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Submicron Polymer Emulsion Inside Twin Screw ExtruderArefi, Ahmad January 2023 (has links)
Solvent-free extrusion emulsification (SFEE) is a recently developed process for producing
submicron particles with high viscosity polymers inside a twin-screw extruder without the use of hazardous solvents. Its dependency on a catastrophic phase inversion makes the process knowingly sensitive to a variety of formulation and operational variables, causing a narrow window of production. The purpose of this thesis was to investigate and improve process stability as well as widening operational window. Transient effects of the start-up procedure was investigated by considering the process stability and particle size distribution. The transient sensitivity corresponded to the residency of material in the dispersion zone. When a sub-optimal water/surfactant fraction was allowed to produce an undesired polymer-water (thick lamella) morphology, this morphology continued to persist until the critical first half of the dispersion zone was purged of existing mass. Lot to lot variability of polyester resin was used to investigate the sensitivities of the SFEE process more deeply to better understand the mechanism involved. In this case, acid number was shown to have a significant effect on the initial amount of water needed in the dispersion zone for phase inversion, resulting in an emulsification boundary dependent on the resin acid number. In fact, a significant correlation was found between the acidic end groups of the resin and the maximum amount of water content that could be used in the dispersion zone. The effect of feed rate, screw speed, dispersion length, and surfactant concentration were studied for their individual influence on widening the emulsification boundary. The most significant improvement was observed by applying a longer dispersion length or lower feed rate because both significantly increase the residence time. The effect of residence time on the emulsification boundary was attributed to the total strain imposed on the polymer/water mixture which was related to interfacial growth in the dispersion zone. / Dissertation / Doctor of Philosophy (PhD)
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Examining the Effectiveness of Different Mixing Elements in the Twin Screw Compounding of Liquid Crystal Polymer and PolypropyleneAgrawal, Akash 02 February 2018 (has links)
No description available.
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Twin Screw Wet Granulation With Various Hydroxypropyl Methylcellulose (HPMC) GradesChen, Jingyi January 2022 (has links)
Twin screw wet granulation has been proved as a feasible alternative for traditional batch granulation process due to its continuous processing feature; considered as a significant processing method especially in the pharmaceutical industry. This thesis will explore the processibility of twin screw wet granulation with various formulations.
The first section of the thesis focused on examining the processibility of wet granulation in a twin screw while using various grades of hydroxypropyl methylcellulose (HPMC) as an extended-release excipient. The method to find the processibility was by modifying the liquid-to-solid ratio for each formulation. The process window was defined by examining the amount of granules that fall in a pre-determined acceptable size range. This part focused on three substitution types of HPMC (Type 2910, Type 2208, and Type 2906) that varied in molecular weights. It was found that only Type 2910 HPMC showed a shift in the process window (also known as granulation range) in relation to the molecular weight of the formulations. A higher demand for binder liquid was found for higher molecular weight Type 2910 HPMC in order to form granules with acceptable sizes.
The second part of this thesis was focused on understanding the process variables that might influence the processibility of the HPMC formulations. This part examined the impact of feed rate on the granulation range of Type 2910 HPMC specifically was examined. Multiple feed rates were tested, and it was found that the granulation range for lower molecular weight Type 2910 HPMC was easier to shrink when higher feed rates were applied. A transition in the granule formation method from liquid-bridging to compaction with respect to the feed rate was found for low molecular weight HPMC, whereas the high molecular weight HPMC always formed granules through compaction at all feed rates due to strong water retainability. / Thesis / Master of Applied Science (MASc)
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<b>Fluid Dynamic, Conjugated Heat Transfer and Structural Analyses of an Internally Cooled Twin-Screw Compressor</b>Abhignan Saravana (18426282) 23 April 2024 (has links)
