Foi preparado o nanocompósito de borracha natural/argila chocolate B modificada por sodificação via seca com variação no processo, utilizando silicato de sódio ao invés de carbonato de sódio e tratada com sal quaternário de amônio, cloreto hexadecil trimetil amônio. A argila no seu estado natural, após sodificação e após quaternização foi caracterizada pelas técnicas de microscopia estereoscópica, análise térmica, infravermelho, difração de raios X e microscopia eletrônica de varredura. Outras cargas orgânicas foram adicionadas, como celulose e piaçava e comparadas com cargas tradicionais, como o negro de fumo. As placas obtidas, após vulcanização, tiveram medidas as suas propriedades mecânicas e foram analisadas por DRX e MEV. Os nanocompósitos obtidos mostraram melhoria nas suas propriedades mecânicas em comparação com as placas sem a adição de argila. / The natural rubber/clay chocolate B nanocomposite modified by dry sodification process with variation processing was prepared using sodium silicate instead of sodium carbonate and treated with quaternary ammonium salt, hexadecyl trimethyl ammonium chloride. The clay in its natural state after sodification and after quaternization was characterized by the techniques of stereoscopic microscopy, thermal analysis, infrared, X-ray diffraction and scanning electron microscopy. Other organic fillers were added, such as cellulose and piaçava, and compared with traditional fillers such as carbon black. The plates obtained after vulcanization had their mechanical properties measured and were analyzed by XRD and SEM. The obtained nanocomposites showed improvement in their mechanical properties in comparison with the plates without the addition of clay.

O conhecimento das diferentes fases do ciclo básico de vida da espécie vegetal constitui uma ferramenta eficaz de manejo e que uma vez identificados possibilita alcançar boas produtividades e melhor qualidade ao produto comercial. O objetivo deste trabalho foi avaliar o desempenho produtivo e as características químicas da borracha de quatro clones de seringueira, sob diferentes sistemas de sangria, estádios fenológicos e condições edafoclimáticas. O experimento foi instalado na área experimental do Departamento de Produção Vegetal da Escola Superior de Agricultura Luiz de Queiroz, da ESALQ/USP, no município de Piracicaba, SP (2242`30``S, 4738`00``W) e na Agência Paulista de Tecnologia dos Agronegócios (APTA) - Pólo Regional do Desenvolvimento Tecnológico de Agronegócios do Noroeste Paulista, no município de Votuporanga, SP (20°20S, 49°50W). O delineamento experimental adotado foi o de blocos casualizados em esquema parcela subdividida com três ou quatro réplicas. Os tratamentos principais (clones GT 1, PB 235, IAN 873 e RRIM 600) foram alocados nas parcelas e os tratamentos secundários (sistemas de sangria: ½S d/2; ½S d/4 ET 2,5%; ½S d/7 ET 2,5%) constituíram as subparcelas. As variáveis analisadas foram: produção de borracha seca, teores de cinzas e de macronutrientes e micronutrientes da borracha natural. As amostras de borracha natural foram obtidas nos estádios fenológicos: refolhamento; folhas maduras e senescência de folhas. Concluiu-se que a produção e as características da borracha são influenciadas pelas condições edafoclimáticas, pelos sistemas de sangria dependendo do estádio fenológico. A produção e os teores de nutrientes são mais influenciados pela prática de sangria do que pelo material genético, no estádio de senescência e em condições restritivas para a planta. / The knowledge of the different phases of the basic life cycle of plant species is an effective tool of management and that once identified possible to obtain good yields and better quality to the commercial product. The objective of this work was to evaluate the yield performance and chemical characteristics of the rubber of four rubber tree clones under different tapping systems, phenological stages and edaphoclimatic conditions. The experiment was carried in experimental area of the Departamento de Produção Vegetal da Escola Superior de Agricultura Luiz de Queiroz, da ESALQ/USP, Brazil (2242`30``S, 4738`00``W) and in Agência Paulista de Tecnologia dos Agronegócios (APTA) - Pólo Regional do Desenvolvimento Tecnológico de Agronegócios do Noroeste Paulista, in Votuporanga city São Paulo State, Brazil (20 ° 20\'S, 49 ° 50\'W). The experimental design was in randomized block design with split plot and three or four replicates. The main treatments (GT 1, PB 235, IAN 873 and RRIM 600 clones) were allocated in the plots and secondary treatments (tapping systems: ½S d/2; ½S d/4 ET 2.5%; ½ S d/7 ET 2.5%) constituted the subplots. The analyzed variables were: dry rubber yield, ash content, macronutrients and micronutrients of the natural rubber. Samples of natural rubber were obtained in the phenological stages: leaves development, mature leaves and leaves senescence. It was concluded that the yield and chemical characteristics of the rubber are influenced by the edaphoclimatic conditions, by the tapping systems and depending of the phenological stages. The yield and nutrients content of natural rubber is more influenced by the tapping practice than the genetic material in the leaves senescence stage and under restrictive conditions for the plant.

