A gestão participativa em administrações municipais:as experiências de Natal e Maceió

Our object is to analyze the experiences in participative management in the cities o Natal and Maceió. The center of our interests is to evaluate if the operational changes in public administration in Brazil have really caused transformations in the municipal government which tend to constitute democracy in our country. The enlargement of civil society participation experiences in public management (at least as a proposal) has led to a great diversity of results even when executed by individuals from the same political party or with the same ideological interests. Thus, we investigate why the participative management process takes place in different forms even when the managers belong to the same party and share the same ideas. We based our analysis in the analytical scheme developed by Esping-Andersen (1991) in his studies about the cause for different welfare states in the world. We defend the thesis that the specifities in management are explained through an integrative analysis between the capacity of organization existent in society, the kind of govern coalition and the institutional legacy present in both cities. The complete analysis of the two experiences studied shows that there are similarities specially in the mayors government forms and in the importance they give in their speech to the participation of society as the element which sustains the management. Nevertheless, although both mayors are connected to the political party project, there are also differences in the advance of such process mainly because of the basis work performed by the left party among the popular movement, the kind of govern coalition which has been developed in the city and by the institutional legacy left by the former administration

O desenvolvimento sustentável na ordem constitucional e sua promoção através do planejamento urbano

The man, being subject and object of their changes, has passed by many process to find a better life way. Since your existence, he finds to live in groups for make easy your life and make concrete yours desires. All by history, when the individual´s rights was establishment, collectives and lonely way, contribute for evaluate the relationship between individuals and they own, and them and state, which has a duty to those, positive or negative, depending on the case. The circle of fundamentals rights has been sustainable development and the concept of growth economy associated to the environment protection. This association reflect a apparent conflict between values very distinct, but the constitutional interpretation can be reunite both of them and make it live in harmony; values of environmental order and economical order can be exist together, as long as the state contribute to this. On the city, where the most of relationships happening, the urban plan appear how a effective way of sustainable development, finding the harmony between the growth economy and environment protection. To effective the socials functions of the city (inhabit, circulate, work and entertainment) and the citizen´s life quality, the city is the scenery that show how the urban plan, across established previously legal instruments, like the governmental public politics, to effective the right to development, right of third generation. The director plan how effective tool for local needs - obligation defined by Citizen Statute that contribute for the program linked defined by the urban plan. The state´s intervention on the private sector of citizen, and the restriction on their rights are be justified by the collective´s rights and their quality of life. So, in front the urban scenery has been the plan to make social functions of city, the healthy way of life, which is the sustainable development

O princípio constitucional da eficiência aplicado à outorga e à cobrança da água produzida na exploração petrolífera

Water production is unavoidable during a petrol well s lifetime. The amount of produced water associated with oil varies a lot. It can reach values which account to 50% in volume up to nearly 100%, at the end of the well s economic life. It could be verified that, once the water reaches the productive wells, there must be a management of this produced water. Its destiny is defined after a precise study, after which the best option is chosen between relieving it into the environment, re-injecting it into the producing container or disposing it into non-producing formations. Whichever option is made by the involved professionals, after the necessary analysis, it shall consider, besides the technical and economical aspects, also the alternatives which entail less environmental impact. The purpose of the present research is to conduct a study about the application of the constitutional principle of efficiency on the instruments worked out by the public administration on water management, specifically the water use licence and charging for the use in the management of water resources applicable to water production at the petrol wells. In this attempt, before entering the proper approach of the efficiency of the mentioned instruments, it was necessary not only bring to light the doctrinal perception about the constitutional principle of administrative efficiency, but also make some considerations concerning to the structure of the national water resources management, set by the Federal Constitution (1988) and the federal legislation (9433/97)

A tutela constitucional da exploração de petróleo em águas internacionais em face do princípio do desenvolvimento sustentável: a possibilidade de responsabilização civil do dano futuro