<p dir="ltr">Current industrial processes are energy and carbon emission intensive. Amidst the growing demand for decarbonization, it is critical to utilize alternate sources of energy and innovative technologies that could improve efficiency and reduce power consumption. In this context, twin-screw compressors are used extensively in commercial and industrial applications. Profile optimization and capacity modulation solutions (e.g., slide valves, variable-speed, etc.) are continuously investigated to improve the performance and operation of the compressors. This study focuses on an exploratory investigation of an additively manufactured twin-screw compressor with internal cooling channels to achieve a near isothermal compression process by evaluating both the potential compressor performance improvement and the structural integrity by means of rotordynamics and fatigue analyses.</p><p dir="ltr">To predict the compressor performance, complex coupling between compression process and heat transfer during the operation of the compressor must be investigated. The interactions between solid (i.e., rotors) and fluid phases (i.e., air and coolant) were modeled using a transient 3D CFD model with conjugated heat transfer (CHT). The CFD model predicted compressor performance parameters such as isentropic efficiency, heat transfer rate, work input and compression forces on the rotors. The performance of the twin-screw compressor with internal cooling channels has been compared with a conventional twin-screw compressor for which experimental data was available. Further investigations have been conducted at different operating conditions, including various pressure ratios, rotational speeds, and mass flow rates to improve the compressor efficiency. The results of the CFD model were used to quantify compression loads, assess the characteristics of the heat transfer processes, and optimize the internal flow through the cooling channels. As the rotors can be affected by stress accumulation and deformations due to their hollowness and reduced wall thickness over time, this study also established a detailed rotordynamic simulation model and a fatigue model using the actual compression forces obtained from previous CFD studies. Both hollow and solid rotors have been analyzed and compared. The bearing loads have been verified against Campbell diagrams whereas the fatigue results have been compared with experimental testing. With the validated model, the hollow rotor compressor durability was analyzed and compared with the conventional rotors. Lastly, a general mechanistic model to better understand bearing loads and frictional losses in a twin-screw compressor is also established and studied.</p><p dir="ltr">The CHT study concluded that the hollow rotor with single-phase internal cooling yielded to an increase in isentropic efficiency of 1% for the higher pressure ratio and 2% for lower pressure ratio at 19,000 RPM. More importantly, the hollow rotors also showed a decrease of 40 K and 20 K in discharge temperatures for the two operating conditions respectively, thereby arriving closer to isothermal conditions and reducing the thermal stresses on the rotors. The rotordynamic study revealed that the male rotor would endure highest amount of von Misses stress reaching up to 338 MPa for the pressure ratio of 3.29 bar and 19,000 RPM. Because of this, a maximum fatigue factor of safety of 5 occurs on the male rotor. From the analyses, the rotors were deemed to be safe and optimized for the designed operating conditions and proof of concept rotors were additively manufacturers with an Inconel alloy through Direct Metal Laser Sintering.</p>
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Investigation of a solvent-free continuous process to produce pharmaceutical co-crystals. Understanding and developing solvent-free continuous cocrystallisation (SFCC) through study of co-crystal formation under the application of heat, model shear and twin screw extrusion, including development of a near infrared spectroscopy partial least squares quantification methodWood, Clive John January 2016 (has links)
This project utilised a novel solvent-free continuous cocrystallisation (SFCC)
method to manufacture pharmaceutical co-crystals. The objectives were to
optimize the process towards achieving high co-crystal yields and to
understand the behaviour of co-crystals under different conditions. Particular
attention was paid to the development of near infrared (NIR) spectroscopy as
a process analytical technology (PAT).
Twin screw, hot melt extrusion was the base technique of the SFCC process.
Changing parameters such as temperature, screw speed and screw
geometry was important for improving the co-crystal yield. The level of
mixing and shear was directly influenced by the screw geometry, whilst the
screw speed was an important parameter for controlling the residence time
of the material during hot melt extrusion. Ibuprofen – nicotinamide 1:1 cocrystals
and carbamazepine – nicotinamide 1:1 co-crystals were successfully
manufactured using the SFCC method.
Characterisation techniques were important for this project, and NIR
spectroscopy proved to be a convenient, accurate analytical technique for
identifying the formation of co-crystals along the extruder barrel. Separate
thermal and model shear deformation studies were also carried out to
determine the effect of temperature and shear on co-crystal formation for
several different pharmaceutical co-crystal pairs.
