Dissertations / Theses on the topic 'Foam'
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1
Braz, Dulce Alexandra. "Particle-stabilised foams and foam films." Thesis, University of Hull, 2009. http://hydra.hull.ac.uk/resources/hull:2185.
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This thesis aimed to investigate and understand the properties of foams and foam liquid films stabilised by colloidal solid particles, in the absence of any surface active substances, e.g. surfactants. Foams occur as end products or during the processing of products in many industries, including detergents, food and the cosmetic industries. A controlled level of foam formation is desirable in many consumer products. Therefore understanding the mechanisms for their control was also important in this research. Colloidal particles act in many ways like traditional surfactant molecules but offer distinct advantages. The main advantage is that particle-stabilised foams offer longer stability in comparison to surfactant-stabilised foams. Most of the studies, however, were focused on mixtures of surfactant systems and solid particles. Physical mechanisms for foam formation in the presence of colloidal particles alone are less known. However, in response to an increasing interest for this subject, a number of research papers on foams stabilised by solid particles alone have been published recently and during the past 5 years.
2
Bhattacharjee, Samita. "Prediction Of Separation Factor In Foam Separation Of Proteins." Thesis, Indian Institute of Science, 1994. https://etd.iisc.ac.in/handle/2005/132.
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Polyhedral foams offer large gas-liquid interfacial area associated with a small amount of liquid. Therefore, if a solute adsorbs preferentially at the interface, the concentration of the solute in the foam will be greater than in the solution from which the foam has been generated. This effect provides a simple method of concentrating materials which have a tendency to adsorb on the gas-liquid interface. This is particularly relevant to biomaterials like whole cells, proteins, enzymes etc., which are surface active and are present in low concentrations in the broth. Foam separation has therefore attracted considerable attention, and several reports exist in literature on concentrating cells, proteins and enzymes using foams.
Foam separation is based on the difference in surface activity of the components to be separated. A surface active molecule consists of a lyophobic and a lyophilic group. (As water is commonly used as a solvent, the lyophilic and lyophobic groups are called hydrophilic and hydrophobic groups, respectively). When dissolved in a solvent, the presence of lyophobic groups in the interior of the solvent distorts the solvent liquid structure, thereby increasing the free energy of the system.
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Bhattacharjee, Samita. "Prediction Of Separation Factor In Foam Separation Of Proteins." Thesis, Indian Institute of Science, 1994. http://hdl.handle.net/2005/132.
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Polyhedral foams offer large gas-liquid interfacial area associated with a small amount of liquid. Therefore, if a solute adsorbs preferentially at the interface, the concentration of the solute in the foam will be greater than in the solution from which the foam has been generated. This effect provides a simple method of concentrating materials which have a tendency to adsorb on the gas-liquid interface. This is particularly relevant to biomaterials like whole cells, proteins, enzymes etc., which are surface active and are present in low concentrations in the broth. Foam separation has therefore attracted considerable attention, and several reports exist in literature on concentrating cells, proteins and enzymes using foams.
Foam separation is based on the difference in surface activity of the components to be separated. A surface active molecule consists of a lyophobic and a lyophilic group. (As water is commonly used as a solvent, the lyophilic and lyophobic groups are called hydrophilic and hydrophobic groups, respectively). When dissolved in a solvent, the presence of lyophobic groups in the interior of the solvent distorts the solvent liquid structure, thereby increasing the free energy of the system.
4
Verdugo, Rodriguez Rogelio Alberto. "Carbon foam characterization tensile evaluation of carbon foam ligaments." Texas A&M University, 2003. http://hdl.handle.net/1969.1/56.
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A methodology for ligament isolation and specimen preparation for tensile testing of single ligaments from the unit cell of open-cell carbon foams has been successfully developed and implemented. Results are presented for ligaments of three different carbon foam designations. Two of them are reticulated vitreous carbon (RVC) foams of 20 and 45 pores-per- inch (ppi) coated with SiC by chemical vapor deposition (CVD) and the other is a RVC 20 ppi foam without coating.
Scanning electron microscopy and digital imaging analysis is used to analyze the fracture surfaces posts tests. The ultimate strength of each ligament evaluated. Weibull statistics is used to describe the strength distribution of ligaments. While the distribution of strengths of the carbon foam ligaments (RVC) could be described with a one-population distribution, it is found that a two-population Weibull distribution is necessary to describe the distribution of strength of the SiC coated ligaments.
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Keltner, Noelle Joy. "Study of PocoFoam (TM) as a heat exchanger element in cryogenic applications." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51774.
