Many workers are daily exposed to chemical risks in their work place that has to be assessed and controlled. Due to exposure variability, repeated and random measurements should be conducted for valid estimates of the average exposure. Traditionally, experts such as safety engineers, work environment inspectors, and occupational hygienists, have performed the measurements. In self assessment of exposure (SAE), the workers perform unsupervised exposure measurements of chemical agents. This thesis studies a prerequisite for SAE, i.e. the workers’ mental models of chemical exposure. Further, the workers’ mental models are contrasted with experts’ reasons and decision criteria for measurement. Both qualitative and quantitative data generated from three studies (Paper I, II, and III) were used to describe the workers’ mental model of chemical exposure. SAE was introduced to workers in three different industries; transports (benzene), sawmill industry (monoterpenes), and reinforced plastic industry (styrene). By interviews, qualitative data were collected on the workers’ interpretation of measurement results and preventive actions. To evaluate the validity of worker measurement, the measurements were compared with expert measurements. The association between each worker’s number of performed measurement and mean level and variability in exposure concentrations was calculated. Mean absolute percent/forecast error (MAPE) was used to assess whether the workers’ decision models were in accordance with a coherence or correspondence model. In Paper IV, experts (safety engineers, work environment inspectors, and occupational hygienists) were interviewed to elucidate their mental models about the triggers and decision criteria for exposure measurements. The results indicate that the workers’ measurement results were in agreement with experts’. However, the measurement results were not a strong enough signal to induce workers to take preventive actions and sustained exposure measurements even if the measurement result were close to the occupational exposure limit. The fit was best for the median model, indicating that the workers’ mental models for interpretation of measurement data can best be described by the coherence theory rather than by the correspondence theory. The workers seemed to mentally reduce the variation in the exposure to a measure of central tendency (the median), and underestimated the average exposure level. The experts were found to directly take preventive actions instead of performing exposure measurements. When they performed exposure measurements, a worst case sampling strategy was most common. An important trigger for measurement for the experts was “request from the employer” (safety engineers), “legal demands” (work environment inspectors), and “symptoms among workers” (occupational hygienists). When there was a trigger, all experts mentioned expectations of high exposure level as a decision criterion for measurements. In conclusion, the studies suggest that workers’ mental interpretation model is best described in terms of a coherence model rather than a model of correspondence. The workers reduced the variation mentally in favor of an estimate of average exposure (median), which may imply that they underestimate short-term, high exposure health risks. A consequence is that interpretation of measurements such as SAE cannot be given to the individual worker without some support, e.g. from an expert. However, experts often chose to directly take preventive actions, without measuring the exposure. The results indicate that also the experts need support e.g. from the legal system if exposure measurements are to be done.

Doctor of Philosophy / The kinetics of electrosterically stabilized emulsion systems was studied. The aim of this was to understand the impact that steric and electrosteric stabilizers have on the kinetics of particle growth and particle formation in the area of emulsion polymerization. The well-established mechanisms that govern these processes for emulsions stabilized by conventional low molecular weight surfactants were used as a reference point for comparative purposes. Model latexes were synthesized that comprised of a poly(styrene) core stabilized by a corona of poly(acrylic acid). The advent of successful controlled radical polymerization techniques in heterogeneous media (via RAFT polymerization) allowed for latexes to be synthesized under molecular weight control. For the first time, the degree of polymerization of the stabilizing block on the particle surface was able to be controlled and verified experimentally using mass spectrometry techniques. Three latexes were made with different average degrees of polymerization of the stabilizing block; five, ten and twenty monomer units respectively. A methodology was developed to remove the RAFT functionality from the polymer chains present in the emulsion while retaining the desired particle morphology. Oxidation with tertbutylhydroperoxide (TBHP) was proven to be successful at eliminating the living character provided by the thiocarbonyl end-group. Extensive dialysis and cleaning of the latex was performed to ensure