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Master's Dissertation
DOI
10.11606/D.3.2009.tde-04092009-154421
Document
Author
Full name
Paula Maria Nogueira Ambrogi
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2009
Supervisor
Committee
Giudici, Reinaldo (President)
Guardani, Roberto
Lona, Liliane Maria Ferrareso
Title in Portuguese
Modelagem matemática do processo de modificação química de polietileno por enxerto de anidrido maleico.
Keywords in Portuguese
Modelos matemáticos
Polímeros (materiais)
Simulação
Abstract in Portuguese
Este trabalho tem como escopo o desenvolvimento de um modelo matemático representativo do processo de enxerto de anidrido maleico em polietileno, processo conhecido como grafting, com o objetivo de prever as modificações no grau de enxerto e teor de gel. Neste processo utiliza-se um iniciador, geralmente um peróxido, para gerar radicais livres, os quais abstraem hidrogênio das moléculas do polímero, gerando radicais poliméricos. O anidrido maleico pode reagir com estes radicais poliméricos, enxertando-se à cadeia polimérica, ou com os radicais fragmentos do iniciador. O mecanismo inclui também as reações de terminação entre os diferentes tipos de radicais presentes. O teor de gel é calculado a partir do grau de formação de ligações cruzadas utilizando-se a aproximação de Charlesby-Pinner. As constantes cinéticas do modelo foram estimadas via regressão não-linear, usando dados experimentais obtidos na literatura, e o modelo foi validado com outros conjuntos de dados, também obtidos da literatura. O modelo obtido mostrou-se capaz de representar adequadamente os dados experimentais em diferentes condições.
Title in English
Mathematical modeling of the chemical modification process of polyethylene by grafting of maleic anhydride.
Keywords in English
Grafting
Maleic anhydride
Polyethylene
Simulation
Abstract in English
The scope of this work is the development of a mathematical model that can represent the process of grafting of maleic anhydride in polyethylene. The objective of this model is to preview the main modifications in polymer structure, as degree of grafting and degree of gel. In this process, an initiator, generally a peroxide) is used to generate free radicals that can abstract hydrogen from the polymer molecules, producing polymeric radicals. Maleic anhydride can react with these polymeric radicals, resulting in grafted polymer chains, or with the initiator radicals. This mechanism includes termination reactions between the different types of radicals present. Gel content was calculated from the crosslinking degree using the approximation of Charlesby-Pinner. Kinetic constants of the model were estimated through non-linear regression, by fitting the model to experimental data taken from literature. The model obtained was further tested using other data sets obtained from literature. The developed model was able to represent adequately the experimental data under different conditions.
 
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DISSERTACAO.pdf (648.84 Kbytes)
Publishing Date
2009-09-24
 
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