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Superconductors present great potential for weight reduction and increased power delivery when compared to traditional copper power delivery systems, but current systems require cryogenic cooling systems. Traditional superconductor cooling systems consist of helium cooled by helical heat exchangers made of Oxygen Free High thermal Conductivity (OFHC) copper tube. The helium is cooled by bulky heat exchangers consisting of OFHC copper coils wrapped around a cryogenic cooler heat sink for heat transfer into the working fluid. Metal foams have recently been studied in a variety of heat transfer applications, and could greatly reduce the weight of heat exchanger modules in superconductor cooling systems while simultaneously providing increased heat transfer effectiveness. Aluminum and Copper foams have been available for several years, but more recently, graphite foams, such as PocoFoam™, have been developed which have particularly good heat transfer characteristics. Using Computational Fluid Dynamics (CFD) to model a cryogenic heat exchanger application, this study examines the effectiveness and pressure drop of several metal foam heat exchangers, and compares their performance with the traditional helical coil design for superconductor cooling applications. The CFD simulation results show that a heat exchanger with the same heat sink contact area as existing helical heat exchangers weighs up to 95 percent less and can be up to 25 percent more effective, depending on system conditions such as pressure, cryogenic cooler temperature and helium inlet temperature. Aluminum and copper foam heat exchangers had comparable weight to the PocoFoam heat exchanger, but were significantly less effective than the helical or PocoFoam heat exchanger models.
6
Yüksel, Sinan Güden Mustafa. "Crushing behaviour of aluminum foam-filled composite tubes/." s.l.]: [s.n.], 2005. http://library.iyte.edu.tr/tezler/master/makinamuh/T000380.pdf.
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Thesis (Master)--İzmir Institute of Technology, İzmir, 2005.Keywords:crushing, aluminum foam, foam filling, energy absorber, composite tubes. Includes bibliographical references (leaves. 93-96).
7
Blandin, Christopher. "Production of dielectric materials." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26568.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Colton, Jonathan; Committee Member: Schultz, John; Committee Member: Zhou, Min. Part of the SMARTech Electronic Thesis and Dissertation Collection.
8
Paknejad, Amir Saman. "Foam drilling simulator." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4792.
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Although the use of compressible drilling fluids is experiencing growth, the flow
behavior and stability properties of drilling foams are more complicated than those of
conventional fluids. In contrast with conventional mud, the physical properties of foam
change along the wellbore. Foam physical and thermal properties are strongly affected by
pressure and temperature. Many problems associated with field applications still exist,
and a precise characterization of the rheological properties of these complex systems
needs to be performed. The accurate determination of the foam properties in circulating
wells helps to achieve better estimation of foam rheology and pressure.
A computer code is developed to process the data and closely simulate the pressure
during drilling a well. The model also offers a detailed discussion of many aspects of
foam drilling operations and enables the user to generate many comparative graphs and
tables. The effects of some important parameters such as: back-pressure, rate of
penetration, cuttings concentration, cuttings size, and formation water influx on pressure,
injection rate, and velocity are presented in tabular and graphical form.
A discretized heat transfer model is formulated with an energy balance on a control
volume in the flowing fluid. The finite difference model (FDM) is used to write the
governing heat transfer equations in discretized form. A detailed discussion on the
determination of heat transfer coefficients and the solution approach is presented.
Additional research is required to analyze the foam heat transfer coefficient and thermal
conductivity.
9
Everington, Ashley Steven. "Foam diagram summation." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620047.
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Cheng, Liang. "Modeling and simulation studies of foam processes in improved oil recovery and acid-diversions." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2002. http://wwwlib.umi.com/cr/utexas/fullcit?p3077619.
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Barros, Daza Manuel Julian. "Numerical Simulation of High Expansion Foam Into Conduits and Mine Openings." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83565.
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High expansion foam (Hi-Ex) is a firefighting technology that has been widely used for fire suppression in underground locations. Hi-ex foam can be applied remotely through boreholes from the surface reducing firefighter exposure to fires. Despite the experimental studies that have been carried out there are still some uncertainties about foam behavior in underground locations. For this reason, the main objective of this thesis was to estimate Hi-Ex foam flow behavior in different underground configurations using computational fluid dynamics (CFD) simulations. An experimental apparatus was built to study the foam rheology in order to determine the rheological model parameters to simulate foam as a continuous Non-Newtonian fluid. Furthermore, numerical and experimental results of Hi-Ex foam flowing in a pipe were compared with the objective of validating numerical results.
Results of this study show that Hi-Ex foam with an expansion ratio between 1:250 and 1:1280 behaves as a shear thinning fluid represented by the power law model. Numerical simulations results were between 0.06% and 14% of experimental results for Reynolds numbers between 200 and 1700. Finally, numerical simulations of Hi-Ex foam in different mine entry slopes were carried out and compared with qualitative results of prior field work.
