abstract: Natural rubber and rubber products can be produced from the guayule plant (Parthenium argentatum Gray), which is a low input perennial shrub native to Mexico and the American Southwest. Guayule rubber has the potential to replace Hevea (Hevea brasiliensis) rubber, the most common natural rubber, and synthetic rubber, which is derived from petroleum, in a wide variety of products, including automobile tires. Rubbers make up approximately 47% of the analyzed conventional passenger tire's weight, with 31% from synthetic rubber and 16% from natural Hevea rubber. Replacing the current rubber sources used for the tire industry with guayule rubber could help reduce dependency on imported rubber in addition to reducing greenhouse gas emissions. Moreover, residues from guayule rubber are being researched as a bioenergy feedstock to further improve the environmental footprint of guayule rubber products. This study used life cycle assessment (LCA), a useful tool to determine environmental impacts from a product or process, to quantify and compare environmental impacts of the raw material extraction, transportation and manufacturing of a conventional and a guayule rubber based passenger tire. The impact results of this comparative LCA identified the major environmental impacts and contributing process and informed how the impacts from the tire production can be reduced through utilization of natural rubber co-products as electricity off-sets and reducing guayule rubber's environmental impacts through agricultural and transportation modifications. Results showed that tire raw material extraction contributed the majority of impacts in all categories, where the production of guayule rubber for guayule tires, and the production of synthetic rubber for conventional tires, were the main contributors. Guayule rubber impacts occurred mainly from electricity consumption for agricultural irrigation, while synthetic rubber is a petroleum-based material resulting in high impacts. Transportation impacts had little significance compared to other stages in the life cycle, except for smog impacts, which occurred mainly from truck transport for guayule tires, and transoceanic transport for conventional tires. Tire manufacturing impacts occurred mainly from electricity use in the facilities and were reduced with the use of guayule rubber in guayule tires. / Dissertation/Thesis / M.S. Civil and Environmental Engineering 2014

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A decomposição natural da borracha é muito lenta, devido às suas estruturas vulcanizadas serem extremamente reticuladas formando uma rede tridimensional, tornando o reprocessamento desse material extremamente difícil. O presente trabalho tem como principal objetivo o estudo da aplicação da radiação gama como forma de desvulcanização para a reciclagem/reaproveitamento. Foi avaliada a interação de elastômeros com a radiação ionizante de fonte gama investigando-se as alterações nas propriedades físico-químicas dos materiais. Foram utilizadas formulações de borracha NBR (copolímero de Acrilonitrila-Butadieno) e EPDM (terpolímero etileno-propileno-dieno), provenientes da indústria de borracha, reticuladas por mistura convencional à base de enxofre. Foram preparados master-batch com pó de borracha (refugo industrial) e borracha virgem. O material processado (master-batch) foi irradiado em fonte de 60Co nas doses de 50, 100, 150 kGy e taxa de dose de 5 kGy h-1, à temperatura ambiente. O material irradiado foi incorporado nas formulações clássicas à base de enxofre. As formulações foram caracterizadas por: espectroscopia no infravermelho (FTIR), análise térmica (TG e DTG), tensão na ruptura, alongamento na ruptura, dureza, resistência à abrasão, reometria e inchamento. Os resultados mostraram uma predominância de cisão de cadeia na dose de 50 kGy para a borracha EPDM. Para a borracha nitrílica foi observada a predominância de cisão de cadeia na dose de 100 kGy. Estes resultados mostram a possibilidade do uso da radiação gama para o reaproveitamento/reciclagem das borrachas EPDM e nitrílica. / The natural decomposition of rubber is a very slow process due to its three-dimensional network formed by vulcanized crosslinked structures becoming extremely difficult to reprocess this material. The present work aims to study the application of gamma irradiation as devulcanization process for material reuse/recycling. The interactions of elastomers with ionizing radiation of a gamma source were investigated and the changes in physicochemical properties of the materials were evaluated. Formulations of NBR (acrylonitrile - butadiene) and EPDM (ethylene - propylene - diene terpolymer) from the rubber industry were crosslinked by conventional sulfur-based mixing. Master - batch was processed with rubber powder (industrial waste) and virgin rubber. The raw material (master batch) was irradiated in 60Co source at doses of 50, 100, 150 kGy and dose rate of 5 kGy h-1 at room temperature. The irradiated material was incorporated in classical sulfur-based formulations. The formulations were characterized by: infrared spectroscopy (FTIR), thermal analysis (TG and DTG), tensile strength, elongation at break, hardness, abrasion resistance, rheometry and swelling. The results showed a predominance of chain scission at a dose of 50 kGy for EPDM rubber. For nitrile predominance of chain scission was observed at a dose of 100 kGy. These results show the possibility of the use of gamma radiation for the reuse/recycling of EPDM and nitrile rubbers.