Piracicaba-SP é situada no extremo Sul da área preferencial para plantio de seringueira no Brasil, com pouca informação disponível sobre o desempenho de clones sob suas condições ambientais. O desempenho de crescimento e produtividade de dez clones de seringueira (Hevea spp.) foi avaliado. Os clones estudados foram CATI 21, IAC 15, IAN 873, GT 1, PB 235, PB 252, PR 107, PR 261, RRIM 526 e RRIM 600. O ensaio foi instalado no campo experimental do Departamento de Produção Vegetal da ESALQ/USP, em Piracicaba-SP, Brasil, sob delineamento de blocos inteiramente casualizados com cinco repetições. Foi avaliado o número e porcentagem de plantas em sangria e a produtividade anual. A sangria iniciou-se com a idade de 6,5 anos das árvores, no sistema de explotação de ½ S d/7 9m/y ET 3.3% 9/y. IAN 873 e PB 252 foram os maiores produtores, suplantando a produção do RRIM 600, que apresentou produtividade similar a do CATI 21 e do IAC 15. PR 107 e GT1 apresentaram produtividade intermediária, logo abaixo daqueles, mas com boas características secundárias como de produtividade e crescimento tardios e crescentes. PB 235, de forma inesperada, foi pouco produtivo. RRIM 526 teve produtividade imediatamente abaixo do PB 235 e sem qualquer característica secundária atrativa para recomendá-lo. PR 261 apresentou a produtividade mais baixa entre todos os clones. IAN 873, PB 252, RRIM 600, pelo bom desempenho no campo experimental e em diversas outras situações, são elegíveis para recomendação aos produtores para plantio comercial em grande escala, na região de Piracicaba. CATI 21 e IAC 15, pelo bom desempenho no campo experimental são elegíveis para recomendação aos produtores para plantio comercial em escala experimental, na região de Piracicaba. PR 261 não deve ser recomendado para plantio na região de Piracicaba. / Piracicaba-SP is on the extreme southern region suitable for rubber planting in Brazil, with little information on the performance of clones under its environmental conditions. The performance of growth and yield of ten rubber tree clones (Hevea spp.) were evaluated. The studied clones were CATI 21, IAC 15, IAN 873, GT 1, PB 235, PB, 252, PR 107, PR 261, RRIM 526 and RRIM 600. The trial was established in the experimental field of de Crop Production Department of the ESALQ/USP, at Piracicaba-SP, Brazil, under complete randomized block design with five replications. It was assessed the number and percentage of trees under tapping and yearly rubber yield. Tapping started at the trees age of 6,5 years, with the ½ S d/7 9m/y ET 3.3% 9/y exploitation system. IAN 873 and PB 252 were the highest producers, out-yielding RRIM 600, which presented similar yield then CATI 21 and IAC 15. PR 107 and GT1 had intermediate yield, immediately below the formers, but with good secondary characteristics as late and increasing growth and yield. PB 235, unexpectedly, was a low yielder. RRIM 526 was immediately below PB 235 without any attractive characteristic to recommend it. PR 261 presented the lowest yield. IAN 873, PB 252, RRIM 600, because their good performance in the experiment and their widely-tested good performance elsewhere, should be recommended for commercial planting in large scale. CATI 21 and IAC 15, because their good performance in the experiment, should be recommended for commercial planting in small scale. PR 261 should not be recommended for commercial planting in Piracicaba.