no residual TBHP or reaction by-products remained. Latexes with poly(styrene) cores were chosen for this work as poly(n-butyl acrylate) latexes were shown to be influenced by chain transfer to polymer, providing an additional kinetic complication. The three electrosterically stabilized emulsions were used as seed latexes in carefully designed kinetic experiments to measure the rate of polymerization as a function of time. Two independent techniques (chemically initiated dilatometry and γ-relaxation dilatometry) were used to measure the rate coefficients of radical entry (ρ) and exit (k) in these systems – the two parameters that essentially govern the rate of particle growth. The latexes were chosen such that they satisfied ‘zero-one’ conditions (i.e. that any given latex particle contains at most one growing radical at any given time) in order to simplify data analysis. Three different chemical initiators were used, each yielding a radical with a different electric charge. Results from γ-relaxation experiments demonstrated that the three electrosterically stabilized latexes gave very long relaxation times when removed from the radiation source, ultimately yielding very small k values. These values were up to a factor of 10 smaller than that predicted by the ‘transfer-diffusion’ model for exit for particles of that size. This reduction was attributed to a ‘restricted diffusion’ effect, where the exiting monomeric radical has to diffuse through a dense layer of polymer on the particle surface, where its mobility will be restricted. Modification of the Smoluchowski equation for diffusion-controlled adsorption/desorption to account for this postulate led to the development of a model that gave excellent semi-quantitative agreement with experiment. Chemically initiated dilatometric experiments (using three different types of initiator) gave the unusual result of very low reaction rates and low steady-state values of 'nbar', the average number of radicals per particle. Using the standard kinetic equations for styrene-based systems (where it is assumed that an exited monomeric radical undergoes re-entry), this led to the calculation of impossibly small values of the entry rate coefficient ρ (far below any background or ‘thermal’polymerization rate). However upon removing the assumption of re-entry and assuming that exited radicals undergo termination, the obtained values of ρ were in almost perfect agreement with the values predicted from the ‘control by aqueous phase growth’ entry mechanism. This unexpected result was attributed to chemical reaction with the poly(acrylic acid) stabilizers through chain transfer to polymer (via hydrogen-atom abstraction). This postulate was verified by separate experiments that demonstrated that poly(acrylic acid) could act as a reasonably efficient chain transfer agent for styrene polymerization. The addition of poly(acrylic acid) to the aqueous phase of a conventionally stabilized emulsion also led to the rate reduction seen previously. NMR experiments demonstrated the existence of poly(acrylic acid-graft-styrene), which could only be formed through termination of a poly(styrene) chain with a poly(acrylic acid) chain bearing a mid-chain radical (as the product of a chain transfer reaction). These additional terms of transfer and termination were included in the governing kinetic equations of emulsion systems (the Smith-Ewart equations) to develop a model to account for the behaviour of electrosterically stabilized latexes. The ultimate fate of an exiting radical was now shown to be a competition between fates; successful desorption into the aqueous phase, or chemical reaction (through transfer or termination) within the hairy layer. These additional terms were shown to significantly reduce the theoretical value of nbar, and were in excellent agreement with experiment. For small electrosterically stabilized particles with a densely packed ‘hairy layer,’ it was seen that transfer/termination is the dominant loss mechanism as opposed to desorption. The developed model showed that as the particle size was increased, the dominant loss mechanism once again became successful desorption into the aqueous phase. The model was shown to give excellent agreement with experimental data from ‘uncontrolled’ emulsion systems. To explain the highly unusual secondary nucleation behaviour seen in systems such as these, it was postulated that beta-scission of a poly(acrylic acid) chain bearing a mid-chain radical is an important mechanistic step in the nucleation mechanisms of these systems. Modelling (both steady-state and time-dependent) gave good agreement with experiment with a minimal number of adjustable parameters. Theory (and supporting experimental evidence) demonstrated that this nucleation mechanism is only significant at high particle numbers; under other conditions the well-known ‘homogeneous nucleation’ mechanism is once again dominant.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Additional advisors: Houston Byrd, Chris Lawson, Sadanandan Velu, Charles Watkins. Description based on contents viewed Feb. 9, 2009; title from PDF t.p. Includes bibliographical references.

