In this study, the effects of chain extension and branching on the properties of nanocomposites produced from recycled poly(ethylene terephthalate) and organically modified clay were investigated. As the chain extension/branching agent, maleic anhydride (MA) and pyromellitic dianhydride (PMDA) were used. The nanocomposites were prepared by twin-screw extrusion, followed by injection molding. Recycled poly(ethylene terephthalate), was mixed with 2, 3 and 4 weight % of organically modified montmorillonite. During the second extrusion step, 0.5, 0.75 or 1 weight % of MA or PMDA was added to the products of the first extrusion. As the second extrusion step is reactive extrusion, the anhydrides were added at three different screw speeds of 75, 150, 350 rpm, in order to observe the change of properties with the screw speed. XRD analysis showed that, the interlayer spacing of Cloisite 25A expanded from 19.21 &amp / #506 / to about 28-34 &amp / #506 / after processing with polymer indicating an intercalated structure. PMDA, MA and organoclay content as well as the screw speed did not have a recognizable effect on interlayer distance. In the first extrusion step, nanocomposites containing 3% organoclay content gave significant increase in Young&rsquo / s modulus and decrease in elongation to break values indicating good interfacial adhesion. After the addition of chain extenders, it was observed that both MA and PMDA gave rise to improved mechanical properties of the nanocomposite owing to the branching and chain extending effects that increase the molecular weight. However, PMDA gave better mechanical properties at lower content which makes it a more effective chain extender. DSC analysis showed that MA was more effective in increasing the glass transition temperature and melting temperature in comparison to PMDA.

Submitted by Gustavo Nascimento (gustavo.diniz@ufcg.edu.br) on 2018-02-02T11:24:55Z No. of bitstreams: 1 KALINE ROSÁRIO MORAIS FERREIRA - TESE PPGCMAT 2014.pdf: 4196427 bytes, checksum: cfa12a2731146e96138a50d4de35c10e (MD5) / Made available in DSpace on 2018-02-02T11:24:55Z (GMT). No. of bitstreams: 1 KALINE ROSÁRIO MORAIS FERREIRA - TESE PPGCMAT 2014.pdf: 4196427 bytes, checksum: cfa12a2731146e96138a50d4de35c10e (MD5) Previous issue date: 2014-08-29 / CNPq / Neste trabalho nanocompósitos à base de olefina termoplástica (TPO) formados pela mistura polipropileno (PP)/terpolímero de etileno-propileno-dieno (EPDM)/argila organofílica foram preparados pelo processo de intercalação por fusão. As TPOs, não compatibilizadas e compatibilizadas com polipropileno modificado com anidrido maleico (PP-g-MA), foram preparadas em um misturador interno de laboratório, empregando duas razões de PP/EPDM: 90:10 e 70:30. A estas TPOs foram incorporadas cinco tipos de argila organofílica em teores de 1, 3 e 5 pcr. A influência da razão PP/EPDM, da presença do compatibilizante orgânico (PP-g-MA), do tipo e do teor de argila na morfologia e propriedades mecânicas em tração destas TPOs foi avaliada. Os resultados obtidos por difratometria de raios X (DRX) sugerem que a adição de 1, 3 e 5 pcr das argilas organofílicas às TPOs, independente do tipo, resulta na formação de nanocompósitos com estrutura possivelmente intercalada desordenada e que as TPOs contendo as argilas organofílicas preparadas com tecnologia local apresentaram resultados semelhantes àquelas com argila organofílica comercial empregada como padrão de comparação para este estudo. Os dados de DRX mostraram também que a fase cristalina do polipropileno foi alterada pela presença do agente compatibilizante. A morfologia das TPOs, conforme dados de microscopia eletrônica de varredura (MEV), foi afetada pela razão PP/EPDM, pela presença do compatibilizante orgânico e pelo tipo e teor de argila. As TPOs com proporção PP/EPDM de 90:10, não compatibilizadas com PP-g-MA e com teor de argilas de 3 pcr apresentaram superfícies de fratura criogênica isentas de vazios. Para estas TPOs quatro das cinco argilas organofílicas estudadas atuaram como compatibilizantes para as misturas PP/EPDM favorecendo a forte interação entre fases, o que resultou no aumento da resistência à tração da referida TPO. Da mesma forma que a argila comercial, três das quatro argilas organofílicas v preparadas com tecnologia local foram efetivas em compatibilizar e, consequentemente, em aumentar a resistência mecânica em tração da TPO PP/EPDM 90:10, quando empregadas no teor de 3 pcr. Isto indica que é possível utilizar argilas organofílicas em substituição de compatibilizantes orgânicos (poliméricos ou oligoméricos) para aumentar a interação interfacial entre PP e EPDM. O PP-g-MA e as argilas organofílicas (independente do tipo e do teor) não favoreceram a compatibilização da TPO PP/EPDM 70:30; por esta razão as propriedades de resistência à tração destas foram inferiores aos da TPO sem argila ou sem compatibilizante orgânico. / In this work nanocomposites based on a thermoplastic olefin (TPO) formed by blending polypropylene (PP), ethylene-propylene-diene (EPDM), and organoclay were prepared by melt intercalation