Modelling the chemical recycling of crosslinked poly (methyl methacrylate): kinetics of depolymerisation

Whereas increasing plastic solid waste production constitutes one of the main challenges of modern society, mainly due to the lack of suitable recycling technologies, chemical recycling represents an attractive solution for the conversion of plastic solid waste into valuable chemical intermediates. Herein, a kinetic model for the pyrolysis of a dental industry waste, ethylene glycol dimethacrylate (EGDMA) crosslinked poly (methyl methacrylate) (PMMA), is presented for the first time. Kinetics parameters and their statistical significance have been estimated from eight non-isothermal thermogravimetric analysis (TGA) experiments with heating rates varying between 5 and 50 °C·min-1 by using nonlinear regression. Our analysis indicates that the mechanism of depolymerisation of EGDMA crosslinked PMMA is likely to involve a consecutive reaction pathway involving two steps. The developed kinetic model - containing five kinetic parameters only - was able to predict well all non-isothermal TGA runs, and was validated against isothermal TGA experiments at 400 °C

Estimação dos parâmetros cinéticos de degradação térmica do polietileno com complexo catalítico heterotrinuclear Ti(IV)/NI(II)/Ti(IV) = Kinetic Parameters Estimation of Polyethylene Thermal Degradation through Heterotrinuclear Catalytic Complex Ti(IV)/Ni(II)/Ti(IV)

A avaliação da cinética de degradação térmica é um dos fatores significativos no aperfeiçoamento de novas rotas para reciclagem de polímeros em escala industrial. O objetivo principal deste trabalho é investigar a cinética de degradação térmica do polietileno produzido na presença do complexo catalítico heterotrinuclear Ti(IV)/Ni(II)/Ti(IV). A análise termogravimétrica do polietileno sintetizado demonstrou um comportamento térmico bimodal e um teor de cinzas em torno de 0,54 % após aquecimento até 700 ºC. A equação de Arrhenius foi proposta como modelo da constante cinética de degradação, sendo estimados a energia de ativação e a constante pré-exponencial. A técnica de otimização enxame de partículas foi utilizada para estimar os parâmetros, obtendo-se um excelente coeficiente de correlação, próximo a 1,00. Os valores dos parâmetros encontrados corroboram com a literatura e o modelo conseguiu predizer adequa - damente os dados experimentais disponíveis. // The evaluation of the kinetics of thermal degradation is one of the significant factors in the improvement of new routes for polymer recycling on an industrial scale. The main goal of this work is to investigate the kinetic of thermal degradation of the polyethylene produced in catalytic heterotrinuclear complex Ti(IV)/Ni(II)/Ti(IV). The thermogravimetric analysis of the polyethylene synthesized showed a bimodal thermal behavior and an ash content around 0.54 % after heating up to 700 ºC. The Arrhenius equation was proposed as a model of the kinetic constant of degradation, in which the activation energy and pre-exponential constant were estimated. The particle swarm optimization technique was used to estimate the parameters, obtaining an excellent correlation coefficient close to 1.00. The estimated parameters corroborate with the literature and the model suceeded in predict well the experimental data available

Education in the stricto sensu: Perspectives and Development of Continuing Interdisciplinary Practice

