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Ziquinatti, Francine. "Estudo da miscibilidade e das propriedades mecânicas de blendas SAN/NBR." Universidade do Estado de Santa Catarina, 2005. http://tede.udesc.br/handle/handle/1600.
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Previous issue date: 2005-02-21<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Aiming the study of miscibility and mechanical properties, blends of poli(styrene-coacrylonitrile) (SAN) with poli(butadiene-co-acrylonitrile) (NBR) rubbers were prepared by casting, co-precipitation and extrusion followed by injection, varying acrylonitrile (AN)
contents from 32,7 to 45% (w/w) in NBR. The blends were prepared in the compositions: SAN/NBR 90/10, 80/20, 70/30, 60/40 and 50/50 (w/w) and valued by Infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), Scanning electron micrographs (SEM), Tensile and Izod impact tests. FTIR analyses of casting blends displayed that not happened reactions or specific interactions between polymers during blending because did not happened a shift in the spectrum blends bands. The DSC analyses of casting blends showed total imiscibility to SAN/NBR 50/50 blend (AN contents in NBR 32,7%), partial miscibility to the 60/40, 70/30 and 80/20 compositions and total miscibility to the 90/10 composition. The SAN/NBR blends (AN contents in NBR 39%), prepared by casting and coprecipitation revealed partial miscibility for all compositions. Coprecipitated blends prepared with AN rubber content of 45% showed partial miscibility to 50/50, 60/40, 70/30 and 90/10 compositions and total miscibility to 80/20 composition. The phase morphology was influenciated by blending methods, casting blends revealed dispersed spherical elastomeric domains in matrix while coprecipitated blends form co continuous phase. The NBR addition result in significant impact resistant increase but decrease in tensile strenght<br>Com o objetivo de estudar a miscibilidade e propriedades mecânicas, foram preparadas blendas do copolímero poli(estireno-co-acrilonitrila) (SAN) com o copolímero poli(butadienoco-acrilonitrila) (NBR). As blendas foram preparadas por três métodos diferentes: evaporação de solvente, co-precipitação e extrusão seguida de injeção, variando o teor de acrilonitrila no NBR de 33 a 45 % (m/m). As blendas foram preparadas nas composições SAN/NBR 90/10, 80/20, 70/30, 60/40 e 50/50 (m/m) e avaliadas por Espectroscopia na região do infravermelho com Transformada de Fourrier (FTIR), Calorimetria diferencial exploratória (DSC), Microscopia eletrônica de varredura (MEV), Ensaios de Tração e Impacto Izod. As análises de FTIR das blendas preparadas por evaporação de solvente mostraram não ter ocorrido nenhuma reação nem interação específica entre os polímeros durante o processo de mistura porque não houve deslocamentos, aparecimento ou desaparecimentos de picos no espectro das blendas em relação ao espectro dos polímeros puros. O DSC avaliou a miscibilidade das blendas preparadas por evaporação de solvente e co-precipitação. A blenda SAN/NBR 50/50, preparada por evaporação de solvente, (NBR contendo 32,7% de acrilonitrila), é totalmente
imiscivel, as composições 60/40, 70/30 e 80/20 são parcialmente miscíveis e a composição
90/10 formou um sistema miscível. As blendas SAN/NBR (NBR contendo 39% de acrilonitrila), preparadas por evaporação de solvente e co-precipitação, mostraram-se parcialmente miscíveis em todas as composições. As blendas preparadas por co-precipitação usando a borracha com 45% de acrilonitrila são parcialmente miscíveis com exceção da composição 80/20 que é totalmente miscível. A morfologia de fase foi influenciada pelo método de preparação das blendas, aquelas preparadas por evaporação de solvente mostraram domínios elastoméricos ovais dispersos na matriz SAN, enquanto que as preparadas por coprecipitação apresentaram fases semi-contínuas. A resistência ao impacto foi significativamente aumentada pela incorporação do NBR no SAN porém com decréscimo do Módulo de Young.
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Leitzke, Tatiana da Cunha Gomes. "Blendas de SAN/NBR: influência do teor de acrilonitrila da borracha nitrílica nas propriedades físico-química e mecânicas." Universidade do Estado de Santa Catarina, 2003. http://tede.udesc.br/handle/handle/1758.
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Previous issue date: 2003-02-27<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Aiming the development of polymer materials with high toughness, poly(butadiene-coacrylonitrile) rubbers (NBRs), with acrylonitrile (AN) contents varying from 32,9 to 45,7%, were added to poly(styrene-co-acrylonitrile) (SAN) by casting, mini-extrusion and
monoscrew extrusion followed by injection molding. Addition of NBR resulted in significant improvements in the impact strength and the elongation at break, that were strongly influenced by the blend composition, the AN contents and the NBR melt viscosities, but the tensile strength is slightly decreased. The best impact strength results (157,1 ± 3.7 J/m) were obtained with a 70/30 (w/w) SAN/NBR blend using NBR with 33,1% of AN and 51 ML 1+4 (100°C), being ca. 700% higher than the values for pure SAN (22,4 ± 1.1 J/m). Differential scanning calorimetry (DSC) measurements indicated a partial miscibility between the copolymers, showing a shifting of the SAN glass transition temperature from 108,1 to 101,7oC for the 70/30 blend with NBR containing 45,7% of AN.
This is in agreement with infrared spectroscopy (FTIR) analysis that displayed a significant
shift of the dienic band from 967 cm-1 to ca. 1060 cm-1 for all 70/30 blends, suggesting segmental interactions between NBR and SAN. Scanning electron micrographs (SEM) from fracture surfaces revealed homogeneously dispersed spherical elastomeric domains, and the appearance of yielding and/or crazing processes for all blends. The size of NBR domains decreased as the AN content increased, while the number of NBR domains decreased as the melt viscosity increased. From these results it can be concluded that SAN
thoughening by the addition of NBR is directly related to the AN content and the melt viscosity of the elastomer, depending on the morphology of the dispersed rubber phase. Higher NBR domain sizes cause better impact strengths, as large rubber particles are more
effective in initiating crazing processes.<br>Com o objetivo de desenvolver materiais poliméricos com elevada tenacidade, borrachas de poli(butadieno-co-acrilonitrila) (NBR), com teores de acrilonitrila variando de 32,9 a 45,7%, foram incorporadas ao poli(estireno-co-acrilonitrila) (SAN), por evaporação desolventes, mini-extrusão e extrusão seguida de injeção. A adição do NBR resultou em um
aumento significativo na resistência ao impacto e na deformação na ruptura, que foram fortemente influenciadas pela composição da blenda, pelo teor de acrilonitrila e pela viscosidade dos NBRs, porém, houve a diminuição da resistência à tração. O melhor resultado de resistência ao impacto (157,1 ± 3.7 J/m) foi obtido para a blenda 70/30 (m/m)
utilizando NBR com 33,1% de acrilonitrila e 51 ML 1+4 (100°C), um valor cerca de 700% maior que o verificado para o SAN puro (22,4 ± 1.1 J/m). A técnica de calorimetria diferencial de varredura (DSC) indicou uma miscibilidade parcial entre os copolímeros, mostrando o deslocamento da temperatura de transição vítrea do SAN de 108,1 a 101,7ºC
para a blenda 70/30 utilizando o NBR com 45,7% de acrilonitrila. Este resultado concorda
com a análise de espectroscopia de infravermelho (FTIR), que mostrou um deslocamento
significativo da banda da parte butadiênica de 967 cm-1 para 1060 cm-1, para todas as blendas 70/30, sugerindo assim interações segmentais entre o NBR e SAN. A análise da
superfície de fratura por microscopia eletrônica de varredura (MEV), revelou homogeneidade dos domínios elastoméricos dispersos na matriz, bem como o aparecimento de microtrincas e/ou deformação plástica para todas as blendas. O tamanho dos domínios de NBR diminui com o aumento do teor de acrilonitrila presente no NBR, enquanto a quantidade de domínios diminui com o aumento da viscosidade. A partir destes resultados conclui-se que a tenacificação do SAN com a adição de NBR está diretamente relacionada com o teor de acrilonitrila e viscosidade do elastômero e depende da morfologia da fase elastomérica dispersa na matriz. Os domínios maiores de NBR proporcionaram melhor resistência ao impacto, sendo que partículas de borracha maioresfavorecem o aparecimento de microtrincas.
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Chirullo, Matteo. "Caratterizzazione e compatibilità di blend polimerici a base NBR." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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L'elaborato è stato svolto in collaborazione con il Centro Ricerca di Ravenna/Ferrara della Versalis SpA, società del gruppo Eni. Lo scopo del lavoro è quello di approfondire le caratteristiche dei blend NBR-PVC di attuale e consolidata produzione nonché di esplorare valide alternative agli attuali blend NBR-PVC utilizzati come gomme resistenti alla degradazione indotta da ozono (gomme OZO), la cui resistenza all’agente chimico è fornita dalla parziale miscibilità del polimero saturo (PVC) con la gomma insatura (NBR). Come sostituenti ozono-protettori al posto del PVC (polivinilcloruro) si è quindi provato ad utilizzare anche altre due tipologie di polimero. L’analisi teorica della possibile compatibilità è avvenuta attraverso l’applicazione di modelli termodinamici classici (Flory-Huggins) ed è stata verificata tramite prove sperimentali di caratterizzazione, quali analisi dinamico-meccanica (DMA), calorimetria (DSC) e spettroscopia dielettrica (DS). I risultati di tali prove hanno mostrato una possibile compatibilità per alcuni blend sperimentali, sui quali ci si è infine focalizzati nel tentativo di ottimizzare le condizioni operative, in primis tempo e temperatura di miscelamento. E’ stata verificata la possibilità di un ulteriore avanzamento verso un’applicazione tecnologica del materiale, in alternativa o a complemento degli attuali blend NBR-PVC. Sulla base dei risultati infine, si è provato applicare il modello di Lodge-McLeish dell'auto-miscibilità per verificare che, anche nel caso dei blend in esame, la presenza di più picchi di transizione vetrosa non sia necessariamente sintomo di incompatibilità.
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Herrera, Julio César Alzate. "Desenvolvimento de borracha termoplástica por vulcanização dinâmica. TPV-(NBR+PP)." Universidade Federal de São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/892.