O texto discute a formação do Acre durante o ciclo da borracha entre 1904 e 1945, fazendo uma análise da economia, política e das representações. O objetivo principal desse trabalho é analisar a inserção do Acre no contexto do ciclo da borracha, procurando assim contribuir para um debate historiográfico mais amplo sobre esse tema. O foco do trabalho são as empresas seringalistas, elaborando uma narrativa que enfoca a maior de todas elas na região, a N & Maia e Companhia. A tese defende que com a falência do ciclo da borracha a partir de 1910, as empresas seringalistas no Acre que souberam se adaptar a esse cenário de crise foram se consolidando como senhoras dos domínios econômicos, políticos e sociais da região. A tese é desenvolvida dividindo-se em três partes, que contextualizam esse cenário da seguinte maneira: a) uma primeira onde se discute como se formou a mão de obra dos seringais e consequentemente aquela capaz de gerar renda aos seringalistas; b) uma segunda onde elabora-se uma investigação sobre a constituição da cadeia de aviamento da borracha e como as empresas seringalistas conseguiram superar essa rede, que entrou em colapso a partir de 1910; c) a última parte debate com as formas de representação do Acre no período do ciclo da borracha, sendo uma delas oriunda de uma visão senhorial ancorada na opulência e outra que se caracteriza pelos registros de uma região precária e marginal perante o restante da Amazônia. / The paper discusses the formation of Acre during the rubber boom between 1904 and 1945, making an analysis of the economy, politics and representations. The main objective of this work is to analyze the insertion of Acre in the context of the rubber, thus seeking to contribute to broader historiographical debate on this topic. The focus of the work will be rubber companies, developing a narrative that focuses on the greatest of them all in the region, the N & Maia and Company. The thesis defend is that with the collapse of the rubber boom from 1910, the Acre rubber companies that were able to adapt to this crisis scenario were consolidated as Ladies domains economic, political and social area . For this thesis is proven text was divided into three parts, which contextualize this scenario as follows: a) a first part where he discusses how it formed the manpower of the rubber and that consequently able to generate income to seringalistas b ) a second where we undertake a research on the formation of the chain of dispensing as rubber and rubber companies were able to overcome this network, which collapsed from 1910 c) the last part discussion with the forms of representation of Acre during the rubber boom, one of them coming from a vision anchored in stately opulence and other records which is characterized by a region of poor and marginal to the rest of the Amazon.

