This study deals with reactively compatibilized Polyamide 6 / High Density Polyethylene blends. More precisely, it focuses on the relationship between (1) the formulation, the processing parameters in corotating twin screw extrusion and (2) the morphologies and the microstructures of blends. Multi-scale morphologies were observed by Scanning and Transmission Electron Microscopy. At the micron scale, the following morphologies were developed: nodular dispersions, stretched nodules and co-continuous morphology. As the processing conditions did not influence the types of morphology, the different morphological regions were reported in ternary diagrams. In the case of compatibilized blends, two mechanisms for morphology development have been proposed: (1) the compatibilization reaction, being very fast, leads to the formation of nano-dispersions by interfacial instabilities and (2) the standard break-up/coalescence mechanism of domains poor in copolymer could lead to the formation of morphologies up to the micron scale. Both the evolution of the largest size as a function of the composition and the distribution of sizes were modeled using percolation concepts. The stability of the morphologies was then studied either during static annealing or controlled shear or in a second step processing. The copolymer formed at the interface allows stabilizing the size of the morphologies. Finally, crystallization at lower temperature was observed by Differential Scanning Calorimetry when the polymers are confined in submicron domains.

Due to their large internal surface area, microporous materials have been widely used in applications where high surface activity is desired. Example applications are extracellular scaffolds for tissue engineering, porous substrates for catalytic reaction, and permeable media for membrane filtration, etc. To realize these potential applications, various techniques such as TIPS (thermal induced phase separation), particle leaching, and SFF (solid freeform fabrication) were proposed and investigated. Despite of being able to generate microporous for specific applications, these available fabrication techniques have limitations on controlling the inner porous structure and the outer geometry in a cost-effective manner. To address these technical challenges, a systematic study focusing on the generation of microporous structures using co-continuous polymer blend was conducted. Under this topic, five subtopics were explored: 1) generation of gradient porous structures; 2) geometrical confining effect in compression molding of co-continuous polymer blend; 3) microporous composite with high nanoparticle loading; 4) micropatterning of porous structure; 5) simulation strategy for kinetics of co-continuous polymer blend phase coarsening process.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第19007号 / 工博第4049号 / 新制||工||1623 / 31958 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 伊藤 紳三郎, 教授 赤木 和夫, 教授 辻井 敬亘 / 学位規則第4条第1項該当

Polymers films and membranes with immobile and irreversible reactive sites can provide significant barrier properties for packaging materials. There is a need to develop mathematical models to understand the behavior of these reactive materials and to confidently extrapolate experimental data. Due to mechanical and optical requirements, barrier films may consist of composites, such as polymer blends and multilayer films with alternating reactive and inert layers. The reactive term that consumes the mobile species in the governing transport equations for such materials is a function of both the mobile species and the immobilized reactive sites, leading to non-linear partial differential equations that typically have to be solved numerically. Composite structures add to the complexity of the model. For the polymer blend, a multiscale model was developed, incorporating the reactive details within the particle into the bulk transport equation. For the multilayer film, initial conditions and diffusion coefficients were assigned independently for reactive or inert layers. The models developed for the three configurations were solved numerically over a wide parameter space. Three regimes were identified, namely early times characterized by an initial flux plateau, and intermediate regime, and long times, characterized by the time lag. Asymptotic analysis of the homogeneous model was used to develop analytical predictions for the three regimes, obviating the need to numerically solve the model’s non-linear equations. These predictions were generalized to polymer blends. For multilayer films, predictions for early and long times were developed. Results for polymer blends and multilayer composites were compared and discussions of the most suitable configuration for different scenarios were presented. The reactive barrier configurations studied require the knowledge of parameters such as reaction rates and coefficients of diffusion and solubility of the reactive polymer. Model and predictive equations have been developed to describe the transient mass uptake in reactive homogeneous films, enabling the extraction of these parameters from sorption experiments. / text