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Previous issue date: 2012-09-14<br>Financiadora de Estudos e Projetos<br>The union of technology of thermoplastic and rubber has contributed to the development of thermoplastic elastomers (TPE), which was evidenced through the study of patents in TPE in the last 20 years, where Japan and the United States are the leaders. Trends in TPE are: modification to polymer structure in styrenic TPEs in order to employ the dynamic vulcanization, use of nanofibres and nanoclays, and resists oil TPEs using hydrogenated nitrile rubber to improve the properties of hot air and aging. The main variables in the development of TPE should take into account the surface energy the thermoplastic and elastomer, the elastomer entanglement, crystallinity of thermoplastic, proportions of the thermoplastic and compatibilizer. Typically the articles produced with nitrile, may be obtained using the technology or conventional rubbers (vulcanized), and not having possibility of recycling of defective products and materials vulcanizates. The purpose is to develop a thermoplastic nitrile rubber by dynamic vulcanization (TPV-(NBR + PP)) using conventional techniques for mixing between nitrile rubber and polypropylene. The development of nitrile rubber thermoplastic by dynamic vulcanization, TPV (NBR+PP) were studied with variation of vulcanization system, variation of proportion of NBR/PP and type of compatibilizer. The main results on development of TPV-(NBR+PP) were obtained with the use of system of vulcanization type phenolic resin, with compatibilizer Ph-PP and with 4,0phr of amine (6PPD). Developed a nitrile rubber thermoplastic by dynamic vulcanization (TPV-(NBR + PP)) with good performance in reprocessabilidade, using equipment and techniques conventional thermoplastic processing, which will help to satisfy the demands of industry.<br>A uniao da tecnologia de termoplastico e da borracha tem contribuido para o desenvolvimento de elastomeros termoplasticos (TPE), que foi evidenciada atraves do estudo de patentes em TPE nos ultimos 20 anos, onde o Japao e os Estados Unidos sao os lideres. As tendencias em TPE sao: modificacao da estrutura do polimero de estireno TPE para empregar a vulcanizacao dinamica, o uso de nanofibras e nanoargilas, e TPEs resistes ao oleo utilizando borracha nitrilica hidrogenada para melhorar as propriedades de ar quente e envelhecimento. As principais variaveis no desenvolvimento de TPE tem em conta a energia de superficie do elastomero e do termoplastico, o emaranhamento do elastomero, cristalinidade do termoplastico, as proporcoes do termoplastico e compatibilizante. Normalmente, os artigos produzidos com borracha nitrilica so podem ser obtidos utilizando-se a tecnologia ou tecnicas de processamento de borrachas convencionais (vulcanizados), apresentando a nao possibilidade de reciclagem de produtos defeituosos e materiais vulcanizados. O proposito e desenvolver uma borracha nitrilica termoplastica por vulcanizacao dinamica (TPV-(NBR+PP)), usando tecnicas convencionais para mistura entre borracha nitrilica e polipropileno. O desenvolvimento de borracha nitrilica termoplastica por vulcanizacao dinamica, TPV - (NBR + PP) foram enchido com variacao de sistema de vulcanizacao, a variacao da proporcao de NBR/PP e do tipo de compatibilizante. Os resultados principais sobre o desenvolvimento de TPV-(NBR + PP) foram obtidos com a utilizacao do sistema de vulcanizacao do tipo de resina fenolica, com compatibilizante Ph- PP e com 4,0 phr de amina (6PPD). Desenvolveu-se uma borracha nitrilica termoplastica por vulcanizacao dinamica (TPV-(NBR+PP)) com bom desempenho na reprocessabilidade, usando equipamentos e tecnicas convencionais de processamento de termoplasticos, que contribuira para satisfazer as exigencias da industria.
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Passador, Fabio Roberto. "Desenvolvimento de blendas poliméricas PVC/NBR através de processamento reativo e vulcanização dinâmica in situ." Universidade Federal de São Carlos, 2008. https://repositorio.ufscar.br/handle/ufscar/769.
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Previous issue date: 2008-02-28<br>Financiadora de Estudos e Projetos<br>Dynamic vulcanization is a process of vulcanization of an elastomer during melt mixing with a thermoplastic which results in a material with better chemical and mechanical properties at high temperature. The PVC/NBR blends were obtained by reactive processing and in situ dynamic curing. The crosslinking of PVC/NBR blends was accomplished using sulphur (S)/tetramethylthiuram disulphide (TMTD) and mercaptobenzothiazyl disulphide (MBTS) curative system during the reactive processing. The blends of PVC/NBR at the ratio of 90/10; 80/20 and 70/30 wt% were melt mixed using an internal mixer at 160°C and rotor speed of 60rpm. The degrees of crosslinking of the blends obtained by the reactive process were analyzed through Fourier Transform InfraRed (FT-IR), swelling and degree of cure. Higher crosslink densities were obtained the systems with higher amount of elastomer. The mechanical properties evaluated by tensile properties, tear strength, hardness and compression set showed that the dynamic vulcanized blends have a better performance compared to the similar conventional ones. It was observed an increase of 92% in the tensile stress to the dynamic vulcanized blend PVC/NBR (70/30) with partitioning agent of PVC and an increase of 205% in the Young´s modulus to the dynamic vulcanized blend PVC/NBR (90/10) with partitioning agent of CaCO3. The morphology of the blends examined by scanning electron microscopy evidenced the crosslinking formation only in the elastomeric phase. The vulcanized rubber particles are responsible by the increase of stiffness and consequently displayed better mechanical properties.<br>Vulcanização dinâmica é o processo de vulcanização de um elastômero durante a mistura no estado fundido com um termoplástico, que resulta em materiais com boa resistência química e mecânica em altas temperaturas. A obtenção de blendas PVC/NBR por processamento reativo e vulcanização dinâmica in situ foi realizada utilizando o sistema de cura a base de enxofre (S) e combinação dos aceleradores 2,2-ditiomercaptobenzotiazol (MBTS) e dissulfeto de tetrametiltiuram (TMTD), utilizando-se dois tipos de borracha nitrílica, com diferentes agentes de partição, que é utilizado para manter o elastômero particulado. As blendas PVC/NBR (90/10, 80/20 e 70/30 % em massa) foram processadas em um reômetro de torque Haake a 160°C, com rotação de 60rpm. Ensaios de FTIR, inchamento em solvente e determinação do grau de cura foram utilizados para quantificar a formação de ligações cruzadas nas blendas obtidas por processamento reativo, sendo obtida maior densidade de ligações cruzadas nos sistemas em que utilizaram maior quantidade de NBR. As propriedades mecânicas das blendas obtidas por processamento reativo foram avaliadas por ensaios de tração, rasgo, dureza e deformação permanente à compressão, sendo observado desempenho mecânico superior das blendas vulcanizadas comparadas às blendas convencionais, com aumento de 92% na tensão de ruptura para blenda vulcanizada com 30% em massa de NBR particulada com CaCO3, em relação à blenda convencional e aumento de 205% no módulo elástico de blendas vulcanizadas com 10% em massa de NBR particulada com PVC. A morfologia das blendas foi avaliada por microscopia eletrônica de varredura, que evidenciou a formação de ligações cruzadas apenas no interior da fase elastomérica, sendo responsável pelo aumento da rigidez e desempenho mecânico superior.
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Fan, Zhirong. "Hyperbranched Aromatic Polyesters and Their Application in Blends of Linear Polyamides." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-24214.
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In the last two decades, hyperbranched (hb) polymers have drawn much attention and obtained intensive research activities both from industry and academia. They are known to have unique and interesting properties which derive from their three dimensional structure and the large number of functional groups. These structural characteristics provide high possibilities for controlling functional group interactions and modifications of other polymers in blends and therefore, they are expected to result in novel materials with desired properties. Furthermore, the easy synthetic accessibility of hb polymers by one-pot synthesis is advantageous as well and allows easy scale-up of laboratory reactions. Having the characteristics as mentioned above, hb polymers are considered good candidates for blend components or melt processing modifiers. In fact, hb polymers have already been used as blend components or additives aiming for different effects. In many cases, reduced viscosity and formation of miscible blends were observed by modification of a linear matrix polymer with hb polymers. More information will be introduced in the following theoretical section. In this work two hb polyester systems based on AB2 and A2+B3 approaches were synthesized and studied. Their possible applications as additives in the blends of linear polyamides were investigated.
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Brito, Susana Maria Guerreiro Faia. "Discriminação de formulações industriais de café torrado através de espectroscopia de infravermelho próximo." Master's thesis, ISA/UTL, 2012. http://hdl.handle.net/10400.5/5346.
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Mestrado em Engenharia Alimentar - Processamento de Alimentos - Instituto Superior de Agronomia<br>This final work of masters focused on the characterization of coffee between blends with
different amounts of robusta coffee and also in the analyze of how the origins of coffee
arabica and robusta, from different regions, affecting behavior of blends.
The samples were separated into blends and origins, which afforded 48 blends with 3
different formulations and 6 samples of sources, 3 of arabica and 3 of robusta.
To obtain this characterization method was used near infrared spectroscopy, FT-NIR, in
which the analysis was restricted to the area of the spectrum of greatest differentiation.
The statistical analysis used was principal component analysis.
It was concluded by a qualitative discrimination, that the amount of robusta coffee present in
coffee blends is one of the most relevant characteristics of the final product.
Other features that were found to be relevant were the degree of roasting, the formulation of
the coffee blends and the storage time.
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Tambelli, Cassio de Campos. "Estudo de RMN dos mecanismos de transporte iônico de vidros e vitro-cerâmicas de PbGeO3 CdF2 PbF2 e de blendas poliméricas de PEO:LiClO4 /POMA." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-30012014-084202/.
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Este trabalho apresenta o estudo de vidros e vitro-cerâmicas oxifluoretos de composição PbGeO3 CdF2 PbF2 (Fluorgermanatos de cádmio e chumbo) e de blendas poliméricas formadas entre o eletrólito polimérico PEO:LiC104 (Poli-óxido de eltileno com perclorato de lítio) e o polímero condutor POMA (Poli-orto metoxianilina). Foram utilizadas as técnicas de ressonância magnética nuclear (RMN), ressonância paramagnética eletrônica (RPE), calorimetria exploratória diferencial (DSC) e impedância complexa. Dentre várias aplicações, estes materiais são importantes devido ao grande potencial como eletrólitos sólidos. Este estudo tem como principal objetivo esclarecer os mecanismos de transporte iônico do flúor e do lítio. Os resultados mostraram que os mecanismos da condução iônica nos vítreos oxifluoretos são caracterizados diferentemente em cada região de temperatura estudada. Em baixas temperaturas (T<300K), o processo de relaxação foi atribuído às excitações de baixas-frequências dos modos desordenados. Acima de 300K, porém abaixo da temperatura de transição vítrea, os movimentos do flúor modulam as interações dipolares F-F. As vitro-cerâmicas, obtidas através de tratamentos térmicos dos vidros de oxifluoretos, são materiais compósitos onde nano ou micro-cristais estão dispersos na matriz vítrea. Os resultados de RMN mostraram no intervalo 100 800K, pelo menos três processos de relaxação, que foram associados com (i) movimentos difusionais dos íons de flúor nos cristais de β-PbF2, (ii) mobilidade iônica na matriz vítrea e (iii) íons de flúor de baixa mobilidade (provavelmente PbGeO3-xFx). Os resultados de RMN 1H mostraram que os tempos de correlação associados aos movimentos das macromoléculas nas blendas poliméricas xii são comparáveis aos encontrados na literatura para o PEO/PMMA. A fim de se garantir resultados reprodutíveis, um cuidadoso método de preparação deve ser seguido, assegurando a estabilidade química e a homogeneidade da blenda<br>This work reports the study of oxifluorides glasses and glass-ceramics of composition PbGeO3 CdF2 PbF2 (Lead cadmium fluorgermanate) and blends formed by the polymer electrolyte PEO:LiC104 (poly etilene oxide and lithium perclorate) and the conducting polymer POMA (poly ortho methox aniline). Nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), differential scanning calorimetry (DSC) and complex impedance techniques were used. Among several applications, these materiais are important as solid electrolytes. The main objective of this work is to study the fluor or lithium ionic transport mechanisms. Results show that the ionic conduction mechanism in oxifluoride glass systems is characteristic of each temperature region. In low temperatures (T < 300K), the relaxation processes were attributed to low-frequency excitations of disorder modes intrinsic to the glassy state of mater. Above 300 K and below of the glass transition temperature the fluorine motions modulate the dipolar F-F interactions. The glasscerarnics, produced form their respective glasses, are composite materiais where nano- or micro-crystals are dispersed on the glassy matrix. The NMR results, in the range 100-800 K, evidenced three separate relaxation process: (i) diffusional motions of fluorine ions in β-PbF2 crystals; (ii) fluorine mobility in the glass matrix and (iii) fluorine ions of low mobility (probably PbGeO3-xFx). The i ll NMR results shown that the correlation time values, associated to the polymeric chains motion in polymer blends, are comparable to those found for PEO/PMMA. In order to get reproducible results, a careful sample preparation process must be undertaken to ensure chemical stability and blend homogeneity.