Finally, NIR spectroscopy was used to create two partial least squares
regression models, for predicting the 1:1 co-crystal yield of ibuprofen –
nicotinamide and carbamazepine – nicotinamide, when in a powder mixture
with the respective pure API. It is believed that the prediction models created
in this project can be used to facilitate future in-line PAT studies of
pharmaceutical co-crystals during different manufacturing processes. / Engineering and Physical Sciences Research Council (EPSRC)
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Extrusion processing of chocolate crumb pasteWalker, Alasdair Michael January 2012 (has links)
This project considers the co-rotating twin screw extrusion of a confectionery paste comprising powdered proteins, sugars, water and fats. As is the case with many food industry products, this process has been developed experimentally with little quantitative understanding of how variations in processing conditions influence the formation of the extrudate. A variety of techniques have therefore been developed to characterise and quantify the dispersive mixing, distributive mixing and rheological flow properties of this complex, multiphase, viscoelastic, unstable material. These techniques have then been utilised in a pilot plant extruder study of the mechanics of mixing and paste formation during extrusion, considering the influence of both processing conditions and screw profile. The internal evolution of paste microstructure has been successfully tracked along the length of screw profile using dead-stop extractions of the screws. A rigorous off-line assessment of shear yield strength behaviour using cone penetrometry has shown the use of conventional off-line rheometers to be unviable due to rapid post extrusion hardening. This highlighted the need for an in-line rheological measurement technique for continuous extrusion analysis where the extruded material is severely time dependent and not extractable. In pursuit of this, a novel arrangement of bender elements is proposed and trialled, to rapidly characterise material parameters of viscoelastic pastes. A second technique looking to extend the application of shear wave interface reflection to multiphase pastes is also trialled. A novel analysis of thermogravimetric data (TGA) has generated a viable index of distributive mixing, suitable for use on complex multi-component materials where thermal decomposition temperatures of the components are not well defined. Quantitative image analysis of pastes using scanning electron microscopy (SEM), optical microscopy protein staining and a novel application of multiphoton microscopy (MPM) have been used to visualise paste microstructure and quantify dispersive mixing. From the pilot plant extruder study, the application of these techniques was successful in mapping the evolution of paste mixing and the resulting microstructure, as well as identifying key differences between pastes mixed by twin screw extrusion and batch mixing.
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Elaboration par extrusion de mélanges de polymères et de nanocomposites biodégradables avec des protéines de soja isolées / Compounding of biodegradable polymer blends and nanocomposites with isolated soy proteins by extrusionRenoux, Jennifer 03 December 2018 (has links)
Les protéines isolées végétales sont une source renouvelable de matière première, disponible en grande quantité. Malgré des propriétés mécaniques faibles par rapport aux polymères traditionnels, elles possèdent d’autres spécificités intéressantes comme leur biodégradabilité, leur filmabilité et leur absence de toxicité. Cette étude s’est focalisée sur l’influence du procédé d’élaboration, la compatibilité et l’ajout de nanocharges sur les propriétés de mélanges poly(butylène succinate - co - adipate)/protéines de soja isolées plastifiées (PBSA/PISP). Dans un premier temps, les protéines de soja sont plastifiées et mélangées au poly(butylène succinate - co - adipate), dans des proportions différentes et extrudées simultanément en une étape d’extrusion. Ensuite, l’effet de l’ajout du poly(2-éthyl-oxazoline) comme compatibilisant a été étudié. L’addition de ce compatibilisant permet d’améliorer l’interface et les propriétés thermiques. En outre, l’addition de nanotubes d’halloysite permet d’améliorer certaines propriétés mécaniques et thermiques. Enfin dans le cas de films préparés avec une composition PBSA/PISP égale (50/50), le compatibilisant améliore les propriétés optiques, tandis que l’ajout des nanotubes d’halloysite améliore les propriétés de barrière à la vapeur d’eau et retarde la dégradation du film enfoui dans un sol. L’ensemble des résultats donne de premières indications sur l’usage potentiel de ces films dans le domaine de l’emballage et éventuellement dans le biomédical. / Vegetable isolated proteins are a renewable source of raw material, available in the large quantities. In spite of weak mechanical properties compared with the traditional polymers, they possess other important characteristics such as biodegradability, filmability and they are non-toxic. This study investigated the effect of processing type, compatibilization and addition of nanofillers on the properties of poly(butylene succinate-co-adipate)/plasticized isolated soy protein blends (PBSA/PISP). Initially, plasticizing and blending of soy protein with poly (butylene succinate-co-adipate) at various composition were carried out simultaneously in a single step extrusion. Then, the effect of adding poly(2-ethyl oxazoline) as compatibilizer has been studied. Addition of compatibilizer improves the interface and thermal properties of the blends. Besides, addition of halloysite nanotubes improves some mechanical and thermal properties. Finally, in the case of blend films prepared with equal PBSA/PISP composition (50/50), the compatibilizer increases the optical properties whereas addition of halloysite nanotubes improves the water vapour barrier properties and delay the degradation of blends as tested by soil buriel test. The overall results gives preliminary insights into potential usage of these films in packaging and possibly in biomedical sector.
