher mechanical and barrier properties than the neat polymer or conventional composites. Among various factors that influence the efficiency of the reinforcing effect of CNCs, their intrinsic characteristics, including crystallinity and aspect ratio, play a key role (Dufresne, 2012; Favier et al., 1995; Mariano et al., 2014). It is also well-known that these characteristics depend on the source of the original cellulose, on the extraction method and its conditions (including pretreatment). However, it is widely accepted that the raw starting material is the most important factor (Beck-Candanedo et al., 2005; Dufresne, 2012; Elazzouzi- Hafraoui et al., 2008). The reinforcement capability of CNCs is therefore directly linked to the source of cellulose as well as its biosynthesis. Thus, the optimization of the extraction procedure and further characterization of CNCs from different sources of cellulose are crucial for an efficient exploitation of these sources, allowing the selection of the appropriate source (i.e. with targeted morphology) to suit specific end user applications (Brinchi et al., 2013). Natural rubber (NR) is a perfect polymer matrix to be used as a model system to study the effect of filler reinforcement, owing to its high flexibility and low stiffness. Its properties can be tailored by the addition of reinforcing fillers of various surface chemistries and aggregate size/aspect ratios to suit the targeted application. CNCs extracted from different sources have already been studied as nanoreinforcement in NRbased nanocomposites, including CNCs isolated from capim dourado (Siqueira et al., 2010), rachis of palm date tree (Bendahou et al., 2009), sugarcane bagasse (Pasquini et al., 2010; Bras et al., 2010), sisal (Siqueira et al., 2011), and bamboo (Visakh et al., 2012). So far, little results have been reported in the literature on the isolation of CNCs from soy hulls or their use in nanocomposites (Flauzino Neto et al., 2013, Silvério et al., 2014). In this study, CNCs were isolated from soy hulls by sulfuric acid hydrolysis treatment. The resulting CNCs, referred to as CNCSH in the following, were characterized using transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), wide-angle X-ray scattering (WAXS). These CNCSH were used as a reinforcing phase in a NR matrix to prepare nanocomposite films by casting/evaporation at 1, 2.5 and 5 wt% (dry basis) loading levels. The effect of CNCSH on the structure, as well as thermal and mechanical properties of NR, was investigated by means of scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), tensile tests and thermogravimetric analysis (TGA). For the acid hydrolysis treatment, were chose milder conditions compared to those described in Flauzino Neto et al. (2013) in order to avoid as much as possible the hydrolysis of crystalline cellulose domains. The CNCSH was found to have a type I crystal structure, high crystallinity (crystallinity index ≈ 80%), large specific surface area (estimated to be 747 m2.g-1 from geometrical considerations) and high aspect ratio (around 100). This aspect ratio is the largest ever reported in the literature for a plant cellulose source. Futhermore, from microscopic observations it is clearly seen that CNCSH does not consist of partially hydrolyzed microfibril since it displays the classical rod-like morphology of CNC. Thus, soy hull was found to be an interesting source of raw material for the production of CNC, due to the characteristics of the obtained nanocrystals associated with low lignin content and wide availability of this agro-industrial residue. In the meantime, the reuse of this agro-industrial residue goes towards sustainable development and environment-friendly materials. To tailor the dimensions of CNC and take full advantage of this source, special care needs to be paid to the extraction process and its conditions. A milder acid hydrolysis is preferable to improve the extraction yield, preserve the crystallinity of native cellulose and obtain high aspect ratio CNC. As expected, a high reinforcing effect is observed even at low filler contents when using this nanofiller (CNCSH) to prepare nanocomposites with a natural rubber (NR) matrix by casting/evaporation. For instance, by adding only 2.5 wt% CNC, the storage tensile modulus at 25°C of the nanocomposite was about 21 times higher than that of the unfilled NR matrix. This reinforcing effect was higher than the one observed for CNCs extracted from other sources. It may be assigned not only to the high aspect ratio of these CNCs but also to the stiffness of the percolating nanoparticle network formed within the polymer matrix. Moreover, the sedimentation of CNCs during the film processing by casting/evaporation was found to take place and play a crucial role on the mechanical properties. Thus, both the high aspect ratio of the CNC and sedimentation due to the processing technique are involved in the good mechanical results obtained. Indeed, if sedimentation occurs, then a multilayered film results and the CNC content in the lowest layers is higher than the average CNC content. It means that CNC mechanical percolation can occur in the lowest layers for an average CNC content which is lower than the percolation threshold. Hence, the system can be considered as constituted of parallel layers in the direction of the mechanical solicitation (tensile mode), and the CNC-rich layers can support a higher stress leading to a higher modulus value. Moreover, if high aspect ratio CNC is used, then percolation can occur in the lowest layers for lower average CNC contents. An important contribution of this work is to highlight the importance of the sedimentation of CNC during the evaporation step on the mechanical properties of the nanocomposites which is rarely mentioned in the literature.

