[pt] Os processos industriais enfrentam novos desafios com o avanço da Indústria 4.0 e a crescente demanda por melhorias na detecção de falhas. A detecção de falha fundamenta-se em diversas técnicas de métodos estatísticos e aprendizado de máquina. Embora sejam eficazes, possuem algumas desvantagens, tais como simplificação do processo, baixa capacidade em lidar com ruído, baixa capacidade em lidar com sistemas complexos não lineares, alta demanda computacional e risco de de overf itting. Em resposta a essas limitações, este trabalho apresenta uma abordagem inovadora na área da polimerização empregando redes neurais siamesas (SNNs) e células long short-term memory (LSTM) para a detecção precoce de falhas na polimerização de estireno. Foi realizado a modelagem da polimerização do estireno em reator CSTR utilizando o método dos momentos para o balanço de massa e energia e, neste sistema, foi adicionado controle proporcional-integral-derivativo (PID) para simular uma situação real de controle de processo no contexto de um processo industrial. A partir do modelo foi possível obter treze simulações, das quais cinco são processos sem falha e oito são processos com falhas. Esses dados foram tratados e serviram para treinar as redes siamesas. Com a capacidade de classificar se esses dados de entrada são semelhantes ou diferentes, foi possível realizar a detecção de falha. Os resultados encontrados demonstram uma taxa de detecção de falhas com uma acurácia de até 100 por cento, demonstrando a capacidade desse modelo em detectar falhas em processos químicos complexos, dinâmicos e não-lineares. Este estudo representa um avanço significativo no campo da detecção de falhas, oferecendo oportunidades valiosas para futuras investigações e aprimoramentos em sistemas inteligentes de detecção de falhas na indústria química. / [en] Industrial processes face new challenges with the advancement of Industry 4.0 and the increasing demand for improvements in fault detection. Fault detection is based on various techniques of statistical methods and machine learning. Although effective, they have some disadvantages, such as process simplification, low capacity to deal with noise, low capacity to deal with complex nonlinear systems, high computational demand, and risk of overfitting. In response to these limitations, this work introduces an innovative approach on the polymerization field that employs siamese neural networks (SNNs) and long short-term memory (LSTM) cells for early detection of faults in styrene polymerization. The modeling of styrene polymerization in a CSTR reactor was carried out using the method of moments for mass and energy balance, and in this system, proportional-integral-derivative (PID) control was added to simulate a real process control situation in the context of an industrial process. From the model, it was possible to obtain thirteen simulations, of which five are non-fault processes and eight are processes with faults. These data were processed and used to train the siamese networks. With the ability to classify whether these input data are similar or dissimilar, it was possible to perform fault detection. The results found demonstrate a fault detection rate with an accuracy of up to 100 percent, demonstrating the capability of this model in detecting faults in complex, dynamic, and nonlinear chemical processes. This study represents a substantial advance in the field of fault detection and also offers valuable findings for future investigations and improvements in intelligent fault detection systems in the chemical industry.

Block copolymer (BCP) thin film patterns, generated using directed self-assembly (DSA) of diblock copolymers, have shown excellent promise as templates for semiconductor device manufacturing since they have the potential to produce feature pitches and sizes well below 20 nm and 10 nm, respectively, using current 193 nm optical lithography. The goal of this work is to explore block copolymers with sufficient thermodynamics driving force (as described by the Flory Huggins interaction parameter, χ) for phase separation at these smallest lengths scales. Here, poly(styrene)-b-poly(hydroxystyrene) is investigated since the PHOST domain is known to form extensive hydrogen bond networks resulting in increased χ due to this strong enthalpic interaction. In this work, nitroxide mediated polymerization (NMP) techniques were utilized to produce PS-b-PHOST diblock copolymers with a range of molecular weights (5000-30000) with low PDI approaching 1.2. The phase separation of low molecular weight PS-b-PHOST on neutral underlayer substrates via solvent annealing provided thin film vertical lamellae with 13 nm pitch. These results illustrate the improved resolution of PS-b-PHOST compared with the current industry standard of PS-b-PMMA (with 20 nm pitch). The directed self assembly of lamellar PS-b-PHOST patterns with 18 nm pitch via graphoepitaxy is demonstrated. Also, a highly selective atomic layer deposition (ALD) and etch technique was investigated which provided selective block removal of (PS-b-PHOST) block copolymer patterns which initially exhibited no inherent etch contrast. In this process, the PS domain is removed leaving a high fidelity etch relief pattern of the original block copolymer template. Finally, an alternative system is presented, namely Poly(trimethylsilylstyrene)-block-poly(hydroxystyrene) (PTMSS-b-PHOST), which utilizes silicon containing functionality in one of the blocks, providing high etch contrast. PTMSS-b-PHOST patterns were also exposed to oxygen plasma allowing selective block removal of the PS domain without the need for additional ALD processing steps.

