O ENSINO DE FÍSICA NA ÁREA DE CIÊNCIAS NATURAIS NO ENSINO FUNDAMENTAL I E ENSINO FUNDAMENTAL II SEGUNDO OS PARÂMETROS CURRICULARES NACIONAIS

The present study aims to verify and report what the National Curricular Parameters (PCNs) suggest regarding Physics subjects in Elementary School and Junior High School in the area of Natural Sciences and compare with what the textbooks of Sciences analyzed by the National Program Of the Didactic Book (PNLD) 2016 and 2017 relate about this. The comparison shows that, although physics content has been contemplated in PCNs since the first years of elementary school, few of these contents are covered in textbooks. There is, therefore, a gap between the knowledge that students are expected to acquire and the knowledge offered in textbooks. This disproportion may be one of the responsible for students’ lack of interest and difficulty in learning Physics in High School.O presente trabalho tem por objetivo verificar e relatar o que os Parâmetros Curriculares Nacionais (PCNs) sugerem a respeito de temas de Física nos Ensino Fundamental I e II na área de Ciências Naturais e comparar com o que os livros didáticos de Ciências analisados pelo Programa Nacional do Livro Didático (PNLD) 2016 e 2017 trazem a respeito. A comparação mostra que, apesar de conteúdos de Física serem contemplados nos PCNs desde os primeiros anos do Ensino Fundamental I, poucos destes conteúdos são abrangidos nos livros didáticos.  Há, portanto, um déficit entre o conhecimento que se espera que os alunos adquiram e o conhecimento ofertado em livros didáticos. Esta desproporção pode ser um dos responsáveis pelo desinteresse e dificuldade dos alunos em aprender Física no Ensino Médio

ANÁLISE DE DUAS PROPOSTAS DE ATIVIDADE EXPERIMENTAL SOBRE MOMENTO DE UMA FORÇA NAS AULAS DE CIÊNCIAS PARA O ENSINO FUNDAMENTAL

The present study aims to compare two activities, conventional experimentation and experimentation in a virtual laboratory, for the teaching of Moment in the Physics classes of students belonged to 9th year of Middle School. In order to do this, an experimental script was prepared for each one of the both experimentation activities and discussed among them advantages and disadvantages in the preparation of the activity, in the execution by the teacher and in the execution by the student. The results of the comparisons demonstrated the particularities that each activity has; in addition, they have shown the importance of both, since the learning can occur in both types of experimentationO presente trabalho tem por objetivo comparar duas atividades, uma elaborada na forma de experimentação convencional e outra na forma de experimentação em laboratório virtual, para o ensino de Momento de uma Força nas aulas de Física dos estudantes do 9° ano do Ensino Fundamental II. Para tanto, foi confeccionado um roteiro experimental para cada uma das atividades e discutidas vantagens e desvantagens na preparação das mesmas, na execução pelo professor e pelo aluno. Os resultados das comparações foram significativos e demonstraram as particularidades que cada atividade possui, além de evidenciarem a igual importância de ambas, uma vez que a aprendizagem pode ocorrer nas duas formas de experimentação

Effect of carbon nanotubes addition on the mechanical and thermal properties of epoxy matrices

In this work, nanocomposites were prepared by adding a small amount of single walled carbon nanotubes (SWCNTs) to an epoxy resin aiming to study the resulting mechanical, viscoelastic and thermal properties of the nanocomposites. To optimize the processing of the nanocomposites and to favor a homogeneous dispersion of the SWCNTs on the matrix, acetone was used to reduce resin viscosity, increasing diffusion of the SWCNTs in the solution. The epoxy/SWCNTs/acetone systems were also sonicated in order to minimize entanglement of the SWCNTs. The systems were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetry, differential scanning calorimetry and dynamic mechanical analysis. The results indicated that the addition of small amounts of SWCNTs to epoxy leads to slight structural changes in the epoxy matrix which, together with the presence of SWCNTs, may reflect on its mechanical and viscoelastic propertie

Effect of carbon nanotubes addition on the mechanical and thermal properties of epoxy matrices

In this work, nanocomposites were prepared by adding a small amount of single walled carbon nanotubes (SWCNTs) to an epoxy resin aiming to study the resulting mechanical, viscoelastic and thermal properties of the nanocomposites. To optimize the processing of the nanocomposites and to favor a homogeneous dispersion of the SWCNTs on the matrix, acetone was used to reduce resin viscosity, increasing diffusion of the SWCNTs in the solution. The epoxy/SWCNTs/acetone systems were also sonicated in order to minimize entanglement of the SWCNTs. The systems were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetry, differential scanning calorimetry and dynamic mechanical analysis. The results indicated that the addition of small amounts of SWCNTs to epoxy leads to slight structural changes in the epoxy matrix which, together with the presence of SWCNTs, may reflect on its mechanical and viscoelastic propertie

The effect of acetone addition on the properties of epoxy

In this work, a varied amount of acetone was employed to dissolve an epoxy resin and then a route was followed to remove the acetone, simulating a frequently used method to disperse nanofillers in thermoset matrices. Analyses were then carried out to address the influence of residual acetone on the curing process and on the epoxy properties. The results showed a detrimental effect on the mechanical properties of the cured epoxy due to the presence of residual acetone and also a less brittle-like fracture of the specimen. Fourier transform infrared spectroscopy and thermogravimetric analyses were additionally used to characterize the cured resins and have also indicated the presence of a small amount of acetone. Nevertheless, rheological measurements indicated that 10.0 wt.% acetone addition on the resin causes a significant decrease in viscosity (around 50%) which may promote a better dispersion of nanofillers