The demands brought by a society doomed to the constant production of global risks, which whose effects are not immediately noticed effects are not perceived immediately, claim from the Law a new Theory about the Risk, that would offer a broad environmental protection, at the same time it would still be compatible with the idea of economic efficiency, required by the Modern Industry. The expansion of the methods and technologies regarding the exploitation and production of oil causes the constant expansion of the exploitable boundaries, especially in ultra-deep waters with the Pre-salt layer, in Brazil, or the still incipient research about the polymetallic nodules and other mineral sources in international waters, like the Atlântico Sudoeste, by the Programme on Ocean Science in Relation do Non Living Resources (OSNLR), a global study performed in partnership with the Intergovernmental Oceanographic Commission, from UNESCO (IOC UNESCO) and also with the Division of Ocean Affairs and Law of the Sea (UNDOALOS). Thus, we aim to analyze the correlation, and possible collisions between the right to a balanced environment and the free exercise of economic activity and the occurrence of environmental damages from the perspective of the exploitation activities of oil and other natural resources in international waters, specifically in the Area, from the constitutional principle of sustainable development and its legitimacy by the environmental international protection. Therefore, this study also aims to evaluate the legal framework for exploration and production of oil in international waters, particularly in the Area, and appraise how the constitutional instruments and mechanisms for environmental protection can impact on the international environmental protection system in order to ensure the present and future generations an ecologically balanced environment, laid down in Article 225 of the Brazilian Constitution, even with so many risks posed by the activities of exploitation and production of oil in international waters. In the meantime, we intend to also intend to investigate the possibility of future liability for environmental damage in order to ensure that constitutional principle and, consequently, and try to define the concept of environmental damage and its implications on the constitutional principle of environmental protection. Given all that was in summary, this work aims to contribute to the evolution of the new Theory of Environmental Risk, turning the law into something more than a punitive or corrective element in this society, but into a legal risk management, that may be triggered even before the consolidation of the damage

Animais não humanos: a construção da titularidade jurídica como novos sujeitos de direito

This work has the main goal on the recognition of the inherent value of nonhuman animals, under the constitutional framework. It is presented the main philosophical formulations of the current pattern of behavior that rules the relationship between man and animals: first those that have excluded animals from moral consideration and then the thinkers which do have included, in some way, in order to elucidate the origin of the anthropocentric thought over the natural world. In this way, the analysis these thinkers that have included animals in moral consideration will contribute to a paradigm change from the anthropocentric view, initiating legal debates. It will be made a simplified analysis of different philosophical and legal points of view that have been demonstrating the posture in which the human beings have been dealing with the environment, with the replacement of the anthropocentric thinking for the biocentric view, in which life becomes the center of existence. Life is life, no matter whether it is human or not, has a value in itself, and must be protected and respected by the legal system. Then, it will be analized the constitutionalization of the nonhuman animal dignity in comparative law; the infraconstitutional legislation which concerning the intrinsic value of all life forms and, finally, the 1988 Constitution. It will be advocated for non-human animals the condition of subjects, presenting some cases that the Habeas Corpus was used in animal defense. In this new Brazilian Habeas Corpus theory of for apes the argument of genetic proximity was used in order to overcome the literal meaning of natural person to achieve hominids in order to assure the fundamental right of physical freedom. It is realized that the fact that the great apes being recognized as a person does not preclude the possibility of other living beings be recognized as subjects of law. In this way, animals can be considered non-human subjects of law, according to the theory of depersonalized entities and may enjoy a legal category that allows a respect for existential minimum, and can hold constitutional fundamental rights

Concentração da posse da terra e o programa nacional de crédito fundiário - uma análise para o estado do Rio Grande do Norte, 2006 - 2012