process. The TPOs, non-compatibilized and compatibilized with PP modified with maleic anhydride (PP-g-MA), were prepared in a laboratory internal mixer, employing two ratios PP/EPDM: 90:10 and 70:30. To these blends, five types of organoclay were incorporated, in amounts of 1, 3 and 5 phr. The influence of PP/EPDM ratio, the presence of organic compatibilizer (PP-g-MA), and the type and amount of clay in the morphology and tensile mechanical properties of theTPO was evaluated. The results obtained by X-ray diffractometry (XRD) suggest that the addition of organoclays, regardless of type, result in the formation of nanocomposites, possible disorderly sandwiched structures, and that the organoclays prepared with local technology showed similar results to those with commercial organoclay, employed as a standard of comparison in this study. The XRD data also showed that the crystalline phase of polypropylene was modified by the presence of coupling agent. The morphology of the TPO, as electron microscopy (SEM) data shows, was affected by the ratio PP/EPDM, the presence of organic compatibilizer, and the type and content of organoclay. The TPO with a proportion PP/EPDM 90:10, not compatibilized, and with 3 phr clay showed void-fee cryogenic fracture surfaces. For this TPO, four of the five organoclays studied acted as compatibilizers for the PP/EPDM mixture, favoring the strong interaction between phases, which resulted in increasing tensile strength. Similar to the commercial clay, three of the four organoclays prepared with local technology were effective as blend compatibilizers and increased the mechanical strength of the composite PP/EPDM 90:10 with 3 phr organoclay content. These findings suggest that organoclays may replace organic compatibilizers (polymeric or oligomeric) to increase the interfacial interaction vii between PP and EPDM. The PP-g-MA and organoclay (regardless of the type and content) did not favor promoted strong PP/EPDM interactions in 70:30 blend; for this reasons, tensile strength was lower than those of TPO without clay or organic without compatibilizer.

Neste trabalho, inicialmente, foram obtidos TPSs (amidos termoplásticos) com diferentes concentrações de amido e plastificantes, por processamento em câmara de mistura, com o objetivo de determinar formulações para estudo em extrusora reativa. As formulações de TPS que apresentaram os melhores resultados de torque reométrico foram as que continham 39%m/m de amido. Investigou-se a influência da velocidade da rosca na obtenção de TPS por extrusora reativa, e os resultados mostraram que este parâmetro teve pequena influência na estabilidade do amido termoplástico, sendo possível utilizar 150 rpm de rotação. Foram produzidas 5 blendas com razões de TPS:PEBDL variando de 30:70; 40:60; 50;50; 60:40 e 70:30 para o desenvolvimento de um sistema ligante para a injeção de alumina pelo processo de moldagem de pós (MPI), a partir das quais foi possível analisar a influência do TPS no PEBDL, através de análises de MEV, IF, TGA, DMA e propriedades mecânicas. Quanto maior a concentração de TPS nas blendas, mais heterogênea foi a morfologia observada por MEV e menor o módulo de armazenamento e de perda obtidos por DMA. Este comportamento foi similar ao encontrado pela análise de resistência à tração, que apresentou propriedades mecânicas pobres para elevadas concentrações de TPS. Foram escolhidas três blendas para testar como veículo orgânico em feedstocks de alumina, com carga de partícula sólida de 45%, 50% e 55%v/v de Al2O3. A carga crítica para o sistema ligante-partículas sólidas determinada por reometria de torque foi de 50%v/v de alumina. / In this work, TPSs (thermoplastic starch), with different concentrations of starch and plasticizers for processing in the mixing chamber, were obtained in order to determine formulations for study in a reactive extruder. The TPS formulations that showed the best results for the rheometric torque were those containing 39% w/w starch. The influence of the screw speed to obtain TPS in the reactive extruder was investigated and the results showed that this parameter had little influence on the stability of the thermoplastic starch, allowing the use of 150 rpm rotation speed. Five blends were produced, with TPS:LLDPE ratios of 30:70; 40:60; 50:50; 60:40 and 70:30, to develop a binder for alumina injection by the powder molding process (MPI). From these five systems it was possible to analyze the influence of TPS in LLDPE through SEM analyzes, MFI, TGA, DMA and mechanical properties. The higher the concentration of TPS in blends, more heterogeneous morphology was observed by SEM and the lowest storage and loss modulus were obtained by DMA. This behavior was similar to that found by analysis of tensile strength, which showed poor mechanical properties for high concentrations of TPS. Three blends were chosen for testing as an organic vehicle in alumina feedstocks, with solid particles load of 45%, 50% and 55% v/v of Al2O3. The critical load for the system binder-solid particles, determined by torque rheometry, was 50% v/v of alumina.