Cette thèse a pour objet la comparaison des procèdes de polymérisation en émulsion et en miniémulsion. L'influence de la combinaison de stabilisants moléculaires et macromoléculaires sur la cinétique réactionnelle et la distribution de tailles de particules sont les critères pertinents dans notre étude. Un stabilisant polymère, le poly (alcool vinylique-co-acétate de vinyle) (PVA), a été synthétisé avec différents taux d'hydrolyse par saponification directe du polyacétate de vinyle. Le taux d'hydrolyse de ce copolymère a été caractérisé par la Résonance Magnétique Nucléaire du proton (RMN 1H). Puis, nous avons étudié l'influence de la composition d'un mélange stabilisant [copolymères poly (alcool vinylique-co-acétate de vinyle) (PVA)/laurylsulfate de sodium (SDS)] et en particulier le taux d'hydrolyse du PVA. La présence de complexe (PVA/SDS) influence légèrement la cinétique de polymérisation. Par contre la capacité des complexes à stabiliser les particules de latex final dépend du taux d'hydrolyse du PVA, plus ce dernier est faible, plus l'agrégation est importante. Enfin, nous avons suivi en ligne par spectroscopie Raman des polymérisations en émulsion et en miniémulsion du styrène. Une exploitation du spectre a été réalisée et a permis d'attribuer les différents pics aux vibrations de certaines liaisons. La consommation du monomère et l'apparition du polymère a pu être suivi tout au long de la polymérisation / The aim of this work is to compare processes of emulsion and miniemulsion polymerization. The influence of the combination of molecular and macromolecular stabilizers on the reaction kinetics and particle size distribution are relevant factors in our study. A stabilizer polymer, poly (vinyl alcohol-co-vinyl acetate) (PVA), was synthesized with different degrees of hydrolysis by a direct saponification of polyvinyl acetate. The degree of hydrolysis of this copolymer was characterized by Nuclear Magnetic Resonance (1H NMR). Then, we studied the influence of the composition of a mixture stabilizer [poly (vinyl alcohol-co-vinyl acetate) (PVA)/sodium lauryl sulfate (SDS)], and particulary the degree of hydrolysis of PVA. The presence of complex (PVA/SDS) influences slightly the kinetic of polymerization. The ability of the complexes to stabilize the particles of latex depends on the degree of hydrolysis of PVA, the lower it is, the more the aggregation is important. Finally, we followed in situ emulsion and miniemulsion polymerizations of styrene by Raman spectroscopy. The exploitation of the spectrum allowed us to assign the different peaks to vibrations of certain bands. The consumption of the monomer and the appearance of the polymer could be followed throughout the polymerization