This work generates some of the necessary numerical parameters for the simulation of Hi-Ex foam flow in mines. Furthermore, results of this work and the methodology used can allow for improved predictions of foam flow in in underground mine fires, while improving safety for mine workersMaster of Science
12
Schreder, Julian. "Thermoforming of PMI foam." Thesis, KTH, Lättkonstruktioner, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-157494.
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Breward, C. J. W. "The mathematics of foam." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300849.
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The aim of this thesis is to derive and solve mathematical models for the flow of liquid in a foam. A primary concern is to investigate how so-called `Marangoni stresses' (i.e. surface tension gradients), generated for example by the presence of a surfactant, act to stabilise a foam. We aim to provide the key microscopic components for future foam modelling. We begin by describing in detail the influence of surface tension gradients on a general liquid flow, and various physical mechanisms which can give rise to such gradients. We apply the models thus devised to an experimental configuration designed to investigate Marangoni effects. Next we turn our attention to the flow in the thin liquid films (`lamellae') which make up a foam. Our methodology is to simplify the field equations (e.g. the Navier-Stokes equations for the liquid) and free surface conditions using systematic asymptotic methods. The models so derived explain the `stiffening' effect of surfactants at free surfaces, which extends considerably the lifetime of a foam. Finally, we look at the macroscopic behaviour of foam using an ad-hoc averaging of the thin film models.
14
Elbadawi, Azhari Mohamed. "Foam finishing of fabrics." Thesis, University of Huddersfield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286082.
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Raukola, Jaakko I. "A new technology to manufacture polypropylene foam sheet and biaxially oriented foam film /." Espoo : Technical Research Centre of Finland, 1998. http://www.vtt.fi/inf/pdf/publications/1998/P361.pdf.
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Pop-Iliev, Remon. "Processing of fine-cell polypropylene foams in compounding-based rotational foam molding." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0001/MQ45622.pdf.
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Osei-Bonsu, Kofi. "Foam-facilitated oil displacement in porous media." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/foamfacilitated-oil-displacement-in-porous-media(f2b2e93b-3a9b-41fa-a841-f81b271e8fad).html.
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Foam flow in porous media is important for many industrial operations such as enhanced oil recovery, remediation of contaminated aquifers and CO2 sequestration. The application of foam in these processes is due to its unique ability to reduce gas mobility and to divert gas to low permeability zones in porous media which otherwise would not be reached. To achieve optimum success with foam as a displacing fluid in oil recovery and remediation operations, it is essential to understand how different parameters influence foam flow in porous media. In this thesis, a variety of experimental techniques were used to study foam stability, foam rheology as well as the dynamics and patterns of oil displacement by foam under different boundary conditions such as surfactant formulation, oil type, foam quality (gas fraction) and porous media geometry. Bulk scale studies showed that foam stability was surfactant and oil dependant such that decreasing oil carbon number and viscosity decreased the stability of foam. However, no meaningful correlation was found between foam stability at bulk scale and the efficiency of oil displacement in porous media for the various surfactants studied in this work. Additionally, our results show that foams consisting of smaller bubbles do not necessarily correspond to higher apparent viscosity as the foam quality is also crucial. For the same foam quality decreasing bubble size resulted in higher apparent viscosity. Although in theory a higher apparent viscosity (i.e. higher foam quality) would be ideal for displacement purposes, increasing foam quality resulted in less stable foam in porous media due to formation of thin films which were less stable in the presence of oil. The effect of pore geometry on foam generation and oil displacement has also been investigated. Our findings provide new insights about the physics and complex dynamics of foam flow in porous media.
18
Ainsworth, Mark J. "Metal-foam interface stability during the filling of lost foam moulds with aluminium alloys." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1481/.
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Aluminium Lost Foam castings were made using gravity and counter-gravity filling techniques. Tensile strength was found to be most uniform in those castings which had been filled slowly from the bottom and where the metal front had remained stable throughout filling sequence. Pores containing carbon deposits were found on the fracture surfaces of all the castings made and this suggested that the defect was caused by polymer entrapment. A Saffman-Taylor instability was observed at the interface between Hg and a viscous glucose syrup which were contained in an analogue, that was used simulate the casting of Lost Foam moulds at room temperature. The liquid degradation products of the polystyrene patterns were also found to be viscous, although this was reduced by treatment with Br. Under the same conditions of temperature and velocity, the interface observed during the filling of a Br-treated pattern was planar whereas that of an untreated pattern was unstable. This demonstrated not only that the interfacial instability entrapped polymer degradation products, which adversely affected casting quality, but was probably of the Saffman-Taylor type.