Foi preparado o nanocompósito de borracha natural/argila chocolate B modificada por sodificação via seca com variação no processo, utilizando silicato de sódio ao invés de carbonato de sódio e tratada com sal quaternário de amônio, cloreto hexadecil trimetil amônio. A argila no seu estado natural, após sodificação e após quaternização foi caracterizada pelas técnicas de microscopia estereoscópica, análise térmica, infravermelho, difração de raios X e microscopia eletrônica de varredura. Outras cargas orgânicas foram adicionadas, como celulose e piaçava e comparadas com cargas tradicionais, como o negro de fumo. As placas obtidas, após vulcanização, tiveram medidas as suas propriedades mecânicas e foram analisadas por DRX e MEV. Os nanocompósitos obtidos mostraram melhoria nas suas propriedades mecânicas em comparação com as placas sem a adição de argila. / The natural rubber/clay chocolate B nanocomposite modified by dry sodification process with variation processing was prepared using sodium silicate instead of sodium carbonate and treated with quaternary ammonium salt, hexadecyl trimethyl ammonium chloride. The clay in its natural state after sodification and after quaternization was characterized by the techniques of stereoscopic microscopy, thermal analysis, infrared, X-ray diffraction and scanning electron microscopy. Other organic fillers were added, such as cellulose and piaçava, and compared with traditional fillers such as carbon black. The plates obtained after vulcanization had their mechanical properties measured and were analyzed by XRD and SEM. The obtained nanocomposites showed improvement in their mechanical properties in comparison with the plates without the addition of clay.

O Acre testemunhou dois momentos históricos fundamentais para a sua colonização, ambos relacionados à extração da borracha, sendo o segundo patrocinado pelos Estados Unidos da América que, na Segunda Guerra Mundial, através dos Acordos de Washington, encontrou, no Brasil, a fonte do látex, matéria prima necessária para a produção bélica, uma vez que a Malásia, fornecedora, até então, não mais o fazia por imposição do governo japonês, que tomou seus campos de produção. Esse processo migratório campanhista levou aos seringais amazônicos, no início da década de 40 do século passado, mais de 75 mil jovens, que trocaram a seca do sertão nordestino pela úmida e tropical Floresta Amazônica, enfrentando dificuldades de adaptação dramáticas, atestadas pela morte de cerca de 25 mil Soldados da Borracha, ao final da guerra. O objetivo foi o de resgatar as memórias e histórias sobre o cuidado da saúde desses brasileiros que foram submetidos a vulnerabilidades e traumas culturais, sociais, familiares e de saúde, em prol de acordo que rendeu ao governo brasileiro pouco mais que o Banco da Amazônia e a Usina de Aço de Volta Redonda (RJ). O estudo foi quali-quantitativo, através de entrevistas, gravadas e transcritas, de trabalhadores procedentes do Nordeste que atuaram nos seringais da Amazônia, e que migraram para a capital do Acre, Rio Branco, entre as décadas de 40 e 60. Para análise das entrevistas foi utilizada a técnica do Discurso do Sujeito Coletivo,por meio do programa QualiQuantiSoft®. Os relatos mostraram situações de desamparo e descreveram a luta pela sobrevivência diante das adversidades desses homens e mulheres que, se hoje estão disponíveis para relatar esses fatos, provavelmente ainda o fazem por terem se transformado, em algum momento logo após a chegada, em amazônidas / The state of Acre has testified two fundamental historical moments in its colonization, both related to rubber extraction, the second being sponsored by the United States of America that, in World War II, through The Washington Agreement, found, in Brazil, a latex source, raw material needed in the war industries, as Malaysia, the supplier until then, no longer could offer it because Japans government took the production fields. This migratory process campaign led to the amazon seringais (rubber camps), in the early 40s of the last century, more than 75 thousand young men, who had chose the wet and humid tropical Amazon rainforest instead of their home, the dry and poor brazilian Northeastern region, facing dramatics adaptation difficulties, proved by the death of approximately 25 thousand Rubber Soldiers by the end of the war. The objective was to restore the