The production of chemicals from solubilization and conversion of cellulosic material is a promised important chemical platform. Several studies have shown that the conversion of cellulose into industrial products, are conducted in the presence of enzymes, inorganic acids and bases or in aqueous supercritical medium. However, in most of these procedures several inconvenient are present, for example, low selectivity and catalytic activity, difficulties to separate the products and recuperate the catalyst, corrosion problems of equipments, and large volumes of liquid wastes neutralization processes, as well as severe reaction conditions employed. If these set of processes and reactions are conducted in the presence of no toxic or corrosive compounds or materials, and that can be also recuperated and reused, several of green chemistry aspects, allied with economical view, can be attained. In this context, we studied the solubility, hydrolysis, and cellulose degradation, employing new solid catalytic systems exhibiting Lewis and/or Brøsnted acid sites. The catalytic properties of those materials were compared to the classical system based on sulfuric acid, and systems runned without addition of catalyst. The new catalytic systems, based on magnetic nanoparticles (Fe3O4/SiO2/Pt0, Fe3O4/SiO2/NH2 e Fe3O4/SiO2), displayed great potential to hydrolyze cellulose, and generating a wide range of products with industrial importance, without the inconvenience of corrosion problems associated to the use of sulfuric acid. The recuperation and reuse of the catalytic material have been carried out and evaluated, in which several recycles have been performed and compared. The reaction temperature and time are the most significant variables in the cellulose solubilization/hydrolysis/degradation process. Independently of the presence or not of catalysts, higher cellulose consumption is observed at reaction temperatures and time of 180 °C and 4 hours, respectively. In terms of selectivity, reaction temperatures of 150 and 180 °C displayed different tendencies. At 150 °C, it was observed higher production of glycosides, but at 180 °C higher production of glycosides derivatives like hydroximethylfurfural (HMF). The order of cellulose consumptions (Fe3O4/SiO2/Pt0> Fe3O4/SiO2/NH2 > Fe3O4/SiO2) was maintained in all reaction conditions tested in this work, and a clear effect of the platinum as catalyst on the conversion of the cellulose was detected / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A obtenção de insumos químicos a partir da solubilização e conversão de material celulósico, presente na biomassa, pode se constituir numa plataforma química de significativa importância. Vários estudos têm mostrado que a conversão da celulose, em produtos de interesse industrial, tem sido conduzida em presença de enzimas, ácidos minerais, bases e em meio aquoso supercrítico. Porém, muito destes processos de transformação têm certas inconveniências, como baixa seletividade e atividade catalítica, ou o emprego de severas condições de reação. Nesse contexto, foram investigadas a solubilização, hidrólise e degradação da celulose, empregando novos sistemas catalíticos sólidos contendo sítios ácidos de Brøsnted e/ou Lewis, suas propriedades catalíticas foram comparadas com o sistema catalítico clássico, ácido sulfúrico, bem como, com processos conduzidos na ausência de catalisador. Os novos sistemas propostos, baseados em nanopartículas magnéticas (Fe3O4/SiO2/Pt0, Fe3O4/SiO2/NH2 e Fe3O4/SiO2), apresentaram grande potencial em hidrolisar a celulose, com a geração de uma grande gama de produtos de importância industrial. A temperatura e o tempo reacional mostraram-se variáveis determinantes no processo de solubilização/hidrólise/degradação da celulose. Um maior consumo de celulose é observado a 180 ºC e 4 horas de reação, independente do catalisador empregado ou da ausência deste. Em termos de seletividade, as duas temperaturas testadas são de grande interesse porque na primeira (150 ºC) há o predomínio na formação de glicosídeos, enquanto na segunda (180ºC) há a formação de glicosídeos e sua posterior degradação, com obtenção de HMF. A ordem de consumo (Fe3O4/SiO2/Pt0> Fe3O4/SiO2/NH2 > Fe3O4/SiO2) foi mantida em todas as condições reacionais empregadas nesse trabalho e um efeito claro da presença da platina sobre a atividade catalítica foi observado

Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2017-02-15T18:01:01Z No. of bitstreams: 1 texto completo.pdf: 5948036 bytes, checksum: 21f531126f660e42de322b4303b17e1a (MD5) / Made available in DSpace on 2017-02-15T18:01:01Z (GMT). No. of bitstreams: 1 texto completo.pdf: 5948036 bytes, checksum: 21f531126f660e42de322b4303b17e1a (MD5) Previous issue date: 2005-06-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Analisaram-se no presente estudo os comportamentos de engenharia das misturas solo-grits e solo-lama de cal, com base em resultados de ensaios de laboratório envolvendo determinações de parâmetros ótimos de compactação, limites de liquidez e plasticidade, capacidade de suporte CBR, resistências a compressão não confinada e a tração e, também, em resultados de avaliações qualitativas do desempenho dessas misturas, em campo, através do desenvolvimento de trechos rodoviários experimentais em subleitos de estradas florestais. Para tanto, trabalhou-se com amostras de solos representativas das ocorrências de três localidades, a saber: (i) microrregião de Viçosa (MG) solo 1 [A-7-5 (20)] e solo 2 [A-2-4 (0)]; (ii) microrregião de Ipatinga (MG) cenibra amarelo [A-7-6 (6)], cenibra róseo [A-6 (3)] e cenibra vemelho [A-7-5 (20)]; e (iii) microrregião de Alagoinhas (Ba) subleito areia [A- 2-4 (0)] e cascalho de primeira [A-1-a (0)]. Os resíduos oriundos da indústria de celulose, grits e lama de cal, foram utilizados como agentes de estabilização química. Foram realizadas misturas solo-grits com solos de Viçosa-MG empregando-se, em massa, grits nos quantitativos de 4, 8, 12, 16, 20, 24 e 28 %. Os estudos com essas misturas contemplaram a etapa 1 do trabalho que abrangeu a análise das diversas variáveis influentes no processo de estabilização química de solos. Misturas solo-grits com solos de Ipatinga-MG, também, foram realizadas, sendo os quantitativos de grits, em massa, de 12, 16, 20 e 24 %. Nesta etapa 2 os estudos abrangeram a caracterização e classificação das amostras de solo e das misturas solo-grits, avaliação da resistência mecânica via ensaio CBR e execução e avaliação de trecho experimental em áreas da empresa CENIBRA S/A. Os solos de Alagoinhas-Ba foram empregados nas misturas com a lama de cal constituindo-se nos estudos referentes a etapa 3 do trabalho. Os teores, em massa, de lama de cal empregados nas misturas foram de 10, 15, 20 e 25 %. Após a caracterização das amostras de solo, avaliou-se a resistência mecânica das misturas solo- lama de cal via ensaio CBR, em laboratório, e de posse das melhores respostas procedeu-se a construção e avaliação de trechos experimentais em áreas da empresa BAHIA PULP S/A. Os resultados obtidos em laboratório e a análise do desempenho das misturas solo-grits, em campo, possibilitou chegar às seguintes conclusões: (i) o teor de 24 % de grits apresentou-se como o teor ótimo desse resíduo para fins de estabilização dos solos; (ii) o tipo de solo, a energia de compactação, o tempo entre a mistura e a compactação, o lote e a granulometria do resíduo, o período de cura e a imersão em água influenciaram a resistência mecânica e expansão das misturas solo-grits; (iii) solos de textura argilosa tiveram seus valores de resistência mecânica influenciados pela ação dispersiva do sódio presente no resíduo grits; (iv) o tratamento térmico do grits tornou-o mais reativo nas misturas solo-grits; (v) o desempenho, em campo, de trecho experimental contendo solo local mais 24 % de grits, avaliado um ano após sua execução, evidenciou falta de cimentação das partículas do solo pelo grits, observando-se ocorrência de erosão laminar com remoção de parte da camada estabilizada. Os resultados obtidos, em laboratório e campo, para as misturas solo-lama de cal possibilitaram chegar às seguintes conclusões: (i) a melhor resposta, em laboratório, de resistência mecânica e expansão foi para a mistura cascalho de primeira + 25 % lama de cal; e (ii) no campo, o melhor desempenho foi para a mistura com 30 % de lama de cal e 70 % de cascalho de primeira. / This study addresses the engineering behavior of soil-grits and soil- whitewash mud mixtures based on data from laboratory testing program and qualitative field evaluation of forest roads testing sites. The laboratory testing program was directed to Atterberg limits (LL and PL), compaction, CBR, unconfined compression and indirect tensile strength tests performed in Brazilian soil samples, as follows: (i) soil 1 [A-7-5 (20)] and soil 2 [A-2-4 (0)], that are from the micro-region of Viçosa, Minas Gerais State; (ii) yellow Cenibra [A-7-6 (6)], pink Cenibra [A-6 (3)] and red Cenibra [A-7-5 (20)], that are from the micro-region of Ipatinga, Minas Gerais State; (iii) sandy sub-grade soil [A-2-4 (0)] and first class gravel [A-1-a (0)], that are from the micro-region of Alagoinhas, Bahia State. The wastes named grits and whitewash mud, both from the cellulose industry, were used as chemical soil stabilizers. The laboratory