19
Gu, Zipeng. "Emulsion Templated Polyimide Aerogel Foam and Hybrid Aerogel Foam as Absorbents for Oil Cleanup." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1525711842824095.
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Rodeheaver, Bret Alan. "Open-celled microcellular themoplastic foam." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/18914.
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Cunningham, Ryan. "Modifications to foam volume measurements." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=92193.
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The amount of foam volume generated in relation to the gas flowrate has long been used to define the foaminess of a solution and to characterize surfactants. The vessel geometry and gas flowrate range can affect the foam volume results. A fixed area column was tested alongside a variable area conical vessel with three surfactants (commercial frothers). It was found that the fixed area vessel would cause foam volume to expand or contract, which masks the effect of the surfactant. The conical vessel showed two regimes of foam volume production dependant on gas flowrate. The low gas flowrate regime was tentatively associated with a quiescent bubbly zone while the high gas flowrate regime associated to a turbulent bubbly zone. Foaming properties of a surfactant are best determined with a variable area vessel at low gas flowrate.L'étude du volume de mousse généré en corrélation avec le flux de gaz est utilisée depuis longtemps afin de déterminer la moussabilité d'une solution et d'en caractériser les agents de surface. La géométrie de la cuve ainsi que l'amplitude du flux de gaz sont connus pour avoir un effet sur les résultats de volume de mousse généré. Une colonne avec une aire de surface prédéfinie a été testée en parallèle avec une cuve conique de surface variable ; trois agents de surface (des moussants commerciaux) ont servi de base d'étude. Les résultats ont montré que la cuve possédant une aire de surface fixe causerait l'expansion ou la contraction de la mousse, masquant l'effet de l'agent de surface. Avec la cuve conique, deux régimes de production du volume de mousse, chacun dépendants du flux de gaz, ont été déterminés. Le régime correspondant à un flux de gaz faible est le produit d'une zone quiescente d'évolution des bulles alors que le régime correspondant à un flux de gaz élevé montre des propriétés typiquement cinématiques dues à une zone turbulente d'évolution des bulles. Les propriétés de moussage d'un agent de surface donné sont déterminées avec une meilleure exactitude en utilisant une cuve de surface variable avec un flux de gaz faible.
22
Ripley, Mark Brian. "Hydrocarbon bioremediation using bioactive foam." Thesis, University of York, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313765.
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Wang, Liguang. "Surface Forces in Foam Films." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/26476.
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Fundamental studies of surface forces in foam films are carried out to explain the stability of foams and froths in froth flotation. The thin film pressure balance (TFPB) technique was used to study the surface forces between air bubbles in water from equilibrium film thickness and dynamic film thinning measurements. The results were compared with the disjoining pressure predicted from the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The contribution from the non-DLVO force was estimated by subtracting the electrostatic double-layer and van der Waals forces from the total force (or pressure) measured. The results obtained in the present work suggest that a strong attractive force (referred to as hydrophobic force) exists at very low surfactant concentrations, and that it decreases with increasing surfactant and/or electrolyte concentrations. In contrast, pH changes have only minor effects on the hydrophobic force.
The changes in the hydrophobic force observed at low surfactant concentration region have been related to foam stability in flotation. In addition, an analytical model applicable to a broad range of surfactant concentration was developed to calculate film elasticity from surface tension. The model finds, however, that the film elasticities change little at low surfactant concentrations. It is, therefore, suggested that bubble coalescence and foam stability at low surfactant concentrations may be largely affected by hydrophobic force.
The TFPB technique was also used to study the surface forces in the foam films stabilized with various frothers such as pentanol, octanol, methyl isobutyl carbinol (MIBC), and polypropylene glycol (PPG). The results were compared with the foam stabilities measured using the shake tests and the film elasticity calculated using the model developed in the present work. It was found that at a low electrolyte concentration foam stability is controlled by film elasticity and surface forces, the relative contributions from each changing with frother concentration and type. It is, therefore, proposed that one can control the foam stability in flotation by balancing the elasticities of foam films and the disjoining pressure in the films, particularly the contributions from the hydrophobic force.Ph. D.
24
Athinarayanan, Madhusudhanan. "Foam filled corrugated board manufacture." Thesis, University of Manchester, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.676723.
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Mishra, Sarthak. "Numerical Analysis and Design of Carbon-Foam-based Garment and Helmet for Firefighters." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1398699034.
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Akseli, Ilgaz Güden Mustafa. "The application of aliminum foam for the heat and noise reduction in automobiles/." [s.l.]: [s.n.], 2005. http://library.iyte.edu.tr/tezler/master/makinamuh/T000343.pdf.