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Singla, Swati. "Topological Effects on Properties of Multicomponent Polymer Systems." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5067.
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Multicomponent polymer systems comprised of two or more chemically different polymer moieties provide an effective way to attain the desired properties from a limited palette of commodity polymers. Variations in macromolecular topologies often result in unique and unusual properties leading to novel applications. This dissertation addresses the effect of topology on properties of two multicomponent polymers systems: blends and polyrotaxanes. Blends of cyclic and linear polymers were compared to their topological counterparts, polyrotaxanes, in which cyclic components are threaded onto the linear polymer chains.
The first part of the dissertation focuses on the synthesis and purification of cyclic polymers derived from linear (polyoxyethylene) (POE). Cyclic POEs of different cycle sizes were synthesized and then purified from their linear byproducts by inclusion complexation with alpha-cyclodextrin. Polystyrene was threaded through the resulting cycles by in situ free radical polymerization of styrene monomer in the presence of an excess of POE cycles. A bulky free radical initiator was utilized to endcap the polystyrene molecule at the two ends to prevent dethreading of cyclic moieties.
In the second part of the dissertation, phase behavior, morphology and dynamics of cyclic POE and polystyrene blends were compared to linear POE and polystyrene blends. Advanced solid-state NMR techniques and differential scanning calorimetry were employed for this purpose. Cyclic POE was found to be much more miscible with polystyrene when compared to linear POE, resulting in nanometer-sized domains and significantly reduced mobilities of the cyclic POE components in the blends. The unusual behavior of cyclic POE in the blends was attributed to topological as well as end-group effects with the topological effects being predominant. Polyrotaxanes composed of polystyrene and cyclic POE components exhibited cyclic POE domain sizes similar to that of physical blends. Cyclic POE dynamics in polyrotaxanes were considerably hindered, however, due to the threaded architecture. Surface segregation studies of cyclic POE/polystyrene blends and polyrotaxanes did not show segregation of POE to the surface because of the improved miscibility and the topological constraints present in these systems.
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CRISENZA, TOMMASO ULISSE FILIPPO. "Thermoplastic elastomers from chlorinated polyethylene/nylon terpolyamide blends." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28398.
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Blends of chlorinated polyethylene (CPE) and Nylon terpolyamide (PA) were
prepared with different ratios. It is generally known that CPE has intrinsic
properties of heat, oil and oxidation resistance, so the obtained materials are well
suitable in the hose, pipe and seal industry. CPE was strengthened by a 6,6-6,12
co-polyamide with the glass transition temperature slightly above room
temperature and a particularly low melting temperature, that allowed to obtain
the blends by typical industrial processes of mixing, milling and injection
molding. Mechanical and rheological properties were investigated both with
tensile tests and dynamic mechanical analysis: the results showed that CPE and
PA form phase separated systems with excellent compatibility as the strength and
modulus were improved. The thermal and mechanical behavior of the blends is
that typical of thermoplastic elastomers. The comparison of the FTIR spectra of
the blends in respect of linear combination of those of the component polymers
allowed the detection of differences attributed to the existence of interactions at
the interface responsible of the enhanced mechanical properties. These results
were corroborated by time-domain proton NMR experiments, with an improved
method for the measurement of the hard/soft ratio in phase separated systems.
With the aim to resolve the morphology of the blends, samples were studied with
laser scanning confocal fluorescent microscopy (LSCFM). CPE rubber was
homogeneously labeled with a fluorescent dye by solution treatment and then
blended with PA in order to increase the contrast between phases in fluorescent
microscopy. Scanning Electron Microscopy and Atomic Force Microscopy
techniques were used to confirm the data collected with LSCFM. A continuous
and interpenetrating structure of the two phases is finally revealed for the blend
with the best mechanical properties.Blends with co-continuous structures may combine the properties of both
components in a favorable way. For example, a co-continuous structure leads to
the maximum contribution of the mechanical modulus from each component
simultaneously. Synergistic effects have also been shown in mechanical
properties. Constituting a stable co-continuous morphology just mixing two
polymers it is not that easy, and even more difficult is to detect such
microstructure within the bulk of the material. For these two reasons, cocontinuous
polymer blends are an interesting and challenging research topic. In
addition, these co-continuous structures offer promising opportunities for
improving properties and creating tailor-made materials.
For these reason, and also as very few examples of Thermoplastic elastomers
based on Chlorinated polyethylene and Nylon are present in the literature, the
project for this thesis came to life. This work is aimed at the achievement of a
material with thermoplastic elastomeric mechanical and processing properties,
for which the structure properties relationships would be completely understood
and explained as due to synergistic interfacial interaction between phases and cocontinuous
morphology within them.
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Meller, Mika. "Dispersive mixing of high viscosity ratio polymer blends /." Lausanne, 2000. http://library.epfl.ch/theses/?nr=2267.
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Mattos, Ritamara Isis de. "Estudo de condutores protônicos a base de macromoléculas naturais." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-25092011-171004/.
Full textAbstract:
Esta tese apresenta os resultados do estudo de eletrólitos poliméricos protônicos obtidos a base de gelatina e quitosana, modificadas através da adição de glicerol e formaldeído - ácidos acético ou clorídrico foram adicionados para promover a condutividade iônica dos filmes. Foram também preparadas blendas a partir de gelatina com quitosana, assim como filmes a base de gelatina e nanopartículas. Com exceção dos filmes com nanopartículas, todos eles possuem boa transparência, estabilidade térmica, maleabilidade, aderência ao vidro e apresentam uma superfície homogênea, sem trincas ou rachaduras. As temperaturas de transição vítrea (Tg) dos eletrólitos foram obtidas do estreitamento de linha de RMN. A taxa de relaxação spin-rede do \'ANTPOT. 1 H\' em função da temperatura mostrou um máximo bem definido cuja posição depende da concentração de ácido no caso da gelatina e da quantidade de glicerol no caso da quitosana, refletindo a alta mobilidade do próton nestes eletrólitos. As técnicas de RPE, onda contínua e pulsada, foram utilizadas para o estudo de eletrólitos dopados com \'CU\'CL\'O IND.4\'. Os valores de condutividade iônica dos eletrólitos são da ordem de \'10 POT.-5\' S/cm para os filmes de gelatina (com ácido acético ou clorídrico), quitosana e blendas e entre \'10 POT.-6\' a \'10 POT.-8\' para os eletrólitos de gelatina com nanopartículas. Estes estudos revelaram que a concentração de ácido acético ou clorídrico (na gelatina), influencia a condutividade iônica dos eletrólitos, mas, para o caso das blendas esta influência é pequena. No caso dos filmes de gelatina com nanopartículas, a condutividade diminui de forma significativa. Em relação aos eletrólitos de quitosana a condutividade iônica é influenciada pela quantidade de glicerol adicionado. Verificou-se que o aumento da temperatura até 80°C promove o aumento da condutividade iônica para todos os filmes estudados.<br>This thesis shows the results from the study of protonic polymer electrolytes obtained from gelatin and chitosan, modified by the addition of glycerol and formaldehyde - acetic and hydrochloric acids are added to promote the ionic conductivity of the films. Blends based on chitosan and gelatin were also prepared, as well as films based on gelatin and nanoparticles. With the exception of the films with nanoparticles, all samples presented good transparency, thermal stability, flexibility, adhesion to glass and homogeneous surface without cracks. The glass transition temperature (Tg) of the electrolytes were obtained from the NMR line narrowing. The spin-lattice relaxation rate of the \'ANTPOT. 1 H\' spin-network as a function of temperature showed a well-defined maximum whose position depends on the concentration of acid in the case of gelatin and on the glycerol content in the case of chitosan, reflecting the high mobility of the protons in the electrolytes. Continuous wave and pulsed EPR techniques were used to study the electrolytes doped with \'CU\'CL\'O IND.4\'. The values of the ionic conductivity of the electrolytes are of the order of \'10 POT.-5\' S/cm for the films of gelatin (with acetic or hydrochloric acids), chitosan and blends and from \'10 POT.-6\' to \'10 POT.-8\' for the electrolytes of gelatin with nanoparticles. These studies revealed that the concentration of acetic or hydrochloric acids (in gelatin), influences the ionic conductivity of the electrolytes but, in the case of blends, this influence is small. In the case of the films based on gelatin with nanoparticles, the ionic conductivity decreases significantly. In relation to the electrolyte based on chitosan, the ionic conductivity is influenced by the amount of glycerol added. It was found that increasing the temperature to 80°C promotes the increase of ionic conductivity for all films studied.
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Deschler, Felix. "How molecular doping affects the charge separation process in polymer-fullerene blends." Diss., lmu, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-153170.
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Stumpe, Katrin. "Hochverzweigte Polyphenylene als Matrixmaterial für nanoporöse Isolatorsysteme mit niedriger Dielektrizitätskonstante." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1210336214273-90686.
