DEMA - Artigos Publicados em PeriódicosColeção de artigos publicados em periódicoshttp://hdl.handle.net/123456789/542024-03-29T06:29:02Z2024-03-29T06:29:02ZInfluence of reprocessing in the formation of functional groups during low density polyethylene agingSelonke, Maurício MMoreira, Tiago FSchafranski, Lincon LBassani, AdrianeCarvalho, Benjamim de MPinheiro, Luís APrestes, Rosilene A.Almeida, Denise Mhttp://hdl.handle.net/123456789/8832013-08-20T17:41:20Z2012-01-01T00:00:00ZInfluence of reprocessing in the formation of functional groups during low density polyethylene aging
Selonke, Maurício M; Moreira, Tiago F; Schafranski, Lincon L; Bassani, Adriane; Carvalho, Benjamim de M; Pinheiro, Luís A; Prestes, Rosilene A.; Almeida, Denise M
In recent years, the interest in polymer recycling has increased. However, in every reprocessing step the material undergoes shear stress and is affected by temperature and oxygen. The aim of this paper is to investigate the influence of multiple extrusion in the generation of functional groups, namely hydroperoxide, carbonyl, and transvinylene. Low density polyethylene was reprocessed three times in a single screw extruder. In each recycling step hot pressed films were prepared. These films were submitted to a heat treatment in an oven with air circulation and renovation to proceed with aging tests at different times and temperatures. The results obtained showed that all functional groups had their concentration increased with the increase in number of reprocessing, the aging time and temperature of the heat treatment. The factorial design was applied to verify the influence of these parameters. All the parameters had significant effects, since their regression coefficients had the same order of magnitude, with the most influential parameter being the aging temperature, followed by the aging time and number of extrusions. Most of the interactions were influential, indicating that the formation of functional groups depends upon their interaction, and not only on their isolated effects.
2012-01-01T00:00:00ZPreparação de dióxido de estanho via decomposição de organometálicosAntunes, Augusto CelsoAntunes, Sandra Regina M.Pianaro, Sidnei AntônioLongo, ElsonVarela, José AranaSantos, Renata Dinnieshttp://hdl.handle.net/123456789/6582011-12-07T16:25:25Z2000-01-01T00:00:00ZPreparação de dióxido de estanho via decomposição de organometálicos
Antunes, Augusto Celso; Antunes, Sandra Regina M.; Pianaro, Sidnei Antônio; Longo, Elson; Varela, José Arana; Santos, Renata Dinnies
Neste trabalho foram obtidos organometálicos por meio da interação química
do Sn2+ com os seguintes ácidos: oxálico, tartárico e cítrico, em meio aquoso. Estes
sais de ácidos carboxílicos foram utilizados como precursores do processo de
preparação de dióxido de estanho.
A estabilidade teórica da formação dos organometálicos foi avaliada por
meio de cálculos teóricos mecânico-quânticos, utilizando-se o método MNDO
(Modified Neglect of Diatomic Overlap). Os pós foram caracterizados pelas seguintes técnicas: espectroscopia de absorção na região do infravermelho, difração
de raios X, adsorção e dessorção de N2 pelo método BET e análise térmica ( DTA
e TG). Pela análise dos resultados pode-se verificar que os orgonometálicos obtidos
estão na forma anidra e suas decomposições ocorrem com a eliminação de CO2 e
H2O, formando como produto final SnO2. Portanto, o citrato, tartarato e o oxalato
de estanho (II) são fontes alternativas de obtenção de SnO2.
2000-01-01T00:00:00ZExtensão universitária: promovendo a interação dos cursos de engenharia da Uepg com o ensino médioChinelatto, Adriana Scoton AntonioVaz, Maria Salete Marcon GomesAlmeida, Mareci MendesModesto, Flávia AndréaFoltran Junior, Dierone CésarKrüger, José AdelinoIelo, Frederico Guilherme de Paula Ferreirahttp://hdl.handle.net/123456789/6372011-11-16T10:53:37Z2007-01-01T00:00:00ZExtensão universitária: promovendo a interação dos cursos de engenharia da Uepg com o ensino médio
Chinelatto, Adriana Scoton Antonio; Vaz, Maria Salete Marcon Gomes; Almeida, Mareci Mendes; Modesto, Flávia Andréa; Foltran Junior, Dierone César; Krüger, José Adelino; Ielo, Frederico Guilherme de Paula Ferreira
Este artigo descreve as atividades de extensão universitária que serão desenvolvidas para promover a Interação dos Cursos de Engenharia da Universidade Estadual de Ponta Grossa com o Ensino Médio. O objetivo principal é despertar o interesse dos alunos do ensino médio em cursar Engenharia. As atividades estão agrupadas em duas etapas. Na primeira, a Universidade se apresenta aos professores e alunos do ensino médio, visando a motivação dos mesmos. E na segunda, os professores (do ensino médio e universitário) e alunos compartilham os conhecimentos dentro do ambiente universitário, estreitando o relacionamento entre as partes.; This paper describes the activities of a university extension project that should be developed to promote the Interaction between Engineering Courses at Ponta Grossa State University and high school students. The main objective is to arouse in high school students interest for attending Engineering courses. The activities will be grouped in two stages. In the first stage the University professors will introduce Engineering subjects to high school students and teachers to motivate them. In the second one, teachers and students will be together at the university to share knowledge in order to straighten the connection between the university and the schools.
2007-01-01T00:00:00ZAnálise matricial preliminar de estruturas estaticamente indeterminadas por meio do método da flexibilidade: um estudo de caso envolvendo duas vigas hiperestáticas e a determinação completa dos seus deslocamentos, rotações e coeficientes de flexibilidadeSantos, Alexandre Manoel dosScheer, SérgioLobeiro, Adilandri MércioAlves, Lucas Máximohttp://hdl.handle.net/123456789/5292011-03-28T17:02:55Z2008-01-01T00:00:00ZAnálise matricial preliminar de estruturas estaticamente indeterminadas por meio do método da flexibilidade: um estudo de caso envolvendo duas vigas hiperestáticas e a determinação completa dos seus deslocamentos, rotações e coeficientes de flexibilidade
Santos, Alexandre Manoel dos; Scheer, Sérgio; Lobeiro, Adilandri Mércio; Alves, Lucas Máximo
The aim of this paper is to describe the use of the Flexibility Method to solve two classical problems pertained by structural analysis knowledge area, in engineering context: the matrix analysis of framed structures. Two beams statically indeterminated are solved. There are three specific motivations to make a presentation of a complete solution for those problems, by this method. The first one is its pedagogic fashion. At graduation level in engineering, it is important to encourage the students to acquire perceptions about the relation existent between actions and deformations of a given framed structure under a given pattern loading. The deflections can be determined precisely and the redundant actions are known by hand work, spite to access directly the set of data localized at suitable tables of reference textbooks. We think that, in academic terms and for academic problems, the analyst must know the complete process to calculate them, precisely, without computers and reference tables. The second one is about the characteristic of Flexibility Method. With it, the analyst can choose alternative paths to implement the compatibility equations associated with the supports configurations. Then, he uses the superposition principle to calculate de deflections and rotations. The third one is that this method represents a good opportunity for the students to learn the basis for the Force Method, another one, so important in analysis of framed structures.
2008-01-01T00:00:00Z