Orientador: Alexandre Luiz Souto [Unesp] Borges / Resumo: Este estudo visou sintetizar e caracterizar mantas não tecidas de nanofibras (NFs) do acrilonitrila butadieno estireno (ABS), poliamida 6 (PA6) e poliestireno (PS), e avaliar sua capacidade de ser utilizada como reforço no polimetilmetacrilato (PMMA). O ABS foi dissolvido em diclorometano e acetona, a PA6 pelo 1,1,1,3,3,3-hexafluoro-2-propanol e o PS pela dimetilformamida, em uma concentração definida em estudo piloto. Após determinados os melhores parâmetros de eletrofiação (tensão contínua, razão de fluxo e distância agulha/anteparo) as amostras de cada grupo foram analisadas em microscopia eletrônica de varredura, análise de molhabilidade, análise de difratometria de raios X, espectroscopia de infravermelho por transformada de Fourier, diâmetro das fibras e resistência a tração. As NFs produzidas foram incluídas na área de tração dos corpos de prova em resina acrílica ativada termicamente (RAAT) conforme ISO1567, perfazendo 4 grupos (n=20), 1 controle (Grupo 1) e 3 experimentais (Grupo 2, RAAT+NF/ABS; Grupo 2, RAAT+NF/PA6; Grupo 4, RAAT+NF/PS), para ensaio de flexão três pontos para analisar suas propriedades mecânicas, como: módulos de elasticidade e resistência a flexão. De acordo com os testes de caracterização, as mantas se apresentaram hidrofóbicas, não houve mudança de sua estrutura polimérica, concluindo-se então que a técnica da eletrofiação foi promissora na síntese de mantas de NFs. A variação dos parâmetros afetou diretamente a morfologia, resultando em fibras u... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study aimed to synthesize and characterize non-woven blankets of acrylonitrile butadiene styrene (ABS), polyamide 6 (PA6) and polystyrene (PS) nanofibers (NFs), and to evaluate their ability to be used as reinforcement in polymethyl methacrylate (PMMA). ABS was dissolved in dichloromethane and acetone, PA6 by 1,1,1,3,3,3- hexafluoro-2-propanol and PS by dimethylformamide at a concentration defined in a pilot study. After determining the best electrospun parameters (continuous voltage, flow rate and needle/shield distance) the samples from each group were analyzed by scanning electron microscopy, wettability analysis, X-ray diffraction analysis, Fourier transform infrared spectroscopy, fiber diameter and tensile strength. The NFs produced were included in the tensile area of the thermally activated acrylic resin (RAAT) specimens according to ISO1567, making up 4 groups (n = 20), 1 control (Group 1) and 3 experimental (Group 2, RAAT+NF/ABS; Group 3, RAAT+NF/PA6 and Group 4 (RAAT+NF/PS), for three point bending test to analyze their mechanical properties, as: modules of elasticity and flexural strength. According to the characterization tests, the blankets were hydrophobic, there was no change in their polymeric structure, concluding that the electrospinning technique was promising in the synthesis of NFs blankets. The parameters variation affected directly in the morphology, resulting in uniform, bulky and without defects (beads) NFs blankets. The Groups 3 and 4 (NF/PA6+RA... (Complete abstract click electronic access below) / Mestre

This master‘s thesis deals with 3D printing for non-commercial RepRap 3D printer type and materials used in printing. The outcome of this work is a brief introduction to 3D printing, the theory of heat transfer and analysis of the two most important parts of the printer hot bed and hot end. To analyze and optimize the temperature profile of the hot bed and hot end are used Computer Aided Engineering systems CAD and CAE, SolidWorks and SolidWorks Flow Simulation.

