163 resultados para acrylonitrile butadiene(NBR) rubbers


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Pós-graduação em Engenharia Civil - FEIS

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Pós-graduação em Engenharia Civil - FEIS

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Pós-graduação em Design - FAAC

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To design connections between timber parts with metal dowels (nails or bolts), two phenomena must be considered: bending of the metal dowel and the embedment strength in the wood. The Brazilian Standard ABNT NBR 7190:1997 proposes the methods used in the laboratory tests to determine the embedment strength with the metal dowell and, in the absence of testing, specifies relations to calculate the embedment strength from the compression strength. The aim of this research was to compare the embedment strength values obtained by experimental tests and calculated by the relationships established by the Brazilian Standard ABNT NBR 7190:1997. By the results of the hypothesis tests, it was possible to conclude that the estimate of the embedment strength parallel to the grain proposed by the Brazilian standard ABNT NBR 7190:1997, establishing equivalence with the strength compression results in the same direction, must be effective to the wood species Pinus taeda L., however, the same was not found in the perpendicular direction with respect to the grain, possibly explained by the alpha(e) values in the equation to calculed fe(90)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Considered the step that constitutes the intellectual work of the indexer, the approach runs the focus of the initial phase of the indexing process - the subject analysis. Among the various denominations that can be achieved, the subject analysis reaches its dimension applied when observed the rules that underlie the indexing process. The release of the documentary information requires the development of contributions to aid in the procedures of analysis, synthesis and representation of the contents documentary, seeking contributions to both the theoretical sedimentation, and for fostering the professional practice of the librarian. Through bibliographic exploratory research, this article aims to contribute to the relevance of subject analysis, concluding that there is a gap in the use of NBR 12676/1992, as well as the need for its updating.

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Pós-graduação em Engenharia Civil e Ambiental - FEB

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The connections in the wood structures are the places with high concentrations of stresses and therefore are more fragile than the rest of the structure. The connections between pieces of wood can be made by metal pins (nails or screws). The compression and embedment strength has significant influence on the calculation of the connections. The main aim of this work was to evaluate the compression and embedment strength in the directions parallel, inclined at 45° and normal to the grain, using standard specimens according to ABNT NBR 7190/1997 standard. The compression and embedment strength were initially evaluated according to ABNT NBR 7190/1997, which admits the deformation of 2‰ as limit of embedment and the ratio between the ultimate strength and the area of application of load in the specimen for the compressive strength. Afterward, the embedment strength was evaluated by the EUROCEDE 5 /1995 European standard, which use the limit of 5 mm of the displacement for the embedment. Specimens of Pinus oocarpa, Cumaru and Pinus taeda were used in tests to calibration of equipment and specimens of Pinus taeda and Eucalipto citriodora were used to compare the results of strength. The results of strength were evaluated based on statistical analysis. The results of compressive strength for the Pinus taeda showed no significant differences in embedment strength in the directions parallel and normal to the grain. For the Eucalipto citriodora only in the direction parallel to grain the compression strength was not significant compared with the embedment strength. For both species, only the parallel compression strength and inclined at 45o to the grain, which were to the grain, which were admitted the strain of 2‰ were not significantly different compared with the compression strength determined according to ABNT NBR 7190/1997. The normal compression strength obtained according to ABNT NBR 7190/1997 and ultimate compression strength not ...

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The properties of the hot melt adhesive pressure sensitive (HMPSA) using an elastomer as a base polymer a copolymer of styrene and butadiene (SBS) and variation of tackifiers resins such as hydrocarbon resins and hydrogenated hydrocarbon were investigated. The formulations were prepared by mixing process within shear. The adhesives prepared were evaluated in test Brookfield viscosity and softening point Ring and Ball to compare the formulations and the influence of variations in raw materials. Infrared analyzes were performed to detect the reactions between the inputs and investigate the chemical interactions of the same properties of the adhesive. In thermal analysis, the assay was performed thermogravimetry (TG) and diferencial exploratory calorimetry (DSC). Were investigated the parameters of the tensile test on each of the formulations. Finally, were analysed comparatively the basic formulations of adhesives with their respective raw materials

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The process of environmental impact assessment (EIA), in the extent of previous environmental studies, has as one of its functions to provide subsidies to the actions of environmental managment of enterprises. However, the proper estructuring of programs that allows to support this managment does not often occurs. This research sought as one of its objectives to evaluate in which extent the process of EIA can be a subsidie for the EMS, providing basic elements of this system. In addition, more specifically, the research had as one of its objetives the development of subsidies for the implantation of an Environmental Managment System (EMS), based on the model of ISO 14001 (2004), for a sewage treatment plant yet to be constructed in the city of President Venceslau / SP. In order to achieve theses objetives, a discussion was held based on the evaluation of environmental studies available in the library of Cetesb / SMA. Still, for the elaboration of subsidies for the EMS of the treatment plant, the research was focused on the structuring of environmental management program, based on the information contained in its Preliminary Environmental Report (PER). The research had as one of its products, the development of subsidies for the planning and control of the environmental aspects and impacts and for the environmental program of the enterprise, based on the use of environmental indicators. It was concluded, based on the results that, in general, the previous environmental studies analyzed showed little emphasis on the phase of development of structured environmental programs that offer guidelines to achieve the desired results for the environmental performance of the company.

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This work was developed to evalute the physical and mechanical properties of a panel of three particle layers from the test specification of NBR 14810-3 (2006), using wood of Eucalyptus sp. and Eucalyptus saligna and Eucalyptus urograndis bark. The mechanical properties were evaluated to obtain the bending modulus of rupture (MOR) and modulus of elasticity (MOE) and Internal bond. The physical properties were obtained thickness sweeling, water absorption, moisture content and board density. Were evaluated four different compositions of panels containing 5, 10, 15 and 20% in the inner layer of bark. The results were compared with the Brazilian standard NBR 14810-2 (2006) and also with studies in the literature. The panels produced were adequate to all the optimal values suggested by the standard only in the composition with 5% skin in the inner layer. The other treatments showed satisfactory results in all tests except for moisture content