Quando a cidade de Corumbá foi fundada no século XVIII demorou muito tempo para encontrar sua vocação econômica. Assim, dentro das referências revisadas para a elaboração deste trabalho desta tese, não houve constatação de uma vocação econômica específica que tenha relevância pelo menos até os 50 primeiros anos do século XIX, só a partir daí, é que a economia corumbaense teve um rumo, quando prevalece o comércio para a extração de excedente e na qual existe uma articulação devido à navegação e a comunicação com os portos principais da Bacia do Prata. Fato diferente ao acontecido com a cidade logo após o conflito bélico. A delimitação temporal estabelecida para este projeto de pesquisa obedece a alguns critérios adotados para sua definição. A delimitação inicial do período, 1870, se justifica em razão do fim da guerra da Tríplice Aliança, evento este que teve uma relevância marcante para esta região do Brasil, porque foi ocupada pelas tropas paraguaias deixando um rastro de destruição e desolação por toda Corumbá, isso ocorreu justamente no momento em que a cidade estava definindo a sua vocação econômica. Já a escolha do ano de 1914 se deve a alguns fatos como a chegada ao Pantanal a estrada de ferro Noroeste do Brasil, que à época se estendia até as margens do Rio Paraguai, a 70 quilômetros de Corumbá. O clima pantaneiro favorece uma adaptação à atividade pecuária, assim a introdução do gado no início do século XVIII, a atividade pecuária encontrou no sul de Mato Grosso as condições climáticas e ecológicas propícias à sua reprodução e proporcionou a fixação da população em torno das grandes fazendas de criação. Desta maneira, a grande parte riqueza desta parte do Mato Grosso foi o gado, base de sua economia no início do povoamento e também foi o fator de articulação da economia incipiente no Pantanal em Corumbá, quando a atividade agrícola ainda era restrita à zona litoral do país. Esta articulação consiste na ligação com outros setores econômicos. Desta forma, o setor primário consiste na própria exploração da atividade pecuária. No setor secundário estavam as charqueadas que, apesar de não apresentarem uma transformação completa da matéria-prima em outro produto, propiciam agregação de valor à carne. E no setor terciário, a distribuição dos produtos que se daria, num primeiro momento, pela via fluvial e mais adiante, pela ferroviária nos principais centros consumidores. Outros produtos passaram pelo porto corumbaense, mas o mais importante foi borracha, ambos comercializados tanto visando o mercado externo, assim como a importação de produtos para toda a região do Mato Grosso. / When the city of Corumba was founded in the 18th century, it took a long time for finding its economic vocation. Thus, among the references herein revised, we found no evidence of a specific and relevant vocation at least until the first 50 years of the 19th century. From that moment on, the corumbaense economy took a direction towards the commerce of the extractions, articulated by the navigation growth and the communication among the main harbors of the Prata river basin, what differs from what happened to the city right after the war. The temporal limits herein established followed some criteria and the starting point of 1870 was chosen for marking the end of the War of Triple Alliance, whose event was strongly relevant for this Brazilian region because the troops occupation of the territories brought together a trail of destruction and desolation all over Corumba city, what happened when the economic vocation was being chosen. The year of 1914 closed the period of research. It coincided with the arrival of the railroad Noroeste do Brasil [Northeast of Brazil], which, at that time, reached the margins of Paraguay river, 70 km away from Corumba. The pantanalian climate favored the adaptation of livestock activity, which dated the beginning of the 18th century, especially in south of the Mato Grosso state, whose climate and ecologic conditions were propitious to reproduction, proportioning the formation of a new villages around the big livestock farms. Thus, the great wealth of this part of the state was based on livestock, which was the basis of the economy during the population settlement and were the main economic factor of the in both Pantanal and Corumba regions in a period which the agriculture was still restricted to the coastal areas of Brazil,whose articulation was bonded to other economic sectors. Thus, the primary sector consisted on the livestock itself. The secondary sector was formed by the charqueadas [area destined to jerk beef maturation] which, although showed no modification on the raw materials, added financial value to the meat. The tertiary sector was the distribution of the products to consume centers, firstly done by waterways and later by railways. Other products were commercialized on corumbaense harbor the most important one was the rubber and their destination were both the foreign market and the importation around Mato Grosso state.