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[pt] O Acrilonitrila-Butadieno-Estireno (ABS) é um polímero de grande uso industrial, sendo empregado em inúmeros produtos. Muitas de suas aplicações necessitam de uma elevada resistência a combustão seja pela presença de cargas elétricas (Efeito Joule) ou a exposição a ambientes de altas temperaturas. No entanto, o ABS, de modo semelhante a maioria dos polímeros, não é tão resistente a combustão, sendo necessário o emprego de aditivos Retardantes de Chamas (RC). A introdução desses aditivos pode, entretanto, acarretar alteração nas propriedades mecânicas, de forma que é necessário se comparar o comportamento do material com e sem aditivos. Particularmente importante é o comportamento a longo prazo, como a fluência. Assim, nesse trabalho foi avaliado o comportamento a fluência do ABS sem aditivo e de três sistemas ABS/RC. Foi usado um sistema empregando um aditivo comercial à base de bromo (ABS − Br), que serviu como base de comparação e dois sistemas recentemente desenvolvidos, empregando bio-retardantes, a saber: ácido tânico (TA) e polifosfato de amônio (APP). Os resultados dos ensaios mostraram que o aditivo comercial não acarretou variação da vida em fluência em relação ao ABS sem aditivo. Por outro lado, os resultados indicaram que a vida em fluência foi reduzida quando o aditivo APP foi incorporado e que aumentou quando o TA foi adicionado. Os dados experimentais dos ensaios de fluência foram usados para avaliar o comportamento viscoelástico dos quatro grupos de materiais. O ABS teve seu comportamento adequadamente representado pelo modelo de Burgers, assim como a ABS com aditivo à base de bromo. O modelo que melhor descreveu o comportamento do ABS com APP foi o modelo modificado de Burgers (Streched Burgers). Nem todas as amostras do ABS com TA apresentaram fluência no intervalo de tempo usado e o modelo que melhor descreveu o comportamento foi o do sólido linear padrão. / [en] Acrylonitrile-Butadiene-Styrene (ABS) is a polymer of great industrial use, being used in numerous products. Many of its applications require a high resistance to combustion, either due to the presence of electrical charges (Joule Effect) or exposure to high temperature environments. However, ABS, like most polymers, is not as resistant to combustion, requiring the use of Flame Retardant (RC) additives. The introduction of these additives can, however, lead to changes in the mechanical properties, so it is necessary to compare the behavior of the material with and without additives. Particularly important is long-term behavior such as fluency. Thus, in this work, the creep behavior of ABS without additive and of three ABS/RC systems was evaluated. A system employing a commercial bromine-based additive (ABS − Br) was used, which served as a basis for comparison and two recently developed systems employing bio-retardants, namely: tannic acid (TA) and ammonium polyphosphate (APP) . The test results showed that the commercial additive did not cause a change in creep life compared to ABS without additive. On the other hand, the results indicated that the creep life was reduced when the APP additive was incorporated and that it increased when the TA was added. Experimental data from creep tests were used to evaluate the viscoelastic behavior of the four groups of materials. ABS had its behavior adequately represented by the Burgers model, as well as ABS with bromine-based additive. The model that best described the behavior of ABS with APP was the modified Burgers model (Streched Burgers). Not all ABS samples with TA showed fluence in the time interval used and the model that best described the behavior was the standard linear solid.

[pt] A reação de copolimerização de estireno com divinilbenzeno gera um polímero reticulado que tem como uma das principais aplicações o uso como recheio em colunas cromatográficas (de permeação em gel ou por troca iônica por exemplo) e também pode ser usado como suporte de biocatalisador, justamente por ter as cadeias reticuladas e suportar condições extremas de reação. Essa polimerização ocorre formando ligações cruzadas entre as cadeias poliméricas, gerando alta estabilidade térmica e mecânica. Uma característica dessa reação é a formação de uma fração de gel que, na verdade, é um copolímero insolúvel com alto grau de reticulação em relação ao produto polimérico que se encontra em solução (fração sol) formado ao final do processo. Por isso, conhecer a distribuição de tamanho de cadeia da fração gel é um desafio para esse sistema tendo em vista que a sua elevada cadeia reticulada impossibilita que ele seja solubilizado para ser analisado por cromatografia por permeação em gel (GPC). O desenvolvimento de modelos cinéticos capazes de predizer qual a contribuição das frações solúvel e gel na distribuição de massa molar na copolimerização em solução desse copolímero é essencial para a mitigação dessa formação de gel, permitindo a operação estável de reatores contínuos industriais. Com base no que foi apresentado, o objetivo principal deste trabalho é propor um mecanismo cinético para a produção do copolímero reticulado via radicais livres em solução. Adicionalmente, desenvolver