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Thesis (Master)--İzmir Institute Of Technology, İzmir, 2005.Keywords: Aluminum matrix composites, thermal conductivity, sound insulation, foam, metal matrix composites, aluminum foam. Includes bibliographical references (leaves. 77-81).
27
Miller, Erin Ashley. "Structure and mechanics of solid foam /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/9633.
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Schick, Christian. "A mathematical analysis of foam films." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972684247.
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Eftekhari, Farzad. "Foam-surfactant technology in soil remediation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0018/MQ54314.pdf.
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Masanja, Daniel. "Foam concrete as a structural material /." Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4002.
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Williams, Andrew M. "Autoselective regeneration of gelcast ceramic foam." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/12526.
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This thesis describes the development and application of an electric discharge for regenerating gelcast ceramic foam diesel particulate filters (DPF) for effective and efficient reduction of particulate matter (PM) emissions from diesel fuelled IC engines. The combustion in diesel compression ignition engines generates a number of unwanted by-products including PM. The PM from diesel engines is believed to be potentially carcinogenic when inhaled into the lungs and, therefore, needs to be controlled. Emission legislation has made it increasingly difficult for engineers to reduce PM emissions whilst meeting NOx targets by combustion optimisation alone, leading to the requirement for exhaust gas aftertreatment, most notably exhaust gas filtration. Filtration and regeneration (filter cleaning) technology must be robust, filter high amounts of PM, be compact, energy efficient and cost effective. A large number of published solutions do not meet all of these criteria. This research has developed a compact, efficient, robust and cost effective solution: The Autoselective regeneration of gelcast ceramic foam DPFs. Gelcast ceramic foam geometry can be optimised on a microscopic and macroscopic scale with a large number of material characteristics. This thesis develops and applies new methodology for rapid optimisation of gelcast ceramic foam DPFs. The optimum foam geometry is found to be highly application-dependent. Filters with >95% filtration efficiency and a low filtration volume have been demonstrated, although are limited in their PM mass holding capacity. It was found that filters with higher PM mass holding capacity require larger pore sizes and filtration volume. Design maps were produced to allow rapid optimisation of gel cast ceramic foams with a novel methodology that can be applied to all forms of deep bed filtration, saving both time and cost in future filter development. Investigation and optimisation of Autoselective regeneration demonstrated that the regeneration system is most effective when the electric discharge is active within the filter volume. Using modelling and novel methods for measuring heat flux from electrical discharges, thermal optimisation of the heat flows in the system were achieved. Rig tests increased the robustness of the regeneration system and developed profiled mesh electrodes to maximise the effective regeneration volume. An engine test programme demonstrated regeneration effectiveness of -12 g kW·1 h-I which is equivalent to -333 W for a typical 56 kW heavy duty diesel engine. Alternatives such as fuel burners and electrical resistance heaters typically consume between I and 5 kW of fuel energy for filter regeneration. Multiple electrode prototypes are presented and evaluated for efficient and effective on-engine and on-vehicle PM control.
32
Oriti, Daniele. "Spin foam models of quantum spacetime." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620008.
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Hipkins, David B. "Class A Foam Water Sprinkler Systems." University of Canterbury. Civil Engineering, 1999. http://hdl.handle.net/10092/8274.
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Class A foam is often used in the suppression of wildland and structural fires, with manual application methods. This report examines the feasibility of utilising class A foam extinguishing medium in automatic wet pipe sprinkler systems.
Previous researchers report that for certain applications the addition of class A foam solution to a sprinkler system increases suppression effectiveness. Researchers investigating applications with manual fire fighting techniques, using this extinguishing medium, report mixed conclusions.
The integration of class A foam hardware with standard wet pipe sprinkler technology is discussed. Consideration is given to potential corrosion effects and compatibility with sprinkler hardware items. A review of environmental issues revealed that some products are readily biodegradable, while others are not, and that results vary with the test method used.
Tests undertaken to investigate the relationship between the applied sprinkler head pressure and the foam expansion ratio, revealed that only a slight increase in the expansion ratio occurred when the pressure was increased from 50 kPa to 85 kPa. Expansion ratios obtained were similar to those obtained by other researchers using AFFF type foam solution. Foam-water distribution tests indicated that the distribution densities obtained with class A foam sprinkler arrays are within close proximity to the densities obtained using pure water.
It is suggested that future work in this area should be based around the protection of extreme class A hazard type fires.
34
Kader, Atef Abd El. "Experimental studies of two dimensional foam." Thesis, Queen's University Belfast, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268219.
