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Santoro, Gianmarco. "Mixed alloy chip extrusion." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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The aim of the investigation is to characterize the behaviour of billets composed of different aluminium alloys chips, shape and size. The billets were processed by plastic deformation in order to obtain useful parameters to make final products with good aesthetic-structural characteristics. This is made possible by direct recycle of chips with plastic deformation processes, in specific with a chip-based hot extrusion process. This technique is very interesting at an industrial level where the chips coming from various aluminium alloy machining procedures are accumulated together.
The classic secondary aluminium production process by re-melting already saves 95% of energy in comparison to primary aluminium production from mineral (Bauxite). As previously shown from researches on Chip Extrusion, there is a higher energy saving through direct extrusion of chips and scraps pre-compacted in chip-based billets without re-melting.
The research has the objective of testing the optimal combination of process parameters for different mixes of alloys in order to obtain the desired profiles; at the same time a FEM (Finite Element Method) simulation is implemented with HyperExtrude and MatLab software. The code is expected to describe processes with different parameters and give results similar to the experimental ones.
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Lüssi, Cécile. "Signature-based extrusion detection." Zürich : Eidgenössische Technische Hochschule Zürich, Institut für Technische Informatik und Kommunikationsnetze, 2008. http://e-collection.ethbib.ethz.ch/show?type=dipl&nr=411.
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Bryner, Thomas K. "The composite extrusion process." Ohio : Ohio University, 1989. http://www.ohiolink.edu/etd/view.cgi?ohiou1182284434.
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Peck, Martin Clive. "Roller extrusion of pastes." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417961.
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Caldwell, L. "Modelling of polymer extrusion." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419561.
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Gerginov, Branimir Borissov. "Investigations into continuous extrusion." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47445.
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Beaumel, Christian. "Extrusion des pâtes d'argiles." Grenoble INPG, 1998. http://www.theses.fr/1998INPG0056.
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L'industrie de la terre cuite valorise les materiaux de la terre en extrudant des pates d'argiles. Le but de cette etude est la maitrise de la mise en forme a vitesse elevee de ces pates et des defauts d'extrusion. La caracterisation des proprietes physiques et rheologiques des pates, notamment dans des conditions non consolidees et non drainees, les fait apparaitre comme des materiaux plastiques heterogenes. Les proprietes d'interface des pates sont caracterisees grace a un tribometre concu pour l'etude des frottements a vitesse elevee. Nous proposons une loi de frottement suggerant un couplage des effets de la vitesse de glissement et de la pression normale. Une etude experimentale systematique a permis d'obtenir les proprietes d'ecoulement des pates et d'etudier les defauts generes durant l'extrusion au travers de filiere axisymetrique. Des mesures locales et directes de la vitesse a l'interface pate-paroi montrent que l'evolution de cette derniere est reliee a celle des defauts. La mise en evidence d'une evolution de la texture et des proprietes mecaniques de la pate au cours de l'extrusion oblige a tenir compte de l'histoire mecanique de la pate. L'analyse montre la necessite de prendre en compte la piezodependance sur le comportement rheologique en volume des pates et sur le comportement a l'interface. Elle a permis de proposer des mecanismes a l'origine des defauts d'extrusion qui permettent d'expliquer la morphologie des defauts dont l'evolution apparait liee a la texture anisotrope des extrudats et au comportement fortement plastique des pates d'argiles etudiees.
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Borghi, Nicolas. "Nanotubes membranaires : extrusion hydrodynamique." Paris 6, 2006. http://www.theses.fr/2006PA066556.
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Almeida, Rosemeire dos Santos. "Influência da velocidade de rotação no processo de extrusão do polipropileno virgem e reciclado." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266923.
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Orientador: João Sinézio de Carvalho CamposDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-17T10:17:41Z (GMT). No. of bitstreams: 1 Almeida_RosemeiredosSantos_M.pdf: 1496479 bytes, checksum: b8bf05066c4483752cebde2f006e95c6 (MD5) Previous issue date: 2010
Resumo: E bem conhecido o amplo uso de materiais poliméricos e o proporcional impacto que eles causam quando são descartados no meio ambiente, especialmente os "commodities" como Polipropileno (PP) e Polietileno (PE). Isso tem preocupado os cientistas, que cada vez mais procuram desenvolver tecnologias para o reaproveitamento desses materiais. Uma das técnicas existentes e o reprocessamento por meio de extrusoras e injetoras, cujos processos, no entanto, tendem a degradar o material, levando a alteração em suas propriedades mecânicas e reológicas. Tendo em vista o contexto apresentado, foi desenvolvido um estudo no qual se avaliou a influencia da velocidade de rotação da rosca no processo de extrusão do polipropileno (PP) virgem e material reciclado, proveniente do setup durante a produção de canudos para refrigerante e rebarbas da fabricação de fraldas descartáveis, absorventes em que existe uma pequena quantidade de polietileno (PE). Observou-se sob quatro diferentes rotações, a saber: 40, 80, 120 e 160 rpm e um mesmo perfil de temperatura ao longo de uma extrusora monorosca. Apos o processo de extrusão, realizado sob as condições citadas acima, injetaram-se corpos de prova para analise de propriedades mecânicas, reológicas e térmicas. Constatou-se que as diferentes rotações estudadas provocaram alterações na deformação máxima de ruptura na tração, sendo que para o material reciclado, a rotação de 160 rpm apresentou a maior alteração dentre as demais rotações estudadas
Abstract: It's well known the broad use of polymeric materials and the proportional impact they cause when discarded in the environment, especially the "commodities" known as polypropylene (PP) and Polyethylene (PE). This has worried scientists, who search to develop technology to recycle these materials. One of these techniques is the reprocessing by extrusion and injection molding, the processes, however, tend to degrade the material, leading to alteration in their mechanical and rheological properties. Considering the context presented, it was developed a study where we evaluated the influence of rotation speed of the screw in the extrusion of virgin polypropylene (PP) and material recycled obtained from soda straws and disposable diapers's burrs, where there are a small amount of polyethylene (PE). It was observed four different speeds, namely 40, 80, 120 and 160 rpm carried out in one temperature profile along a single screw extruder. After the extrusion process, conducted under the above conditions were injected samples for analysis of mechanical, rheological and thermal properties. It was found that the different rotations cause changes in rupture maximum tensile strain. The recycled material processed at 160 rpm has presented the greatest change among the studied rotations
Mestrado
Ciencia e Tecnologia de Materiais
Mestre em Engenharia Química
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Samy, Sekhar. "Multiple extrusion of superconducting wires." Ohio : Ohio University, 1990. http://www.ohiolink.edu/etd/view.cgi?ohiou1183473010.