Full textAbstract:
Neue nanoporöse Materialien mit niedrigen Dielektrizitätskonstanten werden in der Mikroelektronik dringend benötigt. Eine Methode, die Dielektrizitätskonstante eines gegebenen Materials weiter zu reduzieren, ist die Einführung von geschlossenen und luftgefüllten Poren im Nanometerbereich. Die Porosität wird durch die Verwendung eines Zweikomponentensystems bestehend aus einer stabilen Matrix und einem labilen Porenbildner eingeführt; aus diesen wird ein Blend hergestellt, und durch anschließende Zersetzung des Porenbildners entsteht ein poröses Matrixpolymer mit stabilen Aushöhlungen. Im Vordergrund dieser Arbeit stand die Synthese und Charakterisierung hochverzweigter Polyphenylene über die Diels-Alder-Reaktion von phenylierten Cyclopentadienonen mit phenylierten Alkinen zur Verwendung als Matrixmaterialien in nanoporösen Isolatorsystemen. Dabei wurde sowohl von A2- und B3-Monomeren als auch von AB2- und AB-Monomeren ausgegangen. Die hochverzweigten Polyphenylene sind vielversprechende Materialien mit hervorragenden isolierenden und chemischen Eigenschaften wie hohen thermischen Stabilitäten und guten Löslichkeiten in organischen Lösungsmitteln, was eine wichtige Voraussetzung für die Verwendung der Polymere in der Mikroelektronik darstellt. Die verschiedenen Syntheseansätze erlauben dabei eine Kontrolle über die Endgruppen und die Verzweigung. Daneben wurden thermolabile hochverzweigte Polycarbonate und Polytriazenester als Porenbildner synthetisiert und mit Silylether-Endgruppen modifiziert, wobei mit der tert-Butyldiphenylsilyl-Gruppe die besten Ergebnisse bezüglich der Mischbarkeit mit der Polyphenylenmatrix erhalten wurden. Außerdem wurden Blends in Form von dünnen Schichten aus den hochverzweigten Polyphenylenen mit den Porenbildnern im Hinblick auf die potentielle Anwendung der Materialien als nanoporöse Isolatoren charakterisiert.
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Mousavioun, Payam. "Properties of lignin and poly(hydroxybutyrate) blends." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/46668/1/Payam_Mousavioun_Thesis.pdf.
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The Queensland University of Technology (QUT) allows the presentation of a thesis for the Degree of Doctor of Philosophy in the format of published or submitted papers, where such papers have been published, accepted or submitted during the period of candidature. This thesis is composed of Seven published/submitted papers and one poster presentation, of which five have been published and the other two are under review. This project is financially supported by the QUTPRA Grant. The twenty-first century started with the resurrection of lignocellulosic biomass as a potential substitute for petrochemicals. Petrochemicals, which enjoyed the sustainable economic growth during the past century, have begun to reach or have reached their peak. The world energy situation is complicated by political uncertainty and by the environmental impact associated with petrochemical import and usage. In particular, greenhouse gasses and toxic emissions produced by petrochemicals have been implicated as a significant cause of climate changes. Lignocellulosic biomass (e.g. sugarcane biomass and bagasse), which potentially enjoys a more abundant, widely distributed, and cost-effective resource base, can play an indispensible role in the paradigm transition from fossil-based to carbohydrate-based economy. Poly(3-hydroxybutyrate), PHB has attracted much commercial interest as a plastic and biodegradable material because some its physical properties are similar to those of polypropylene (PP), even though the two polymers have quite different chemical structures. PHB exhibits a high degree of crystallinity, has a high melting point of approximately 180°C, and most importantly, unlike PP, PHB is rapidly biodegradable. Two major factors which currently inhibit the widespread use of PHB are its high cost and poor mechanical properties. The production costs of PHB are significantly higher than for plastics produced from petrochemical resources (e.g. PP costs $US1 kg-1, whereas PHB costs $US8 kg-1), and its stiff and brittle nature makes processing difficult and impedes its ability to handle high impact. Lignin, together with cellulose and hemicellulose, are the three main components of every lignocellulosic biomass. It is a natural polymer occurring in the plant cell wall. Lignin, after cellulose, is the most abundant polymer in nature. It is extracted mainly as a by-product in the pulp and paper industry. Although, traditionally lignin is burnt in industry for energy, it has a lot of value-add properties. Lignin, which to date has not been exploited, is an amorphous polymer with hydrophobic behaviour. These make it a good candidate for blending with PHB and technically, blending can be a viable solution for price and reduction and enhance production properties. Theoretically, lignin and PHB affect the physiochemical properties of each other when they become miscible in a composite. A comprehensive study on structural, thermal, rheological and environmental properties of lignin/PHB blends together with neat lignin and PHB is the targeted scope of this thesis. An introduction to this research, including a description of the research problem, a literature review and an account of the research progress linking the research papers is presented in Chapter 1. In this research, lignin was obtained from bagasse through extraction with sodium hydroxide. A novel two-step pH precipitation procedure was used to recover soda lignin with the purity of 96.3 wt% from the black liquor (i.e. the spent sodium hydroxide solution). The precipitation process is presented in Chapter 2. A sequential solvent extraction process was used to fractionate the soda lignin into three fractions. These fractions, together with the soda lignin, were characterised to determine elemental composition, purity, carbohydrate content, molecular weight, and functional group content. The thermal properties of the lignins were also determined. The results are presented and discussed in Chapter 2. On the basis of the type and quantity of functional groups, attempts were made to identify potential applications for each of the individual lignins. As an addendum to the general section on the development of composite materials of lignin, which includes Chapters 1 and 2, studies on the kinetics of bagasse thermal degradation are presented in Appendix 1. The work showed that distinct stages of mass losses depend on residual sucrose. As the development of value-added products from lignin will improve the economics of cellulosic ethanol, a review on lignin applications, which included lignin/PHB composites, is presented in Appendix 2. Chapters 3, 4 and 5 are dedicated to investigations of the properties of soda lignin/PHB composites. Chapter 3 reports on the thermal stability and miscibility of the blends. Although the addition of soda lignin shifts the onset of PHB decomposition to lower temperatures, the lignin/PHB blends are thermally more stable over a wider temperature range. The results from the thermal study also indicated that blends containing up to 40 wt% soda lignin were miscible. The Tg data for these blends fitted nicely to the Gordon-Taylor and Kwei models. Fourier transform infrared spectroscopy (FT-IR) evaluation showed that the miscibility of the blends was because of specific hydrogen bonding (and similar interactions) between reactive phenolic hydroxyl groups of lignin and the carbonyl group of PHB. The thermophysical and rheological properties of soda lignin/PHB blends are presented in Chapter 4. In this chapter, the kinetics of thermal degradation of the blends is studied using thermogravimetric analysis (TGA). This preliminary investigation is limited to the processing temperature of blend manufacturing. Of significance in the study, is the drop in the apparent energy of activation, Ea from 112 kJmol-1 for pure PHB to half that value for blends. This means that the addition of lignin to PHB reduces the thermal stability of PHB, and that the comparative reduced weight loss observed in the TGA data is associated with the slower rate of lignin degradation in the composite. The Tg of PHB, as well as its melting temperature, melting enthalpy, crystallinity and melting point decrease with increase in lignin content. Results from the rheological investigation showed that at low lignin content (.30 wt%), lignin acts as a plasticiser for PHB, while at high lignin content it acts as a filler. Chapter 5 is dedicated to the environmental study of soda lignin/PHB blends. The biodegradability of lignin/PHB blends is compared to that of PHB using the standard soil burial test. To obtain acceptable biodegradation data, samples were buried for 12 months under controlled conditions. Gravimetric analysis, TGA, optical microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), FT-IR, and X-ray photoelectron spectroscopy (XPS) were used in the study. The results clearly demonstrated that lignin retards the biodegradation of PHB, and that the miscible blends were more resistant to degradation compared to the immiscible blends. To obtain an understanding between the structure of lignin and the properties of the blends, a methanol-soluble lignin, which contains 3× less phenolic hydroxyl group that its parent soda lignin used in preparing blends for the work reported in Chapters 3 and 4, was blended with PHB and the properties of the blends investigated. The results are reported in Chapter 6. At up to 40 wt% methanolsoluble lignin, the experimental data fitted the Gordon-Taylor and Kwei models, similar to the results obtained soda lignin-based blends. However, the values obtained for the interactive parameters for the methanol-soluble lignin blends were slightly lower than the blends obtained with soda lignin indicating weaker association between methanol-soluble lignin and PHB. FT-IR data confirmed that hydrogen bonding is the main interactive force between the reactive functional groups of lignin and the carbonyl group of PHB. In summary, the structural differences existing between the two lignins did not manifest itself in the properties of their blends.
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Streller, Rouven Cornelius. "Boehmite als Nanofüllstoffe für Polypropylen-Nanocomposites und Nanopartikel-modifizierte Polypropylen/Kautschuk-Blends." [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:25-opus-61139.
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Ghazy, Omayma. "Binary blend nanoparticles with defined morphology." [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-63345.
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Tahir, Muhammad. "Development of Novel Blends based on Rubber and in-situ Synthesized Polyurethane-urea." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-232718.
Full textAbstract:
Polyurethane and the analogous ‘polyurethane-urea’ are high performance polymeric materials having remarkable properties such as high stiffness, abrasion and tear strengths. In many studies, the low strength rubbers have been blended with various types of polyurethanes for new and improved materials. However, until now, the reported heterogeneous blends offer only a narrow temperature range of application due to the high temperature softening of their polyurethane (-urea) phase. In addition, the conventional solution-or melt-blending methods are time and energy intensive, which tend to forfeit the economical realization of the reported blends. In contrast to earlier studies, a simplified reactive blending process is suggested to synthesize polyurethane-urea via a prepolymer route during blending with rubbers to obtain novel elastomeric materials having extended performance characteristics.
The reactive blending process is opted to prepare blends based on nitrile butadiene rubber (NBR) and in-situ synthesized polyurethane-urea (PUU). The blending is carried out in an internal mixer at a preset temperature of 100°C. The critical temperatures of the reactive blending process are determined from the chemo-rheological analysis of a premix, composed of a 4,4′-diphenylmethane diisocyanate (MDI)/polyether (PTMEG) based prepolymer admixed with 1,3-phenylene diamine (mPD). The prepared NBR/PUU blends exhibit highly improved mechanical properties. Contrary to previous reports, the reinforced dynamic-mechanical responses of the novel blends remain stable till very high temperatures (≥180°C).
The influence of diamine type on the in-situ synthesized polyurethane-urea and the performance of prepared blends are investigated. Four different diamines, namely 1,3-Phenylene diamine, 1,4-Bis(aminomethyl)benzene, 4,4′-Methylene-bis(2-chloroaniline) and 4,4ʹ-(1,3-Phenylenediisopropylidene)bisaniline, are selected to chain extend the prepolymer to PUU during blending with NBR. The chemical and domain structure of the PUUs are found to greatly influence the reinforced tensile and dynamic-mechanical responses of the NBR/PUU 70/30 blends.
The PUU (based on MDI/PTMEG prepolymer and mPD) is blended with polar (CR, XNBR) and nonpolar (NR, EPDM, sSBR) rubbers. PUU compatibilizes with all the rubbers irrespective of their polarity and reinforces their tensile and dynamic-mechanical characteristics. The use of blends in industrial applications, for example, in a truck tire tread compound and as a roller covering material, is examined. In a simplified tire tread formulation, the carbon black for NR-CB composite is partially replaced with an equivalent quantity of PUU for NR/PUU-CB composite of similar hardness. The dynamic mechanical investigations reveal that the energy dissipation and strain dependent softening is high in NR-CB as compared to the NR/PUU-CB composite. In another application, NBR/PUU blend is successfully tested as a rubber roller covering material. The tested blend-covered roller retains its structural integrity and develops less heat build-up as compared to the silica filled NBR-covered roller. This shows a substantial suitability of the blend-covered rollers for film, printing and textile processing machinery.