testing program was divided in three steps, as follows: (i) step 1, concerning the study of Viçosa soils-grits mixtures stabilization process at grits contents of 4, 8, 12, 16, 20, 24 e 28 %; (ii) step 2, encompassing Ipatinga soils- grits mixtures at grits contents of 12, 16, 20 e 24 %, which was directed to soil characterization and engineering classification, determination of mechanical strength via CBR, as well as construction and evaluation of field performance of a forest road test site at Cenibra S/A; (iii) step 3, considering Alagoinhas soils- whitewash mud mixtures at waste contents of 10, 15, 20 and 25 %, which took into account geotechnical characterization and CBR laboratory tests in order to determine best waste content to be used in the construction of forest road test sites at the Bahia Pulp S/A company. Data from the laboratory and field testing program executed with soil-grits mixtures support the following conclusions: (i) best mechanical responses of soil-grits mixtures were associated to 24 % grits content; (ii) parameters such as soil type, compaction effort, elapsed period of time between mixture and compaction, grits production run, grits size distribution, curing period of time and water immersion before testing affect ed significantly the mechanical behavior of mixtures; (iii) sodium presents in grits samples influenced significantly the mechanical strength and swelling of mixtures; (iv) thermal treatment produced more reactive grits samples; (v) one year after construction, field evaluation of the forest road test site at CENIBRA S/A generally showed lack of cementation among soil particles, as well as mixture mass losses due to laminar erosion. Data from the laboratory and field testing program carried out with soil-whitewash mud support the following conclusions: (i) best laboratory testing mechanical response was associated to 25 % whitewash mud plus 75 % first class gravel gavel; (ii) best field performance of test sites was related to 30 % whitewash mud content plus 70 % first class gravel.

Made available in DSpace on 2010-04-20T20:54:44Z (GMT). No. of bitstreams: 3 RaphaelAlmeidaVideira2005.pdf.jpg: 14673 bytes, checksum: 6bb82016c88319ba325f1405c78187a1 (MD5) RaphaelAlmeidaVideira2005.pdf.txt: 115776 bytes, checksum: bf2ac1c722c9f885c08ea24a71569ba6 (MD5) RaphaelAlmeidaVideira2005.pdf: 192934 bytes, checksum: 3b05da2be234891400d65dc59ceae526 (MD5) Previous issue date: 2005-12-15T00:00:00Z / This paper studies the brazilian pulp industry and tries to answer two main questions. The first is about the definition of geographic relevant market. The second one intends to verify the existance of market power in this industry. The product relevant market, bleached eucalyptus pulp, was defined by qualitative aspects. The first question used a methodology proposed by Forni (2004), who used unit root tests (ADF and KPSS) to define the geographic relevant market. The results of these tests indicated an international geographic relevant market which was corroborated analysing the functioning of this market. After these tests, a market power test was done, because in this market, the world leader is a brazilian company, Aracruz. This test was proposed by Mayo, Kaserman e Kahai (1996) and they used a demand residual model. The estimation of this test was proposed by Motta (2004). The results indicated that Aracruz does not have market power in this sector. / Este trabalho analisa o setor brasileiro de celulose e tenta responder a duas questões principais: a abrangência do mercado relevante e a existência de poder de mercado das empresas que atuam neste setor. A dimensão produto do mercado relevante foi definida a partir de dados qualitativos. Devido à indisponibilidade de dados para uma análise qualitativa mais apurada, a opção foi pela celulose de fibra curta de eucalipto, produto mais importante do setor, tanto pela posição brasileira em tecnologia como pela pauta de exportações. Já quanto à dimensão geográfica, o procedimento realizado baseou-se em Forni (2004) que utiliza testes de raiz unitária para a definição do mercado. Concluiu-se que, com os dados disponíveis, o mercado deste produto pode ser considerado como internacional, não somente pelo resultado do teste como também pelo modo de funcionamento deste mercado. Definido o mercado de produto e geográfico, realizou-se um teste de poder de mercado, pois neste nicho, a Aracruz é líder mundial. Tal teste foi realizado com base na demanda residual descrita por Mayo, Kaserman e Kahai (1996) e estimado segundo Motta (2004). Concluiu-se que, apesar de a Aracruz possuir um elevado market share no setor, ela não possui poder de mercado.