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Hurysz, Kevin Michael. "Paste mechanics for fine extrusion." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/19424.
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Flitta, Isaac. "Simulation of aluminium extrusion process." Thesis, Bournemouth University, 2004. http://eprints.bournemouth.ac.uk/314/.
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The aim of this thesis is to model the extrusion process conditions for some aluminium alloys using Finite Element Modelling (FEM) program. All the simulations were performed with the implicit finite element code FORGE20 (2-D) and FORGE3® (3-D). In this work only the alloys AA2024, AA2014, Al-1 %Cu and AA6063 where experimental work is available were considered. The FORGE2® program was used to investigate and select an appropriate flow stress constitutive equation to describe the material behaviour to model the process conditions. The extrusion pressure and the temperature rise were predicted and the pressure-displacement trace and the events which take place in the deformed material during the extrusion process were also simulated. The effect of the initial billet temperature on friction, and the extent of the surface zone affected by surface friction and the consequence changes in material flow were investigated. The changes in the subgrain size during quasi-static deformation were predicted. This allows a construction of velocity-displacement profiles which would ensure consistent properties over the length of the extrudate. The FORGE3® program was used to simulate the effect of changing the die geometry on material flow during extrusion for rod, shapes and tube extrusion and the effect of the initial temperature on the deformation zone. The load required, temperature evolution, surface formation of the extrudate and material flow during the process, were also predicted. These included solid sections and the production of tubes using bridge die. Two most commonly used constitutiveflow stress equations,the Zener-Hollomon and the Norton-Hoff were analysed and compared with experimental results. It was found that the Zener-Hollomon relationship provided a better representation of the experimental flow stress under high working conditions than the Norton-Hoff relationship. FEM has been successfully applied to model the deformation patterns in the load/displacement traces and temperature evolution during the extrusion cycle. The effect of the initial billet temperature on the deformation zone pattern and its consequent effect on friction using both numerical simulation and experimental work are presented. A specific function relationship to measure directly interfacial friction under conditions approaching those encountered in the quasi-static deformation process is described. The results revealed that the friction factor increases with increase in initial billet temperature and varies during the extrusion cycle. The dead metal zone (DMZ) is observed to vary in form and has a greater volume at high temperatures. FEM proved to be a very effective and efficient way to design the ram speed profile to control the extrudate properties. The control of the properties of the extrudate under a constant (Z) parameter resulted in a more uniform distribution of the subgrain size across and along the extrudate cross-section. Furthermore, the speed profile under constant Z conditions resulted in an improved extrusion speed and hence greater productivity coupled with better control of the subgrain size and the exit temperature. This new extrusion process is termed iso-Z Extrusion, and is considered an improvement on Iso-Thermal extrusion. The usefulness and the limitation of FEM when modelling complex shapes are discussed. Methods to assess the difficulty of hollow and section shapes are presented. The work also illustrates the essentials of numerical analysis in the comprehension of the thermo-mechanical events occurring during extrusion through bridge and shape dies. Results are presented for velocity distribution in the extrusion chamber, Iso-temperature contours and pressure/displacement traces. It is shown that for most of the shapes investigated, the material making up the extrudate cross-sections originated from virgin material within the billet. The outside surface of the extrudate originates from the material moving along the DMZ and the core of the extrudate from the central deformation zone. When simulating tube extrusion, it is shown that the FE program is able to predict the pressure requirements: the pressure/displacement trace showing a double peak for tube extrusion which is discussed in some detail. The FE program appears to predict all the major characteristics of the flow observed macroscopically.
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Sander, R. "Modelling of slit die extrusion." Thesis, Swansea University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638761.