Made available in DSpace on 2014-10-09T12:48:45Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:09Z (GMT). No. of bitstreams: 1 09306.pdf: 2901463 bytes, checksum: 25d5cd94a337a371809e1ba699428d99 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Submitted by Edileide Reis (leyde-landy@hotmail.com) on 2013-04-23T13:14:32Z No. of bitstreams: 1 Raphael Holt.pdf: 5449117 bytes, checksum: 052b88f3a4242aebdef5fdf978a8b5ce (MD5) / Made available in DSpace on 2013-04-23T13:14:32Z (GMT). No. of bitstreams: 1 Raphael Holt.pdf: 5449117 bytes, checksum: 052b88f3a4242aebdef5fdf978a8b5ce (MD5) Previous issue date: 2008 / A principal rota utilizada industrialmente para a produção de estireno é a desidrogenação catalítica do etilbenzeno, responsável por mais de 90% da produção mundial de estireno. O processo industrial é operado na faixa de temperatura de 550-700 oC, em excesso de vapor d’água aquecido, sobre catalisadores de óxido de ferro promovidos com potássio e cromo, que são tóxicos e possuem vida útil limitada a 2 anos. Neste contexto, existe a demanda por catalisadores que sejam ativos e seletivos nessa reação e que apresentem elevada vida útil, além de não serem tóxicos. Na busca de sistemas alternativos, neste trabalho foram desenvolvidos catalisadores de vanádio e magnésio suportados em carvão ativado obtido pela pirólise do copolímero estireno-divinilbenzeno, em atmosfera não oxidativa. Os catalisadores foram caracterizados pela medida da área superficial específica e de porosidade, difração de raios X, termogravimetria, análise térmica diferencial, espectrofotometria de absorção atômica, microscopia eletrônica de varredura acoplada ao sistema de quantificação por energia dispersiva. Os catalisadores foram avaliados na desidrogenação do etilbenzeno em ausência de vapor d’água, a 530 oC e 1 atm, para a produção de estireno. Verificou-se a presença de trióxido de vanádio e de aglomerados de vanádio e magnésio de diferentes tamanhos, nos sólidos. Os materiais apresentaram isotermas de adsorção e dessorção de nitrogênio do Tipo II ou IV, que são típicas de sólidos meso e macroporos com microporos associados, e uma histerese do Tipo H I, característica de materiais com poros cilíndricos. Estes sólidos apresentaram áreas superficiais específicas entre 378 e 611 m2/g. Os catalisadores com vanádio e magnésio apresentaram menor perda da área superficial específica que o carvão ativado, durante a desidrogenação do etilbenzeno. A adição de magnésio e vanádio provocou um aumento da atividade catalítica do carvão ativado e da seletividade ao estireno. Todos catalisadores foram mais ativos que uma amostra de catalisador comercial. O catalisador contendo 5 % de vanádio foi o mais promissor. Esta amostra conduziu, em ausência de vapor d’água, 35% de conversão do etilbenzeno, que é cerca de três vezes o valor obtido com uma amostra de catalisador comercial em presença de vapor d’água. Isto foi atribuído à ação catalítica do vanádio e à presença de grupos oxigenados na superfície do carvão que possuem atividade na desidrogenação do etilbenzeno. / Salvador

abstract: With the aid of metabolic pathways engineering, microbes are finding increased use as biocatalysts to convert renewable biomass resources into fine chemicals, pharmaceuticals and other valuable compounds. These alternative, bio-based production routes offer distinct advantages over traditional synthesis methods, including lower energy requirements, rendering them as more "green" and "eco-friendly". <italic>Escherichia coli</italic> has recently been engineered to produce the aromatic chemicals (S)-styrene oxide and phenol directly from renewable glucose. Several factors, however, limit the viability of this approach, including low titers caused by product inhibition and/or low metabolic flux through the engineered pathways. This thesis focuses on addressing these concerns using magnetic mesoporous carbon powders as adsorbents for continuous, in-situ product removal as a means to alleviate such limitations. Using process engineering as a means to troubleshoot metabolic pathways by continuously removing products, increased yields are achieved from both pathways. By performing case studies in product toxicity and reaction equilibrium it was concluded that each step of a metabolic pathway can be optimized by the strategic use of in-situ adsorption as a process engineering tool. / Dissertation/Thesis / Masters Thesis Chemical Engineering 2014