Palladium complexes have the ability to catalyse cross-coupling of two organic moieties through the formation of transient metal-carbon bonds, thus bringing them closer to each other to facilitate the formation of a new bond. Palladium-catalysed coupling reactions are one of the most important carbon-carbon forming reactions available to organic chemists and many of these reactions rely on the reactivity of aryl-palladium complexes. The investigation of new aryl-palladium precursors is thus of great interest, especially as more sustainable and economic methods can be developed. This thesis describes the use of carboxylic acids and sodium arylsulfinates as such new arylating agents. Protocols for microwave-assisted palladium(II)-catalysed decarboxylative synthesis of electron-rich styrenes and 1,1-diarylethenes were developed. However, these transformations had very limited substrate scopes which prompted the investigation of sodium arylsulfinates as alternative arylating agents. These substrates were employed in the microwave-assisted palladium(II)-catalysed desulfitative addition to nitriles, and the substrate scope was demonstrated by combining a wide array of sodium arylsulfinates and nitriles to yield the corresponding aryl ketones. The application of the desulfitative reaction in a continuous flow setup was demonstrated, and aluminium oxide was identified as safe alternative to borosilicate glass as a reactor material. The mechanisms of the decarboxylative and desulfitative transformations were investigated by density functional theory (DFT) calculations. The desulfitative reaction was also investigated by direct electrospray ionization mass spectrometry (ESI-MS), providing further mechanistic insight. Finally, a protocol for the safe and convenient synthesis of a wide range of sodium arylsulfinates was developed.

The maintenance or replacement of deteriorated pipes and culverts is a constant and significant concern for municipalities and transportation agencies in the United States (Donaldson and Wallingford, 2010). Trenchless technologies and especially the Cured-in-place pipe (CIPP) method have become increasingly common ways to preserve infrastructures owing to their feasibility, cost-effectiveness, and fewer social impacts (Jung and Sinha, 2007). Therefore, there is a growing need to understand the direct and indirect effects of pipeline rehabilitation activities on the environment. Nearly all past CIPP studies have focused on its mechanical properties, and its environmental impacts are poorly investigated and documented (Allouche et al. 2012). Sewer pipelines and storm-water culverts are administered by municipalities and transportation agencies who bear the responsibility for rehabilitation and renewal of these infrastructures. In consequence, they rarely allow sampling and research projects in the field due to liability issues. This is a main obstacle to conducting comprehensive, precise, and unbiased research on CIPP environmental impacts and to date, the degree of relevant health effects and related environmental impacts have remained unknown. Numerous building indoor air contamination incidents indicate that work is needed to understand the magnitude of styrene emission from CIPP sanitary sewer repairs. The main goal of this study was to better comprehend Volatile Organic Compounds emission at three CIPP sanitary sewer installation sites in one U.S. city. Results showed that CIPP chemical emissions may be a health risk to workers and nearby building inhabitants. Additional testing and investigations regarding chemical emissions from CIPP should be commissioned to fill in the environmental and public health knowledge gaps. The acute and chronic chemical exposure risks of CIPP chemical steam constituents and styrene to sensitive populations should be further examined. Other goals of this study were to estimate the magnitude of solid waste generated as well as the amount of certain criteria air pollutants and greenhouse gases emitted from onsite heavy equipment for both CIPP and open-cut sites in a U.S city. The results indicated that the amount of open-cut related solid waste, criteria air pollutants, and greenhouse gases were greater than those during CIPP activities. Additional work is needed to quantify pollutant emissions from CIPP and open-cut activities and consider emissions from a cradle-to-grave standpoint.