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The present work is concerned with the investigation of the slit die extrusion of molten polymers, and a systematic strategy is developed for the modelling of its major aspects. The objective is to provide a fundamental understanding of the flow phenomena within such a die, coupled with thermal and mechanical interaction of melt and die body, and to provide user friendly software for analysis and design. Isothermal, non-Newtonian flow in the large aspect ratio channels of such dies is modelled using a Hele-Shaw formulation. The pressure field in the die causes a change of the flow channel dimensions, and hence alters the melt distribution. An experimental technique is applied to determine this die body deflection in a 1.3m commercial die; it is found to be substantial. Modelling of the die deformation using a commercial 3-D finite element package is described, with the load being based on a pressure field previously determined in the undeflected flow channel geometry. Prompted by unsatisfactory results, an algorithm is developed to evaluate the die body deflection iteratively, by coupling a 2-D thick plate analysis with the Hele-Shaw flow analysis, resulting in significantly improved results. Modelling of the conjugate melt flow/die heat transfer problem on the die cross-section is also carried out. Viscous heat generation, conduction and convection energy transport in the melt coupled with heat conduction in the die body are considered, together with the influence of electrical die heating and heat losses from the die surfaces by convection and radiation. Conclusions are drawn on thermal aspects of die design and operation. A graphical user interface embedded in Microsoft Windows is developed for a number of finite element codes, facilitating their use by non-specialists, and providing graphical displays of results. An outline of the operation of the complete package is described, including a convenient contouring algorithm.
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Crook, S. J. "The cold extrusion of chocolate." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598171.
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The objective of this thesis was to gain an understanding of the cold extrusion of chocolate, both physically and mathematically. This was achieved by quantifying the effect of pertinent process variables upon the pressure difference across a die as a chocolate flowed through it. Changes in the chocolate's cross-sectional area were found to have a large effect upon the extrusion pressure, whereas increases in its flowrate did not. It was also observed that the pressure on cessation of extrusion remained at a finite value. In addition, the boundary condition during cold extrusion was directly visualised and it was concluded that slip was occurring at the wall. This slippage was quantified by a low Coulomb friction coefficient. Therefore, it was concluded that during cold extrusion chocolate was deforming as a near-perfect plastic material. This characteristic allowed the successful use of a relatively simple theory to model the extrusion of chocolate through axisymmetric dies. The extension of this modelling by finite element techniques was investigated with the use of a commercial code (ABAQUS/Standard). The pressure difference across a die was found to be very sensitive to the temperature of the chocolate. The relationship between the pressure and the reciprocal of the temperature was fitted with a straight line. This relationship was extended to other chocolate compositions by scaling the chocolate's temperature by its nominal melting point. Across most of the flowrate range studied the flow pressure difference was either independent of, or increased slightly with, increases in the flowrate. However, at low flowrates and temperatures, the flow pressure was seen to decrease on increasing the flowrate. For dies with long capillaries, extruding in this region resulted in a flow instability. This instability showed a stick-spurt extrudate motion which was accompanied by large pressure oscillations, from which the chocolate's compressibility was calculated to be approximately the same as for some common polymers. The instability was successfully modelled by the combination of two simultaneous differential equations and a non-monotonic pressure-flowrate curve.
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Botten, Aleksandra Joanna. "Modelling single screw extrusion processes." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396429.
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Macauley, Nicola Jayne. "Extrusion and thermoforming of polypropylenes." Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337017.
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Namutebi, Agnes Ssekaalo. "Extrusion processing of sweet potato." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247561.
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Jones, Sylvia Anna. "Extrusion cooking of confectionery systems." Thesis, Cranfield University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310905.
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Amarasinghe, Angodage Don Upul Shantha. "Interpretation of paste extrusion data." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285008.
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Domanti, Annette Therese Jocelyn. "Surface fracture in paste extrusion." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242554.
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Parson, N. C. "Extrusion of aluminium-lithium alloys." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37814.
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Depenbusch, Brandon E. "Extrusion processing of feedlot diets." Diss., Kansas State University, 2009. http://hdl.handle.net/2097/4622.