O objetivo do trabalho é propor um estudo sobre a relação do Programa Nacional de Crédito Fundiário - PNCF, no estado do Rio Grande do Norte, e sua concentração fundiária. Ou seja, se o PNCF está sendo direcionado, para as microrregiões que apresentam maior índice de concentração, de acordo com o índice de Gini, e se as áreas adquiridas através do crédito fundiário estão emergindo nestas microrregiões. Para isto, o estudo levantou a hipótese de que o PNCF no estado do Rio Grande do Norte não está sendo conduzida, de modo a reduzir a concentração fundiária, dentre as microrregiões do estado. Ou seja, não existe correlação entre o índice de Gini, da concentração fundiária, e as áreas adquiridas através do programa. Além disso, o trabalho buscou realizar uma discussão da literatura sobre os programas de reforma agrária assistida pelo mercado. Apresentando os autores que são exaltadores do modelo e das suas potencialidades, atrelando as causas dos problemas levantados como sendo de ordem técnica e operacional, onde os principais autores desta linha são: Van Zyl, Kirsten & Binswanger, (1996), Deininger & Binswanger, (1999). Têm-se também a apresentação da posição dos autores adeptos as políticas fundiárias pautadas na dinâmica e liberação dos mercados de terras, mas que visam contribuir com estudos que permitam uma redução para o custo elevado e a sua incapacidade de abarcar a esfera social, em decorrência do pagamento á vista e a preço de mercado aos donos das terras, são eles: De Janvry & Sadoulet (2002), Gordillo (2002), Banerjee (1999), Jaramillo (1998) e Burki & Perry (1997). Todavia, apresentou-se a corrente de autores que ressalta a natureza socialmente agressiva da Reforma Agrária Assistida pelo Mercado (RAAM), sendo os seus principais contribuidores: El-Ghonemy (2001); Barros, Schwartzman & Sauer (2003); Borras Jr. (2006, 2003 e 2003a); Garoz et al. (2005); Sauer & Pereira (2006); Pereira (2005, 2006 e 2010); Sauer (2010); Lahiff, Borras Jr. & Kay (2007). Em sequência, o trabalho apresentou a transição e características dos programas de acesso à terra, no Brasil, a partir da década de 1990, bem como, alguns indicadores do PNCF, no Brasil e o estado do Rio Grande do Norte. Apresentou-se também os indicadores da concentração fundiária, no Brasil e no estado. Através dos dados do Censo Agropecuário de 2006 foi possível calcular o índice de Gini da distribuição fundiária nas microrregiões no estado do Rio Grande do Norte. Com os dados fornecidos pela Secretaria de Estado de Assuntos Fundiários e de Apoio à Reforma Agrária - SEARA mostrou-se a distribuição das linhas de crédito do PNCF e as áreas adquiridas, entre os anos de 2006 e 2012. Por fim, o valor do coeficiente de correlação simples (r) igual a (0,2865), que com base no teste bilateral da distribuição de t de Student chegou-se no resultado para T calculado no valor de (1,2333), que ao ser comparado com o valor de T crítico igual a (2,898), com 17 graus de liberdade, a um nível de significância de 1%, pode aceitar a hipótese de partida, ou seja, que o PNCF não estava sendo direcionado para diminuir a concentração fundiária no estado

De Escola Normal de Natal a Instituto de Educação de Presidente a Kennedy (1950−1965): configurações, limites e possibilidades da formação docente

La recherche ci-présentée consiste dans une narrative historique problematisée par rapport à la trajectoire de l École Normale de Natal. Dans ce parcours, nous distingons sa transformation en Institut d Éducation Président Kennedy, en envisageant la période de 1950 jusqu à 1965. L investigation a été procédée ayant pour base les principes de l histoire des institutions éducatives, on a pris deux catégories d analyse historique : la culture scolaire, utile à la compréhension des pratiques éducatives developpées dans l institution d enseignement ; et celle de genre, l École Normale de Natal/Institut d Éducation pour avoir été fréquentés principalement par des femmes qui voulaient travailler dans l enseignement primaire ; alors, une place de genre. Dans cette perspective, nous estimons sa multiplicité d acteurs et de leurs pratiques dans l institution. Nous mettons en évidence sa création et les cycles de son développement (matérialisés dans les plusieurs configurations), en les reliant aux faits locaux et nationaux. Nous distingons les conflits tout le long des années en ce qui concerne l inexistence de l espace physique pour le fonctionnement adéquat de l école, et les changements du savoir apporté moyennant la renovation du programme d enseigement et de la pratique pédagogique. Ainsi, de la tradictionnelle École Normale de Natal à l Institut d Éducation Président Kennedy, cette institution éducative a gardé, dans son identité, le caracter de modèle et d innovation, quand elle a pu assimiler les changements didactico- pédagogique qui avaient eu lieu dans le scénario national se transformant en un centre de référence pour la formation des professeurs, particulièrement des femmes, en différentes époques dans l enseignement potiguar. L École Normale de Natal s est constituée surtout en un établissement pour la conquête, un chemin pour l élargissement de l univers du rôle de ces femmes qui se déplacent de la sphère de l enseignement privé pour accéder au domaine de l enseignement publique, acquérant ainsi un travail rémunéré