These novel blends are considered to be the promising new materials for many commercial applications including wheels, rubber rollers, belts or pump impellers.
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Euchler, Eric, Radek Stocek, Michael Gehde, Jörg-Michael Bunzel, Wolfgang Saal, and Reinhold Kipscholl. "Fracture behavior of rubber powder modified rubber blends applied for conveying belt top covers." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-198136.
Full textAbstract:
The aim of this study is concentrated on the experimental investigation of wear resistance of rubber powder modified rubber blends. Styrene-Butadiene-Rubber (SBR) blends applied for conveying belt top covers have been modified by ground rubber (rubber powder) based on SBR. We theoretically described the rubber wear mechanism due to loading conditions occurring at conveyor belts in the field, to simulate wear behavior of top cover rubber materials. An own developed testing equipment based on gravimetric determination of mass loss of rubber test specimen was used investigating dynamic wear with respect to fracture properties of top cover materials. Furthermore we investigated fatigue crack growth (FCG) data over a broad range of tearing energy by Tear Analyzer to characterize crack propagation behavior of rubber powder modified rubber blends. Thus, we demonstrate the influence of rubber powder on resistance against occurrence of fracture as well as dynamic wear as a function of the rubber powder content in rubber blends applied for conveying belt top covers.
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Anders, Jörg. "Character-Animation mit Blender." Universitätsbibliothek Chemnitz, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200800841.
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Alshahrani, Rasha. "Liquid Organic Electrolytes: Blends of Low Molecular Weight Methoxyoligooxyethylene (MPEGs)/LiTFSI Salt." DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2017. http://digitalcommons.auctr.edu/cauetds/111.
Full textAbstract:
Blends containing methoxyoligooxyethyleneglycol (MPEGs) (MW 350 and 550) and bis(trifluoromethane)sulfonimide lithium (LiTFSI) salt were prepared by solution blending process using tetrahydrofuran (THF) as a solvent. The ionic conductivity of the blends of different compositions were determined at four temperatures i.e. 25°C, 40°C, 60°C and 70°C. A maximum ionic conductivity value of 3.9x10-3 S cm-1 at 25°C was obtained for the blends containing MPEG-350 at an ethylene oxide to lithium salt ratio of 1:10. The ionic conductivity increases with increasing temperature and shows that the ion transport is aided by the segmental motion of the MPEG chains. 7Li NMR spectroscopy was used to study the nature and dynamics of the salt clusters in the blends
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Launer, Rebecca. "Blended Learning im Fremdsprachenunterricht." Diss., lmu, 2008. http://nbn-resolving.de/urn:nbn:de:bvb:19-89054.
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Dill, Svenja [Verfasser], Dietmar Werner [Gutachter] Auhl, and Roger [Gutachter] Weinlein. "Verarbeitung und Charakterisierung von Polyamid 6-Polyhydroxybutyrat-Blends / Svenja Dill ; Gutachter: Dietmar Auhl, Roger Weinlein." Berlin : Universitätsverlag der TU Berlin, 2020. http://nbn-resolving.de/urn:nbn:de:101:1-2020061702025924763757.
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Arndt, Martin. "Forschungsorientierte Gruppenlernprozesse "blended" gestalten." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-229146.
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„Wurzeln und Flügel“ sollten Kinder bekanntlich von ihren Eltern bekommen um Bindung und Freiheit zu erfahren. Möchte man engagierte forschungsorientierte Gruppenlernprozesse gestalten spielen diese beiden Aspekte ebenfalls eine zentrale Rolle. Die Teilnehmenden solcher Prozesse erarbeiten sich gemeinsam den Zugang zu einem Themengebiet, finden sich in Gruppen zusammen, um sich gegenseitig zu unterstützen und bekommen durch die Auflösung der Seminarstruktur die Freiheit, sich intensiv mit den selbst gewählten Schwerpunkten auseinanderzusetzen. Sie teilen Erfahrungen und Erkenntnisse mit der Gesamtgruppe und profitieren von einem umfassenden Peer-Review im Prozess der Verschriftlichung der Ergebnisse. Einblicke in die Planung, die Durchführung und vor allem die umfassende Evaluation eines solchen „blended“ gestalteten Seminars der Kunstdidaktik (Fachdidaktische Kritik digitaler Arbeitsmittel im Kunstunterricht) bilden in diesem Workshop die Basis für Diskussionen, praktische Überlegungen und kleine Anwendungen.
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Albrecht, Mirko, and Michael Gehde. "Welding of incompatible thermoplastic polymers." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-204024.
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Due to the wide range of properties of plastics (e.g. low density), more and more conventional materials are substituted by polymer materials. Complex requirement profiles on technical parts increase the demand for joining processes that enable the reliable joining of otherwise incompatible thermoplastics. In this case, material bonded connections are approaching their limits. In the following study two incompatible thermoplastic polymers were welded by using polymer blends that are compatible to both components. Industrially relevant thermoplastics polyethylene (PE) and polyamide 12 (PA12) were chosen to demonstrate the potential of an innovative joining technology.
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Barth, Jan. "Kombinatorisches Compoundieren und mechanische Online-Prüfungen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-113594.
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Durch das Einbringen von Additiven, Füll- und Verstärkungsstoffen in eine polymere Matrix oder durch das Blenden unterschiedlicher Polymere ist es möglich, die Eigenschaften von Kunststoffen gezielt auf den Anwendungsfall hin zu optimieren. Gerade durch diese „Einstellbarkeit“ der Eigenschaften und infolge ihrer vergleichsweise geringen Dichte verdrängen Kunststoffe zunehmend klassische Werkstoffe und erobern so neue Anwendungsgebiete. Die Entwicklung solcher innovativer Kunststoffrezepturen (Compounds) ist jedoch zeitaufwendig und kostenintensiv. Um die gewünschten Gebrauchseigenschaften des Endproduktes zu erreichen, ist oft eine Vielzahl unterschiedlicher Zusatzstoffe erforderlich; somit werden entsprechende Rezepturen schnell sehr komplex. Bei der klassischen Materialentwicklung wird zumeist nicht erfasst/ermittelt, welche Synergien die einzelnen Bestandteile - positiver oder negativer Art - untereinander haben. Eine gezielte systematische Untersuchung dieser Synergien mit klassischen Methoden ist aus Kosten- und Zeitgründen kaum möglich. Für eine zeitgemäße Materialentwicklung sind daher neue Methoden gefragt, die eine schnelle Rezepturvariation, gepaart mit einem schnellen Eigenschaftsscreening, ermöglichen.
Mit der Entwicklung des kombinatorischen Compoundier und High Throughput Screening Systems (CC/HTS-Systems) wurde im Rahmen dieser Arbeit eine, auch industriell einsetzbare, Basisanlage für die schnelle Entwicklung von neuen und innovativen Compoundrezepturen erstellt und hinsichtlich der Übertragbarkeit der Ergebnisse verifiziert. Das CC/HTS-System besteht aus:
• einem Doppelschneckenextruder (ZSK 18 MegaLab)
Eine entscheidende Besonderheit dieses System resultiert aus der Möglichkeit, die Materialzufuhr und damit die Zusammensetzung über rechnergesteuerte Dosierwaagen kontinuierlich zu verändern. Die im Vergleich zur klassischen Vorgehensweise somit vorhandene schnelle Rezepturänderung ermöglicht es in kürzester Zeit, eine große Rezepturvielfalt abzuarbeiten.
• einer Flachfolienanlage
Durch die direkte Kopplung der Flachfolienanlage mit der Folienextrusion wird der Rezepturgradient in einer Folie, im Sinne einer 1-dimensionalen Library „eingefroren“.
• integrierten Prüfeinrichtungen
Durch den Einsatz von in das System zu integrierenden unterschiedlichen HTS-Methoden ist eine schnelle und aussagefähige Charakterisierung der so hergestellten Rezepturen direkt online möglich.
Erst diese im Rahmen dieser Arbeit entwickelten und validierten mechanischen Online-Prüfungen, als neue HTS-Methoden, ermöglichen durch deren Integration in das Gesamtsystem ein schnelles Materialscreening, indem die im Rahmen des CC hergestellten Folien (Library) online auf ihre mechanische Performance hin geprüft werden. Die mechanische Online-Prüfeinrichtung wurde so konzipiert, dass drei unterschiedliche Tests simultan in einer Vorrichtung durchgeführt werden. Hierbei handelt es sich um:
• einen Durchstoßversuch,
• einen Weiterreißversuch
(wahlweise in oder travers zur Folienabzugsrichtung),
• einen modifizierten Zugversuch
(wahlweise in oder travers zur Folienabzugsrichtung).
Anhand dieser drei zeitgleich online gemessenen Werkstoffkennwerte sind Aussagen über die wichtigsten mechanischen Eigenschaften - Steifigkeit, Zähigkeit und Festigkeit - abhängig von der Werkstoffzusammensetzung möglich. Die Prüfeinrichtungen für den Zug- und den Weiterreißversuch sind so konstruiert, dass sie sich je nach Entwicklungsaufgabe in der Prüfeinrichtung um 90° drehen lassen, um auch mechanische Eigenschaften in und/oder travers zur Folienabzugsrichtung zu ermitteln. Durch das Entfernen der Kerbmesser in der Prüfeinrichtung des Weiterreißversuchs lässt sich dieser zu einem zweiten Online-Zugversuch umrüsten, um z. B. gleichzeitig in und travers zur Folienabzugsrichtung die Zugfestigkeit zu erfassen. Hierdurch ist es möglich, in einem Prozessdurchlauf das anisotrope Werkstoffverhalten rezeptur- und prozessabhängig zu charakterisieren.
Die Entwicklung der mechanischen Online-Prüfeinrichtung wurde durch stetige Validierung der Prüfergebnisse abgesichert. Als Ergebnis dieser Validierungsschritte ist festzuhalten, dass die online und offline ermittelten mechanischen Eigenschaften gut miteinander korrelieren.
Eine entscheidende Frage beim CC war neben der Korrelierbarkeit der mechanischen Eigenschaften die Zuordnung der Rezepturzusammensetzung - welche sich kontinuierlich infolge der Gradientendosierung verändert - zu den online ermittelten Materialeigenschaften. Hierbei ist das Verweilzeitverhalten des Gesamtsystems, bestehend aus Extruder und Flachfolienanlage, zu berücksichtigen. Zur Beantwortung dieser Fragestellung wurden zunächst verschiedene theoretische Modelle auf ihre Anwendbarkeit hin untersucht. Es konnte gezeigt werden, dass das Double Backflow Cell Model die gewählte Versuchsanordnung am besten beschreibt. Als Ergebnis dieser theoretischen Überlegungen ist festzuhalten, dass für eine gute Korrelation von Rezepturzusammensetzung und online ermittelten Materialeigenschaften nur die System-Totzeit bei hinreichend langer Gradientenzeit zu berücksichtigen ist. Diese Arbeitshypothese konnte durch einen Versuch mittels Gradientenzugabe von Glasfasern von 0 w% auf 30 w% in Polypropylen und anschließender Glührückstandsbestimmung experimentell bestätigt werden.