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Black, Ian James. "The properties of aqueous foam films." Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316158.
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Ball, Sarah K. M. "The foam separation of protein solutions." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388469.
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Jodoin, Jeffrey Joseph. "The production of polypropylene microcellular foam." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/14857.
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Fox, Timothy J. "Aging in closed-cell phenolic foam." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/15025.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Bibliography: leaves 126-127.
by Timothy J. Fox.
M.S.
39
Colton, Jonathan Stuart. "The nucleation of microcellular thermoplastic foam." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/14986.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Vita.
Includes bibliographies.
by Jonathan Stuart Colton.
Ph.D.
40
Hyatt, Daniel (Daniel Elliot). "Proposed testing method for foam padding." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/69778.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 31).
One very basic necessity for foam padding testing technology is the ability to test two different padding samples and compare the results. The current standard for testing is to use a steel anvil backing for the padding, create an impact and record the parameters of the collision. The standardized method of testing with a steel anvil backing may not truly depict which foam or padding is actually the most protective, and this project aims to demonstrate how using a more humanlike backing produces more accurate test results. The experimentation setup used a projectile shot with a known velocity at various padding samples, where both a steel anvil and urethane foam are used as separate backings for the experiment. The steel anvil represents the current industry testing standard, whereas the urethane foam is meant to physically replicate the characteristics of human flesh. Using a load cell which is calibrated with an oscilloscope, a curve of the force applied over time will be recorded for each test run. From this force curve, the peak force, total impulse, and energy dissipated were calculated for each collision. By comparing these metrics across different foam padding specimens using the two padding backings across different velocities, the effect of varying the padding backing are demonstrated in the experimental results. Although using the steel anvil backing lead to generally similar recommendations for the best padding, it does not capture a lot of the details which are necessary to truly understand how different foam specimens compare with each other. Two main conclusions are drawn regarding the difference between the steel anvil and urethane foam setups: the difference in the shape of the force over time curves and the significance of changing the velocity of the impact. Using the urethane foam backing also established two different regimes which define whether or not the padding user would feel a significant impact. The parameters of these regimes provide the best data for deciding on appropriate foam specimens. The steel anvil backing lacks any capacity to test or predict which impacts are severe enough to cause serious injury.
by Daniel Hyatt.
S.B.
41
Sin, Lim Khai. "Studies of foam microstructure and rheology." Thesis, University of Birmingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633208.
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Foams are ubiquitous in many industrial processes and therefore have been subjected to extensive research in the past few decades. However, a number of fundamental issues relating to foams remain poorly understood including the production and control of bubbles and how they contribute to product structure, appearance, and rheology. The work in this thesis thus sets out to study the foam rheological behaviour and its related structural evolution, to explore a potential method in controlling bubble structure during foam generation, and to introduce a novel non-invasive technique in probing foam microstructure. Foam rheological behaviour was studied by using two approaches. In a rheometric approach, the foam response to external shear and the related microstructural change, its time dependency, thixotropic behaviour and viscoelastic properties were investigated for both detergent (Gillette) and protein (egg white protein) foams. The flow curves constructed were well fitted with four-parameter rheological models, the Cross and Carreau models and revealed the true flow behaviour of foam; there was no yield stress as reported in the literature. On the other hand, the macroscopic flow behaviour of a protein foam (WPC) in straight pipes and through fittings (sudden expansion, orifice plates and perforated plates) were studied. A friction factor analysis approach which treats foam as a non-Newtonian power law fluid was successfully used to model the flow of WPC foam, this has a practical significance in that pressure drop can be calculated using a constant friction factor along a pipe of a constant cross section in any flow regime. The potential of ultrasound in controlling foam structure during the foam generation process was investigated. Depending on the types of surfactant and concentrations, ultrasound reduced the mean bubble size of foams and improved foam homogeneity. Single bubble formation in an ultrasound field managed to shed light onto the possible mechanism involved; ultrasound increased the bubble formation rate and reduced the bubble coalesce events at the nozzle. X-ray micro-computed tomography was used successfully in revealing the true three dimensional structure of some cellular/foam food products, both solid and semi liquid. Both two- and three-dimensional quantitative analyses of structural parameters were done and the spatial bubble size distribution was reconstructed using a stereology technique.
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Stone, Robert Michael 1957. "Shear modulii for cellular foam materials." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277020.