Projeto político-pedagógico: instrumento de ação educativa na Escola Municipal Ascendino de Almeida Natal-RN (2002-2003)

In this dissertation, we investigate the process of elaboration of the Political-Pedagogical Project in the Municipal School Ascendino de Almeida , situated in the west zone of Natal city, in Rio Grande do Norte State, Brazil. We performed a qualitative research, using information provided by several sources as: interviews carried out in the Municipal Department of Education and also in the mentioned School, document analysis, and literature reviews, mainly with the objective of knowing more about the complexity of this particular reality. This was done in order to establish a mediation between the actual reality and the social, political, and economic context that surrounds it. We analyze the Political-Pedagogical Project according to the visions of Education theoreticians, under the political-normative plan, and also as a process of educational planning that can collaborate significantly for the introduction of changes in school Education. This instrument of the educative action, as a fruit of the participation of the school community, may constitute itself in an important learning instrument of the participation in the social sphere, demanding from the educators the development of complex abilities so that they can construct the Project. In the data analysis, we describe and analyze the process of elaboration of the Political-Pedagogical Project of the mentioned School. We also determine how participation of the school community was constructed as well as the consequences of this envolvement. We also discuss the abilities they needed to develop, the process of studies and dialogues that gave support to the whole process, and the democratic participation in the school decisions, including a dialogical interaction

Tear identitário:a prática docente em arte como conhecimento compartilhado

This investigative tissue is about the formation of identification processes of teachers and pedagogical practice of Art, in Teresina city. This search comprised the sum of the needs presented, agreed upon with the teachers engaged in the process, it was developed through the establishment of interactive environment Loom Team where collaboration and critical reflection were steering actions to promote the understanding of existing connections or relations within the processes of identifications and the pedagogical practice of Art. The tissue is formed by the polyphonic plot of the critical reflection of nine teachers of Art who engaged voluntarily and this investigation of formative nature and a production of knowledge. All these teachers have degree and the course of artistic education and especial qualification in Fine Arts and/or Drawing. The texture, which we denominated Identification Loom: The pedagogical practice of Art as share knowledge is (de) (re) construction of knowledge resulting from the critical reflection, in an environment of collaboration, which may have implications and ethical political attitudes in the pedagogical practice of the group. Within this context, we pose the following question: - How does the pedagogical practice in Art influence and/or be influenced by the identification processes of the teachers, and how do they interfere with the search and manifestation of the knowledge involved and the investment in professionalization? In view of this query, we make use of the cooperative investigation, having social history as theoretical reference and as analytic perspective of interactive and dialogical-reflexive processes. Thus, social historic theory, cooperative approach and pedagogical practice were the major components of the plot. The methodological texture counted on the threads of dialogical reflexion, of mediation and of collaboration. The conceptual formulation, the recording in videos of classes and the narratives of formations were the main threads of the analytic substrate of the investigation. With this articulation, theses threads appear as developers of processes leading to a major approximation of the thought on the identity/alterity dialectical pair of the participants involved. The language within this plot had a decisive importance in all the moments of the search of signification, embracing and connecting the identification/alterative processes, the pedagogical practice of Art and the knowledge shared. In such processes involving (de) (re) construction, one can notice a close correlation of the triad social identity, pedagogical practice and knowledge shared. For this reason, the vigotskian, guetmanovian and kopnian theoretizations were the major framework for the analysis of conceptual formulations; and, as for discourse analysis, Baktin and Orlandi were our masters. For these teachers, the experience shared throughout the process of this typology of tri-axial investigation focused the experience of many theoretical and practical assumptions. Such an experience enabled them to state that this, with collaboration, can make reflection on the practice a starting and promoting element, within the individual level of self-management, in addition to being a space of (de)(re)construction of meanings, of knowledge and of reinvention per se