Im Anschluss an die Entwicklung und Validierung des Gesamtsystems (Gradientendosierung und mechanische Online-Prüfung) wurden die Möglichkeiten des CC/HTS-Systems anhand eines praxisrelevanten Zweistoffsystems, bestehend aus Polypropylen und verschiedenen POEs, welche sich im Viskositätsverhältnis zum Polypropylen und dem α-Olefin-Anteil unterscheiden, aufgezeigt. Durch das Blenden von Polypropylen mit einem Polyolefinelastomer (POE) lässt sich Polypropylen schlagzäh modifizieren. Bei einem solchen Blend aus zwei in der Regel nicht mischbaren Polymeren ist die sich einstellende Phasenmorphologie für das mechanische Werkstoffverhalten von entscheidender Bedeutung. Die Phasenmorphologie, also die Form und Größe der POE-Partikel, in der Polypropylenmatrix ist stark von der ausgewählten POE-Type abhängig.
Um Aussagen zur Blendmorphologie zu erhalten, wurde im Rahmen dieser Untersuchungen die mechanische Online-Prüfung erstmals mit einer Online-Kleinwinkellichtstreuung als HTS-Methoden gekoppelt. Durch die Online-Kleinwinkellichtstreuung ist es möglich, simultan zu den mechanischen Eigenschaften auch online Rückschlüsse auf die Blendmorphologie zu erhalten. Diese Untersuchungen zeigten, wie die Morphologie und die mechanischen Eigenschaften korrelieren und welche Bedeutung der Auswahl der Blendpartner - des POEs – für das mechanische Werkstoffverhalten zukommt. Interessant war, dass die untersuchten Prozessparameter von untergeordneter Bedeutung für die Performance eines solchen Blends sind.
Abschließend wurde die CC/HTS Methode auf eine industrielle Fragestellung - Dreistoffsystem bestehend aus Polypropylen/Glasfasern/Koppler – angewandt. Die Anwendbarkeit des Systems auch auf komplexere Werkstoffzusammensetzungen wurde dabei bestätigt. Es konnte gezeigt werden, dass mit Hilfe dieser Methode / Versuchseinrichtung die Compoundentwicklung deutlich beschleunigt und ressourcenschonender durchgeführt werden kann und die Ergebnisse mit den klassisch erarbeiteten Werten korrelieren.
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Perevosnik, Kathleen A. "Investigation of the Mechanical and Thermal Properties of Poly(styrene-block-isobutylene-styrene) (SIBS) and its Blends with Thymine-Functionalized Polystyrene." Akron, OH : University of Akron, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1226647131.
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Thesis (M.S.)--University of Akron, Dept. of Polymer Science, 2008.<br>"December, 2008." Title from electronic thesis title page (viewed 01/13/2010) Advisor, Judit E. Puskas; Faculty Reader, Gary R. Hamed; Department Chair, Ali Dhinojwala; Dean of the College, Stephen Z. D. Cheng; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Weissbach, Randy. "Blended Learning in der doppelten Buchführung." Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-138320.
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Mit der Ergänzung der bestehenden E-Learning-Angebote um ein Mobile-Learning-Tool wurde ein zusätzliches Angebot geschaffen, mit dem sich Studierende selbstständig und in graduell wählbaren Lerntiefen Aufgabengebiete der Buchführung erarbeiten können. Der Einsatz des Blended Learning-Angebotes ermöglichte den Studierenden eine auf die Präsenzveranstaltung aufbauende - aber zeitlich und räumlich unabhängige - Vertiefung der Lerninhalte.
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Izraylit, Victor [Verfasser], Andreas [Akademischer Betreuer] Lendlein, Dieter [Akademischer Betreuer] Neher, Jonny [Gutachter] Blaker, and Jukka [Gutachter] Seppälä. "Reprogrammable and tunable actuation in multiblock copolymer blends / Victor Izraylit ; Gutachter: Jonny Blaker, Jukka Seppälä ; Andreas Lendlein, Dieter Neher." Potsdam : Universität Potsdam, 2021. http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-518434.
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Tripathi, Rupali [Verfasser], Heinz Günter [Akademischer Betreuer] Pitsch, and S. Mani [Akademischer Betreuer] Sarathy. "Detailed chemical kinetic modeling of biofuels and their blends with conventional fuel components / Rupali Tripathi ; Heinz Pitsch, S. Mani Sarathy." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://nbn-resolving.de/urn:nbn:de:101:1-2020080423315879685573.
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Fischer, Janine. "Density of States and Charge Carrier Transport in Organic Donor-Acceptor Blend Layers." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-184493.
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In the last 25 years, organic or "plastic" solar cells have gained commercial interest as a light-weight, flexible, colorful, and potentially low-cost technology for direct solar energy conversion into electrical power. Currently, organic solar cells with a maximum power conversion effciency (PCE) of 12% can compete with classical silicon technology under certain conditions. In particular, a variety of strongly absorbing organic molecules is available, enabling custom-built organic solar cells for versatile applications. In order to improve the PCE, the charge carrier mobility in organic thin films must be improved. The transport characterization of the relevant materials is usually done in neat layers for simplicity. However, the active layer of highly efficient organic solar cells comprises a bulk heterojunction (BHJ) of a donor and an acceptor component necessary for effective charge carrier generation from photo-generated excitons. In the literature, the transport properties of such blend layers are hardly studied. In this work, the transport properties of typical BHJ layers are investigated using space-charge limited currents (SCLC), conductivity, impedance spectroscopy (IS), and thermally stimulated currents (TSC) in order to model the transport with numerical drift-diffusion simulations. Firstly, the influence of an exponential density of trap states on the thickness dependence of SCLCs in devices with Ohmic injection contacts is investigated by simulations. Then, the results are applied to SCLC and conductivity measurements of electron- and hole-only devices of ZnPc:C60 at different mixing ratios. Particularly, the field and charge carrier density dependence of the mobility is evaluated, suggesting that the hole transport is dominated by exponential tail states acting as trapping sites. For comparison, transport in DCV5T-Me33:C60, which shows better PCEs in solar cells, is shown not to be dominated by traps. Furthermore, a temperature-dependent IS analysis of weakly p-doped ZnPc:C60 (1:1) blend reveals the energy-resolved distribution of occupied states, containing a Gaussian trap state as well as exponential tail states. The obtained results can be considered a basis for the characterization of trap states in organic solar cells. Moreover, the precise knowledge of the transport-relevant trap states is shown to facilitate modeling of complete devices, constituting a basis for predictive simulations of optimized device structures<br>Organische oder "Plastik"-Solarzellen haben in den letzten 25 Jahren eine rasante Entwicklung durchlaufen. Kommerziell sind sie vor allem wegen ihres geringen Gewichts, Biegsamkeit, Farbigkeit und potentiell geringen Herstellungskosten interessant, was zukünftig auf spezielle Anwendungen zugeschnittene Solarzellen ermöglichen wird. Die Leistungseffzienz von 12% ist dabei unter günstigen Bedingungen bereits mit klassischer Siliziumtechnologie konkurrenzfähig. Um die Effzienz weiter zu steigern und damit die Wirtschaftlichkeit zu erhöhen, muss vor allem die Ladungsträgerbeweglichkeit verbessert werden. In organischen Solarzellen werden typischerweise Donator-Akzeptor-Mischschichten verwendet, die für die effziente Generation freier Ladungsträger aus photo-induzierten Exzitonen verantwortlich sind. Obwohl solche Mischschichten typisch für organische Solarzellen sind, werden Transportuntersuchungen der relevanten Materialien der Einfachheit halber meist in ungemischten Schichten durchgeführt. In der vorliegenden Arbeit wird der Ladungstransport in Donator-Akzeptor-Mischschichten mithilfe raumladungsbegrenzter Ströme (space-charge limited currents, SCLCs), Leitfähigkeit, Impedanzspektroskopie (IS) und thermisch-generierter Ströme (thermally stimulated currents, TSC) untersucht und mit numerischen Drift-Diffusions-Simulationen modelliert. Zunächst wird mittels Simulation der Einfluss exponentiell verteilter Fallenzustände auf das schichtdickenabhängige SCLC-Verhalten unipolarer Bauelemente mit Ohmschen Kontakten untersucht. Die Erkenntnisse werden dann auf Elektronen- und Lochtransport in ZnPc:C60-Mischschichten mit verschiedenen Mischverhältnissen angewendet. Dabei wird die Beweglichkeit als Funktion von elektrischem Feld und Ladungsträgerdichte dargestellt, um SCLC- und Leitfähigkeitsmessungen zu erklären, was mit einer exponentiellen Fallenverteilung gelingt. Zum Vergleich werden dieselben Untersuchungen in DCV2-5T-Me33:C60, dem effizientesten der bekannten Solarzellenmaterialien dieser Art, wiederholt, ohne Anzeichen für fallendominierten Transport. Des weiteren werden erstmals schwach p-dotierte ZnPc:C60-Mischschichten mit temperaturabhängiger IS untersucht, um direkt die Dichte besetzter Lochfallenzustände zu bestimmen. Dabei werden wiederum exponentielle Fallenzustände sowie eine Gaußförmige Falle beobachtet. Insgesamt tragen die über Fallenzustände in Mischschichten gewonnenen Erkenntnisse zum Verständnis von Transportprozessen bei und bilden damit eine Grundlage für die systematische Identifizierung von Fallenzuständen in Solarzellen. Außerdem wird gezeigt, dass die genaue Beschreibung der transportrelevanten Fallenzustände die Modellierung von Bauelementen ermöglicht, auf deren Grundlage zukünftig optimierte Probenstrukturen vorhergesagt werden können
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Sailer, Christian Friedrich. "Blends of polyamide 6 and styrenic polymers : influence of reactive compatibilization on melt rheology and morphology /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17964.
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Israeo, Dagmar, and Verena Jahn. "Der Einsatz von Blended Learning im berufsbegleitetenden Weiterbildungsangebot." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-163432.
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Das postgraduale Bildungsangebot „Nachhaltigkeit in gesamtwirtschaftlichen
Kreisläufen – Sustainability 2020“ wird an der
Hochschule Mittweida seit März 2012 in unterschiedlichen Entwicklungsstufen
auf Masterniveau erprobt.
Besondere Herausforderung des weiterbildenden Studiengangs ist
es, einer heterogenen Zielgruppe das Studium neben Beruf und
Familie zu ermöglichen. Da die Studierenden aus der Berufspraxis
kommen, sind zudem Konzepte und methodische Ansätze gefragt,
die ein forschendes Lernen und das Erlernen wissenschaftlicher
Methoden der Nachhaltigkeit in Verbindung mit der praktischen
Anwendbarkeit der vermittelten Kompetenzen ermöglichen. Insbesondere
die Einbindung zeit- und ortsflexibler Lernformen sind
bei der Gestaltung des Blended Learning-Angebotes in Präsenz,
E-Learning und Selbststudium wesentliche Erfolgsfaktoren. Ein
Entwicklungsziel bildet zudem die Einbindung von Web 2.0-Technologien
in den Lernprozess in definierten Entwicklungsstufen....