A preocupação com a saúde tem levado ao uso de produtos com propriedades antimicrobianas, visando reduzir a proliferação de micro-organismos patogênicos. Ao mesmo tempo em que aditivos antimicrobianos são benéficos, pois reduzem a transmissão de doenças, os efeitos negativos, ainda, não estão bem elucidados. Estes aditivos podem afetar organismos essenciais ao meio ambiente e no desenvolvimento de plantas de interesse agrícola. Este trabalho tem o objetivo de avaliar o impacto ambiental causado por resíduos de elastômeros termoplásticos aditivados com três antimicrobianos comerciais à base de prata e pelos aditivos puros: (1) nanopartículas de prata adsorvida em sílica pirogênica (AgNp_sílica); (2) bentonita organomodificada com prata (Ag+_bentonita) e (3) prata em vidro fosfato (Ag+_fosfato). Os aditivos foram incorporados em uma formulação de composto termoplástico, a base de copolímero em bloco estireno-etileno/butileno-estireno (SESB), polipropileno (PP) e óleo mineral por mistura no estado fundido em extrusora dupla rosca e moldados por injeção. Os aditivos foram caracterizados por tamanho, forma e composição com o objetivo de avaliar a influência destas características nas seguintes propriedades do composto: mecânicas, térmicas, químicas, físicas, morfológicas e antimicrobianas. Além disso, foram avaliadas a variação na degradação abiótica e biótica dos compostos termoplásticos. A influência na degradação abiótica e a consequente redução de vida útil dos compostos foram avaliadas pelo ensaio de intemperismo. Já para a avaliação do impacto no solo foi realizado ensaio de biodegradação em câmara respirométrica (degradação biótica) e germinação de plantas no solo contendo os aditivos. O microcrustáceo aquático Daphnia magna (D. magna) foi utilizado como bioindicador de toxicidade dos aditivos na água. Os resultados indicam que compostos com AgNp_sílica possuem melhor propriedade antibacteriana que os demais aditivos testados, eliminando mais de 95% da população de Escherichia coli e 80% da população de Staphylococcus aureus após 24 horas de contato. A incorporação dos aditivos teve pouco efeito sobre as propriedades mecânicas, térmicas, químicas, físicas e morfológicas dos compostos. Os compostos aditivados e sem aditivo não apresentaram diferença no ensaio de intemperismo. No ensaio respirométrico, as amostras aditivadas tiveram pouca variação na produção de gás carbônico em comparação ao composto padrão. No teste de toxicidade em água com D. magna, houve mortalidade de todos os organismos, mesmo na concentração de 0,0001 mg L-1 de aditivo. No ensaio de germinação, os resultados foram adversos, não possibilitando estabelecer um padrão de toxicidade. Por fim, conclui-se que com o manejo adequado dos resíduos, compostos termoplásticos antimicrobianos são ambientalmente seguros, além de auxiliar no controle da propagação de doenças. / The concern with health has led to the use of products with antimicrobial properties aiming to reduce the proliferation of pathogenic microorganisms. At the same time that antimicrobial additives are useful to reduce the transmission of disease, adverse effects under human and environmental health still not well understood. These additives can affect organisms essential to the environment and plant development. The objective of this work was to evaluate the environmental impact caused by residues from thermoplastic elastomers (TPE) containing three commercial, silver-based antimicrobial additives and the pure additives. The additives tested were: (1) silver nanoparticles adsorbed on fumed silica (AgNp_silica); (2) bentonite organomodified with silver (Ag+_bentonite) and (3) silver phosphate glass (Ag+_phosphate). The additives were incorporated into a thermoplastic compound formulation, based on styrene-ethylene/butylene-styrene block copolymer (SESB), polypropylene (PP) and mineral oil by melt-blend in a twinscrew extruder and injection molded. A non loaded sample (standard) was used as control. The additives were characterized according to their size, shape and composition to evaluate the influence of these characteristics on the properties of the compound (mechanical, thermal, chemical, physical, morphological and antimicrobial). The influence on the abiotic degradation and consequent reduction in the life cycle of the compounds was evaluated by weathering test. To evaluate the impact of loaded TPE in soil, a soil biodegradation test was carried out in a respiratory chamber (biotic degradation) and germination of plants. The aquatic microcrustacean Daphnia magna (D. magna) was used as a bioindicator of toxicity of the additives in water. The results indicate that AgNp_silica compounds have better antibacterial properties than the other additives tested, eliminating more than 95% of the Escherichia coli population and 80% of the Staphylococcus aureus population after 24 h of contact. The incorporation of the additives had little effect on the mechanical, thermal, chemical, physical and morphological properties of the compounds. The results indicated that the additives presented a moderate effect on the properties of the above-mentioned metal loaded TPE compounds. The loaded and standard samples showed no difference in the weathering tests. In the respirometric assay, loaded samples had little variation in the production of carbon dioxide compared to the standard one. In the D. magna assay, there was mortality of all organisms, even at the concentration of 0.0001 mg L-1 of additive. In the germination test, the results were inconsistent and it was not possible to determine the toxicity potential of the additives tested. Lastly, it is possible to conclude that, taking into account the correct final disposition of TPE residues; thermoplastic compounds are environmentally safe and can assist in the control of diseases.