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Doctor of PhilosophyDepartment of Animal Sciences and Industry
James S. Drouillard
A series of studies were conducted to evaluate extrusion processing of finishing diets on growth performance, carcass characteristics, and meat quality attributes of feedlot cattle. Extruded diets were processed in a 24:1 (length/diameter) corotating, fully intermeshing twinscrew extruder (model BCTG-62, Bühler AG CH-9240, Uzwil, Switzerland). In Experiment 1, extrusion processing of corn based diets decreased dry matter intake (DMI) and improved gain efficiency (G:F) by 15% compared to heifers fed steam-flaked corn (SFC) diets. Carcass characteristics were not different between treatments. Steaks from heifers fed SFC diets were juicier and had a less pronounced off-flavor than steaks from heifers fed extruded diets. In Experiment 2, average daily gain (ADG), DMI, G:F, carcass characteristics, and meat quality attributes were not different between heifers fed SFC and extruded processed corn diets. In Experiment 3, we evaluated different degrees of extrusion processing by altering the level of process water added to the extruder. Mechanical energy inputs, die pressure, die temperature, and torque of drive motor decreased as the level of water added to the extruder increased from 4% to 12%. Water addition did not affect DMI or ADG of feedlot heifers. However, live body weight (BW) and G:F decreased as the level of process water increased. Gain efficiency (carcass-adjusted basis) was 3% greater for extruded corn diets processed with 4% water compared with SFC diets and was 6% poorer than SFC diets when processed with 12% water. Apparent total tract digestibility was not different, but IVDMD improved with increasing levels of water. Improvements in G:F when fed extruded feed was variable among the 3 studies. This may be due, in part to severe infestation by European Starlings during Experiment 1. Impact of feed depredation by starlings was therefore evaluated. Starlings consumed 86% of the SFC diet offered to them compared to, none of the extruded corn diets. In addition, starlings preferentially selected for the energy dense portion of the rations (steam-flaked corn). Therefore, it is plausible that a portion of the 15% improvement in G:F observed in Experiment 1 for heifers fed extruded corn diets can be attributed to differences in feed depredation by starlings. Finally, two studies were conducted to evaluate extrusion processing of sorghum-based diets. In the first experiment, DMI was greater and G:F was poorer for heifers fed extruded sorghum diets compared to heifers fed steam-flaked sorghum (SFS) diets. However, carcass characteristics and meat quality attributes were not different. In the second study, particle size of the ground sorghum added to the extruder was evaluated. Processing sorghum to a smaller particle size (581 μm) prior to extrusion processing decreased DMI, improved G:F, and increased apparent total tract digestibility compared with larger particle sizes (1,264 μm). However, heifers fed SFS diets were still more efficient that heifers fed extruded diets made with either particle size of sorghum. Overall, this research suggests that extruding complete diets into homogeneous pellets may improve G:F of cattle fed corn-based diets while reducing feed depredation of starlings. It is also clear from our results that G:F is improved to a greater extent to processing diets under high shear conditions (i.e., high mechanical energy inputs) than when processed under low shear conditions.
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Horrobin, Daniel Joseph. "Theoretical aspects of paste extrusion." Thesis, University of Cambridge, 1999. https://www.repository.cam.ac.uk/handle/1810/283825.
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Haberbusch, Diane. "Viscosity Regulation In Polymer Extrusion." Cleveland State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=csu1386782032.
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Zhao, Zhiyang. "Reactive Extrusion Synthesis of Ionomers." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1408030685.
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Alevizos, Konstantinos. "Tube extrusion of hexagonal metals." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6049.
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Zr-2.5 wt % Nb (Zr-2.5Nb) is the main alloy used in the pressure tubes of CANDU nuclear reactors, which are manufactured by hot extrusion. Pressure tubes are subjected to high irradiation fields and corrosion, in addition to the applied stress at operating temperatures of around 330°C, which leads to irradiation creep that is often life-limiting; re-tubing the reactors, is a source of significant through-life cost of the reactor system. However, significant variability in performance is observed between tubes and stations, which is felt to be due to variability in the fabrication and operation conditions. The performance of Zr-2.5Nb is sensitive to both microstructure and texture and therefore it is desirable to be able to understand the extrusion conditions more fully. In this thesis, the extrusion of Zr-2.5Nb is examined, along with commercially pure titanium (CP Ti), commercially pure magnesium (CP Mg) and AA2014. The effect of extrusion ratio, die geometry and rod versus tube conditions are examined. The resulting microstructures and textures are rationalised with the aid of a finite element model for the process. After the introduction and literature review (Chapters 1-2), the modelling procedure and extrusion theory are examined (Chapter 3). Constitutive data (including friction conditions) are gathered and a Norton-Hoff constitutive model is generated in Chapter 4. It is found that adiabatic heating can be important at high strain rates and low temperatures, particularly in CP Ti and CP Mg. Recrystallization during deformation can be observed in the flow curves, particularly in CP Mg and AA2014 at low strain rates and high temperatures. The extrusion of AA2014 tubes is examined in Chapter 5. It is found that satisfactory textures and microstructures can be obtained, and that the model can reproduce the observed load curves. Partially extruded gridded billets are also used to verify the flow conditions predicted by the model and to obtain textures and microstructures part-way through the extrusion process. The extrusion of CP Mg and CP Ti are examined in Chapters 6 and 7, respectively. It was found that CP Mg recrystallized very easily, dominating the microstructures and textures observed. The CP Ti extrusions were performed in the [alpha]+[beta] regime in order to match Zr-2.5Nb conditions. The high extrusion ratio rod textures were dominated by the [beta]->[alpha]transformation, while those in the tubes were more characteristic of deformation of the [alpha] phase. Zr-2.5Nb extrusion is examined in Chapter 8. Satisfactory microstructures with elongated grains surrounded by thin ligaments of [beta] were obtained in the tube extruded through a flat-faced die, with the expected texture for this ratio of wall to diametral reduction (paragraph 2.5.7.1, Figure 2.25). The microstructures obtained were found to be a product of the temperature in the die and the cooling rate of the material. Excessive cooling rates lead to the production of basket-weave microstructures, and breakup of the grain boundary [alpha] to very fine microstructures. Again, the extrusion modelling allowed the results obtained to be rationalised. Finally, the reader is referred in Chapter 9 for a discussion of the obtained result. Conclusions drawn and suggestions for further work can be found in Chapter 10, together with recommendations for the industrial modelling of tube extrusion and for industrial practice.
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Westermann, Kira. "Extrusion von physikalisch geschäumten Kautschukprofilen /." Aachen : Mainz, 2009. http://d-nb.info/995461023/04.