Recently, considerable attention has been focused on the generation of nano- and micrometer scale multicomponent polymer particles with specifically tailored mechanical, electrical and optical properties. As only a few polymer-polymer pairs are miscible, the set of multicomponent polymer systems achievable by conventional methods, such as melt blending, is severely limited in property ranges. Therefore, researchers have been evaluating synthesis methods that can arbitrarily blend immiscible solvent pairs, thus expanding the range of properties that are practical. The generation of blended microparticles by evaporating a co-solvent from aerosol droplets containing two dissolved immiscible polymers in solution seems likely to exhibit a high degree of phase uniformity. A second important advantage of this technique is the formation of nano- and microscale particulates with very low impurities, which are not attainable through conventional solution techniques. When the timescale of solvent evaporation is lower than that of polymer diffusion and self-organization, phase separation is inhibited within the atto- to femto-liter volume of the droplet, and homogeneous blends of immiscible polymers can be produced. We have studied multicomponent polymer particles generated from highly monodisperse micrordroplets that were produced using a Vibrating Orifice Aerosol Generator (VOAG). The particles are characterized for both external and internal morphology along with homogeneity of the blends. Ultra-thin slices of polymer particles were characterized by a Scanning Electron Microscope (SEM), and the degree of uniformity was examined using an Electron Dispersive X-ray Analysis (EDAX). To further establish the homogeneity of the polymer blend microparticles, differential scanning calorimeter was used to measure the glass transition temperature of the microparticles obtained. A single glass transition temperature was obtained for these microparticles and hence the homogeneity of the blend was concluded. These results have its significance in the field of particulate encapsulation. Also, better control of the phase morphologies can be obtained by simply changing the solvent/solvents in the dilute solutions. Evaporation and drying of a binary droplet containing a solute and a solvent is a complicated phenomenon. Most of the present models do not consider convection in the droplet phase as solvent is usually water which is not very volatile. In considering highly volatile solvents the evaporation is very rapid. The surface of the droplet recedes inwards very fast and there is an inherent convective flow that is established inside the solution droplet. In this dissertation work, a model is developed that incorporates convection inside the droplet. The results obtained are compared to the size obtained from experimental results. The same model when used with an aqueous solution droplet predicted concentration profiles that are comparable to results obtained when convection was not taken into account. These results have significance for more rigorous modeling of binary and multicomponent droplet drying.

Universiẗat, Diss., 2003--Freiburg (Breisgau).