Avaliação do programa escola ativa como política pública para escolas do campo com turmas multisseriadas: a experiência em jardim do seridó/rn (1998-2009)

This work aims at developing an evaluation of the implementation of the Program Escola Ativa as a public policy for rural schools with combined grade classrooms in Jardim do Seridó RN (1998 2009) focusing on the following dimensions: school s physical environment, training, follow up, and didactic usage of the methodology. In order to develop this research we refer to the literature that analyzes the cycle of policies (FREY, 2000). In this approach, evaluation represents an important step in the process of analyzing the implementation of public policies, as a way of measuring up their performance, as well as a guide for realignments and redefinitions (PRESSMAN; WILDAVSKY, 1998). In order to accomplish this function, the evaluator of policies must be acquainted with scientific concepts and methods that consist of describing, interpreting and analyzing the policies in the governmental sphere (MENY; THOENIG, 1992; LIMA JÚNIOR, 1978). In this perspective, we intend to investigate whether in its proposition of minimizing the blanks in the Brazilian educational system, the implementation of the Program would be contributing to the improvement of the political-pedagogical practices in the rural schools with combined grade classrooms in Jardim do Seridó RN. In order to do this research, we have developed a theoretical-methodological matrix made of analysis dimensions, variables, indicators and instruments, such as literary revision, documental analysis, semi-structured interviews with four teachers and three supervisors that work and/or have worked in Escola Ativa in that town in the period comprised among 1998 2009, besides notes taken from field observation and photographs from four rural schools with combined grade classrooms. With this research we have identified that the Program, at a national level, has gone through different phases in its implementation process, for the town was not ready to fully take the responsibilities of the autonomous expansion, in 2002. From that period on, the execution of Escola Ativa has suffered several discontinuities, such as the lack of professional training and supervising. It is also noted that the methodology contributes to the dynamization of the didactic-pedagogical activities and promotes the cooperation and autonomy of the students in the organization and the applicability of the components of the curriculum, especially of Governo Estudantil and Cantinhos de Aprendizagem. Although the directions of the Program (BRASIL, 2005) point out that Escola Ativa has among its principles social transformation, we identified that, isolated, the initiative is not capable of promoting the changes that the rural schools need, namely investments in the physical, material, pedagogical and technological infra-structure, besides the estimation and a career plan for the teachers. In a general draft of the results of this research, we realized that some aspects presented about the peculiarities of Escola Ativa in Jardim do Seridó as a governmental Program, reinforce the need for the public policies to be evaluated, in order to confront critic and operationally the planning with the practice, revising action, whenever necessary

O desafio da parceria na implementação do PRONERA: o caso do projeto alfabetização cidadã no nordeste Paraense.