O crescimento na geração de rejeitos de equipamentos elétricos e eletrônicos (REEE), legislações mais rigorosas e o valor agregado destes materiais incentivam o desenvolvimento de tecnologias de reciclagem. Contudo, a reciclagem dos componentes poliméricos dos REEE (CP-REEE) precisa superar desafios como a degradação durante o uso e reprocessamento, a presença de diferentes aditivos nos rejeitos e a depreciação de propriedades causada pela mistura não controlada de polímeros. Assim, o objetivo deste trabalho foi desenvolver um estudo sobre a reciclagem mecânica na forma de blendas poliméricas de rejeitos do copolímero acrilonitrila-butadieno-estireno (ABS) e do poliestireno de alto impacto (HIPS), empregando agentes compatibilizantes. No desenvolvimento do trabalho foram realizadas a caracterização dos CP-REEE, análise das propriedades mecânicas, químicas, térmicas e morfológicas dos polímeros e das blendas de ABS/HIPS nas proporções de 1:3, 1:1 e 3:1 com variações na composição dos polímeros reciclados e virgens e por fim, realizado um estudo do envelhecimento foto-oxidativo acelerado de uma blenda ABS/HIPS. Os resultados mostraram que os polímeros ABS e HIPS reciclados ainda apresentam boas propriedades mecânicas e que a presença de agentes compatibilizantes provoca o aumento da tenacidade nas blendas ABS/HIPS. A incorporação de polímeros virgens nos materiais reciclados não promove ganho significativo nas propriedades mecânicas das blendas. Blendas com até 50% de ABS demonstraram ter propriedades próximas às do HIPS, enquanto as blendas com altos teores de ABS não alcançaram valores de propriedades mecânicas similares aos do ABS virgem. O comportamento das propriedades das blendas virgens e recicladas frente ao envelhecimento fotoquímico foi similar, indicando que o material reciclado apresenta grande potencial para aplicações. O estudo de blendas ABS/HIPS de CP-REEE demonstra que o controle da composição das blendas definem a sua aplicação. / The growth in waste electrical and electronic equipment (WEEE) generation, directives more stringent and the aggregate value presents in these waste are encouraging the development of recycling technologies. However, recycling of polymeric components from WEEE (PC-WEEE) must overcome challenges such as degradation during use and reprocessing, the presence of various additives in the waste and the depreciation of properties caused by uncontrolled polymers mixture. The aim of this work was to develop a study of the mechanical recycling in the form blends with of polymeric waste of acrylonitrile-butadiene-styrene copolymer blends (ABS) and high impact polystyrene (HIPS) using compatibilizers. During the study was carried out the characterization of the PCWEEE and mechanical, chemical, thermal and morphological analysis of the polymers and the ABS / HIPS blends in proportions of 1:3, 1:1 and 3:1 with recycled and virgin polymers, as well as a study of the accelerated photo-oxidative aging of the ABS/HIPS blends. The results showed that ABS and HIPS recycled polymers still have good mechanical properties and the presence of compatibilization agents leads to increased toughness in ABS/HIPS blends. The incorporation of virgin polymers in recycled materials does not promote significant gain in the mechanical properties of the blends. Blends with up to 50% ABS have demonstrated to be closer to the HIPS, while blends with high content of ABS did not reach values of mechanical properties similar to the virgin ABS. The mechanical properties of virgin and recycled blends during the photochemical aging were similar, indicating that the recycled material has great potential for applications. The study of ABS/HIPS blends from PC-WEEE demonstrated that control of the blend composition establish their applications.