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The use of cellular foam as a core material in light-weight structural applications is of considerable interest. However, advances in this technology have been limited due to the lack of information concerning the macroscopic material behavior of cellular foams. Of particular interest in the design of composite structures is the shear modulus, G, of the core material, which must be established with a high degree of accuracy. Current ASTM test methods for shear modulus determination were researched and found inadequate for testing cellular foam materials. The difficulty in testing foam and the inaccuracies associated with the standard test methods established the need for the development of a test method for these materials. The test method (test fixture and test procedure) developed for cellular foam materials is presented. The design of the test fixture and the finite element analysis performed to determine fixture accuracy are discussed in detail. Additionally, the test procedure is presented, as well as the results for the 32 tests performed.
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Kamalanathan, Ishara Dedunu. "Foam fractionation of surfactant-protein mixtures." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/foam-fractionation-of-surfactantprotein-mixtures(a6484b1a-d796-45ff-bc5c-420ef9130363).html.
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Foam fractionation is an adsorptive bubble separation technology that has shown potential as a replacement to the more costly and non-sustainable traditional downstream processing methods such as solvent extraction and chromatography for biological systems. However biological systems mostly tend to be a mixture of surface active species that complicates the foam fractionation separation. In this thesis a detailed experimental study on the application of foam fractionation to separate a well-defined surfactant-protein mixture was performed with emphasis on the competitive adsorption behaviour and transport processes of surfactant-protein mixtures in a foam fractionation process. Surface tension and nuclear magnetic resonance (NMR) measurements showed that nonionic surfactant Triton X−100 maximum surface pressure, surface affinity and diffusivity were a factor of 2.05, 67.0 and 19.6 respectively greater than that of BSA. Thus Triton X−100 dominated the surface adsorption at an air-water surface by diffusing to the surface and adsorbing at the surface faster than BSA. This competitive adsorption behaviour was observed in foam fractionation experiments performed for Triton X−100/BSA mixtures for different feed concentration ratios and air flow rates. The recovery and enrichment of Triton X−100 were found to increase and decrease respectively with increasing air flow rate for all foam fractionation experiments as expected for a single component system. However the recovery and enrichment of BSA were both found to increase with increasing air flow rate for high feed concentrations of Triton X−100.Bubble size measurements of the foamate produced from foam fractionation experiments showed that at steady state conditions the bubbles rising from the liquid pool were stabilised by BSA. However at the top of the column the recovery of Triton X−100 in the foamate (75% to 100%) was always greater than the recovery of BSA (13% to 76%) for all foam fractionation experiments. In addition, for high feed concentrations of both components and at low air flow rates, the enrichment of BSA remained at almost unity for most experiments and only increased when the recovery of Triton X−100 reached 100%. Thus it was concluded that Triton X-100 displaced the adsorbed BSA from the surface. The foam drainage properties of Triton X−100/BSA mixtures were characterised using two methods; forced foam drainage and from pressure profiles of steady state foam fractionation experiments (pressure method). The drainage data from the forced foam drainage was found not to be compatible with experimental foam fractionation results, by indicating that stable foam was not produced during the foam fractionation experiments. However stable foam was repeatedly produced during foam fractionation experiments. The drainage data from the pressure method was found to be in close agreement to experimental foam fractionation experiments. The work in this thesis takes a significant step beyond the literature experimental foam fractionation studies for multicomponent systems. In addition to investigating the effect of foam fractionation process parameters on the separation of mixed systems, the results from the characterisation studies of surface adsorption and foam properties provided insight and deeper understanding of the competitive adsorption behaviour of surfactants and proteins in a foam fractionation process.
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Wang, Yingjie. "Modelling and prediction of foam structure." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/4664.
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The primary objective of this thesis is to explore the relationship between the surface and underlying structure of dry foams. This relationship is important for both research and industry because the surface film size distribution is typically the only information available in opaque foams when referring to the underlying bubble size distribution. This study is carried out by simulating foams with free surfaces. Firstly, the method of simulating 3D dry foams with free surfaces is presented. The simulation method is verified for foams with uniform bubble sizes by comparing their simulation results to experimental values reported in literature. The validity of the method and its ability to accurately model the structure of both surface and internal bubbles is demonstrated by the excellent agreement between the experimental study and the simulation results. Secondly, the simulation results are shown for the relationship between the surface film size distribution and the surface bubble size distribution. The results show that, for a given surface bubble size, there is a distribution of possible surface film sizes. However, for the range of polydispersity used in this thesis, the distribution of the ratio of film size to the size of bubble to which it is attached is found to be independent of the underlying bubble size distribution. A functional form of this relationship is obtained by nonlinear regression. Based on the functions obtained, the surface film size distributions can be computed using the underlying surface bubble size distribution. This is the inverse of what is acquired and therefore a numerical procedure for obtaining the surface bubble size distributions using the corresponding surface film size distribution is developed. This method is demonstrated to accurately reproduce the results from the full structural foam simulations.