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O'Connell, Sean Patrick. "Hot-melt Extrusion Through Syringes." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/338734.
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The use of solid dispersions to formulate poorly water soluble drugs is a growing field in the pharmaceutical sciences. Hot-melt extrusion is a common method for producing dispersions. However, bench-top extruders require large amounts of powder to run and are inappropriate for early formulation screens. Plastic and glass syringes are readily available in most laboratories. 250 mg of drug-polymer blend is placed in a plastic syringe body that has the tip covered with a bent needle. The syringe is heated for 5 minutes and the extrudate is pushed through the syringe. Extrudates are characterized by differential scanning calorimetry and powder x-ray diffraction. Acetaminophen, griseofulvin, indomethacin, salicylamide, and sulfamethoxazole extruded with polyvinylpyrrolidone K12 match or exceed the performance of solvent evaporated controls. Glass syringes can be used when polymers have processing ranges above the melting point of the plastic syringes. Syringe extrusion is effectively demonstrated as a rapid process for early formulation screening.
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Coleman, Brandon F. "High Moisture Extrusion of Oatmeal." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1390.
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Oats are considered to be a highly nutritious breakfast food available to consumers. Heightened consumer interest in functional food products and advances in human nutrition have led to increased levels of interest in the development of new oat based products (Webster and Wood 2011). Developments in technology have led to manufacturing of instant oatmeal, making the product more convenient to consumers. Low moisture extrusion processing is one of the most widely used methods to produce ready to eat breakfast cereals; however, there has been little research carried out to determine if high moisture extrusion methods would be viable. This study evaluated the economic and technical feasibility to utilize high moisture extrusion processing to produce ready to eat oatmeal. A process economics evaluation included measuring the capital requirements to implement the system, process costing to estimate the weighted average unit cost, and net present value of high moisture extrusion production. The capital expense was significantly high. However, the unit cost is comparable to similar products in the market. The net present value of implementing the technology revealed a significant profit over the course of 20 years. Six different technical experiments were performed using a twin screw extruder, each experiment testing for the effect of different extrusion variables on finished product texture. Reference texture data was measured using a control product currently made in the industry using an alternative batch process. The processing parameters which seemed to have the biggest influence on product quality were high rates of water injection, low feed rate, high reaction zone temperature, reduction of particle size, and the use of functional ingredients in the formula. Technical hurdles such as low dwell times, steam plugging, and inconsistent feeding prevented complete starch gelatinization and the steady state of extrusion. Overall, the high moisture methodology did not yield product quality that was consistent and cannot be recommended for use.
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Goetz, Robert L. "An analysis of canned extrusion using analytical methods and the experimental extrusion of cast IN100." Ohio : Ohio University, 1990. http://www.ohiolink.edu/etd/view.cgi?ohiou1183490628.
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Narayan, Sujatha. "Post-fiber extrusion solid-state polymerization of nylon 46." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/8228.
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Chen, Tao. "Recycling carpet waste by reactive extrusion." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/8485.
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Marques, Marcelo Rodrigues. "Ação hipocolesterolêmica de hidrolisados de feijões caupi (Vigna unguiculata L. Walp)." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/6/6138/tde-09102013-152334/.
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Introdução - Devido ao perfil de mortalidade e de danos patológicos associados, as doenças cardiovasculares são consideradas um sério problema de saúde pública. Níveis de colesterol plasmático elevados fazem parte dos fatores de risco mais importantes para o desenvolvimento dessas doenças. Pesquisas recentes demostraram que a proteína do feijão caupi promove a redução dos níveis de colesterol em hamsters e em seres humanos, possivelmente pela ação de peptídeos bioativos advindos da dieta. Entretanto, a via pela qual o colesterol é inibido por esses peptídeos, assim como os efeitos do processamento na ação biológica ainda são desconhecidos. Objetivo - Verificar a via de ação hipocolesterolêmica dos hidrolisados do feijão caupi e o efeito do processamento térmico nesta propriedade. Métodos - Parte da farinha integral foi submetida ao isolamento de proteína e o restante dos grãos foi submetido à cocção em autoclave e à extrusão. Após ser cozido em autoclave, o feijão cozido também teve sua proteína isolada. Posteriormente, a proteína isolada do feijão integral e do feijão cozido foi submetida à hidrólise in vitro. O processo de extrusão foi modelado em função da expansão dos extrusados segundo a metodologia de superfície de resposta. A farinha do feijão extrusado foi submetida à hidrólise enzimática in vitro sem isolamento prévio da proteína. Os três hidrolisados foram submetidos à ultrafiltração e a fração menor que 3 kDa foi utilizada nos ensaios de inibição da enzima 3-hidroxi-3-metilglutaril coenzima A redutase (HMGR) e no ensaio de inibição da solubilização micelar do colesterol para avaliar a ação dos hidrolisados na via hepática e na via entérica do metabolismo do colesterol respectivamente. Resultados - Os hidrolisados provenientes dos isolados proteicos apresentaram comportamentos semelhantes. Em doses mais elevadas de proteína (acima de 70 µg/mL), a inibição apresentou-se estável, por volta dos 75 por cento. Em relação ao hidrolisado da farinha de feijão extrusado, à medida que se aumenta a quantidade de proteína a capacidade inibitória diminui. Os hidrolisados foram capazes de inibir a solubilização micelar do colesterol de 5 a 39 por cento. O processamento térmico foi fator determinante para diminuir a solubilização do colesterol in vitro. Conclusão Os hidrolisados do feijão caupi são capazes de inibir a enzima HMGR e reduzir a solubilização micelar do colesterol in vitro, mesmo após o feijão ser processado termicamente. A