El desafío de la parcería en la implantación del PRONERA: el caso del Proyecto Alfabetización Ciudadana en Noreste de Pará se constituye en un estudio sobre las políticas públicas de educación del campo. El trabajo tiene como objeto de análisis la implantación del PRONERA, a partir del estudio de caso del Proyecto de Alfabetización Ciudadana en Noreste de Pará, con el objetivo de comprender como la parcería, principio operacional y metodológico propuesto por el PRONERA, se concretó en la implantación del Proyecto y cuales sus posibles implicaciones en las políticas públicas de educación del campo. Entre los procedimientos metodológicos, realizamos la investigación bibliográfica y documental que nos permitieron situar la educación del campo en términos históricos y políticos, sistematizar la constitución y la organización del PRONERA y reflexionar acerca de la parcería a partir de diferentes ópticas. Realizamos también la investigación de campo por medio de entrevistas semi-estructuradas, con el propósito de analizar la implantación del Proyecto da Alfabetización Ciudadana, a partir del dialogo con los actores sociales involucrados. Los resultados de las análisis indicaron que, históricamente, las políticas públicas de educación destinadas a las poblaciones de la zona rural fueron instituidas verticalmente, desvinculadas de la realidad del campo e incompatibles con las necesidades e intereses de los sujetos. Constatamos que, en período reciente, movimientos sociales del campo reivindican y proponen acciones que se establezcan como políticas públicas de educación del campo. Identificamos que el PRONERA resulta de ese movimiento y se presenta como anuncio de una política pública de educación del campo, teniendo como diferencial el hecho de ser un programa del gobierno federal idealizado fuera de la esfera gubernamental, construido por los movimientos sociales del campo y presentar, entre otras innovaciones, el modelo de parcería y la gestión compartida, participativa y democrática. En esta perspectiva, en este estudio de caso, se evidenció que la parcería, frente a los conflictos y las disputas entre sus miembros participantes, no es el problema de la implantación del PRONERA, sino su punto fuerte. De este modo, la parcería es uno de los elementos necesarios para la construcción de políticas públicas, en particular, de educación del campo, una vez que posibilita la interacción de instituciones públicas y movimientos sociales locales, atribuyendo legitimidad a la educación del campo. Al promover un proceso de aprendizaje democrático, la parcería se presenta como estrategia de democratización de la educación del campo.

O memorial autobiográfico: uma tradição acadêmica do ensino superior no Brasil

The thesis has as object of study the autobiographical memmorials. The general objective is to describe the history of the memmorial as an academic tradition of higher education in Brazil. Considered a hybrid genre, memmorials are known for focusing on life stories from a scientific perspective. The investigation revolves around three intertwined branches: History of Education, educational practices and language usages, which allow us to conduct a dialogue with multiple theoretical-methodological references with a view to supporting our analyses. The corpus used for the analysis was made up of 40 autobiographical memmorials, distributed as follows: 16 academic memmorials, dated from 1935 to 1970; 07 academic memmorials, dated from 1980 to 2007; and 17 formation memmorials, dated from 1995 to 2000. In this corpus, we also included official documents, which relate to legislation contained in edicts, resolutions, ordinances, regulations, which we used with a view to: 1) getting to know and understanding the big picture of higher education regulation in Brazil and the aspects related to the higher education teaching career; 2) investigating the text of memmorials in the light of the injunctive discourse characteristic of the edicts and resolutions in which they were based. The analysis of the memmorial supported by the legislation which regulates it allowed us to reconstitute the image of the professor throughout 80 years in the Brazilian public university. For this purpose, the study was conducted in the theoretical-methodological perspective of the (auto)biographical research in Education and of the sociolinguistic studies on discourse genres and discursive traditions. The investigations reveal the memmorial as an academic genre in which the professor's academic-professional history and the history of the higher education teaching career in Brazil intertwine. Anchored in the Bakhtinian perspective on discourse genres, according to which the memmorials evolve and become more complex as their contexts of usage also evolve and become more complex themselves, the results of our analyses allowed us to correlate genre changes to the sociohistorical context and to its usage as an educational practice in the university, in the decades under study. Therefore, the analyses showed that these self-writings: go from latent subjectivity to pure objectivity from the 1930s to 1960s; they show total annulment of the subject from the 1960s to the 1970s; they reappear in the 1980s, having Professor Magda Soares' memmorial as perspective; they expand and diversify from the 1990s onwards, taking on a formative role and a perspective of future as well. So far as language usages are concerned, we investigated the relationship of the subject with the language, especifically the manifestation of alterity on the discursive tissue of the memmorials. In this branch, the analyses pointed to the influence of the authoritative discourse on the formation of the professor and of the injunction and reinventing discourses on the authorship process. Therefore, the autobiographical memmorial reveals itself as a specific expression of the Brazilian academy's cultural sphere and allows us to confirm the hypothesis that each memorial tackles a singular-plural situation, by presenting a dialectical articulation between private and public, according to the institutional structures, in which and with which the professor has already formed him/herself and with which he/she dialogues