Orientador: Carlos Henrique Daros / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-23T13:53:37Z (GMT). No. of bitstreams: 1 Borges_RicardoVendrame_M.pdf: 7836020 bytes, checksum: 6416c1d8724fe2108b090c71bec11800 (MD5) Previous issue date: 2013 / Resumo: A presente dissertação concentra-se no estudo da elasticidade não-linear através do Método dos Elementos de Contorno. A elasticidade não-linear possui um importante campo de aplicações, da simulação de materiais que se comportam como a borracha a novas aplicações como a simulação de tecidos biológicos. A dissertação apresenta como resultado principal a elaboração de um código computacional em Matlab ®, o qual é capaz de modelar materiais elásticos, não-lineares, sujeitos à deformações não-lineares, incrementais. O programa de elementos de contorno foi utilizado na simulação da resposta quasi-estática em materiais incompressíveis como a borracha, aproximados através do modelo constitutivo de Mooney-Rivlin / Abstract: The present work focuses on the modelling of non-linear elastic problems via the Boundary Element Method. Non-linear elasticity has several important applications, from the modelling of rubber-like materials to new areas of research such as the study of biological tissues. The work's main result is the construction of a computer code (in Matlab ®) which can model non-linear elastic materials subjected to incremental non-linear deformations. The code was used within the realm of quasi-static simulations of incompressible rubber-like materials, approximated via the Mooney-Rivlin constitutive model / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestra em Engenharia Mecânica

Doctorat en sciences sociales, politiques et économiques / info:eu-repo/semantics/nonPublished

Gummiwerkstoffe zeigen unter Belastung ein hochkomplexes Verhalten. Besonders markant sind dabei die von der Belastungsgeschichte und Belastungsrichtung abhängigen Entfestigungseffekte. Für die Entwicklung zuverlässiger und optimierter Produkte aus Gummi ist ein vertieftes Verständnis dieser Eigenschaften essentiell. Sie lassen sich aber nur schwer mit den Eigenschaften der bei der Herstellung des Werkstoffs verwendeten Grundkomponenten in Zusammenhang bringen. Die genauen Vorgänge auf molekularer Ebene, die zu dem typischen Materialverhalten führen, sind unbekannt. In der Arbeit wird als Erklärungsansatz die von Ihlemann entwickelte Theorie selbstorganisierender Bindungsmuster untersucht. Die zentrale These der Theorie besagt, dass sich unter Deformation infolge eines Selbstorganisationsprozesses eine inhomogene Verteilung schwacher physikalischer Bindungen im Material einstellt. Dieses Bindungsmuster verändert sich mit dem Deformationsvorgang und stellt damit das Gedächtnis des Materials dar. In der Arbeit werden zunächst allgemeine Aspekte selbstorganisierender Systeme untersucht und die Theorie anschließend unter diesen Aspekten analysiert. Außerdem wird der Erklärungsansatz geeignet erweitert und demonstriert, dass sich auch neue messtechnische Befunde damit problemlos erklären lassen. Insgesamt wird gezeigt, dass die Theorie selbstorganisierender Bindungsmuster als überzeugende Begründung für eine Vielzahl beobachteter Eigenschaften von Gummiwerkstoff geeignet ist. Um die Theorie zu testen, wurde ein Simulationsprogramm erstellt. Es verwendet eine starke Abstraktion der Molekularstruktur von gefülltem Gummiwerkstoff. Die einzelnen Modellelemente wurden dabei so einfach wie möglich gehalten. Sie sind alle elastisch, es existiert aber eine Regel zum dynamischen Einfügen und Entfernen der physikalischen Bindungen. Daher können alle inelastischen Eigenschaften des Modells direkt mit einer Veränderung der Bindungsstruktur assoziiert werden. Es werden Verfahren vorgestellt, mit denen die zeitliche und deformationsabhängige Evolution des Modellzustands verfolgt werden kann. Damit werden die Abläufe von Messungen nachgebildet. Die Resultate der Simulation werden mit den Messergebnissen verglichen. Dabei zeigt sich, dass mit dem Programm eine Vielzahl typischer inelastischer Eigenschaften von gefülltem Gummiwerkstoff reproduziert werden kann. Dieses Resultat ist bemerkenswert, weil keines der Grundelemente des Modells diese Eigenschaften aufweist. Eine Analyse des Modells zeigt eindeutig, dass das Modellverhalten auf einem Selbstorganisationsvorgang des Modellelements, welches die physikalischen Bindungen repräsentiert, basiert. Der