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2016-09-26T17:09:58Z No. of bitstreams: 1 texto completo.pdf: 595764 bytes, checksum: 003daec8e86d7c6b2e064d3705a7f8f0 (MD5) / Made available in DSpace on 2016-09-26T17:09:58Z (GMT). No. of bitstreams: 1 texto completo.pdf: 595764 bytes, checksum: 003daec8e86d7c6b2e064d3705a7f8f0 (MD5) Previous issue date: 2016-02-18 / A madeira de eucalipto tem se tornado uma das principais matérias primas para a produção de polpa celulósica, principalmente na América do Sul. Apesar de sua alta produtividade florestal, os custos de produção da madeira de eucalipto tem apresentado tendências de aumento nos últimos anos. A madeira representa em algumas unidades fabris produtoras de polpa celulósica valores superiores a 50% dos custos de produção. Esse fato aponta para a necessidade de se investigar alternativas de processos que melhorem a sua processabilidade. O presente estudo teve como objetivo principal avaliar a influência da tecnologia de impregnação prolongada no cozimento kraft e o seu impacto na branqueabilidade da polpa. Foi utilizada uma mistura de madeiras provenientes do hibrido Eucalyptus urophylla x Eucalyptus grandis (Eucalyptus urograndis) coletadas aos sete anos de idade. Nesse estudo foram realizados caracterização química e física da amostra de madeira utilizada. O processo kraft foi utilizado como referência. Pelos processos kraft convencional e impregnação prolongada, foram obtidas polpas celulósicas de números kappa 15, 19, 23 e 27 as quais foram branqueadas pela sequência OD(DP)D para uma alvura de 90% ISO. Os principais resultados obtidos pelo desenvolvimento desse estudo foram: (1) a qualidade da madeira de Eucalyptus urograndis usada neste trabalho apresentou composição química e densidade básica (528 kg/dm 3 ) compatível com clones de eucaliptos comerciais segundo dados da literatura; (2) o processo de polpação com impregnação prolongada teve melhores resultados para o rendimento depurado, em geral, 1% acima em relação à polpação convencional; (3) a impregnação prolongada apresentou melhores branqueabilidades quando comparada a polpação kraft convencional; (4) as polpas obtidas pelo processo de polpação com impregnação prolongada apresentaram melhores estabilidades de alvura; (5) o teor de carbono orgânico total, sólidos orgânicos e totais apresentaram forte correlação com o rendimento depurado da polpação. / The eucalyptus is becoming the most important raw material for pulp production, mainly in South America. In spite of its high forest productivity, the cost of eucalypt wood has grown largely in the last year. In some pulp mills the wood represents values higher than 50% of the overall cost composition of pulp production. This fact indicates the demand to investigate alternative processes to improve its processability into pulp. This study aimed to evaluate the influence of prolonged impregnation kraft cooking technology and its impact on pulp bleachability. It was used a mix of the hybrid of Eucalyptus urophylla x Eucalyptus grandis (Eucalyptus urograndis) harvested at 7 years old. In this study were carried out chemical and physical characterization of the wood sample used. The Kraft process was used as a reference. By the processes kraft conventional and prolonged impregnation kraft cooking were obtained pulps at kappa number 15, 19, 23 and 27. The pulps were bleached by the sequence OD(DP)D aiming brightness of 90% ISO. The main findings of this work were: (1) the wood quality of the Eucalyptus urograndis used presented chemical composition and basic density (528 kg/dm 3 ) similar to the commercial eucalypt clones according to the literature; (2) the prolonged impregnation kraft cooking showed a better screened yield, in general 1% higher than the conventional cooking; (3) the prolonged impregnation kraft cooking showed a higher bleachability when compared to the conventional cooking; (4) the pulps obtained from prolonged impregnation kraft cooking showed higher brightness stability than the conventional cooking; (5) the contents of organic carbon, organic solids and total solids showed a high correlation with the pulping screened yield.