um modelo capaz de predizer a distribuição de massa molar nas frações solúveis e gel. Para atingir essa proposta, foi utilizado o método de Monte Carlo baseando-se na divisão das moléculas do copolímero em cadeias lineares e em grupos com reticulações. O modelo desenvolvido foi validado com dados experimentais coletados de outros trabalhos e previu os dados de conversão, massas molares médias e ponderais, distribuição de massas molares com distinção da fração solúvel e gel, apresentando como resultado que a fase solúvel deste sistema representa somente cadeias que sofreram somente uma reticulação. Este modelo proposto pode ser usado para fins de monitoramento e otimização, como encontrar condições experimentais nas quais a fração gel é gerada em menores quantidades. / [en] The copolymerization reaction of styrene with divinylbenzene creates a cross-linked polymer, which one of the main applications is its use as a filling in chromatography columns (gel permeation or ion exchange, for example) and it can also be used as a biocatalyst support, precisely because it has cross-linked chains and supports extreme reaction conditions. This polymerization occurs by forming cross-links between the polymeric chains, resulting in high thermal and mechanical stability. A characteristic of this reaction is the formation of a gel fraction which, in fact, is an insoluble copolymer with a high degree of cross-linking in relation to the polymeric product that is in solution (sol fraction) formed at the end of the process. Therefore, knowing the chain size distribution of the gel fraction is a challenge in this system, considering that its high molecular weight makes it impossible to solubilize a sample for gel permeation chromatography analysis (GPC). The development of kinetic models capable of predicting the contribution of the soluble and gel fractions to the molar mass distribution in solution copolymerization of this copolymer is essential for the mitigation of this gel formation, allowing the stable operation of continuous industrial reactors. Based on what has been presented, the main objective of this study is to investigate the kinetics of cross-linked copolymer formation via free radical solution polymerization. Additionally, it was also intended to develop a model capable of predicting the molecular weight distribution of the sol and gel fractions. To achieve these goals, the Monte Carlo method was used, based on the division of the copolymer molecules in linear chains and in crosslinking groups. The developed model was validated with experimental data collected from other studies and predicted the conversion data, average and weight molar masses, molar mass distribution with distinction of the soluble fraction and gel, showing as a result that the soluble phase of this system represents only chains that they underwent only one crosslinking. This proposed model can be used for monitoring and optimization purposes, such as finding experimental conditions in which the gel fraction is generated in smaller amounts.

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1. Investigations of styrene polymerized in wood using ionizing radiation as the chain initiator indicate that property improvements are of the same order as for thermally initiated polymerization. 2. Free radicals have been detected in irradiated cellulose, Dioxane lignin, Spruce Periodate lignin and Beaun’s “Isolated Native Lignin” as well as in wood subjected to radiation. Consequently, wood radical identification is not possible. 3. Analysis of radical concentrations and decay suggest the presence of one or more decaying radical species in irradiated wood. The persistent maximum in radical concentration found corresponds to one or two unique radical sites per molecule; possibly the terminal hydroxyl group. 4. Results suggest that in the grafting reaction the initiation is a direct radical-monomer couple and does not involve decomposing peroxides. / Thesis / Master of Engineering (ME)

Styrol-Monooxygenasen (SMOs) spielen im bakteriellen Abbau von Styrol eine wichtige Rolle. Sie epoxidieren den Kohlenwasserstoff zu (S)-Styroloxid und waren bis vor kurzem vor allem aus Gram-negativen Vertretern wie Pseudomonaden bekannt. Das Grampositive nocardioforme Bodenbakterium Rhodococcus opacus 1CP kann Styrol als Energie- und Kohlenstoffquelle nutzen und verfügt über zwei Typen von SMOs. Neben StyA2B, einer fusionierten FAD:NADH-Oxidoreduktase (StyB) und Monooxygenase (StyA2) findet sich eine weitere Monooxygenase StyA1, deren Gen direkt stromaufwärts zu styA2B lokalisiert ist. Zusätzlich zum natürlichen Fusionsprotein StyA2B gelang kürzlich die Konstruktion künstlicher Fusionen StyAL1B und StyAL2B aus Pseudomonas fluorescens ST. Um sowohl StyA1/StyA2B als auch die künstlichen Fusionen StyAL1B und StyAL2B für eine biotechnologische Anwendung nutzen zu können, wurde im Rahmen dieser Arbeit angestrebt, ihre spezifische Oxygenierungsaktivität (StyA1/StyA2B: 0,24 U/mg) mit Hilfe der error prone PCR zu erhöhen. Um Veränderungen der katalytischen Aktivität in einer großen Zahl von Mutanten schnell zu erkennen, ist ein einfacher Screeningtest erforderlich. Die