Selbstorganisationsvorgang verläuft genau so, wie von der Theorie vorhergesagt. Die erstaunliche Ähnlichkeit zum Materialverhalten und die geringe Anzahl von getroffenen Annahmen ist ein starkes Indiz dafür, dass in Gummiwerkstoff ebenfalls ein solcher Selbstorganisationsprozess abläuft und das Materialverhalten maßgeblich beeinflusst. / Filled rubber material exhibits a complex behavior in mechanical testing. Especially characteristic is a softening of the material depending on direction and history of loading. For the development of reliable and optimized products deep knowledge about these properties is essential. They are, however, difficult to connect to the properties of the employed molecular components. Overall, the precise molecular scale processes which lead to the material behavior are unknown. In this work the theory of self-organizing linkage patterns by Ihlemann is investigated. Its central claim is, that under deformation a self-organization process occurs, which leads to an inhomogeneous distribution of weak physical links. This linkage pattern evolves during deformation and therefore represents the memory of the material. First of all, some general properties of self-organizing systems are considered. Thereafter, this theory is analysed under these aspects. Moreover, the approach is extended in order to explain some recent experimental observations. It is demonstrated that these new results clearly support the concept. Overall, it is shown that the theory of self-organizing linkage patterns is capable of explaining how a wide variety of material properties emerges from the microstructure. In order to test the theory, a simulation program is developed. It is based on an abstract model of the molecular structure of filled rubber. The model elements are kept as simple as possible. Their characteristic is always elastic. However, there is a rule for dynamically inserting and removing the model element representing the physical links. Hence, all inelastic properties of the model can be associated with a modification of the linkage structure. Algorithms for tracking the evolution of the linkage pattern over time and during a deformation process are presented. These allow to replicate the schedule of published experiments in simulation. The simulation can reproduce a wide variety of typical rubber properties. This is a remarkable result, as none of the basic model elements show any inelastic behavior. An analysis of the model shows clearly that the model behavior is due to a self-organization process based on the model element representing the physical linkages. The self-organization is structured exactly as predicted by the theory. The surprising similarity between simulation and experimental results and the small number of asumptions made lead to the conclusion that in filled rubber most probably such a self-organization process with decisive impact on the material properties is occuring.

Le caoutchouc naturel (CN), un produit dérivé du latex d'Hevea brasiliensis, est connu pour ses propriétés mécaniques supérieures pour certaines à celles de ses concurrents synthétiques. Néanmoins, le haut degré d'insaturation du poly(cis-1,4-isoprene) le rend susceptible à la thermo-oxydation. Heureusement, le CN est doté de composés non-isoprènes dont certains ont des propriétés antioxydantes. Les lipides sont les plus importants non-isoprènes retenus dans le caoutchouc et contiennent des molécules à activité antioxydante en particulier les tocotriènols. Il est connu que durant la maturation de coagula de latex, la composition chimique et les propriétés du caoutchouc obtenu sont altérées, mais les mécanismes complexes de cette altération ne sont pas encore complètement élucidés. Dans cette étude, l'évolution de certaines molécules antioxydantes natives pendant la maturation a été suivie en relation avec certaines propriétés physiques du caoutchouc. Deux expérimentations de maturation ont été mises en œuvre. La première mettait en jeu des conditions non contrôlées de maturation suivies d'un procédé de confection du caoutchouc basé sur celui des feuilles fumées (RSS) ou non (USS). La seconde a été conduite dans un dispositif expérimental dédié permettant le contrôle des facteurs de l'environnement tels que l'humidité relative, la température et la concentration en oxygène. Le procédé de confection du caoutchouc était dans ce cas basé sur celui des