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Thiem, Elfi, and Gerhard Thiem. "Blended Learning-Formate für berufsbegleitende Studiengänge und Kurse." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-163482.
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Um einen Betrag zur Fachkräftesicherung vor allem im MINTBereich
zu leisten, bietet das Institut für Technologie- und
Wissenstransfer der Hochschule Mittweida (ITWM) einen Bacherlorstudiengang
Industrial Engineering (B. of Eng.) berufsbegleitend an.
Das Studium ermöglicht Berufstätigen als Ingenieur_in in der Automatisierungs-
und Energietechnik sowie der Mechatronik flexibel und
fachübergreifend tätig zu sein. Neben der fundierten ingenieurtechnischen
Ausbildung erlangen die Studierenden spezielle Kompetenzen
im Management und in Vertriebstechniken. Die Regelstudienzeit
umfasst 8 Semester, dabei werden 180 Credits erreicht. Der Studiengang
ist akkreditiert.
35
Bukvova, Helena, Steffen Gilge, and Eric Schoop. "Virtual Collaboration in Higher Education Blended Learning Arrangements." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-140125.
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Pachtmann, Katrin, Norbert Pengel, and Sylvia Schulze-Achatz. "Tasktrain - Blended Learning für Hochschullehrende zum Thema E-Assessment." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-163401.
Full textAbstract:
Die Unterstützung des Studiums und die Begleitung der Hochschullehre
durch Lernplattformen ist bereits gängige Praxis an deutschen
Hochschulen und damit Realität im Studienalltag. Bisher werden
digitale Medien vorrangig zur Lehr- und Studienorganisation, weniger
für komplexe digitale Lehrszenarien eingesetzt (vgl. ZfW 2013,
30). Im Rahmen eines drittmittelgeförderten Kooperationsprojektes
der Technischen Universität Dresden und der Universität Leipzig
wurde daher eine hochschuldidaktische Blended Learning-Weiterbildung
zur Konzeption und Erstellung von E-Prüfungsaufgaben
entwickelt und pilotiert: TASKtrain. Bezüglich des Transfers in die
eigene Lehrpraxis sind für die teilnehmenden Hochschullehrenden
dabei das Lernen aus der persönlichen Erfahrung mit dem Blended
Learning-Szenario einerseits und die thematische Ausrichtung auf
summatives E-Assessment andererseits von Bedeutung.
37
Oberhoff, Ralph Wilhelm. "Modifizierung und Verarbeitung von Poly(3-hydroxybuttersäure-co-3-hydroxyvaleriansäure) (PHBV) mit kugelförmigen Mikropartikeln." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1132658328714-05584.
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Poly(3-hydroxybuttersäure-co-3-hydroxyvaleriansäure), PHBV, ist ein Copolyester, der auf biologischem Weg durch Bakterien herstellbar und ein steifes sowie relativ festes Polymer ist. Seine Biokompatibilität und biologische Abbaubarkeit weckt das Interesse für diverse Anwendungen in Pharmazie und Medizin. PHBV reagiert mit Abbau empfindlich auf zugleich thermische und mechanische Belastungen, was ein Problem für die Verarbeitung darstellt. Produkte aus PHBV aus einmal geschmolzenem und verarbeitetem Pulver sind hochkristallin. Daher ist das Material spröde. Ferner wirkt sich die hohe Kristallinität sowie eine große Änderung der Dichte beim Abkühlen der Schmelze nachteilig auf die Spinnbarkeit des Materials aus. Nach dem Passieren der Spinndüse ziehen sich die Spinnfäden zusammen, was die Gefahr eines Fadenrisses beim Spinnen erhöht. Aufgrund der relativ hohen Kristallinität des Materials und einer verzögerten Kristallisationskinetik bei gesponnenen Polymerfäden kommt es zur Nachkristallisation in einem erheblichen Ausmaß, die Fäden verkleben nach dem Aufwickeln auf den Galetten und reißen beim Abwickeln. Zur Behebung der Nachteile wurden Verarbeitungsbedingungen vor allem bei Schmelzspinnprozessen mit der Kolbenspinnanlage und bei Mischungsprozessen optimiert. Die Polymermischungen und ?verbundstoffe enthalten kugelförmige Mikropartikel verschiedener Morphologie, die zuvor synthetisiert und charakterisiert wurden. Vor allem mit Vinylgruppen modifizierte Silikat-Submikropartikel mindern die Sprödigkeit von PHBV.
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Schoop, Eric, Helena Bukvova, and Claudia Lieske. "Blended-Learning arrangements for higher education in the changing knowledge society." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-26183.
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This paper presents an advanced – international – blended learning arrangement. It has been developed, implemented and reviewed regularly in the last 4 years at the authors’ institution. Instead of referring solely to traditional classroom teaching, we use and continually refine this arrangement in our every-day formal teaching and learning processes at Technische Universitaet Dresden. By this we take into regard the changes induced by the Bologna Roadmap and try better to support its “new” didactical objectives: more interactive and interdisciplinary modules with focus upon the (practical) integration of professional and methodical
responsibility, decision-making and soft skills.
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Lapointe-Garant, Pierre-Philippe. "Développement d'une méthode PAT basée sur la technique NIR pour le suivi de l'uniformité d'un mélange particulaire pharmaceutique et l'évaluation de la taille moyenne des particules." Mémoire, Université de Sherbrooke, 2009. http://savoirs.usherbrooke.ca/handle/11143/1493.
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En 1992, le cas de Barr Laboratories vs. US Food and Drug Administration (FDA) est le sujet de l'heure dans l'industrie pharmaceutique. La FDA poursuit le manufacturier contractuel de produit pharmaceutique pour ses mauvaises pratiques de validation de procédés et de tests de routine. Le mélange des matières premières est particulièrement visé. Les procédures de validation y sont en effet négligées et les contrôles et évaluations de la qualité du produit fini sont alors restreints aux tests de quelques comprimés sur un lot parfois de plusieurs millions de comprimés. Un besoin est ainsi identifié : mettre en place un nouveau système d'évaluation de la qualité ou de contrôle de la production plus représentatif. C'est ainsi qu'en 2004 est lancée l'initiative des technologies d'analyse des procédés, ou"Process Analytical Technologies" ou PAT. Cette initiative, chapeautée par la FDA, prend rapidement de l'ampleur bien que restant à ce jour une recommandation plus qu'une loi. Dans la même veine, le projet de Recherche et Développement Coopératif (RDC) entre l'Université de Sherbrooke et Wyeth Pharmaceutiques sur l'étude des phénomènes granulaires d'écoulement et de ségrégation identifie ce même besoin important pour la continuation des travaux. C'est ainsi que naquit ce présent projet de maîtrise. Afin de faire suite aux recommandations de la FDA et afin de continuer les études sur les systèmes particulaires, un outil de suivi de la qualité en ligne doit être développé pour les mélangeurs utilisés dans l'industrie pharmaceutique. Cet outil devra éventuellement être viable pour la production de l'entreprise et servira de critère de relâche des produits finis. La technologie de la spectroscopie en proche infrarouge (NIR) a rapidement été identifiée pour ce besoin. Cette technologie possède les avantages nécessaires afin d'être installée sur le mélangeur et suivre la qualité de mélange en temps réel. Les travaux ici présentés ont été effectués entre janvier 2006 et septembre 2008 sur une véritable formulation pharmaceutique et ont été appliqués à l'échelle laboratoire tout comme à l'échelle de production conventionnelle. Les travaux ont permis d'identifier trois techniques d'analyse statistique viables pour le suivi de l'homogénéité de mélange en ligne : l'analyse de la variance, l'analyse de la distance et l'analyse quantitative. Ces trois techniques possèdent toutes leurs avantages et désavantages et le choix d'une de ces techniques dépend de la formule visée et du besoin du client. De plus, grâce à l'application d'un Design d'Expérience (DoE), les paramètres critiques ayant une influence sur le spectre NIR ont été évalués. La distribution de tailles de particules est un de ces facteurs ayant une influence importante. Son influence a été évaluée grâce à l'application du modèle de Kubelka-Munk. Les recommandations de ces travaux ont été transmises à l'entreprise Wyeth Pharmaceutiquess à Montréal et seront appliquées pour la future implantation de la technologie NIR pour le suivi de l'homogénéité de mélange lors des procédés de mélanges granulaires pharmaceutiques.
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Ricci, Andrea. "Thermoplastic lignin esters as polymeric plasticizers for bioplastics." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/24906/.
Full textAbstract:
In this thesis, a sustainable and scalable process for modifying the structure of technical lignin to make it suitable for mixing with common bioplastics is studied. More specifically, this project deals with the development of a method of grafting fatty acids onto lignin. First, an updated state of the art concerning the processes for lignin production and its esterification is introduced and thoroughly discussed. Next, the materials and methods used to perform one-pot synthesis on lignin are described. The grafting process is initially optimized using a model reaction; afterwards, these conditions are adapted to technical lignin. The resulting process is also scaled up, overcoming unexpected issues due to mass and energy transfer. The modified lignins have been characterized through various thermal and analytical analyses (such as DSC, TGA and NMR), to provide a detailed description of their properties and structures. Finally, modified lignin was used to produce blends with commercial PLA as a proof of concept. As a matter of fact, this thesis is leading the basis for the fabrication of new-concepts materials based on plasticized lignin, aiming to conjugate sustainable industrially scalable processes and material performances.
41
Bauer, Petra. "Vermittlung von Medienkompetenz und medienpädagogischer Kompetenz in der Lehrerausbildung." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-76434.
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In diesem Beitrag wird ein Blended-Learning-Konzept zur Vermittlung von Medienkompetenz und medienpädagogischer Kompetenz bei Lehramtsstudierenden in der universitären Lehrerausbildung vorgestellt. Dieses Seminarkonzept beinhaltet die Kombination von Vorlesung, Workshop, Nutzung einer Onlinebibliothek, eines Lernmanagementsystems und selbstgesteuerter sowie selbstorganisierter Gruppenarbeit von Studierenden. Dieses Konzept zeigt Möglichkeiten auf, wie mit großen Studierendengruppen an der Hochschule gearbeitet werden kann. Im Beitrag wird ein Schwerpunkt auf die Workshops und Gruppenarbeit gelegt. Zunächst werden dabei die zugrunde liegenden Theorien und Konzepte vorgestellt. Diese sind die Medienkompetenz, die Schüler und Schülerinnen in der Schule erwerben sollten. Zusätzlich die medienpädagogische Kompetenz, mit der sich Studierende der Bildungswissenschaften in ihrem Hochschulstudium zur Vorbereitung auf ihre lehrende Tätigkeit an Schulen auseinandersetzen sollten. Neben diesen Kompetenzen bedarf es auch bestimmter Voraussetzungen hinsichtlich der Organisationsentwicklung an Schulen. Diese werden in einem Mehrebenenmodell dargestellt. Im Anschluss erfolgt die Darstellung des Blended-Learning-Konzeptes.