El Programa de Maestría Académica en Enseñanza PPGEn fue creado vía Término de Cooperación Técnica Científica entre el Instituto Federal de Educación, Ciencia y Tecnología de Mato Grosso-IFMT y Universidad de Cuiabá-UNIC, mediante Resolución CONSUP IFMT nº 100 el 26 de noviembre de. El curso tiene por objetivo el desarrollo de un trabajo interdisciplinario que integre las diversas áreas del conocimiento. Este artículo resulta de la práctica de la investigadora como docente del Programa y tiene por objetivo comprender sobre la enseñanza de la formación ofrecida por el programa a sus discentes en la perspectiva interdisciplinaria. Se trata de una investigación cualitativa, que utilizó como metodología las Narrativas de Formación, que trabaja puntualmente con recorridos personales y colectivos de sujetos involucrados en ambientes educativos. Como resultado, se percibió que la práctica desarrollada en el Máster en Enseño ocurre mediante la percepción de que el profesor es por excelencia investigador, posibilidad que la práctica interdisciplinaria desarrollada mediante acciones colectivas ha generado. Esta ha sido realizada como reflexión de la acción pedagógica educativa, para posibilitar que el docente la examine con la mirada de quien es mediador del proceso de construcción de saberes.O Programa de Mestrado Acadêmico em Ensino PPGEn foi criado via Termo de Cooperação Técnico Científico (Autores, verifiquem se é cientifico ou cientifica???) entre Instituto Federal de Educação, Ciência e Tecnologia de Mato Grosso- IFMT e Universidade de Cuiabá- UNIC, mediante Resolução CONSUP IFMT nº 100 em 26 de novembro de 2015.O curso tem por intento o desenvolvimento de um trabalho interdisciplinar que integre as diversas áreas do conhecimento. Este artigo resulta da prática da pesquisadora como docente do Programa e tem por objetivo compreender sobre o ensino da formação oferecida pelo programa aos seus discentes na perspectiva interdisciplinar. Os autores que sustentam o estudo discutem sobre formação de professores que envolvem saberes docentes, professor reflexivo e interdisciplinaridade. Trata-se de uma pesquisa qualitativa, que utilizou como metodologia as Narrativas de Formação, que trabalha pontualmente com percursos pessoais e coletivos de sujeitos envolvidos em ambientes educativos. Como resultado, percebeu-se que a prática desenvolvida no Mestrado em Ensino ocorre mediante a percepção de que o professor é por excelência pesquisador, possibilidade que a prática interdisciplinar desenvolvida mediante ações coletivas tem gerado. Esta tem sido realizada como reflexão da ação pedagógica educativa, para possibilitar que o docente a examine com o olhar de quem é mediador do processo de construção de saberes.The Academic Master's Program in Teaching PPGEn was created by means of a Technical Scientific Cooperation Agreement between the Federal Institute of Education, Science and Technology of Mato Grosso - IFMT and University of Cuiabá-UNIC, through Resolution CONSUP IFMT nº 100 on November 26 The course aims to develop an interdisciplinary work that integrates the different areas of knowledge. This article results from the practice of the researcher as a teacher of the Program and aims to understand about the teaching of the training offered by the program to its students in the interdisciplinary perspective. It is a qualitative research that used as a methodology the Training Narratives, which works punctually with personal and collective paths of subjects involved in educational environments. As a result, it was realized that the practice developed in the Master in Teaching takes place through the perception that the teacher is par excellence researcher, possibility that the interdisciplinary practice developed through collective actions has generated. This has been done as a reflection of educational pedagogical action, to enable the teacher to examine it with the look of who is mediator of the process of knowledge construction

Energy and system size dependence of \phi meson production in Cu+Cu and Au+Au collisions

We study the beam-energy and system-size dependence of \phi meson production (using the hadronic decay mode \phi -- K+K-) by comparing the new results from Cu+Cu collisions and previously reported Au+Au collisions at \sqrt{s_NN} = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented are from mid-rapidity (|y|<0.5) for 0.4 < pT < 5 GeV/c. At a given beam energy, the transverse momentum distributions for \phi mesons are observed to be similar in yield and shape for Cu+Cu and Au+Au colliding systems with similar average numbers of participating nucleons. The \phi meson yields in nucleus-nucleus collisions, normalised by the average number of participating nucleons, are found to be enhanced relative to those from p+p collisions with a different trend compared to strange baryons. The enhancement for \phi mesons is observed to be higher at \sqrt{s_NN} = 200 GeV compared to 62.4 GeV. These observations for the produced \phi(s\bar{s}) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems.Comment: 20 pages and 5 figure

Longitudinal scaling property of the charge balance function in Au + Au collisions at 200 GeV

We present measurements of the charge balance function, from the charged particles, for diverse pseudorapidity and transverse momentum ranges in Au + Au collisions at 200 GeV using the STAR detector at RHIC. We observe that the balance function is boost-invariant within the pseudorapidity coverage [-1.3, 1.3]. The balance function properly scaled by the width of the observed pseudorapidity window does not depend on the position or size of the pseudorapidity window. This scaling property also holds for particles in different transverse momentum ranges. In addition, we find that the width of the balance function decreases monotonically with increasing transverse momentum for all centrality classes.Comment: 6 pages, 3 figure