caoutchoucs spécifiés techniquement (TSR). L'évolution des échantillons pendant la maturation a été étudiée à différentes échelles : propriétés en masse (P0, P30 et PRI), mésostructure (% gel, Mw and Mn) et composition biochimique (lipides). En parallèle, l'activité antioxydante in vitro des extraits lipidiques correspondants a été mesurée en utilisant une méthode DPPH optimisée. La quantité et la qualité des lipides extraits évoluent pendant la maturation, en particulier en aérobiose. La quantité totale de lipides décroit, avec, en début de maturation, une libération d'acides gras dont la quantité diminue ensuite, avec une disparation des espèces insaturées en premier. La quantité de γ-tocotrienol libres extraits change peu au cours de la maturation alors que sa forme estérifiée montre un enrichissement en acides gras saturés. L'activité antioxydante de l'extrait lipidique mesurée in vitro est corrélée avec la concentration de γ-tocotrienol libre mais pas avec les valeurs de P30 et PRI qui estiment la résistance du caoutchouc à la thermo-oxydation. Cette absence de corrélation pourrait être due à la différence des conditions de mesure in-vitro de celles existantes au sein du matériau caoutchouc. La localisation des antioxydants dans le caoutchouc et en particulier leur possibilité physique d'interagir avec les doubles liaisons du poly(cis-1,4-isoprene) ou avec des espèces oxydantes reste à étudier afin de comprendre ce qui régit la chute de P30 au cours de la maturation. Des lipides non extractibles ou des molécules non-isoprènes plus polaires (protéines, polyphénols, …) pourraient également influencer la résistance du caoutchouc à la thermo-oxydation. / Natural rubber (NR), a derived product from H. brasiliensis latex, is known for its high mechanical properties that are, for some, superior to those of its synthetic counterparts. However, the high degree of unsaturation of poly(cis-1,4-isoprene) makes it susceptible to thermo-oxidation. Fortunately, NR is endowed with non-isoprene components of which some have antioxidant properties. Especially, lipids, the main non-isoprene component retained in NR, have been reported to contain antioxidant substances, especially tocotrienols. It is well known that during the maturation of latex coagula, both NR physical properties and chemical composition are altered, but the complex mechanisms of this alteration are still to be elucidated. In the present work, the evolution of some native antioxidant molecules during maturation was followed in relation with some physical properties. Two experimental conditions of maturation were chosen. The first experiment involved uncontrolled conditions based on traditional unsmoked (USS) or ribbed smoked sheet (RSS) processing, while the second was performed in a dedicated maturation device with full control of environmental factors (relative humidity, temperature and oxygen content) followed by a processing based on that of Technically Specified Rubber (TSR). The evolution of samples during maturation was studied at different scales: bulk properties (P0, P30 and PRI), mesostructure (% gel content, Mw and Mn) and biochemical composition (lipids components). In parallel, in vitro antioxidant activity of NR lipid extracts was also investigated using an optimized DPPH method. Lipid quantity and quality evolved during maturation, especially under aerobic conditions. The total amount of lipid extract decreased, with a release of free fatty acids at early stage of maturation followed by a later decrease, unsaturated fatty acids being the first to disappear. The amount of extractable free γ-tocotrienol did not change much during maturation, while its esterified form was enriched in saturated fatty acids. The antioxidant activity measured in vitro correlated well with free γ-tocotrienol concentration but not with the resistance of rubber to thermo-oxidation assessed by P30 or PRI. Indeed, the in vitro conditions of measurement were far from those occurring inside rubber material. The localization of antioxidants in rubber and especially their physical possibility to interact with the double bonds of poly(cis-1,4-isoprene) or with oxidant species should be further investigated to understand what drives the drop of P30 along maturation time. Non extractable lipids or more polar non-isoprene molecular species (proteins, polyphenols, etc…) could also influence the resistance to thermo-oxidation.