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Modelagem e simulação de uma bomba multifásica de duplo parafuso com recirculação interna. / Modeling and simulation of a twin screw multiphase pump with internal recirculation.Ramirez Duque, Jose Luis Gerardo 09 September 2016 (has links)
As crescentes exigências sobre o desempenho de sistemas de bombeamento multifásico combinadas aos aspectos relacionados com a maior disponibilidade operacional desses sistemas, bem como as futuras condições de funcionamento atingindo pressões perto de 150 bar, destacam a importância de desenvolver modelos matemáticos precisos para prever o comportamento do desempenho nestes equipamentos. Nesta tese foi aperfeiçoado o modelo termo-hidráulico de uma bomba multifásica de tipo duplo parafuso desenvolvido por Nakashima (2005) e foram incluídos os efeitos da abertura gradual da última câmara, recirculação de líquido entre a sucção e descarga, transferência de calor através do liner e expansão térmica. Uma vez fornecidos os dados geométricos da bomba e as suas condições de operação, é possível calcular os parâmetros de desempenho mais importantes, como: eficiência volumétrica, vazão de sucção e refluxo, potência consumida e distribuição de pressão e temperatura. As equações implementadas foram desenvolvidas a partir dos balanços de massa e energia nas câmaras, tendo em conta a geometria da bomba e a variação das fendas durante sua operação. As rotinas e métodos necessários para a sua solução numérica foram implementadas utilizando programação orientada a objetos (C++). Os resultados fornecidos pelo modelo aperfeiçoado foram comparados com dados experimentais da literatura e uma boa concordância foi encontrada na faixa de até 95 % FVG, nos casos estudados, para bombas com e sem tecnologia de recirculação. Devido à complexidade dos fenômenos físicos envolvidos durante a operação da bomba, o impacto de cada um dos efeitos incorporados nos cálculos do modelo foi avaliado e discutido individualmente. Assim, foi demonstrada a grande influencia da recirculação, da abertura gradual da câmara de descarga e da expansão térmica nos cálculos dos parâmetros de operação mais importantes da bomba. Além disso, a transferência de calor pode ser considerada desprezível, já que seu valor é baixo quando comparado com a potência fornecida pela bomba e, portanto, não influencia os balanços de energia que determinam os estados termodinâmicos das câmaras. No entanto, esse efeito é necessário para calcular a distribuição de temperatura da bomba e a expansão térmica nos parafusos e no liner. / The increasing requirements about the performance of multiphase pumping systems combined with those related to a higher operational availability of such systems, as well as future operating conditions with pressure increase at about 150 bar, highlights the importance of developing accurate mathematical models to predict the performance behavior of these equipments. In this thesis it was improved the thermo-hydraulic behavior of a twin screw multiphase pump developed by Nakashima (2005), and were included the effects of the gradual opening of the last chamber, fluid recirculation between suction and discharge of the pump, heat transfer though the liner, thermal expansion and different working fluids (water-air and oil-gas). Giving pump geometry and operational conditions, it is possible to calculate the most important pump parameters performance, such as, volumetric efficiency, suction flow, back-flow, power consumption and pressure and temperature distribution. The model equations were developed based on mass and energy balances in the chambers taking into account the pump geometry and the clearance variation due to operation. Its implementation was made in C++. The results obtained by the new model were compared with experimental data of the bibliography, and a good accuracy was found in it with values till 95% GVF for the studied cases, with and without recirculation technology. Due to the physical phenomenon complexity related with the pump operation, the impact of each effect in the model calculations was evaluated and discussed separately. So, it was demonstrated the importance of the recirculation, the gradual opening of the last chamber and the thermal expansion in the calculation of the most important pump operation parameters. However, the heat transfer can be neglected, because its value is very low when compared with the pump power supply, and therefore, it does not influence the energy balances that determine thermodynamic state in the chambers. However, this effect is necessary to calculate the temperature distribution along the pump and the thermal expansion in the screws and the liner.