capacidade dos hidrolisados de insolubilizar o colesterol foi melhorada pelo cozimento em autoclave e pela extrusãoIntroduction- The cardiovascular diseases, due to mortality and associated pathological damage, are considered a serious public health problem. Elevated plasma cholesterol levels are part of the most important risk factors for the development of these diseases. Recent research indicated that Cowpea protein promotes the reduction of cholesterol levels in hamsters and humans, possibly by the action of bioactive peptides from the diet. However, the route by which cholesterol is inhibited by peptides, as well as the processing effects on biological action are still unknown. Objective - To verify the hypocholesterolemic pathway of hydrolyzed cowpea and the effect of thermal processing on this property. Methods - Part of wholemeal flour was subjected to isolation of protein, and the remaining of the grains was subjected to retort and extrusion cooking processes. After autoclaving the grain, protein was also isolated from the flour. Subsequently, the isolated protein from wholemeal and cooked flour was subjected to in vitro hydrolysis. The extrusion process was optimized according to response surface methodology using the expansion ratio of extrudates as the dependent variable. The extruded bean flour was subjected to in vitro enzymatic hydrolysis without the isolation of the protein. The three hydrolysates were subjected to ultrafiltration and and fractions smaller than 3 kDa was used for inhibition assays of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) and for inhibition assay of micellar solubilization of cholesterol to evaluate their effect on the liver and enteral cholesterol metabolism respectively. Results - The hydrolysates from the protein isolates showed similar. At higher doses of protein (above 70 mg/mL), the inhibition was stable at around 75 per cent. Regarding the hydrolyzate of bean flour extruded as it increases the amount of protein inhibitory capacity decreases. The hydrolysates were able to inhibit the micellar solubilization of cholesterol between 5 and 39 per cent. The thermal processing was the determining factor to decrease the solubility of cholesterol in vitro. Conclusion The hydrolysates of cowpea are able to inhibit the enzyme HMGR micellar solubilization and reducing cholesterol in vitro, even after being thermally processed beans. The ability of hydrolysates insolubilize cholesterol was improved by cooking in an autoclave and by extrusion
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Soto, Yatsen Jepthe Maldonado. "Adequação de formulações para a produção de placas de fibrocimento por extrusão." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-04072012-180623/.
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Este trabalho propõe contribuir no desenvolvimento do processo de extrusão para a produção de compósitos cimentícios, mediante metodologia que possibilite a obtenção de formulações extrudáveis utilizando cimento Portland de alta resistência inicial, sílica ativa, calcário, polpa de celulose de eucalipto, fibras de polipropileno e aditivos. Para isso, foram caracterizadas as matérias-primas como subsidio para as discussões. O efeito dos diferentes componentes da formulação no comportamento reológico da mistura foi avaliado utilizando reômetro extrusor. As propriedades físicas e mecânicas dos compósitos elaborados com combinações de calcário, sílica ativa e cimento foram modeladas estatisticamente com o propósito de estimar o comportamento das matrizes. A demanda de água dos sistemas cimentícios foi determinada experimentalmente e utilizada na extrusão das matrizes. Selecionada uma matriz, suas propriedades mecânicas e físicas foram modeladas, estatisticamente, com diferentes teores de polpa celulósica de eucalipto e fibras de polipropileno. As formulações com características desejadas foram avaliadas ao envelhecimento acelerado por 200 ciclos de imersão-secagem. Finalmente foi analisada a reprodutibilidade utilizando o módulo de Weibull para as formulações selecionadas. O estudo reológico constatou que as fibras de polipropileno apresentam os maiores aumentos nos valores dos parâmetros reológicos se comparados com os efeitos do calcário, sílica ou celulose de eucalipto, repercutindo em maiores pressões de extrusão. O incremento do modificador reológico hidroxipropilmetilcelulose reduz no compósito cimentício o módulo de ruptura mesmo que durante o processamento, promova o incremento da pressão de extrusão. Os modelos estatísticos empregados para modelar a matriz reforçada foram de maior complexidade e com menor coeficiente de determinação se comparados com os utilizados na modelagem das matrizes. O preço de mercado do fibrocimento é aproximadamente 64% menor do que os determinados utilizando unicamente os valores das matérias-primas e aditivos do fibrocimento extrudado no presente estudo.This work intends to contribute in the development of the extrusion process for the production of cementitious composites, through methodology that makes it possible to obtain formulas using high resistance Portland cement, silica fume, limestone, eucalyptus pulp, polypropylene fibers and admixtures. With this intention, the raw materials were characterized as a support for the discussions. The effects of the different components of the formula on the rheological behavior of the mixture were evaluated using an extrusion rheometer. The physical and mechanical properties of the composites elaborated with the combinations of limestone, silica fume and cement were modeled statistically with the purpose of estimating the behavior of the matrix. The water demand of the cementitious systems was determined experimentally and used in the matrixes extrusion. After the Matrix Selection, their mechanical and physical properties were modeled statistically, with different pulp eucalyptus and polypropylene fibers quantities. The formulas with the expected characteristics were evaluated to the accelerated aging for 200 wet-drying cycles. Finally the reproducibility was analyzed using the Weibull module for the selected formulas. The rheological studies verified that the polypropylene fibers demonstrate the largest increase in the values of the rheological parameters when compared with the effects of the limestone, silica fume or eucalyptus pulp, inducing larger extrusion pressures. The increment of the rheological modifier hydroxypropyl methylcellulose decreases the module of rupture in the cementitious composite, and simultaneously during the process it promotes the increment of the extrusion pressure. The statistical models used to reinforce the matrix modeling were of large complexity and with smaller coefficient determination when compared to matrixes used for modeling. The fiber cement market price is approximately 64% smaller than the raw materials and admixtures used in extruded fiber cement in this study.