Universiẗat, Diss., 2003--Stuttgart.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-06-26T11:43:08Z No. of bitstreams: 1 UÉDSON ALEXANDRE DO NASCIMENTO - TESE (PPGCEMat) 2016.pdf: 2537041 bytes, checksum: 43e8f4d37a08e791d0323dc0ce915cb4 (MD5) / Made available in DSpace on 2018-06-26T11:43:08Z (GMT). No. of bitstreams: 1 UÉDSON ALEXANDRE DO NASCIMENTO - TESE (PPGCEMat) 2016.pdf: 2537041 bytes, checksum: 43e8f4d37a08e791d0323dc0ce915cb4 (MD5) Previous issue date: 2016-02-26 / Neste trabalho, blendas de polietileno de alta densidade com polietileno linear de baixa densidade metalocênico, PEAD/m-PELBD, foram preparadas empregando uma extrusora dupla rosca, cônica, contrarotacional interpenetrante e os efeitos do tipo e do teor do m-PELBD nas propriedades de impacto e de tração foram estudados. A blenda PEAD/m-PELBD com melhor relação de propriedades, tenacidade/rigidez, foi modificada com argila montmorilonita organofílica comercial Cloisite 20A, nos teores de 1, 3, 5 e 10 pcr, visando à obtenção de um híbrido com propriedades comparáveis, particularmente, em processamento e tenacidade/rigidez, às da resina de PEAD importada, PEAD Dowlex IP–10262, utilizada para fabricação de embalagens injetadas para o envase e transporte de produtos químicos perigosos. De acordo com os resultados da caracterização mecânica (impacto e tração), ficou evidenciado que o tipo e o teor de m-PELBD influenciaram nestas propriedades. Dentre os m-PELBDs estudados, Flexus 7200 e Flexus 9200, o Flexus 7200 resultou na melhor relação de propriedades e dentre os teores avaliados (10, 17 e 25%), o teor de 17% foi mais efetivo. A blenda PEAD/17% m-PELBD, blenda 7217, apresentou resistência à tração no escoamento comparável a da resina importada; resistência ao impacto 57,7% superior e módulo elástico 23,6% inferior. Como a rigidez da blenda 7217 foi inferior à da resina importada, a mesma foi modificada com a argila Cloisite 20A. De acordo com os dados de difratometria de raios X (DRX), a incorporação da argila à blenda 7217, em todos os teores estudados, não resultou na formação de nanocompósitos. Apesar disso, as propriedades de cristalinidade (determinada por calorimetria exploratória diferencial – DSC) e de estabilidade térmica (determinada por termogravimetria - TGA) da blenda 7217 modificada com 10 pcr de argila (7217AO-10), foram superiores as da blenda pura. A resistência à tração foi mantida, a resistência ao impacto diminuiu e o módulo elástico aumentou, em relação a blenda pura. Em comparação com a resina importada, a resistência à tração do híbrido 7217AO-10 foi 8% superior, a resistência ao impacto foi 12% inferior e o módulo elástico 7% inferior. De forma geral, a blenda 7217, modificada com 10 pcr de argila, apresentou processabilidade e propriedades mecânicas comparáveis as da resina importada (PEAD Dowlex IP–10262). / Blends of high density polyethylene with metallocene linear low density polyethylene, HDPE/m-LLDPE, were prepared by melt compounding in a twin-screw extruder. The m-LLDPE type and content effects on impact and tensile properties were studied. According to the results, these parameters influenced the properties of m-LLDPE. The blend prepared with m-LLDPE Flexus 7200 with the 17% concentration (7217 blend) showed the best properties. However, their hardness was lower than the HDPE Dowlex IP-10262 resin, used for dangerous chemicals transport containers manufacture. The 7217 blend was modified with organophilic montmorillonite (Cloisite 20A organoclay). The diffraction X-ray data (XRD) showed that the 7217 blend modification, with organoclay, on all studied concentrations, did not result in nanocomposites. Nevertheless, the crystallinity properties (determined by differential scanning calorimetry – DSC) and thermal stability (determined by thermogravimetric analysis – TGA) of the 7217 blend, modified with 10 phr of organoclay (7217AO-10) were higher than the pure blend. In addition, the modified blend showed decreased impact resistance, increased elastic modulus and the same tensile strength. As compared to Dowlex IP-10262 HDPE, the tensile strength of 7217AO-10 hybrid was 8% higher, the impact strength was 12% lower and the elastic modulus was 7% lower. In general, the processability and mechanical properties of 7217 blend, modified with 10phr of Cloisite 20A, were similar to that HDPE Dowlex IP-10262. Therefore, this hybrid has great use potencial for dangerous chemicals transport containers manufacture, replacing the HDPE Dowlex IP-10262 resin.