Made available in DSpace on 2014-10-09T12:43:46Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:55Z (GMT). No. of bitstreams: 1 06650.pdf: 4804396 bytes, checksum: 4f29fb57f44398a132f7549c46a4c525 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Orientador: Maria Isabel Felisberti / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-17T08:46:35Z (GMT). No. of bitstreams: 1 Santos_LuisEduardoPaisdos_D.pdf: 4191396 bytes, checksum: d2ee438006096211a78208eaecc89877 (MD5) Previous issue date: 2010 / Resumo: Este trabalho objetivou a síntese de copolímeros contendo grupos iônicos. Foram utilizadas diferentes rotas sintéticas para a obtenção de copolímeros de estireno (S) e ácido vinilfosfônico (AVF) (P(S-co-AVF)): 1. Copolimerização radicalar destes monômeros; 2. Copolimerização de estireno e vinilfosfonato de dimetila (VFDM) (P(S-co-VFDM)), seguida de hidrólise. Foram variadas as composições e condições de síntese. Copolímeros P(S-co- AVF) foram obtidos por polimerização radicalar em solução de dimetilformamida, utilizando peróxido de benzoíla (BPO) como iniciador. Estes copolímeros apresentaram baixo grau de inserção de AVF, entretanto, observou-se aumento da temperatura de transição vítrea (Tg), da resistência térmica e do teor de resíduos a 900°C, assim como a diminuição da massa molar com o incremento de AVF. Copolímeros P(S-co-VFDM) foram sintetizados por polimerização em solução de tolueno e em bulk, utilizando BPO como iniciador. Os copolímeros obtidos em bulk apresentaram maior inserção de VFDM, em comparação aos copolímeros obtidos em solução, partindo-se das mesmas frações molares dos monômeros, como conseqüência do maior tempo de reação para o primeiro caso. O aumento do teor de VFDM nos copolímeros causa a diminuição da massa molar, da Tg, da resistência térmica e do aumento no teor de resíduo a 900°C. Enquanto os copolímeros obtidos em bulk apresentaram degradação térmica complexa, os copolímeros obtidos em solução apresentam basicamente despolimerização. Os parâmetros de copolimerização dos monômeros S (rS) e VFDM (rVFDM) foram determinados pelos métodos de Mayo e Lewis e de Kelen e Tüdõs, sendo o parâmetro de copolimerização consideravelmente maior para o estireno (rS/rVFDM ~ 30). Os copolímeros obtidos em bulk foram hidrolisados em meio alcalino, obtendo-se ionômeros e polieletrólitos. Apesar da hidrólise não ser completa, a presença de grupos iônicos nestes copolímeros aumenta a Tg, o teor de resíduos e a complexidade da degradação térmica. / Abstract: The main purpose of this work was to synthesize copolymers with ionic groups. Different synthetic routes were applied to obtain copolymers of styrene (S) and vinylphosphonic acid (AVF) (P(S-co-AVF)): 1. Radical copolymerization of these monomers; and 2. Copolymerization of styrene and dimethyl-vinylphosphonate (VFDM) (P(S-co-VFDM)), followed by hydrolysis. The P(S-co-AVF) copolymers were obtained by radical polymerization in dimethylformamide solution using benzoyl peroxide (BPO) as an initiator. These copolymers presented low AVF insertion level. However, increase of the glass transition temperature (Tg), thermal resistance and residue at 900°C were observed. Besides, a decrease of the molar mass was observed with the increase of AVF content. P(S-co-VFDM) copolymers were synthesized by polymerization in toluene solution and in bulk, using also BPO as the initiator. The copolymers obtained by bulk polymerization presented higher VFDM insertion level than the copolymers obtained in solution, considering the same monomers molar fractions in the reactional medium. This behavior was a consequence of the higher reaction time involved in the first method. The increase of the VFDM content in the copolymers caused decreases of the molar mass, of the Tg and of the thermal resistance, and an increase of the residues level at 900°C. Moreover, the copolymers obtained in bulk presented a complex thermal degradation mechanism, while the copolymers obtained in solution presented basically a depolymerization. The copolymerization parameters of the monomers S (rS) and VFDM (rVFDM) were determined by Mayo and Lewis method and by Kelen and Tüdõs method. The copolymerization parameter of the styrene was significantly higher than the parameter of the (rS/rVFDM ~ 30). The copolymers obtained in bulk were hydrolyzed in an alkaline medium, resulting in ionomers and polyelectrolytes. Even though the hydrolysis was incomplete, the presence of the ionic groups in these copolymers has altered significantly its solubility and thermal degradation mechanism and has increased its Tg and residue level. / Doutorado / Físico-Química / Doutor em Ciências