Ce travail porte sur la détection de l’endommagement de matériaux composites. Une première partie concerne l’élaboration de méthodes permettant d’estimer les termes sources de chaleur d’un matériau sollicité mécaniquement. Lors de ce processus, un ensemble de défauts mécaniques mènent à des productions de chaleur. La détection des sources peut permettre la détection de ces défauts. Deux principales méthodes sont présentées : une méthode dite « directe » basée sur une discrétisation du champ de température mesuré et une méthode « itérative » basée sur la méthode du gradient conjugué. A ces méthodes sont couplées des techniques de filtrages des données comme la SVD. Les équations sont résolues par différences finies sous leur forme linéaire. Des modifications sont apportées à l’algorithme itératif pour améliorer sa convergence ainsi que les résultats. Les problématiques envisagées font partie des problèmes inverses en thermique. L’objectif de la première partie est de trouver un lien entre l’apparition de macro-fissure et la localisation de termes sources de chaleur au sein d’un matériau composite. La seconde partie consiste à élaborer des méthodes d’estimation des diffusivités thermiques directionnelles. Les méthodes reposent sur une modélisation du transfert de chaleur à l’aide des quadripôles thermiques. Les estimations de paramètres sont réalisées sur des zones ciblées à risque sur un matériau déjà endommagé. Le but est de faire le lien entre un endommagement mécanique connu diffus et une dégradation des propriétés thermiques. Ce manuscrit est présenté en deux parties : une partie de validation des méthodes. Une partie expérimentale où sont analysés les composites. / This work deals with the damage detection of composite materials. These materials are used in the aeronautics industry. The first part concerns the development of methods to estimate the heat sources terms of a stressed material. During this process, a set of mechanical defects leads to heat productions. The sources detection can conduct to the detection of these defects. Two main methods are presented: a "direct" method based on a discretization of the measured temperature field and an "iterative" method based on the conjugate gradient method. These methods are coupled with data filtering techniques such as SVD. In order to optimize computation time, equations are solved by finite differences in their linear form. Modifications are also made for the iterative algorithm to improve its convergence as well as the results of the estimation. These problems are considered as thermal inverse problems. The main objective of the first part is to find an experimental link between the appearance of a macro fissure and the localization of a heat source term within a composite material. The second part consists in the elaboration of methods for estimating thermal directional diffusivities. The methods are based on a modeling of heat transfer using thermal quadrupoles. Parameter estimations are made on targeted "risked" areas on a material, which is already damaged but not under stress. The aim is to link a known mechanical damage, which is called "diffuse" to thermal properties degradation in the main directions. This manuscript is presented in two parts: a validation part of the methods, and an experimental part in which composites are analyzed.