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Kite, Matthew J. S. "Computational modelling of clay pipe extrusion." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources. Online version available for University members only until June 9, 2014, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25966.
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Boss, Brienne. "Blue Cornmeal Extrusion and Anthocyanin Stability." Fogler Library, University of Maine, 2011. http://www.library.umaine.edu/theses/pdf/BossB2011.pdf.
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Perez, Gonzalez Alejandro Jose. "Specialty sorghums in direct-expansion extrusion." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4872.
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Whole-grain, high-fiber, or decorticated extrudates of excellent properties were
made from white (nonwaxy, heterowaxy, waxy) sorghums or brown tannin-sorghums.
Intact grains or prepared raw materials (cracked, cracked and sifted, decorticated) were
extruded in a high-temperature, short-time (HTST) extruder. Waxy extrudates expanded
less and were softer than those from nonwaxy or heterowaxy sorghums. Waxy
extrudates had bigger air cells and thicker cell walls. Low moisture used in this type of
extrusion and its interaction with the different amylose contents were the causes of the
differences. Whole-grain extrudates from white sorghum had similar sensory
acceptability to those from white decorticated sorghum. They had bland flavor and
appearance and texture characteristic of whole-grain products. Extrudates from tannin
sorghums were reddish brown due to their high levels of phytochemicals. The more
expanded, softer products from whole-grain tannin sorghum were obtained when the
grain was cracked and sifted. Decreased expansion was caused by higher levels of fiber
and greater particle sizes (as in the extruded intact grain), and by reduced particle sizes
(as in the cracked non-sifted grain). Expansion was correlated to smaller air cells with
smooth walls. A simple enzymatic method was developed that isolates the 'gritty'
particles from whole-grain/high-fiber extrudates, which closely correlated with
expansion. Gritty particles were fiber (bran) plus undegraded starchy material. Whole
grain/high fiber extrudates from white and tannin sorghums are an excellent option for
food processors because of their excellent taste, appearance and texture.
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Grubbström, Göran. "Reactive extrusion of wood-thermoplastic composites." Licentiate thesis, Luleå tekniska universitet, Materialvetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16932.
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The interest in Wood-thermoplastic composites (WPCs) has increased during the last decades. WPCs are commonly used as building material for decking and railing because of its low need of maintenance. Wood is a renewable resource of good mechanical properties and this make wood fibers interesting to use as reinforcement in a thermoplastic composite. A drawback with this type of composite is the poor long-term mechanical properties which limit its field of applications. The objective of this work was to optimize the process and understand structure-property relations of silane-crosslinked WPCs produced in a one-step reactive extrusion. The specific goal of crosslinking the composite was to improve the interfacial strength and stabilize the polymer matrix in order to improve these composites long-term mechanical properties.Silane-crosslinked WPC was produced by adding wood flour, polyethylene and a silane-peroxide solution to a compounding extruder. The composites were thereafter conditioned in different environments to promote the formation of silane-crosslinks. Parameters like wood flour moisture content, amount/composition of silane-peroxide solution and different general types of polyethylene was studied and related to the efficiency of the process.It was found that silane-technology applied to WPCs can be optimized in terms of processability and achieved property improvements. All crosslinked composites in this study have improved in strength, toughness and creep resistance but it was shown that the tested parameters have affect on both processing and properties. A gentle use of peroxides in the process was concluded to be positive for both processability and resulting property improvements. The unintentional crosslinking in the extrusion process is a drawback but was limited by lower peroxide concentrations. The use of low density polyethylene as polymer matrix lead to twice as high crosslinking rate compared to a high density polyethylene matrix. However, too excessive moisture uptake in the composites appears to lower the efficiency of crosslinking. Future studies should evaluate long-term load behavior more thoroughly and also investigate the conditioning step more carefully.Godkänd; 2009; 20090922 (grubb)
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Robinson, Jeremy St John. "Extrusion of rapidly solidified powder compacts." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/46338.
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Wang, Xiao Chuan. "Branching of polypropylene through reactive extrusion." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21396.pdf.
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Verhoeven, Vincent Wilhelmus Andreas. "The reactive extrusion of thermoplastic polyurethane." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2006. http://irs.ub.rug.nl/ppn/292374224.