memories and histories about the health care of those Brazilians who were submitted to all cultural, social and family vulnerabilities as much as health trauma experiences, this all to participate in the Brazilian-North American agreement which promoted to the Brazilian government a little more than the Bank of Amazonia and the Volta Redonda Steel Mill (RJ). This was both a qualitative and quantitative study, made through interviews, recorded and transcribed, with the Rubber Soldiers (RBs) who had worked in the Amazon seringais and later, between the 40s and 60s, went to live in the capital of Acre, Rio Branco. The interviews analysis was done by the Collective Subject Discourse Analysis through the QualiQuantiSoft® software. Reports collected from the RBs showed helplessness scenario and described the struggle for survival facing adversities of living in the middle of the jungle. The RBs probably are still here to tell it because they have transformed themselves, at some point soon after their arrival, in amazon natives

The factors affecting the supply of rubber from Sarawak, East Malaysia, were identified and reviewed in an historical framework. A methodical framework for the general analysis of economic relationships between variables was reviewed and a practical application of the methodology to the supply of rubber from Sarawak was carried out. An econometric analysis of the long run factors affecting the production of rubber was carried out. (1) Two log-differenced autoregressive models of the rubber supply were formulated. (2) The models were tested for parameter constancy to identify structural breaks in the time series and for structural invariance to determine whether they were suitable for policy analysis, forecasting and backcasting. (3) The variables were tested for bivariate Granger Causality to determine the relationships between the factors of production and the output of rubber. (4) Forecast Error Variance Decomposition analysis of multivariate Granger Causality was carried out using a Vector Autoregressive Model. The results confirm the a priori economic theory that long run changes in supply have been affected primarily by changes in area under rubber production and long term price trends. The area planted to rubber has depended upon price incentives and the availability of scarce labour resources. Prices have been affected by the supply of rubber from Sarawak but this is posited to be a reflection of global supply trends affecting prices. While the results generally confirm the economic theory, caution is urged when interpreting the results. The severe inadequacies of the data used highlights the need for more accurate time series and the mainly methodological approach of this study.

No description available.

During the last years rubber nanocomposites obtained by incorporating anisotropic clay nanoparticles within a rubber matrix to tailor material properties have attracted steadily growing interest. However, one main complication preventing rubber-clay nanocomposites from many potential applications is the difficulty to achieve a high degree of exfoliation particularly in case of melt mixing or compounding (using mixing equipment like internal mixer, two roll mills which can be up-scaled in industry). Albeit commercially available organomodified montmorillonite clays (OMt) are fairly compatible with the polar rubber like Acrylo-nitrile butadiene rubber (NBR), carboxylated nitrile rubber (XNBR), chloroprene rubber (CR) etc., its dispersion in non-polar rubbers like natural rubber (NR), is rather unsatisfactory. Incorporation of only 5 phr of OMt in NR by mechanical mixing leads to very poor dispersions with larger aggregates. Large agglomerates of OMt were observed with bare eyes throughout the matrix. Even in the TEM micrographs, highly agglomerated structures of clay particle were observed. A high degree of exfoliation of such clay is achieved in NR utilizing the so called ‘Propping-open approach’ where stepwise expansion of interlayer spacing of Mt took place. A series of long chain fatty acids (C16-C22) are intercalated into the interlayer space of OMt and a gradual expansion of the interlayer space were observed as the chain length of the fatty acid increased. Wide angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR) and contact angle measurement indicated successful intercalation of the