Metal nanoclusters exhibit unique properties which differ from their bulk materials, owing to the quantum size effects. For example, the catalytic activity of transition metal nanoclusters generally increases with decreasing particle size. However, nanoclusters tend to be fairly unstable with respect to the agglomerate into bulk metal in solution and thus special precautions have to be taken to avoid their aggregation or precipitation during the preparation of such nanoclusters in solution. In order to obtain stable nanoclusters dispersed in solution, a stabilizing agent is usually added into the reaction system. The stabilization of metal nanoclusters in solution can be achieved either by electrostatically by using charged ions such as acetate ion or sterically by long chain molecules such as polymers. Polymers are one of the most widely used steric stabilizers for the preparation of stable metal nanoclusters in solution. The use of polymers as stabilizer for the synthesis of transition metal nanoclusters provides advantegous regarding solubility, conductivity, thermal stability and reusability. The metal nanoclusters stabilized by polymers generally show higher catalytic activity, stability and optical properties. In this dissertation we report the preparation and characterization of water soluble polymer stabilized transition metal(0) (metal= Ni, Co and Ru) nanoclusters and their v catalysis in hydrogen generation from the hydrolysis of sodium borohydride (NaBH4) and ammonia borane (AB) which are the best candidates as chemical hydrogen storage materials for on-board applications. The water soluble polymer stabilized nickel(0), cobalt(0) and ruthenium(0) nanoclusters were prepared by using two different facile methods / (i) the reduction of metal precursors by sodium borohydride in the presence poly(N-vinyl pyrrolidone) (PVP) in methanol solution after 1h reflux, (ii) the in situ generation during the hydrolysis of ammonia borane in the presence of poly(4-styrene sulfonicacid-co-maleic acid) (PSSA-co-MA). The characterization of both type of polymer stabilized transition metal(0) nanoclusters were done by using UV-Visible electronic absorption spectroscopy (UV-Vis), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and FT-IR techniques. The catalytic activity of PVP stabilized nickel(0), cobalt(0) and ruthenium(0) nanoclusters was tested in the hydrolysis of NaBH4 and AB. The catalytic acitivity of PSSA-co-MA stabilized nickel(0), cobalt(0) and ruthenium(0) nanoclusters was tested only in the hydrolysis of AB in which they were in situ generated. The kinetics of hydrogen generation from both hydrolysis reactions in the presence PVP or PSSA-co-MA stabilized nickel(0), cobalt(0) and ruthenium(0) nanoclusters were studied depending on the polymer to metal ratio, catalyst concentration, substrate concentration and temperature as well as the activation parameters (Arrhenius activation energy (Ea), activation enthalpy (

No description available.

No description available.

Natural organic matter (NOM) is a diverse blend of decomposed animal and plant material found in different natural water sources. Due to its large and complex structure, NOM is difficult to both remove and characterize in water. Therefore, there is a need to separate NOM into its components before it can be characterized. The aim of this project was to fractionate NOM through a novel size exclusion chromatography (SEC) composite (poly (styrene-divinyl benzene) (PS-DVB) and Polysilsesquioxane (PSQ)) packed column. Raw and final water samples from Mid-Vaal (MV), Olifantspoort (LO), Mtwalume (MT) and Preekstoel (P) were investigated. Poly (styrene-divinyl benzene) (PS-DVB) and polysilsesquioxane were both synthesized and optimized at various temperatures, compositions and time periods. An end-capping material such as hexamethyldisilizane (HMDS) was added on the PSQ to prevent active silanol groups on the polysilsesquioxane (PSQ) from reacting with active sites of NOM (our analyte). The E-PSQ (end-capped PSQ) and PS-DVB materials were packed in eight different SPE cartridges first, before the materials could be packed in the SEC column. This packing was done to check for the best mass composition of the E-PSQ and PS-DVB. From the obtained SPE results, both the EPSQ and PS-DVB were packed in one SEC/GPC column at a ratio of 1:1 in order to form the composite hybrid material. The packed SEC column was connected to an HPLC instrument and various column efficiency tests were evaluated. The results for the test of interactions with acidic compounds implied that the column can be used for the acidic analytes such as those forming NOM composition (humic acids, fulvic acids) and the column had minimum silanol groups. For hydrophobic interactions the stationary phase strength was different to that of the commercial columns and it could selectively elute molecules based on their different masses. The steric selectivity test showed that the stationary phase could separate and distinguish between molecules with similar hydrophobicity and structure but different shapes (o-terphenyl and triphenylene). The Hydrogen bonding capacity (HBC) test showed that the column had minimum silanol groups and the end-capping was successful on the E-PSQ. After fractionation of all the water samples, the MT raw showed NOM peaks around 1.8 mins, 3.4 mins and 5.3, and the final showed NOM peaks around 1.8 mins and 5.5 mins. The Mid-Vaal (MV) raw and final samples shows NOM peaks at around 1.8 mins and 6 mins. The Preekstoel (P) final water had one NOM peak at around 1.8 mins and raw samples had two NOM peaks around 1.8 mins and 6 mins. / Chemistry / M. Sc. (Chemistry)