Un des objectifs majeurs de la neuroimagerie moderne est l'identification de nouveaux marqueurs qui puissent aider au diagnostic et au suivi des pathologies neurologiques. L'imagerie par résonnance magnétique multimodale (IRMm) est une approche permettant l'évaluation de plusieurs biomarqueurs complémentaires au cours d'un seul examen d'IRM. Cette approche a montré son efficacité dans de nombreuses études récentes et notamment dans la maladie de Parkinson. A l'approche IRMm précédemment utilisée, nous avons introduit un nouveau biomarqueur i.e. les changements de forme des structures sous-corticales à partir d'images pondérées en T1. Ce dernier marqueur vient enrichir l'approche IRMm composée de la quantification de : (i) la volumétrie à partir d'images pondérées en T1 (ii) de l'intégrité et l'orientation microstructurales à partir des images pondérées en diffusion et (iii) des dépôts de métaux à partir de la relaxométrie T2*. Nous avons appliqué l'approche IRM multimodale à une autre maladie neurodégénérative, la maladie d'Alzheimer à un stade précoce. Les résultats de cette étude préliminaire nous ont permis de suggérer la présence de processus physiopathologiques différents à la phase prodromique de la maladie d'Alzheimer. En effet nous avons observé pour l'hippocampe et l'amygdale une atrophie avec modification de l'intégrité microstructurale alors que seule une atrophie a été observée pour le thalamus et le putamen. Ces résultats nous ont aussi permis de confirmer l'importance d'une approche multimodale pour les études portant sur les maladies neurodégénératives. Parmi les marqueurs de l'IRMm, la quantification du fer intracérébral par relaxométrie T2* est une des méthodes qui a été développé ces dernières années à l'unité Inserm U825. Le dérèglement du métabolisme du fer et son accumulation sont en effet impliqués dans la physiopathologie de nombreuses maladies neurodégénératives telles que la maladie de Parkinson. L'expérience acquise à travers les différentes validations cliniques de cette méthode ces dernières années nous a conduit à améliorer cette dernière. Nous avons dirigé nos travaux sur l'amélioration de la méthode de relaxométrie R2* en optimisant l'acquisition d'une part et le traitement des images d'autre part. Nous avons donc comparé différentes résolutions, antennes, facteurs d'accélération, et nombres d'acquisitions par temps d'écho afin de déterminer les paramètres permettant d'obtenir le plus haut rapport signal sur bruit. Pour la partie traitement des images nous avons comparé la méthode utilisée comme référence, la méthode des moindres carrés par algorithme de Levenberg-Marquardt, à une autre méthode, la décomposition en valeur singulière pour estimer avec le plus de justesse le taux relaxation R2*. Nous avons ainsi pu mettre au point une séquence de relaxométrie T2* optimisée que nous avons comparé à celle utilisée lors de la première étude, dans le modèle du vieillissement physiologique. Au final en plus de permettre la discrimination entre sujets âgés et jeunes, les résultats obtenus avec cette nouvelle séquence se sont révélés être beaucoup moins sensibles au bruit. / One of the main goals of modern neuroimaging is the identification of new markers that can help in the diagnosis and monitoring of neurological pathologies. Multimodal magnetic resonance imaging (MRIm), is an approach allowing the evaluation of several complementary biomarkers within one MRI. This approach has already demonstrated its efficiency in several recent studies, and in particular in Parkinson's disease. We added a new biomarker to the MRIm approach previously used i.e. shape changes of subcortical structures based on T1 images. This marker is now a part of our MRIm approach along with: (i) volumetry from T1 images, (ii) microstructural integrity and orientation from diffusion images and (iii) metal deposits from T2* relaxometry. We applied this multimodal MRI approach to an other neurodegenerative disease, the Alzheimer's disease at a prodromal stage. Results of this preliminary study gave us the opportunity to suggest the existence of two different physiopathological processes at the prodromal phase of the Alzheimer's disease. In fact we observed atrophy with modification of the microstructural integrity for the hippocampus and the amygdala, while only atrophy has been observed for the thalamus and the putamen. Those results also confirmed the necessity of studying neurodegenerative diseases in a multimodal way. Among MRIm markers, the T2* relaxometry for the quantification of intracerebral iron is one of the methods which has been developed lately at the Inserm U825. Dysregulation of iron metabolism and its accumulation are involved in the physiopathology of several neurodegenerative diseases like Parkinson's disease. The experience gained through the different clinical validation of this method in recent years has led us to improve it. Our work was to improve T2* relaxometry by optimizing the acquisition of the images on one hand, and the processing of the images on the other hand. We compared several resolutions, acquisition antennas, number of acquisition by echo time, to determine which parameters gave the higher signal to noise ratio. For the part about the process of the images, we compared the method used as a reference, the least square method using a Levenberg-Marquard algorithm, to an other method, the singular value decomposition to obtain the best estimation of the relaxation rate R2*. Then we were able to develop an optimized T2* relaxometry sequence, which we compared to the one used in the first study, but in the physiological ageing model. Finally in addition to allowing discrimination between elderly and young people, the results obtained with this new sequence were found to be much less sensitive to noise.