Constituintes quimicos de amostra de licor preto, não-tratado, proveniente de efluentes industriais de polpa de celulose do Sul do Brasil foram extraidos utilizando a resina macroreticular Amberlite XAD-4. Foram identificados os seguintes . compostos, alguns com concentrações determinadas, utilizando-se cromatografia gasosa com coluna capilar de SE-30: fenol; guaiacol; catecol; 3,4-diclorocatecol (288 ug/l); triclorocatecol (5885 ug(l); tetraclorocatecol (16461 ug/l); 4,5,6- tricloroguaiacol (500 ug/1); 3,4,5-tricloroguaiacol; pentaclorofenol (21 ug/1); tetracloroguaiacol (423 ug/1) e triclorosirin gol (173 ug/1). Foram tamb~m determinados os indices de retenção com programação linear de temperatura sendo encontrados os seguintes valores: fenol (935); guaiacol (993); catecol (1192); 4,5, 6-tricloroguaiacol (1623); 3,4-diclorocatecol (1668); 3,4,5- tricloroguaiacol (1693), pentaclorofenol (1730); 3,4,5-triclorocatecol (1751); triclorosiringol (1764); tetracloroguaiacol (1769) e tetraclorocatecol (1908). Foi feita uma comparação entre o efluente não-trata do com o que sofreu tratamento primário e secundário e verificou-se que mesmo apos o referido tratamento persistia a existência dos compostos acima mencionados apenas em menor concentração. Também foi feita uma comparação dos efluentes industriais com um efluente"artificial" obtido em laboratório através de branqueamento de papelão com hipoclorito de sódio. Verificou-se que os efluentes são bastante semelhantes. O estudo destes compostos organoclorados nos efluentes industriais e de suma importância uma vez que eles geralmente apresentam elevado grau de toxidez e mutagenidade. Não sendo eliminados pelos processos convencionais de tratamento de efluentes terão efeito cumulativo no meio ambiente causando graves danos a fauna e a flora. / Chemical components of untreated black liquor from industrial effluents of cellulose pulp from Southern Brazil were extracted using macroreticularJI.mberlite XP..C-4 resin. The followin9 compounds were identified qualitatively and/or quantitatively by capillary 9as chromato9raphy on a SE-30 co1umn: phenol; guaiacol catechol; 3,4-dichlorocatecho1 (288 119!1); 4, 5, 6 5-trichlorocate(hol (5885 11911); pentachlorophenol (21 l-1911) tetrachloro9uaiacol (423 11911); trich1orosyringol(173 '11911) and tetra ch 1 o r o cate c h o 1 ( 1 6 4 6 1 lJ g !l) . The retention índices were also determined usin9 linear temperature programmin9 for the following compounds and the values obtained are indicated in parenthesis: pheno1 (935); guaiacol (993); catechol (1192); 4,5,6-trichologuaiacol (1623); 3 , 4- di c h 1 o r o cate cho 1 (1668}; 3,4,5-trichloroguaiacol (1663); pentachlorophenol (1739); 3,4,5-trich1orocatechol (1751) trichlorosyrin9ol (1764); tetrachloroguaiacol (1769) and chlorocatechol (1908). Comparison between untreated samples of black liquor and samples subjected to primary and secondary treatment showed that the effluent continues containing all the above mentioned compounds, only in lesser quantity. A comparison was also made between the industrial effluents and an "artificial" one obtained in tfte laboratory by bleaching of cardboard with sodium hypochlorite. It was found that the effluents are rather similar. The study of these chlorinated organic compounds in industrial effluents is of great importance because they are generally toxic and mutagenic. Since they are not eliminated by conventional treatment of effluents, they have a cumulative effect in the environment and cause serious damage to flora and fauna.