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ESTUDO DA DEGRADAÇÃO TERMOMECÂNICA E OXIDATIVA DA BLENDA POLIMÉRICA PEAD/PSNascimento, Eduardo do 11 February 2011 (has links)
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Previous issue date: 2011-02-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The degradation of polymer blends has been the subject of few scientific studies. Further studies are of great importance for understanding the degradation mechanisms in polymer blends. The degradation of the blend of HDPE / PS was
studied as a function of their composition, processing temperature and number of processes. The material was extruded in a twin screw extruder co-rotacional
interpenetrating at temperatures of 200, 240 and 280 ° C, reprocessed five times in the compositions of 25/75, 50/50 and 75/25 % (w.t) HDPE / PS, in addition to pure materials. An estimate of the distribution curve of molecular weight was made using data from parallel plate rheometry and degradation characteristics of the groups were analyzed by infrared spectroscopy with Fourier transformants. The results reveal two distinct regions of behavior in relation to the degradation of the blend. A domain with the mechanism of degradation of PS in which random chain scission occurs without the change in polydispersity, extending from pure PS to blend 50% HDPE / 50% PS. In this region the behavior is closer to the additivity of effects between the pure materials, tending to the field of mechanism of PS and greater balance between the mechanisms in that it increased the concentration of HDPE. It is inferred that this behavior go to about 40% of PS, where nearly co-continuity occurs between the phases. Another region is seen from the 75% HDPE blend. 25% PS to the pure HDPE, where the dominant mechanism is HDPE, with predominant chain branching and polydispersity increased at lower temperatures, in this case 200 ° C, and high rise of chain scission at higher temperatures, 280 ° C. In this region there is a synergistic effect towards the mechanism of HDPE, i.e. the addition of 25% of BP leads to a show very similar behavior to that of pure HDPE, distinguishing the effect of additivity. There is greater resistance to oxidation, synergistic effect, especially in the composition of 75% HDPE/PS 25% attributed to the dispersed morphology of the blends in this composition. / A degradação de blendas poliméricas tem sido alvo de poucos trabalhos científicos. Estudos mais aprofundados são de grande importância para o entendimento dos mecanismos de degradação em misturas de polímeros. A degradação da blenda
PEAD/PS foi estudada em função da sua composição, temperatura de processamento e número de processamentos. O material foi extrudado numa extrusora dupla rosca corrotacional interpenetrantes nas temperaturas de 200, 240 e
280 °C, reprocessada cinco vezes nas composições de 25/75, 50/50 e 75/25 % (g/g) PEAD/PS, além dos materiais puros. Uma estimativa da curva de distribuição de massa molar foi feita através de dados de reometria de placas paralelas e os grupos característicos da degradação foram analisados por espectroscopia de infravermelho com transformada de Fourier. Os resultados revelam duas regiões de comportamentos distintos em relação à degradação da blenda. Uma com domínio do mecanismo de degradação do PS, no qual ocorre cisão aleatória das cadeias sem a variação da polidispersão, estendendo-se do PS puro até a blenda 50 % PEAD/ 50%
PS. Nesta região o comportamento fica mais próximo à aditividade dos efeitos entre os materiais puros, tendendo para o domínio do mecanismo do PS e maior equilíbrio
entre os mecanismos na medida em que é aumentada a concentração de PEAD. Infere-se que este comportamento siga até cerca de 40 % de PS, aproximadamente onde ocorre a cocontinuidade entre as fases. Outra região é vista a partir da blenda 75 % PEAD. 25 % PS até o PEAD puro, onde o mecanismo dominante é o do PEAD, apresentando preponderante ramificação de cadeia e aumento da polidispersão em menores temperaturas, neste caso 200 °C, e elevado aumento da cisão de cadeia em temperaturas maiores, 280 °C. Nesta região encontra-se um efeito sinérgico no sentido do mecanismo do PEAD, ou seja, a adição de 25 % de PS mostra conduz a um comportamento muito próximo ao de PEAD puro, distinguindo-se d efeito da aditividade. Há uma maior resistência à oxidação, efeito sinérgico, principalmente na composição 75 % PEAD. 25 % PS atribuído à
morfologia dispersa da blenda nessa composição.
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Modeling and optimization of tubular polymerization reactorsBanu, Ionut 17 July 2009 (has links) (PDF)
The aim of this thesis is the investigation of modeling and optimization particularities of tubular polymerization reactors. The original work is divided in two sections, the first treating a modeling and optimization study of tubular reactors for methyl methacrylate polymerization in solution, and the second, an experimental and theoretical study of L-lactide reactive extrusion. In the first section, reactor simulations in similar operating conditions were performed in order to select a representative kinetic model among the published kinetic models for MMA solution polymerization. Two widely used numerical algorithms, one based on Pontryagin's Minimum Principle and the other a Genetic Algorithm, were compared for an average-complexity optimization problem. The results showed a superior robustness of the Genetic Algorithm for this category of problems. The second part of the thesis deals with the modeling and optimization of L-lactide reactive extrusion. A kinetic model is proposed and its parameters estimated using nonlinear estimation numerical procedures based on experimentally measured data. Reactive extrusion experiments were performed in representative operating conditions. The Llactide/ polylactide flow in the extruder was characterized by simulation using the commercial software LUDOVIC®. The simulated residence time distributions characteristics are used to model the reactive extrusion process of two approaches, an axial dispersion model and a compartment model, based on compartments whose characteristics are deduced from the simulations using LUDOVIC®. The modeling results are in good agreement with the measured data in the same operating conditions.
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