A preocupação com a saúde tem levado ao uso de produtos com propriedades antimicrobianas, visando reduzir a proliferação de micro-organismos patogênicos. Ao mesmo tempo em que aditivos antimicrobianos são benéficos, pois reduzem a transmissão de doenças, os efeitos negativos, ainda, não estão bem elucidados. Estes aditivos podem afetar organismos essenciais ao meio ambiente e no desenvolvimento de plantas de interesse agrícola. Este trabalho tem o objetivo de avaliar o impacto ambiental causado por resíduos de elastômeros termoplásticos aditivados com três antimicrobianos comerciais à base de prata e pelos aditivos puros: (1) nanopartículas de prata adsorvida em sílica pirogênica (AgNp_sílica); (2) bentonita organomodificada com prata (Ag+_bentonita) e (3) prata em vidro fosfato (Ag+_fosfato). Os aditivos foram incorporados em uma formulação de composto termoplástico, a base de copolímero em bloco estireno-etileno/butileno-estireno (SESB), polipropileno (PP) e óleo mineral por mistura no estado fundido em extrusora dupla rosca e moldados por injeção. Os aditivos foram caracterizados por tamanho, forma e composição com o objetivo de avaliar a influência destas características nas seguintes propriedades do composto: mecânicas, térmicas, químicas, físicas, morfológicas e antimicrobianas. Além disso, foram avaliadas a variação na degradação abiótica e biótica dos compostos termoplásticos. A influência na degradação abiótica e a consequente redução de vida útil dos compostos foram avaliadas pelo ensaio de intemperismo. Já para a avaliação do impacto no solo foi realizado ensaio de biodegradação em câmara respirométrica (degradação biótica) e germinação de plantas no solo contendo os aditivos. O microcrustáceo aquático Daphnia magna (D. magna) foi utilizado como bioindicador de toxicidade dos aditivos na água. Os resultados indicam que compostos com AgNp_sílica possuem melhor propriedade antibacteriana que os demais aditivos testados, eliminando mais de 95% da população de Escherichia coli e 80% da população de Staphylococcus aureus após 24 horas de contato. A incorporação dos aditivos teve pouco efeito sobre as propriedades mecânicas, térmicas, químicas, físicas e morfológicas dos compostos. Os compostos aditivados e sem aditivo não apresentaram diferença no ensaio de intemperismo. No ensaio respirométrico, as amostras aditivadas tiveram pouca variação na produção de gás carbônico em comparação ao composto padrão. No teste de toxicidade em água com D. magna, houve mortalidade de todos os organismos, mesmo na concentração de 0,0001 mg L-1 de aditivo. No ensaio de germinação, os resultados foram adversos, não possibilitando estabelecer um padrão de toxicidade. Por fim, conclui-se que com o manejo adequado dos resíduos, compostos termoplásticos antimicrobianos são ambientalmente seguros, além de auxiliar no controle da propagação de doenças. / The concern with health has led to the use of products with antimicrobial properties aiming to reduce the proliferation of pathogenic microorganisms. At the same time that antimicrobial additives are useful to reduce the transmission of disease, adverse effects under human and environmental health still not well understood. These additives can affect organisms essential to the environment and plant development. The objective of this work was to evaluate the environmental impact caused by residues from thermoplastic elastomers (TPE) containing three commercial, silver-based antimicrobial additives and the pure additives. The additives tested were: (1) silver nanoparticles adsorbed on fumed silica (AgNp_silica); (2) bentonite organomodified with silver (Ag+_bentonite) and (3) silver phosphate glass (Ag+_phosphate). The additives were incorporated into a thermoplastic compound formulation, based on styrene-ethylene/butylene-styrene block copolymer (SESB), polypropylene (PP) and mineral oil by melt-blend in a twinscrew extruder and injection molded. A non loaded sample (standard) was used as control. The additives were characterized according to their size, shape and composition to evaluate the influence of these characteristics on the properties of the compound (mechanical, thermal, chemical, physical, morphological and antimicrobial). The influence on the abiotic degradation and consequent reduction in the life cycle of the compounds was evaluated by weathering test. To evaluate the impact of loaded TPE in soil, a soil biodegradation test was carried out in a respiratory chamber (biotic degradation) and germination of plants. The aquatic microcrustacean Daphnia magna (D. magna) was used as a bioindicator of toxicity of the additives in water. The results indicate that AgNp_silica compounds have better antibacterial properties than the other additives tested, eliminating more than 95% of the Escherichia coli population and 80% of the Staphylococcus aureus population after 24 h of contact. The incorporation of the additives had little effect on the mechanical, thermal, chemical, physical and morphological properties of the compounds. The results indicated that the additives presented a moderate effect on the properties of the above-mentioned metal loaded TPE compounds. The loaded and standard samples showed no difference in the weathering tests. In the respirometric assay, loaded samples had little variation in the production of carbon dioxide compared to the standard one. In the D. magna assay, there was mortality of all organisms, even at the concentration of 0.0001 mg L-1 of additive. In the germination test, the results were inconsistent and it was not possible to determine the toxicity potential of the additives tested. Lastly, it is possible to conclude that, taking into account the correct final disposition of TPE residues; thermoplastic compounds are environmentally safe and can assist in the control of diseases.