fatty acids into the interlayer space of the clay minerals. Since the fatty acid containing 22 carbon atoms has the largest interlayer distance among the modified samples studied, it has been selected for further study to understand the reinforcing behavior in NR matrix. An unusual mechanical percolation behavior of EOMt nanoparticles was observed in a NR matrix. The value of the mechanical percolation threshold (φp) and the fractal nature of nanoparticle clusters were determined through an analysis of the experimental data based on a theory put forward by Huber and Vilgis. This phenomenon was discussed in terms of fractal dimensions of the nanoparticle cluster. The impact of filler dispersion and rubber-filler interactions on the viscoelastic behavior of NR nanocomposites was systematically investigated. Significant non-linear viscoelastic behavior (Payne effect) was observed at very low EOMt content. Kraus and Maier-Göritz models were utilized to interpret such non-linear viscoelastic behavior. The nanocomposites showed enormous improvement in different physic-mechanical properties in the presence of EOMt. Technical elastomers are generally filled with certain fillers (e.g. carbon black) in order to reinforce the rubber matrix for some typical applications like tires, conveyer belts etc. Such rubber goods are always exposed to cyclic stress and deformations attributed to their dynamic application. Under constant and repeated applied stress, cracks develop at a stress concentration point, which could lead to ultimate failure. Therefore, the crack initiation and propagation behavior in such rubber products is very fundamental and need proper attention. The role of EOMt nanoparticles on the microstructure and fracture mechanical behavior of CB filled NR composites was investigated. Using pure-shear test specimen tear fatigue analysis (TFA) tests under cyclic conditions were carried out to explicate the crack growth behavior of CB filled NR in the presence of EOMt. A significant reduction in crack growth rate was noticed in the presence of only 5 phr of EOMt. Furthermore, instrumented tensile-impact tests (IT-IT) were also performed for the characterization of the crack resistance of the materials under impact-like loading conditions. / Die Einarbeitung von nur 5 phr organisch modifizierten Montmorillonite (OMt) in Naturkautschuk (NR) durch mechanisches Mischen führt zu einer sehr schlechten Verteilung mit größeren Aggregaten. Große Agglomerate von OMt waren mit bloßem Auge in der NR Matrix sichtbar. Sogar in TEM Aufnahmen wurden stark agglomerierte Strukturen beobachtet. Ein hoher Grad der Exfolierung von diesem Clay in NR wird durch die Nutzung des so genannten ‘Propping-open’ Ansatzes erreicht, in dem eine stufenweise Aufweitung des Zwischenschichtabstandes des OMt stattfindet. Eine Reihe langkettiger Fettsäuren (C16 – C22) wurde in die Zwischenschicht des OMt eingefügt. Mit zunehmender Kettenlänge der Fettsäuren wurde eine allmähliche Aufweitung der Zwischenschicht beobachtet. Da OMt, der mit einer Fettsäure mit 22 Kohlenstoffatomen modifiziert wurde, den größten Zwischenschichtabstand aller untersuchten Proben hatte, wurde diese Fettsäure für die weiteren Untersuchungen ausgewählt, um das Verstärkungsverhalten in der NR Matrix zu verstehen. Ein ungewöhliches Perkolationsverhalten der expandierten OMt (EOMt) Nanopartikel wurde in einer NR Matrix beobachtet. Der Wert der mechanischen Perkolationsschwelle (φp) und die fraktale Natur der Nanopartikel Cluster wurden durch eine Analyse der experimentellen Daten bestimmt, wobei eine Theorie, die von Huber und Vilgis vorangetrieben wurde, zur Anwendung kam. Dieses Phänomen wurde in Bezug auf die fraktalen Dimensionen der Nanopartikel Cluster diskutiert. Die Einfluss von EOMt Nanopartikel auf die Mikrostruktur und das mechanische Bruchverhalten von russgefüllten NR Kompositen wurde untersucht. Unter Verwendung reiner Schertestproben wurden Rissermüdungsanalysen unter zyklischer Belastung ausgeführt, um das Risswachstumsverhalten von russgefülltem NR in der Gegenwart von EOMt zu untersuchen und zu erklären. Eine signifikante Reduktion der Rissausbreitungsrate wurde in Gegenwart von nur 5 phr EOMt erreicht. Des Weiteren wurden auch instrumentierte Schlagzugprüfungen zur Charakterisierung des Risswiderstandes von Materialien unter schlagartigen Belastungsbedingungen durchgeführt.