Made available in DSpace on 2016-06-02T20:36:51Z (GMT). No. of bitstreams: 1 5970.pdf: 5125436 bytes, checksum: d76a64e8b67b6eb80ac6a87036cd5be2 (MD5) Previous issue date: 2014-04-29 / This research proposed the obtainment of cellulose whiskers from cotton fibers and their application in low density polyethylene matrix (LDPE). Cellulose whiskers was obtained from acid hydrolysis of cotton fibers and the reaction conditions were defined after study of different acid in hydrolysis reaction (under 45°C and 75 minutes, with HCl sample WCl, or H2SO4 sample WS, or mix of them in a proportion 1:1 sample WSCl). The main difference observed was the amount sulfate groups on whiskers surface due the use sulphuric acid in hydrolysis. These groups affected the properties of samples, increasing stability of whiskers in aqueous suspension, decreasing the tendency to agglomeration. However, due to these groups, cellulose is degraded at low temperatures. Once the nanocellulose (hydrophillic) needs to interact with LDPE (hydrophobic), two strategies was studied to compatibilize them: (i) production a nanocomposite based EVA poly (ethylene-covinyl acetate), a copolymer compatible with matrix and filler, since it have a polar phases (vinyl acetate monomer) and a nonpolar phase (ethylene monomer), and (ii) surface modification of cellulose whiskers by esterification reactions. Nanocomposites based EVA was prepared by polymeric solution where EVA was solubilized in mineral oil and then, the whiskers without surface modification (WS) was added, with aim dispersing them in LDPE. The characterizations this study showed that the solvent remained inside the structure polymeric, modifying their original properties and difficulting the interaction between cellulose and copolymer molecules. The sample WS and WCl was applied in esterification reactions with acetic acid, propionic acid and maleic anhydride. Whiskers extracted by hydrochloric acid and modified by maleic anhydride (WClMal), was produced by a simple methodology and presented thermal stability at processing temperatures. Thus, this sample was used to obtain nanocomposites with cellulose whiskers and LDPE, which was produced as films by extrusion process. Nanocomposites with LDPE and whiskers not modified (WCl) was produced to comparison. The characterizations of these materials confirmed the incorporation of whiskers in a polymeric matrix. The concentration that showed good dispersion and lower clusters was 1% (w/w) cellulose whiskers in LDPE matrix. / Este trabalho buscou a obtenção de whiskers de celulose a partir de fibras de algodão e sua incorporação em matriz de polietileno de baixa densidade (PEBD). Os whiskers de celulose foram obtidos a partir da hidrólise ácida das fibras de algodão e as condições reacionais foram determinadas após estudo de variação da natureza do ácido reagente (a 45°C e 75 minutos, com HCl amostra WCl, ou H2SO4 amostra WS, ou mistura de ambos na proporção 1:1 amostra WSCl). A principal diferença observada foi a quantidade grupos sulfatos incorporados como consequência do uso de ácido sulfúrico na hidrólise. Estes grupos interferiram nas propriedades dos whiskers, de modo a aumentar a estabilidade em suspensão aquosa, diminuindo a tendência à aglomeração. Entretanto, estes grupos deslocaram a degradação termooxidativa da celulose para temperaturas inferiores. Devido à necessidade de interação entre a nanocelulose (hidrofílica) e o PEBD (hidrofóbico), foram estudadas duas estratégias de compatibilização: (i) produção de nanocompósito com EVA (poli [etileno(co-acetato de vinila)]), uma vez que este copolímero é composto por uma fase polar (meros de acetato de vinila) e uma fase apolar (meros etilênicos), e (ii) modificação superficial dos whiskers de celulose via reações de esterificação. O nanocompósito a base de EVA foi preparado via solução polimérica de EVA em óleo mineral, e após adição de whiskers sem modificação (WS), visando a dispersão dos whiskers de celulose no PEBD. As caracterizações relativas a este estudo mostraram que o solvente permaneceu adsorvido à estrutura do EVA, modificando suas propriedades originais e dificultando a interação entre as moléculas de celulose e do copolímero. As amostras WS e WCl foram aplicadas em reações de esterificação com ácido acético, ácido propiônico e com anidrido maleico. Assim, esta amostra foi utilizada na formulação de nanocompósitos com PEBD sob a forma de filmes planos a partir de extrusão. Nanocompósitos com PEBD e whiskers não modificados (WCl) foram produzidos para fins comparativos. As caracterizações destes materiais confirmaram a incorporação e interação destes à matriz polimérica. A concentração com melhor dispersão e menor formação de aglomerados foi a de 1% (m/m) de whiskers de celulose em PEBD.