Orientador: Cecília Amélia de Carvalho Zavaglia / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-23T08:49:24Z (GMT). No. of bitstreams: 1 Brito_TalitaAlmeidaVidade_M.pdf: 2327615 bytes, checksum: 1370c441c447a5a8dae05303883562b5 (MD5) Previous issue date: 2013 / Resumo: Este trabalho apresenta a preparação e caracterização de nanofibras da blenda poli (L-ácido láctico) (PLLA)/poli (?-caprolactona) (PCL) através dos processos de eletrofiação e rotofiação destinada à produção de fibras visando futuras aplicações como suporte para a engenharia tecidual. As blendas foram preparadas através da dissolução do polímero em clorofórmio e clorofórmio mais acetona, resultando em uma solução de 6%. A eletrofiação é um processo relativamente simples e de baixo custo, que consiste na aceleração de uma solução polimérica, inicialmente contida em um capilar metálico, pela presença de um campo elétrico externo, para produzir fibras com diâmetro médio reduzido. Apesar da popularidade e da versatilidade, o processo de eletrofiação apresenta algumas desvantagens, tais como o uso de fonte de alta tensão, baixa taxa e longo tempo de produção das fibras. Com a necessidade de encontrar um método de produção de fibras para sanar eventuais obstáculos encontrados na eletrofiação, foi realizado um estudo com um novo processo: a rotofiação. O processo de rotofiação é um processo simples que forma fibras durante o jateamento da solução polimérica através de um orifício central utilizando alta velocidade de rotação e não utiliza campo elétrico de alta voltagem, como na eletrofiação. As fibras obtidas por meio dos dois processos foram analisadas e caracterizadas pelos seguintes métodos: microscopia eletrônica de varredura (MEV), análise termogravimétrica (TGA), calorimetria exploratória diferencial (DSC), e espectroscopia na região do infravermelho por transformada de fourier (FTIR). A análise das fibras por microscopia eletrônica de varredura (MEV) mostrou que é possível a formação de nanofibras da blenda PLLA/PCL através dos dois processos. Verificou-se que ocorreram diferenças significativas no diâmetro médio dos fios entre os processos, onde na rotofiação, os diâmetros foram maiores, os dois processos estudados permitiram a obtenção de fibras porosas, uma característica importante requerida na engenharia tecidual. Os resultados das análises térmicas indicaram o comportamento imiscível das blendas PLLA/PCL. Através da análise de FTIR foi possível demonstrar eliminação completa dos solventes durante o processamento e também a imiscibilidade dos polímeros / Abstract: This work presents the preparation and characterization of nanofibers of poly (L-lactic acid) (PLLA) / poly (?-caprolactone) (PCL) through electrospinning and rotary jet spinning processes for the production of fibers aiming future applications as scaffolds for tissue engineering. The blends were prepared using the two polymers cited above in chloroform and chloroform plus acetone, resulting in a solution of 6%. Electrospinning is relatively simple and low cost process, which consists in the acceleration of a polymer solution initially contained in a capillary, the presence of an external electric field to produce fibers with reduced average diameter reduced. Despite the popularity and versatility, the electrospinning process has some disadvantages such as the use of high voltage supply, low spinning rates and takes time for long fiber production. With the need to find a method of producing fibers to remedy any obstacles encountered in electrospinning, a study was conducted with a new process: rotary jet spinning. The process of rotary jet spinning is a simple process that forms fibers during the blasting of the polymer solution through a central hole using high-speed rotation and does not use high intensity electric fields, as in electrospinning. The fibers obtained by the two processes were analyzed and characterized by the following methods: scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and infrared spectroscopy fourier transform (FTIR). The fiber analysis by scanning electron microscopy (SEM) showed that it is possible to form nanofibers of PLLA / PCL through two processes. It was found that there were significant differences in the average diameter of the fibers between the processes, where higher diameters were observed in rotary jet spinning, the two processes studied allowed to obtain porous fibers, an important feature required in tissue engineering. The results of thermal analysis indicated that it was formed immiscible blends of PLLA / PCL. By FTIR analysis it was demonstrated complete elimination of the solvents during processing and also the immiscibility of the polymers / Mestrado / Materiais e Processos de Fabricação / Mestra em Engenharia Mecânica

This thesis presents the study of nanocomposites based on immiscible polymer blend of polycarbonate and acrylonitrile-butadiene-styrene (PC/ABS) filled with multi-walled carbon nanotubes (MWCNT). The aim is to achieve an improvement of mechanical properties and electrical conductivity of the nanocomposites. In an initial stage, a twin-screw extruder was used to obtain nanocomposites by melt compounding. Three methods of carbon nanotubes addition were studied: direct addition, dilution from a masterbatch and feeding of MWCNT suspension in ethanol. For each method, the influence of nanofiller content and processing parameters on morphology and final properties of the nanocomposite was analyzed. Furthermore, the influence of two types of carbon nanotubes modifications was studied: covalent modification by surface-oxidation (MWCNT-COOH) and non-covalent modification by an addition of surfactant promoting the nanofiller-matrix interactions. A good dispersion of the MWCNT was obtained for masterbatch dilution and suspension feeding. Both methods showed preferential localization of carbon nanotubes in polycarbonate phase (PC). Samples processed by masterbatch dilution showed the 30 % increase of rigidity and a decrease of ductility of PC/ABS for 0.5 wt. % MWCNT. Electrical conductivity was influenced by processing temperature and carbon nanotubes type. The percolation threshold value was 2.0 wt. % for pristine MWCNT and 1.5 wt. % for modified MWCNT-COOH. Better balance of mechanical properties and electrical conductivity was achieved in the samples obtained by the masterbatch route. These properties were studied in a subsequent phase, when the extruded nanocomposite was injection molded in order to obtain a defined geometry. / Wegrzyn, M. (2014). Nanocomposites of Multiphase Polymer Blend Reinforced with Carbon Nanotubes: Processing and Characterization [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/36869 / TESIS