Fähigkeit von SMOs zur Oxidation von Indol zu blauem Indigo bietet diese Möglichkeit. Allerdings ist hierfür die Expression löslicher Proteine eine wesentliche Voraussetzung. Versuche zur Veränderung der Gene styA2B und styA1A2B mit Hilfe eines kommerziellen error prone PCR Kits lieferten ca. 300 bis 1.200 mutmaßlich veränderte Klone, welche jedoch keinerlei Aktivität für den Indolumsatz zeigten. Als Ursache wurde eine Expression der Proteine in Form inaktiver Inclusion Bodies vermutet. Die Fusionsproteine StyAL1B und StyAL2B bilden lösliches Protein, welche Indol zum blauen Farbstoff Indigo umsetzen. Verschiedene Kultivierungsbedingungen wurden auf den Umsatz von Indol untersucht. Dabei wurde erkannt, dass die Klone sich nicht identisch bezüglich ihrer Proteinlöslichkeit verhalten. Mit Hilfe dieser Ergebnisse wurde ein Test für das Aktivitätsscreening von Styrol-Monooxygenasen auf Platte entwickelt. Die Erhöhung der NaCl-Konzentration im Medium steigerte die Indoloxidation, welche sich jedoch durch zusätzliche physiologisch Faktoren schwer beeinflussen lassen. Auch für die Fusionsproteine erfolgte die Durchführung einer error prone PCR. Der Schritt der error prone PCR stellte kein Problem dar, jedoch die Einbindung des veränderten Genfragmentes in den Vektor, beziehungsweise dessen Transformation in E. coli. Alternative Strategien, wie die Nutzung alternativer DNA Polymerasen und eines konventionellen Konzepts, bei dem veränderte Gene in geschnittene Expressionsvektoren ligiert werden, führte zu keinen detektierbaren Klonen. Die Kultivierung von identischen Klonen auf Festmedium wirkte sich aufgrund nicht näher identifizierter Einflüsse auf das Verhalten bezüglich der Indoloxidation sehr unterschiedlich aus. Um diese Einflüsse zu minimieren, erfolgte die Untersuchung des Systems in einer Flüssigkultur. Im Blickpunkt stand hierbei die Indigoproduktion von E. coli BL21 (pET_StyAL2B) die in Abhängigkeit der optischen Dichte der Kultur untersucht wurde. / Styrene monooxygenases (SMOs) play an important role in the bacterial degradation of styrene. They epoxidize the hydrocarbon highly enantioselective to (S)-styrene oxide. Most of the styrene monooxygenases known so far were identified in Gram-negative microorganisms like pseudomonads. Rhodococcus opacus 1CP, a Gram-positive nocardioform actinobacterium, which uses styrene as energy and carbon source was recently found to possess a novel type of SMO, StyA2B. This protein represents a natural fusion between an FAD:NADH oxidoreductase (StyB) and a single monooxygenase subunit (StyA2) and might act in combination with another single oxygenase StyA1 in strain 1CP. Two artificial analogs to StyA2B, designated StyAL1B and StyAL2B, were recently prepared by a fusion of styA and styB of Pseudomonas fluorescens ST and both showed oxygenating activity. For StyA1/StyA2B as well as the artificial fusion proteins StyAL1B and StyAL2B, it was tried to enhance the specific oxygenation activity in order to support their biotechnological applicability. The method of error prone PCR was used for that purpose. In order to identify favorable modifications with increased catalytic activity from a high number of mutants, an easy and simple screening test is necessary. Therefore, it is reasonable to use the ability of SMOs to oxidize indole to the blue dye indigo. However, the expression of SMOs as soluble proteins is an important requirement for any activity screening. Attempts to modify the genes styA2B and styA1/styA2B by means of a commercial error prone PCR kit yielded 300 to 1,200 potential mutants. Unfortunately, none of the obtained colonies showed any indole-oxidizing activity and the formation of insoluble inclusion bodies was assumed to be a likely explanation. In contrast to StyA2B and StyA1, recombinant expression of the artificial fused SMOs StyAL1B und StyAL2B should yield detectable amounts of active proteins. In fact, cultivation of clones expressing both types of proteins showed a blue coloration. Since the coloration of clones from one single solid medium evolved in a non-uniform manner, cultivation conditions were varied in order to identify factors which promote a more uniform tendency for indole oxidation. Although a high NaCl concentration in the medium was shown to favor indole oxidation, the latter one seems to be influenced by additional physiological factors, hardly to control. For the artificially fused proteins an error prone PCR was carried out, too. Although the initial step of mutagenic PCR was found to be successful, completing the vector system by a second ll-up PCR reaction failed. Alternative strategies like the usage of alternative DNA polymerases as well as a conventional cloning approach of various genes into a digested expression vector did not lead to detectable clones. The cultivation of identical clones on petri dishes provided no uniform tendency for indole oxidation and thus did not allow the reliable comparison of mutants in respect of their specific SMO activities. Cultivation of mutants in liquid medium should lead to more reproducible conditions and for that purpose a method was successfully established to quantify indigo formation and cell density.