42
Pabst, Rebekka. "Neue Bilder, neue Möglichkeiten." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-201713.
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In der heutigen Filmindustrie bietet das 3D-Design ein anerkanntes Mittel, um virtuelle Welten oder Charaktere zu erschaffen. Doch das 3D-Design dringt mittlerweile auch in andere Bereiche vor, so etwa der Medizin und der Architektur. Dabei bietet die virtuelle Rekonstruktion auch vielfältige Möglichkeiten für die Archäologie/Ägyptologie. Beispielsweise können von kleineren Objekten oder Papyri virtuelle 3D-Modelle erstellt werden. Der große Vorteil dabei ist, dass die Originale nicht beschädigt werden und mehrere Wissenschaftler zur gleichen Zeit an ein und demselben Objekt forschen können. Selbst für die Bauforschung dürfte das 3D-Design immer bedeutender werden. Gebäude, die sich heute nur in ihren Grundrissen erhalten haben, können mithilfe des 3D-Designs nahezu vollständig rekonstruiert werden. Nicht zu unterschätzen ist dabei auch die Wirkung, die virtuelle Rekonstruktionen von ägyptischen Tempeln, Gräbern, Gebäuden auf die Gesellschaft erzielen. Durch die 3DRekonstruktionen kann nicht nur Wissenschaftlern, sondern auch Interessierten ein anschaulicher Eindruck von der Lebenswelt des Alten Ägypten vermittelt werden. Bislang steht das 3D-Design allerdings in dem Ruf, besonders schwer erlernbar und sehr kostenintensiv zu sein. Doch gibt es neben einigen aufwendigen 3D-Design-Programmen auch nahezu kostenfreie Alternativen, die man sowohl privat wie beruflich nutzen kann. Diese Programme sind dabei sehr anwenderfreundlich gestaltet und relativ leicht zu erlernen. Ziel des Vortrages ist es, diese Programme und ihre Möglichkeiten für die Ägyptologie vorzustellen.
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Schmidt, Joel T. "Preparing Students for Success in Blended Learning Environments: Future Oriented Motivation and Self-Regulation." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-65617.
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Clarke, Wil. "Using Online Textbooks and Homework Systems: In Particular MyMathLab and WebAssign." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-82442.
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Schicker, Peter. "Vergleich der Blended Learning Lehrmethode mit den Lehrmethoden Vorlesung, Seminar und E-Learning in der kieferorthopädischen Lehre - Eine Fragebogenstudie." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-115944.
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Im Zeitraum 2007-2008 wurde die vorliegende Fragebogenstudie mit dem Ziel durchgeführt, die Lehrmethoden Vorlesung, Seminar, E-Learning und Blended Learning zu vergleichen und die Akzeptanz der verschiedenen Konzepte durch die Studierende der Zahnmedizin gegenüber zu stellen. Als Lerninhalt diente die kieferorthopädische Profil- und EnFace Analyse. Entsprechende Patientenfälle wurden mit Arbeitsbögen in den Gruppen Vorlesung und Seminar durchgeführt. Eine für diese Arbeit entwickelte Software diente der Fallauswertung in den Gruppen E-Learning und Blended Learning. Ein am Ende der jeweiligen Lehrveranstaltung ausgegebener Fragebogen sollte die Erfahrung der Teilnehmer zur jeweils erlebten Lehrmethode erfassen. Der deskriptive Vergleich der einzelnen Fragebogenitems lässt eine deutliche positivere Einschätzung der Studenten zu Gunsten der Blended Learning Methode erkennen. Die Auswertung der jeweils richtigen Antworten der Profildiagnostik zeigte dagegen kaum Unterschiede in den einzelnen Gruppen.
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Kummer, Christian, Romy Wolff, Claudia Lieske, and Eric Schoop. "Untersuchung der Wirksamkeit einer Lernhandlung in einem Blended-Learning-Arrangement in der universitären Ausbildung." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-101253.
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1 Unterstützung der Lernhandlung zur Förderung der beruflichen Handlungskompetenz in der universitären Ausbildung
Ein Großteil der Hochschulabsolventen ist nach Beendigung des Studiums in Unternehmen tätig. Diese fordern von den Absolventen neben fachlichen Kompetenzen vor allem Methoden- und Sozialkompetenz. Fachspezifische Kompetenzen bilden gemeinsam mit Methoden- und Sozialkompetenzen die Grundlage für die Berufsfähigkeit im Sinne beruflicher Handlungskompetenz der Absolventen. In einer Studie des Institutes der deutschen Wirtschaft Köln aus dem Jahre 2010 gaben rund zwei Drittel der befagten Unternehmen an, dass sie es im Bereich der Fach- und Methodenkompetenzen für sehr wichtig halten, dass die Absolventen in der Lage sind, sich in neue Fachgebiete selbstständig einzuarbeiten und vorhandenes Wissen auf neue Probleme anwenden zu können. Das Vorhandensein speziellen Fachwissens spielt hingegen für die Arbeitgeber eher eine untergeordnete Rolle (Konegen- Grenier, Placke & Stangl, 2011, S. 86 ff.). In einer repräsentativen Befragung unter Studierenden im Jahre 2010 gaben ca. 25 Prozent der Befragten an bisher nicht oder eher nicht gefördert worden zu sein (Heine, Woisch & Ortenburger, 2011, S. 31). Einen entscheidenden Einfluss auf die Kompetenzförderung hat die Lernhandlung. In Anlehnung an Richter (2001, S. 46) werden Lernhandlungen in diesem Aufsatz als zielgerichtete Handlungen angesehen, welche sich auf die bewusste und reflektierte Weiterentwicklung der eigenen Handlungskompetenz (Berufsbefähigung) beziehen. Die Lernhandlung zeichnet sich durch die Merkmale des handlungsorientierten Lernens aus. Handlungsorientiertes Lernen ist gekennzeichnet durch Selbststeuerung, Wahl von Handlungsalternativen und Vollständigkeit, im Sinne von Zielbildung, Planung, Durchführung und Kontrolle. Es ist auf Lernzuwachs und Wissenserwerb ausgerichtet und erfolgt bewusst und reflexiv (Richter, 2001, S. 47).
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Vasconcelos, Fernanda Vera Cruz de. "Uso da região espectral de sobretons para determinação do teor de biodiesel e classificação de misturas diesel/biodiesel adulteradas com óleo vegetal." Universidade Federal da Paraíba, 2011. http://tede.biblioteca.ufpb.br:8080/handle/tede/7033.
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Previous issue date: 2011-04-29<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES<br>This work evaluates the use of overtone regions (NIR) for the classification and determination of biodiesel content in diesel/biodiesel blends adulterated with vegetable oil. For this purpose, NIR spectra were obtained using three different optical paths: 1.0 mm (9000-4000 cm-1); 10 mm (9000-6300 cm-1) e 50 mm (7500-6300 cm-1). Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) with the Successive Projections Algorithm (SPA) were employed to build screening models to identify adulteration of diesel/biodiesel blends with vegetable oils. The multivariate calibration models (Partial Least Square - PLS, Partial Least Square with significant regression coefficients selected by Jack-Knife algorithm - PLS/JK and Multiple Regression Linear with variable selection by Successive Projections Algorithm - MLR/SPA) were developed to determine the biodiesel content. The results showed that the overtone regions with the classification strategy LDA/SPA can be used in preliminary studies to detect adulteration of diesel/biodiesel blends with vegetable oil. This strategy showed positive results for classifying, with a correct classification rate of 86% for the optical paths of 10 mm and 50 mm. In addition, the work demonstrated the potential of overtone regions with MLR/SPA regression strategy to determine biodiesel content in diesel/biodiesel blends, in the range from 0.0% to 10.0%v/v, considering the possible presence of raw oil as a contaminant. This strategy is simple, fast and uses a fewer number of spectral variables. Considering this, the overtone regions can be usefull to develop low cost instruments for the quality control of diesel/biodiesel blends, considering the lower cost of optical components for this spectral region.<br>Neste trabalho foi avaliado o uso da região espectral de sobretons (NIR) para classificação e determinação do teor de biodiesel em misturas diesel/biodiesel adulteradas com óleo vegetal (in natura). Para tanto, foram utilizados espectros NIR registrados em diferentes caminhos ópticos: 1,0 (9000-4000 cm-1), 10 (9000-6300 cm-1) e 50 mm (7500-6300 cm-1). A Análise de Componentes Principais (PCA) e a Análise Discriminante Linear com seleção de variáveis pelo Algoritmo das Projeções Sucessivas (LDA/SPA) foram utilizadas na identificação de adulteração de misturas diesel/biodiesel com óleo vegetal. Os modelos de calibração multivariada (Regressão por Mínimos Quadrados Parciais - PLS, Regressão por Mínimos Quadrados Parciais com coeficientes de regressão selecionados pelo algoritmo Jack-Knife - PLS/JK e Regressão Linear Múltipla com seleção de variáveis pelo Algoritmo das Projeções Sucessivas - MLR/SPA) foram desenvolvidos para determinação do teor de biodiesel. Os resultados obtidos demonstraram que a região espectral de sobretons aliada à estratégia de classificação LDA/SPA pode ser utilizada em estudos preliminares para detecção de adulteração de misturas diesel/biodiesel por óleos vegetais in natura, visto que apresentou bons resultados de classificação, com índice de acerto de 86% para os caminhos ópticos de 10 mm e 50 mm. Além disso, foi demonstrada a aplicabilidade da região de sobretons associada à estratégia de regressão MLR/SPA para determinação do teor de biodiesel em misturas diesel/biodiesel na presença de óleos vegetais in natura, na faixa de 0,0 a 10,0% v/v. Tal estratégia é simples, rápida e utiliza poucas variáveis espectrais. Neste contexto, a região espectral de sobretons pode ser útil na construção de instrumentos de baixo custo para controle de qualidade de misturas diesel/biodiesel, considerando-se o menor custo dos componentes ópticos para essa região espectral.
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Staudinger, Ulrike. "Morphologie und Bruchverhalten von Block- und Multipfropfcopolymeren." Doctoral thesis, [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1187261828675-34703.
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Bartelsen, Jan, and Johannes Brauer. "Kooperatives Lernen mit einem Wiki." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-141961.
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Meyer-Ross, Kerstin, and Jana Halgasch. "E- und Blended-Learnung in der Lehre an der HTW Dresden, umgesetzt mit der Lernplattform OPAL." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-163503.
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Die HTW Dresden bietet ihren Studienanfänger_innen einen auf
OPAL basierenden Blended Learning-Kurs Einführung in das wissenschaftliche
Arbeiten an, der mit den Bereichen Selbstmanagement,
wissenschaftliches Schreiben, Präsentieren und Poster die
Studierenden auf ihr Studium, ihre Abschlussarbeit und deren Verteidigung
vorbereitet. Durch engagierte Betreuung bleibt der enge
Kontakt zum/zur Lehrenden bestehen und der/die Studierende wird
in Problemsituationen aufgefangen und motiviert.