Neste trabalho, inicialmente, foram obtidos TPSs (amidos termoplásticos) com diferentes concentrações de amido e plastificantes, por processamento em câmara de mistura, com o objetivo de determinar formulações para estudo em extrusora reativa. As formulações de TPS que apresentaram os melhores resultados de torque reométrico foram as que continham 39%m/m de amido. Investigou-se a influência da velocidade da rosca na obtenção de TPS por extrusora reativa, e os resultados mostraram que este parâmetro teve pequena influência na estabilidade do amido termoplástico, sendo possível utilizar 150 rpm de rotação. Foram produzidas 5 blendas com razões de TPS:PEBDL variando de 30:70; 40:60; 50;50; 60:40 e 70:30 para o desenvolvimento de um sistema ligante para a injeção de alumina pelo processo de moldagem de pós (MPI), a partir das quais foi possível analisar a influência do TPS no PEBDL, através de análises de MEV, IF, TGA, DMA e propriedades mecânicas. Quanto maior a concentração de TPS nas blendas, mais heterogênea foi a morfologia observada por MEV e menor o módulo de armazenamento e de perda obtidos por DMA. Este comportamento foi similar ao encontrado pela análise de resistência à tração, que apresentou propriedades mecânicas pobres para elevadas concentrações de TPS. Foram escolhidas três blendas para testar como veículo orgânico em feedstocks de alumina, com carga de partícula sólida de 45%, 50% e 55%v/v de Al2O3. A carga crítica para o sistema ligante-partículas sólidas determinada por reometria de torque foi de 50%v/v de alumina. / In this work, TPSs (thermoplastic starch), with different concentrations of starch and plasticizers for processing in the mixing chamber, were obtained in order to determine formulations for study in a reactive extruder. The TPS formulations that showed the best results for the rheometric torque were those containing 39% w/w starch. The influence of the screw speed to obtain TPS in the reactive extruder was investigated and the results showed that this parameter had little influence on the stability of the thermoplastic starch, allowing the use of 150 rpm rotation speed. Five blends were produced, with TPS:LLDPE ratios of 30:70; 40:60; 50:50; 60:40 and 70:30, to develop a binder for alumina injection by the powder molding process (MPI). From these five systems it was possible to analyze the influence of TPS in LLDPE through SEM analyzes, MFI, TGA, DMA and mechanical properties. The higher the concentration of TPS in blends, more heterogeneous morphology was observed by SEM and the lowest storage and loss modulus were obtained by DMA. This behavior was similar to that found by analysis of tensile strength, which showed poor mechanical properties for high concentrations of TPS. Three blends were chosen for testing as an organic vehicle in alumina feedstocks, with solid particles load of 45%, 50% and 55% v/v of Al2O3. The critical load for the system binder-solid particles, determined by torque rheometry, was 50% v/v of alumina.