Orientador: Teresa Massako Kakuta Ravagnani / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-17T16:55:35Z (GMT). No. of bitstreams: 1 Possani_Germano_M.pdf: 3312667 bytes, checksum: 30058f7ade4b339ee579a28950283ff8 (MD5) Previous issue date: 2011 / Resumo: Dentre os termoplásticos mais utilizados atualmente na indústria, pode-se mencionar o estireno, principal responsável pela produção de plásticos e borrachas. No processo de fabricação de estireno, a principal rota química é por meio da desidrogenação de etilbenzeno, com o hidrogênio como subproduto. A conversão de etilbenzeno nesta reação é em torno de 50,0 %, devido ao equilíbrio termodinâmico. Para deslocar esse equilíbrio e aumentar a produtividade de estireno,foram desenvolvidas novas configurações de reatores, tal como os reatores com membrana. eatores equipados com membranas de paládio fornecem uma seletividade maisalta ao estireno uando comparados com reatores equipados apenas com membranas porosas. Para explorar o otencial desse tipo de reator, modelagens matemáticas foram desenvolvidas a fim de determinar os parâmetros cruciais que regem esses processos. O objetivo deste trabalho foi modelar e simular um reator de leito fixo catalítico, envolto por uma membrana inerte permseletiva ao hidrogênio com transferência de calor e massa, sendo composta por uma camada de aço inoxidável de 1,6 mm de espessura, a qual serviu de suporte para a deposição de um filme de 20 µm de paládio. Para essa modelagem foram utilizados os métodos de Runge-Kutta-Gill para o cálculo das variáveis no sentido axial, tanto no retentato quanto no permeado, considerando no retentato um leito fixo catalítico descrito pelo modelo Pseudo-homogêneo, e para os cálculos das equações não lineares das frações molares das espécies e do fluxo mássico de hidrogênio na direção radial do reator foi utilizado o método de Newton-Raphson. Foram analisados os perfis de temperatura, pressão e concentração dos componentes da reação axialmente, considerando a transferência de massa e energia através da membrana, além dos valores para a conversão do etilbenzeno e produtividade em relação ao estireno. Como resultados das simulações foram obtidos valores para a conversão e produtividade de 50,3 % e 35,2 %, respectivamente, para o reator na condição de reator de leito fixo catalítico convencional, e 71,2 % e 60,2 %, para o reator na condição de reator de leito fixo catalítico envolto por uma membrana permseletiva ao hidrogênio, sendo estes valores 41,6 % maiores para a conversão do etilbenzeno e 71,0 % maiores para a produtividade em relação ao estireno. Concluiu-se que com a implementação da membrana no reator em estudo, considerando também a troca térmica na membrana, esta é uma boa opção como nova alternativa para o processo de fabricação do estireno / Abstract: Among the most widely used thermoplastics in the industry, styrene can be mentioned, the main responsible for the production of plastics and rubbers. In the manufacturing process of styrene, the principal chemical route is by means of dehydrogenation of ethylbenzene, with hydrogen as a byproduct. The conversion of ethylbenzene in this reaction is around 50,0 % due to thermodynamic equilibrium. To overcome this equilibrium and increase the productivity of styrene, new reactor configurations were developed such as membrane reactors. Membrane reactors equipped with a palladium membrane provide a higher selectivity compared with reactors that are equipped only with a porous membrane. To explore the potential of this type of reactor, mathematical models were developed to determine the crucial parameters governing these processes. The aim of this study was to model and simulate a fixed bed catalytic reactor, surrounded by a permselective to hydrogen inert membrane with heat and mass transfer, composed by a layer of stainless steel of 1,6 mm thickness, which served as support for deposition of a 20 µm film of palladium. For this modeling the Runge-Kutta-Gill method was used to calculate the variables in the axial direction, both in tube side and in permeate side, considering in tube side a catalytic fixed bed described by Pseudo-homogeneous model, and for the calculations of nonlinear equations of the mole fractions of species and the mass flow of hydrogen in the radial direction it was used the method of Newton-Raphson. Profiles of temperature, pressure and concentration of reaction components on axial toward were analyzed considering the heat and mass transfer across the membrane, besides the values for ethylbenzene conversion, selectivity and productivity in relation to styrene. As the simulation results, values were obtained for the conversion and productivity of 50,3 % and 35,2 %, respectively, putting the reactor on condition of conventional catalytic fixed bed reactor, and 71,2 % and 60,2 % for the reactor on condition of catalytic fixed bed reactor surrounded by a permselective membrane to hydrogen, then , the obtained values were 41,6 % higher for the conversion of ethylbenzene and 71,0 % higher for the productivity of styrene. It was concluded that with the implementation of a membrane in reactor under study, also considering the heat transfer in the membrane, this technology is a good option as new alternative to the styrene manufacturing process / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

