Lignocellulose is the most abundant biopolymer on earth and offers excellent potential for sustainable manufacturing. Because lignocellulose is structurally complex and resistant to decomposition, innovative degradation strategies are necessary to unlock its value. In this dissertation, a green manufacturing process through enzyme-triggered self-cultured bacteria retting for lignocellulosic fiber was developed and investigated. The mechanism of the lignocellulosic fiber retting at a controlled degradation strategy was studied. This enzymatic degradation strategy utilizes a small amount of enzyme to trigger a large aggregation of specific bacteria to obtain clean fibers. Industrial hemp (Cannabis sativa L.) fiber was successfully retted with this strategy. The degradation of pectin was proved through an environmental scanning electron microscope and reducing sugar analysis. The bacterial successions were identified by 16S rRNA gene metagenomic sequencing. The results showed that Bacillaceae dominated the hemp retting conditions containing 1% pectinase, suggesting that pectinase can manipulate bacterial community succession by changing the nutrients available to bacteria through the degradation of pectin. This degradation strategy has 20-25% less environmental impact than the thermochemical degradation strategy, resulting in better fiber consistency and much shorter processing time (3-5 days) than the traditional water degradation strategy. The study on the degradation of lignin-rich lignocellulose also contributes to the understanding of the natural formaldehyde release mechanisms from wood.

Made available in DSpace on 2014-12-17T14:58:19Z (GMT). No. of bitstreams: 1 JulianaRMP_DISSERT.pdf: 1714227 bytes, checksum: 8cb7005a86931b335594250a74884834 (MD5) Previous issue date: 2012-09-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Concern for the environment and the exploitation of natural resources has motivated the development of research in lignocellulosic materials, mainly from plant fibers. The major attraction of these materials include the fact that the fibers are biodegradable, they are a renewable natural resource, low cost and they usually produce less wear on equipment manufacturing when compared with synthetic fibers. Its applications are focused on the areas of technology, including automotive, aerospace, marine, civil, among others, due to the advantageous use in economic and ecological terms. Therefore, this study aims to characterize and analyze the properties of plant fiber macambira (bromelia laciniosa), which were obtained in the municipality of Ielmo Marino, in the state of Rio Grande do Norte, located in the region of the Wasteland Potiguar. The characterization of the fiber is given by SEM analysis, tensile test, TG, FTIR, chemical analysis, in addition to obtaining his title and density. The results showed that the extraction of the fibers, only 0.5% of the material is converted into fibers. The results for title and density were satisfactory when compared with other fibers of the same nature. Its structure is composed of microfibrils and its surface is roughened. The cross section has a non-uniform geometry, therefore, it is understood that its diameter is variable along the entire fiber. Values for tensile strength were lower than those of sisal fibers and curau?. The degradation temperature remained equivalent to the degradation temperatures of other vegetable fibers. In FTIR analysis showed that the heat treatment may be an alternative to making the fiber hydrophobic, since, at high temperature can remove the hemicellulose layer, responsible for moisture absorption. Its chemical constitution is endowed with elements of polar nature, so their moisture is around 8.5% which is equivalent to the percentage of moisture content of hydrophilic fibers. It can be concluded that the fiber macambira stands as an alternative materials from renewable sources and depending on the actual application and purpose, it may achieve satisfactory results / A preocupa??o com o meio ambiente e com o aproveitamento de recursos naturais tem motivado o desenvolvimento de pesquisas na ?rea de materiais lignocelul?sicos, principalmente de fibras vegetais. Os grandes atrativos desses materiais incluem o fato das fibras serem biodegrad?veis, serem um recurso natural renov?vel, terem geralmente baixo custo e produzirem menor desgaste nos equipamentos de fabrica??o quando comparadas com as fibras sint?ticas. Suas aplica??es est?o voltadas para a ?rea tecnol?gica, incluindo