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Hansson, Sofia. "Simulation of stainless steel tube extrusion." Licentiate thesis, Luleå : Luleå University of Technology, 2006. http://epubl.ltu.se/1402-1757/2006/13/index.html.
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Desai, Dipen. "Solid-state plasticizers for melt extrusion /." View online ; access limited to URI, 2007. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3276980.
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Popescu, Catalin Nicolae. "Modeling and control of extrusion coating." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/13700.
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Fichtali, Jaouad. "Production of caseins using extrusion technology." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74580.
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Preliminary experiments indicated that an acid casein co-precipitate could be produced by extrusion from skim milk powder (SMP). In assessing the problems encountered, experiments were designed to model and optimize the coagulation/washing process using response surface methodology (RSM), to minimize residual whey components and losses of fines. This study yielded useful information relative to improving our understanding of the coagulation mechanism and the most important variables affecting the process. In addition, RSM allowed multiresponse optimization of acid casein production using unique and newly developed optimization techniques. In order to simplify the process, an extruder die was designed to assist with the dewheying process, however, plugging problems occurred due to screw design limitations. Studies were implemented to determine the rheological behaviour of sodium caseinate and to evaluate the extruder performance in terms of energy consumption, and in terms of mixing and conveying through mathematical description of residence time distributions in the extruder. The knowledge gained from these studies was integrated to produce acid casein and sodium caseinate at pilot plant level and to conceive a plant layout of the process for the dairy industry. The process developed has many advantages, including the ability to produce a high quality product.
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Samaras, V. "The calibration process in thermoplastics extrusion." Thesis, Swansea University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638758.
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In the first part of this research work a new version of the cooling simulation software was constructed by changing the old convection module, which used the commercial software package POLYFLOW, to a new version using an alternative code developed in the Centre for Polymer Processing at the University of Wales Swansea, called Fantazt. This change introduced a large number of modifications in order for the new convection module to work in harmony with the rest of the program. Also many improvements have taken place in the new version, with respect to the computational time and the functionality of the software. The new version had to be tested on a large variety of profiles and be able to reproduce results identical with the computed results that have been previously provided by Kömmerling using the POLYFLOW version. In addition, a detail investigation regarding the convergence of the cooling simulation software was carried out. In the second part of this research work, a critical overview of the mechanical model has been presented. The main scope of this section was to carry out a detailed investigation of all the aspects of the mechanical model. Throughout this research, aspects as the convergence behaviour of the software were thoroughly examined. The outcome of this detailed investigation was the development of a new version of the mechanical model. The present work has provided detailed insights and understanding of the performance of the mechanical software, and produced improved versions of the code. The work has identified a number of further developments that are required. Throughout the research period, strong and valuable synergies have been developed with previous and parallel research works between Swansea University and Kömmerling Kunststoffe, aiming to provide a better understanding of the parameters that affect the calibration process and the use of the simulation software.
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Oates, Christopher G. "Soya/alginate interactions in extrusion cooking." Thesis, University of Nottingham, 1988. http://eprints.nottingham.ac.uk/11161/.
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Previous work has shown that following the inclusion of alginate high in mannuronic acid there is a reduction in the viscosity of soya melt during extrusion, this work attempts to identify the mechanism for this effect. The effect of water content and hydrocolloid inclusion on the denaturation behaviour and water binding properties of soya protein has been investigated, mainly by the use of differential scanning calorimetry. Of a range of parameters investigated, transition onset temperature and enthalpy, change in specific heat function and coopertivity of the transition all show a dependence on initial moisture content. These parameters are all changed if soya is heated in the presence of a high mannuronic acid alginate. With the exception of changes in enthalpy these effects are not seen to the same extent with other added hydrocolloids. These changes have been attributed to the production of water during heating. Measurements of freezable water and sorption isotherms suggest that alginate addition increases the water binding ability of soya isolate after denaturation. When heated at high temperatures only soya and gluten (out of 7 proteins tested) produced measurable quantities of additional water. In the presence of 2% Manucol DM the formation of water was markedly increased in the soya and gluten samples but not in the other proteins. Production of increased amounts of water after alginate addition was demonstrated to be dependent on the quantity of mannuronic acid in the alginate. The dependence of this effect on water activity suggests that it is the result of browning or condensation reactions. Glutamic acid was implicated with the specific reaction between soya and alginate, though in heated soya both loss of lysine and serine were found. Differential rates of degradation were found between a high mannuronic acid alginate and a high guluronic acid alginate after heat treatment. The alginate high in mannuronic acid was shown to depolymerise to a far greater extent. Various estimates for the molecular weight of the heat treated samples were obtained and no correlation could be found between increased reducing capability of the sample and extent of depolymerisation. Furthermore the production of volatiles that may be expected from sugar ring degradation were not found. Increased brown colour formation and water production and concomittant decreased glutamic acid content were found in soya samples extruded in the presence of 1% Manucol DM. It was concluded that the chemical reactivity of glutamic acid with alginates rich in mannuronic acid explains the well established effect of this type of polysaccharide in extrusion processing.
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Senouci, A. "Rheology and modelling in food extrusion." Thesis, University of East Anglia, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235484.
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Edmondson, Michael James. "Metals in zeolites : inclusion and extrusion." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395736.
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Farzad, A. "Rationalization of tool design in extrusion." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234073.
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