Orientador: Liliane Maria Ferrareso Lona / Dissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-07T07:49:45Z (GMT). No. of bitstreams: 1 Franco_CileneMeinberg_M.pdf: 1835289 bytes, checksum: 8c7c34fee69d338538caffa2e9546741 (MD5) Previous issue date: 2006 / Resumo: Iniciadores mono funcionais são largamente utilizados em polimerizações VIa radical livre. Muitas vezes, na busca de maiores produtividades, utilizam-se temperaturas de operação mais elevadas e/ou maiores concentrações iniciais de iniciador, que por conseqüência, geram polímeros com pesos moleculares mais baixos. O uso de iniciadores difuncionais permite o aumento da produtividade sem a redução no peso molecular do produto final, o que pode ser urna característica desejável. A pesquisa com iniciadores difuncionais é atual e de grande interesse industrial. O objetivo deste trabalho é analisar o efeito da funcionalidade do iniciador, no caso mono e difuncional, sobre a polimerização via radical livre, considerando corno caso estudo um polímero linear, o poliestireno, e um ramificado, o poli (acetato de vinila). Para isso, foram feitas, experimentalmente, reações de polimerização em ampolas de vidro (polimerização em massa), com o iniciador mono funcional (Luperox TBEC) e o di funcional (Luperox 531). Foram analisados também o efeito da temperatura de polimerização e a concentração de iniciador. Também neste trabalho é apresentado um estudo estatístico através de um Planejamento Fatorial, a fim de analisar o efeito das variáveis temperatura e concentração de iniciador na polimerização do estireno com iniciador difuncional. Observou-se, tanto para o estireno corno para o acetato de vinila, que quando utilizado o iniciador difuncional é possível obter conversões maiores, sem alterar o peso molecular médio mássico e numérico, sendo que em alguns casos pode se até obter um aumento no peso molecular. O uso de iniciador di funcional é também mais viável economicamente, pois apresenta melhores resultados frente ao monofuncional, mesmo quando utilizado em concentrações ou temperaturas menores do que as utilizadas com o iniciador mono funcional. É importante salientar o caráter inovador desta pesquisa, já que não foram encontrados, em literatura aberta, dados experimentais da polimerização do acetato de vinila (ou outro monômero que produza ramificações de cadeia longa) utilizando iniciadores difuncionais / Abstract: Monofunctional initiators are extensively utilized in free radical polymerization. In order to increase productivity, higher temperature or higher initial initiator concentration are used, therefore polymers with lower molecular weights are obtained. Bifunctional initiators increase the polymerization rate without decreasing the average molecular weight and this can be desirable. They are an important issue to be investigated and are of great interest to industries. The objective of this work is to analyze the effect of the functionality of the initiator, by using mono and bifunctional, in free radical polymerization, for linear polymer (poly styrene) and branched polymer (poly(vinyl acetate)). Polymerizations were experimentally performed in glass ampoules (bulk polymerization) using both mono(Luperox TBEC) and bi- (Luperox 531) functional initiators. The effects of temperature and initiator concentration were also analyzed for various polymerization conditions. This work includes a statistical study using the factorial design to analyze the effect of temperature and initiator concentration in styrene polymerization with bifunctional initiator. It is observed in this study, that high conversions with no effect in the molecular weigh of the dead polymer can be achieved using bifunctional initiators in the polymerization of styrene and vinyl acetate. In many cases, it is possible to obtain higher molecular weights. Bifunctional initiator can also be used to provide reduction costs to initiators. They showed better results than the monofunctional initiator when lower concentration or temperature lower were utilized. / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química