Construção e controle inteligente de um manipulador robótico com dois graus de liberdade

The present work shows the development and construction of a robot manipulator with two rotary joints and two degrees of freedom, driven by three-phase induction motors. The positions of the arm and base are made, for comparison, by a fuzzy controller and a PID controller implemented in LabVIEW® programming environment. The robot manipulator moves in an area equivalent to a quarter of a sphere. Experimental results have shown that the fuzzy controller has superior performance to PID controller when tracking single and multiple step trajectories, for the cases of load and no load

Desenvolvimento e caracterização de nanocompósito de resina epóxi com nanopartículas de sílica para revestimento de dutos para transporte de petróleo

The use of polymer based coatings is a promising approach to reduce the corrosion problem in carbon steel pipes used for the transport of oil and gas in the oil industry. However, conventional polymer coatings offer limited properties, which often cannot meet design requirements for this type of application, particularly in regard to use temperature and wear resistance. Polymer nanocomposites are known to exhibit superior properties and, therefore, offer great potential for this type of application. Nevertheless, the degree of enhancement of a particular property is greatly dependent upon the matrix/nanoparticle material system used, the matrix/nanoparticle interfacial bonding and also the state of dispersion of the nanoparticle in the polymer matrix. The objective of the present research is to develop and characterize polymer based nanocomposites to be used as coatings in metallic pipelines for the transportation of oil and natural gas. Epoxy/SiO2 nanocomposites with nanoparticle contents of 2, 4, and 8 wt % were processed using a high-energy mill. Modifications of the SiO2 nanoparticles‟ surfaces with two different silane agents were carried out and their effect on the material properties were investigated. The state of dispersion of the materials processed was studied using Scanning and Transmission Electron Microscopy (SEM and TEM) micrographs. Thermogravimetric analysis (TG) were also conducted to determine the thermal stability of the nanocomposites. In addition, the processed nanocomposites were characterized by dynamic mechanical analysis (DMA) to investigate the effect of nanoparticles content and silane treatment on the viscoelastic properties and on the glass transition temperature. Finally, wear tests of the pin-on-disc type were carried out to determine the effects of the nanoparticles and the silane treatments studied. According to the results, the addition of SiO2 nanoparticles treated with silane increased the thermal stability, the storage modulus and Tg of the epoxy resin and decreased wear rate. This confirms that the interaction between the nanoparticles and the polymer chains plays a critical role on the properties of the nanocomposites

Mecanismos de desgaste de poliuretano em ensaios de microabrasão

Wear mechanisms and thermal history of two non-conforming sliding surfaces was investigated in laboratory. A micro-abrasion testing setup was used but the traditional rotative sphere method was substituted by a cylindrical surface of revolution which included seven sharp angles varying between 15o to 180o. The micro-abrasion tests lead to the investigation on the polyurethane response at different contact pressures. For these turned counterfaces with and without heat treatment. Normal load and sliding speeds were changed. The sliding distance was fixed at 5 km in each test. The room and contact temperatures were measured during the tests. The polyurethane was characterized using tensile testing, hardness Shore A measurement, Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Thermomechanical Analyze (TMA). The Vickers micro-hardness of the steel was measured before and after the heat treatment and the metallographic characterization was also carried out. Worn surface of polyurethane was analysed using Scanning Electron Microscope (SEM) and EDS (Electron Diffraction Scanning) microanalyses. Single pass scratch testing in polyurethane using indenters with different contact angles was also carried out. The scar morphology of the wear, the wear mechanism and the thermal response were analyzed in order to correlate the conditions imposed by the pressure-velocity pair to the materials in contact. Eight different wear mechanisms were identified on the polyurethane surface. It was found correlation between the temperature variation and the wear scar morphology.