ind?strias automotiva, aeroespacial, naval, civil entre outras, devido ao uso vantajoso em termos econ?micos e ecol?gicos. Portanto, o presente trabalho tem como objetivo caracterizar e analisar as propriedades da fibra vegetal macambira (bromelia laciniosa), cuja foram obtidas no munic?pio de Ielmo Marinho, no estado do Rio Grande do Norte, situado na regi?o do Agreste Potiguar. A caracteriza??o da fibra se deu pelas an?lises de Microscopia Eletr?nica de Varredura (MEV), ensaio de tra??o, Termogravimetria (TG), Espectroscopia no Infravermelho por Transformada de Fourier (FTIR), an?lise qu?mica, al?m da obten??o de sua densidade linear. Os resultados mostraram que na extra??o das fibras, apenas 0,5% do material ? convertido em fibras. Os resultados para densidade foram satisfat?rios quando comparados com outras fibras de mesma natureza. Sua estrutura ? constitu?da por microfibrilas e sua superf?cie ? rugosa. A se??o transversal n?o apresenta uma geometria uniforme, portanto, entende-se que seu di?metro ? vari?vel ao longo de toda fibra. Os valores para resist?ncia a tra??o foram inferiores aos de outras fibras lignocelul?sicas. A temperatura de degrada??o permaneceu equivalente ?s temperaturas de degrada??o das demais fibras vegetais. Na an?lise de FTIR, mostrou-se que o tratamento t?rmico pode provocar um rompimento das mol?culas. O percentual Regain confirmou-se em 8,5%. Pode-se concluir que a fibra de macambira destaca-se como mais uma alternativa dentre os materiais de fontes renov?veis e dependendo da sua real aplica??o e finalidade, a mesma pode alcan?ar resultados satisfat?rios

A travers cette thèse, nous avons pu valoriser les rejets agricoles du palmier dattier (Phoenix L. dactylifera) (fibres issues des folioles) par leur introduction comme renfort fibreux dans la préparation des biocomposites à matrice polyépoxyde (DGEBA/IPD). Le but de la première partie de la thèse était l’étude de la modification chimique des fibres de palmier par oxydation au 2,2, 6,6–tétraméthylpipéridine-1-oxyle (TEMPO). Le suivi cinétique et la topologie de la réaction, ainsi que la caractérisation des fibres à l’état brut et à l’état oxydé, ont été aussi étudiés. Un modèle cinétique original a été proposé ensuite rendant compte du caractère hétérogène de cette réaction chimique. La deuxième partie était consacrée à l’étude cinétique et rhéocinétique de la polymérisation du système DGEBA/IPD seul et en présence de fibres brutes et oxydées. Parallèlement, l’étude thermique de la polymérisation du réseau final a été également réalisée. La dernière partie avait comme but l’étude des propriétés mécaniques aux petites et grandes déformations de ces composites et mettre en évidence l’effet de l’oxydation des fibres sur ces propriétés. D’autre part, le suivi de mise en forme par RTM (moulage par transfert de résine) a montré un effet positif de l’oxydation sur le déroulement de l’injection. Une meilleure mouillabilité du mat des fibres oxydées par la résine est à l’origine de l’amélioration du procédé. / To increase in value the agricultural waste products of the date palm tree -phoenix dactylifera l-, especially the fibers from the leaflets, their use as filler in polyepoxide matrix (dgeba / ipd) was investigated to prepare new bio-based composites. Our goal in the first part is to study the chemical modification of palm fiber by oxidation mediated by 2,2,6,6-tetramethylpiperidine-1-oxyl (tempo). The kinetic and the topology of the reaction, as well as the characterization of fibres in rough and oxidized state, were also studied. An original kinetic model was proposed taking into account the heterogeneous character of this chemical reaction. The second part was devoted to study the kinetics and rheokinetic of the polymerization of dgeba / ipd with and without modified and unmodified fibers. This enabled to show the effect of the introduction of the date palm tree fibers (oxidized and non oxidized) on the composite formation. The thermal properties of the prepared composites were also investigated in this part of work. In the last part of this work, the mechanical properties of these composites were investigated and enabled to highlight the effect of the fibers oxidation on these properties. In addition, the effect of oxidation on the course of the injection during the rtm process (moulding by transfer of resin) was investigated. A positive effect of the oxidation of the fibers on the course of the injection was obtained and was attributed to the higher wettability of oxidized fibres by the resin.