Experimental characterisation of rubber in uniaxial, equi-biaxial and planar tension under cyclic quasi-static loading shows strain-induced stress softening, hysteresis and unrecoverable strain. The objective of this work is to study the applications and limitations involved in predicting the behaviour of rubber with hyperelastic models. To assume a preconditioned perfectly elastic material, the data obtained from experiments must first be simplified. The data is then fitted to popular hyperelastic models in the finite element analysis (FEA) software ANSYS(TM). A single hyperelastic model (with given coefficients) is shown to only provide a good fit to a single characterisation test and level of preconditioning at the time. A two-iteration preconditioning method is developed using different hyperelastic models for a given material to approximate the softening effect of cyclic loading in a static FEA simulation. A biaxiality test is developed, providing information on the dominant mode of simple strain in the elements of a FE model. FEA simulations and experimental tests of a cantilevered rubber plate subjected to a bending load at its free end as well as a rubber guide lug subjected to a transverse deflection are presented and discussed. It is shown that using a single hyperelastic model is insufficient to predict the behaviour of these experiments in FEA simulations. The preconditioning iteration, when applied to these simulations, shows very good agreement with the experiments, both qualitatively and quantitatively. The biaxiality test provides insight on which characterisation test is the most appropriate for curve fitting hyperelastic models for a given analysis.

One of the current problems faced by mankind is the problem of safe disposal of waste rubber. Statistics show that the number of waste tires is continuously increasing at a very rapid rate. Since rubber materials do not decompose easily (due to their crosslinked structure), they end up being a serious ???environmental problem???. An intuitive solution to prevent the accumulation of the scrap tires is to continuously reuse them. A new patented reclamation method was discovered in our laboratory, which makes use of a twin screw extruder (TSE) in order to produce reclaimed rubber (referred as devulcanized rubber (DR) from here on) of very high quality. Also, this method has proven to be more economical than other commercial reclaiming methods. Products made solely from a reclaimed material face challenges from those made by virgin materials because of relatively poor properties. However, the striking advantage of using reclaimed rubbers is the cost reduction. Hence, it is important to work on establishing methods by which these reclaimed rubbers could be efficiently used and incorporated into present day products. The deterioration of properties could be minimized by blending them with varying amounts of other materials. A possibility in this direction is manufacturing of thermoplastic vulcanizates (TPVs) using reclaimed rubber and general purpose thermoplastics. In accordance with this idea, the focus of this research is to prepare DR and polypropylene (PP) based TPVs. DR is unique as the rubber itself consists of two phases- one phase consisting of uncrosslinked (including devulcanized rubber molecules), and the other phase consisting of crosslinked (un-devulcanized) rubber. These un-devulcanized crumbs act as stress concentrators because they do not break-up easily, and lead to poor physical properties. Hence, this project tries to find out ways to increase the interfacial adhesion between the rubber and PP by using reactive and non-reactive techniques. Preliminary experiments were carried out in a batch mixer to compare DR and rubber crumb (CR). DR based TPVs showed better properties than CR based TPVs, however, the properties were not useful for commercial applications. Sulphur based dynamic vulcanization was studied in a batch mixer and found to be not effective in improving the properties of DR based blends. On the other hand, DCP/ sulphur based curing system was found to show significant improvement in properties. Therefore, DCP/sulphur based curing package was studied in detail on the blends consisting of DR and PP. The optimum ratio of DCP/sulphur was found to vary depending on the ratio of DR/PP. A hypothesis regarding the mechanism of DCP/sulphur curing has been proposed, which seem to correlate well with the experimental results observed. Additionally, it was determined that DR prepared from tire rubber (DRT) performed better than DR prepared from waste EPDM (DRE) for the curing system used. Accordingly, experiments on a TSE were carried out using DRT and a combination of compatibilizing resins and curatives. This combination showed a drastic improvement in blends properties and once again the optimum ratio of compatibilizing resins seemed to depend on the ratio of DRT/PP. As a result of the work, successful strategies based on reactive compatibilization techniques were developed in order to prepare useful TPVs having up to 70% DR. A series of compatibilization techniques has been evaluated using design of experiments and various characterization techniques such as mechanical tests, scanning electron microscopy, thermal analysis and crosslink density measurements. This led to the development of a formulation, which could improve the blend properties significantly. A tensile strength of around 10 MPa and an elongation-at-break of 150-180 % could be achieved for devulcanized rubber (70%) based TPVs, which has broadened the scope for its commercial applications. In addition to that, the process was established on a TSE that has enabled a continuous and steady production of these TPVs with reasonable throughputs.