Prof. Dr. Derval dos Santos Rosa / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, 2016. / A grande quantidade de resíduos provenientes da agroindústria que são descartados no meio ambiente tem despertado o interesse de pesquisadores que os veem como fonte de matéria prima para aplicações em diversas áreas da ciência, como por exemplo a utilização como reforço de compósitos poliméricos biodegradáveis. Devido ao alto teor de celulose contido nesses resíduos, com várias formas de processamento e tamanho de partícula, é viável o estudo de novas metodologias de obtenção de nanocristais de celulose (CNC). Estes são muito versáteis nas diferentes aplicações em nanocompósitos. O desenvolvimento de metodologia de obtenção de CNC será o foco deste estudo, onde buscará obter partículas com dimensões em escala nanométrica. Os resíduos de folha de bananeira e palha de milho foram utilizados como matéria-prima do estudo. Inicialmente os resíduos foram submetidos ao processo 1, com apenas uma etapa de cada tratamento químico (mercerização, branqueamento e hidrólise) e diferentes concentrações de ácido sulfúrico (H2SO4) na hidrólise final, onde verificou-se a necessidade de melhorias nesse processo, gerando o processo 2, com várias etapas de branqueamento para cada resíduo e apenas uma concentração de H2SO4. Após todos os processos de tratamento aos quais foram submetidos, os cristais foram caracterizados por meio de análise de espectroscopia na região do infravermelho com transformada de Fourier (FTIR), análise termogravimétrica e sua derivada (TGA e DTG), difração de raio-X (DRX), determinação de teores de celulose, hemicelulose e lignina, microscopia eletrônica de varredura (MEV), espalhamento de luz dinâmico (DLS) e microscopia de força atômica (AFM), buscando verificar as suas composições, índice de cristalinidade, sua morfologia e o tamanho das partículas obtidas. Os resultados obtidos no processo 1, foram essenciais para a determinação da concentração de 30% v/v para a hidrólise ácida. Através dos resultados obtidos no processo 2, observou-se que a extração de hemicelulose e lignina foi mais eficaz com o segundo processo aplicado, assim como o uso de partículas virgens em tamanho milimétrico melhorou a ação dos tratamentos químicos. Os cristais de celulose obtidos apresentaram tamanho de partícula em escala nanométrica, embora a metodologia tenha se mostrado inviável para a aplicação em folha de bananeira, visto que há a necessidade de mais etapas de tratamento, gerando muito resíduo de processo. / The large amount of waste from the agricultural industry that discarded in the environment has aroused the researchers interest on it as a source of raw materials for applications on a wide science fields, for example, the use as biodegradable polymer composites reinforcement. Due to the high cellulose content contained in these residues, with various processing forms and particle sizes, is viable the cellulose nanocrystals (CNC). These are very versatile in the different applications in nanocomposites. The development of CNC obtaining methodology will be the focus of this study, which will seek to obtain particles with dimensions on the nanoscale. The banana leaf and corn stover residues used as raw materials of this study. Initially the waste subjected to process 1, with one stage for each treatment (mercerizing, bleaching and hydrolysis) and different concentrations of sulfuric acid (H2SO4) in the final hydrolysis, where there is a need for improvements in the process, generating the process 2, with various bleaching stages for each residue and only a concentration of H2SO4. After all treatment processes to which it was subjected, the crystals were characterized by the Fourier Transform Infrared Spectroscopy Analysis (FTIR), Thermogravimetric Analysis and its derived (TGA e DTG), X-ray Diffraction (XRD), determining of cellulose, hemicellulose and lignin, Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS) and Atomic Force Microscopy (AFM), seeking to verify their compositions, crystallinity index, morphology and size of the particles obtained. The results obtained in process 1, were essential for determining the concentration of 30% v/v to acid hydrolysis. By the results obtained in process 2, it observed that the hemicellulose and lignin extraction was more effective in the second process as well as the use of virgin particles millimeter size improved the action of chemical treatments. The obtained cellulose crystals had particle size in the nano-scale, although the method has proved impracticable for use in banana leaves, since there is the need for further processing steps, generating a lot of waste process.

Plate-out is defined, in the context of this research, as a hard deposit that can be found adhered to the surface of screw, barrel and die resulting in the loss of output performance and ultimate extrude quality. It is typically is seen as a coloured deposit, ranging from white through to brown that can occur at any time in the process. Plate-out occurs randomly with SantopreneTM TPV products within a manufactured lot, or from lot-to-lot without any changes to the base formulation or manufacturing procedures or practices. The aim of the research was firstly to understand the influences of various elements of the extrusion process and any interactions on the formation of plate-out. The second aspect of the research was to investigate whether deposited plate-out had in itself any form and structure. Two experimental routes were taken. The first was a university based small scale laboratory extrusion study; the second complementary approach was industrially based; involving the ExxonMobil Newport manufacturing plant supported by the company analytical laboratories based in Brussels. The programme of work explicitly excluded in depth analysis of the chemistry involved in the manufacture of SantopreneTM TPV, this remaining proprietary to the company. The results of the study of the effects of the processing variables conclude that plate-out formation is complex and no single variable removed or reduced it. With a combination of lower process temperature, longer residence times and higher melt compression there is an increased likelihood that plate-out will form. For the film type deposit which contains novolac resin and zinc chloride, the onset of migration of these materials is seen to occur in the transition zone. This is believed to be the tie-layer precursor to plate-out deposition further along the screw. Two types of plate-out were identified, a powdery deposit and a film deposit. Both contained clay filler, stannous chloride, zinc oxide but the film deposit also contained traces of novolac resin and zinc chloride. The plate-out was confirmed to have its own distinct cross sectional structure.