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Pope, Ellen Grace. "Sepiolite/polyurethane open cell foam composites." Thesis, University of Bristol, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.738272.
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Vitasari, Denny. "Adsorption and transport of surfactant/protein onto a foam lamella within a foam fractionation column with reflux." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/adsorption-and-transport-of-surfactantprotein-onto-a-foam-lamella-within-a-foam-fractionation-column-with-reflux(8258925c-455b-4df4-8aa7-d8cff0e3b4e0).html.
Full textAbstract:
Foam fractionation is an economical and environmentally friendly separation method for surface active material using a rising column of foam. The system of foam fractionation column with reflux is selected since such a system can improve the enrichment of the product collected from the top of the column. Due to the reflux, it is assumed that there is more surface active material (surfactant and/or protein) in the Plateau border than that in the foam lamella, so that the Plateau border acts as a surfactant/protein reservoir. The aim of this thesis is to investigate the adsorption and transport of surface active material such as surfactant and/or protein onto the surface of a lamella in a foam fractionation column with reflux using mathematical simulation. There are two steps involved in adsorption of surface active material onto a bubble surface within foam, which are diffusion from the bulk solution into the subsurface, a layer next to the interface, followed by adsorption of that material from the subsurface onto the interface. The diffusion follows the Fick's second law, while the adsorption may follow the Henry, Langmuir or Frumkin isotherms, depending on the properties of the surface active material. The adsorption of mixed protein-surfactant follows the Frumkin isotherm. When there is a competition between protein and surfactant, the protein arrives onto the interface at a later time due to a slower diffusion rate and it displaces the surfactant molecules already on the surface since protein has a higher affinity for that surface than surfactant. The surfactant transport from a Plateau border onto a foam lamella is determined by the interaction of forces applied on the lamella surface, such as film drainage, due to the pressure gradient between the lamella and the Plateau border, the Marangoni effect, due to the gradient of surface tension, and surface viscosity, as a reaction to surface motion. In this thesis, there are two different models of film drainage. One approach uses assumption of a film with a mobile interface and the other model assumes a film with a rigid interface. In the absence of surface viscosity, the Marangoni effect dominates the film drainage resulting in accumulation of surfactant on the surface of the foam lamella in the case of a lamella with a rigid interface. In the case of a film with a mobile interface, the film drainage dominates the Marangoni effect and surfactant is washed away from the surface of the lamella. When the drainage is very fast, such as that which is achieved by a film with a mobile interface, the film could be predicted to attain the thickness of a common black film, well within the residence time in a foam fractionation column, at which point the film stops draining and surfactant starts to accumulate on the lamella surface. The desirable condition in operation of a foam fractionation column however is when the Marangoni effect dominates the film drainage and surfactant accumulates on the surface of a foam lamella such as the one achieved by a film with a rigid interface. In the presence of surface viscosity and the absence of film drainage, the surface viscous forces oppose the Marangoni effect and reduce the amount of surfactant transport onto the foam lamella. A larger surface viscosity results in less surfactant transport onto the foam lamella. In addition, the characteristic time scale required for surfactant transport is shorter with a shorter film length.
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Dahlström, Karolina. "How fining agents affect the tendency of pear base wine to form and stabilize foam." Thesis, Linnaeus University, School of Natural Sciences, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-7520.
Full textAbstract:
The company Kiviks Musteri AB produces a pear base wine that forms stable foam, which is problematic from a production perspective. The aim of this thesis was to investigate the factors underlying foam stability in the pear base wine and to find means for its reduction. This was done by foam testing wines and varying several variables, such as the fining agents normally used in the wine production (bentonite, gelatin, siliceous earth and activated carbon), enzyme treatment, and by changing the fermenting yeast species.
Results: The wine started to form stable foam during fermentation, and foam stability could be reduced by using more bentonite and carbon during the fining process. The other fining agents appeared to have only limited impact on foaming characteristics. No pectin was present according to the pectin test, but protein bands were evident from SDS PAGE analysis, though absent in samples treated with increased doses of bentonite.
In conclusion, pectin is not a major foaming agent in the wine, the yeast is most likely the producer of the foaming agents, carbon and bentonite have a reducing effect on foam stability, bentonite also reduces protein content. Proteins are likely to be involved in the foam stabilization but are not the sole contributors to stable foam.
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Suggs, James Alfred. "Generation of microbubble foam using a packed column." Thesis, This resource online, 1987. http://scholar.lib.vt.edu/theses/available/etd-04272010-020313/.
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Bo, Chong. "Nanohybrids Based on Solid and Foam Polyurethanes." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc799520/.
Full textAbstract:
Polymer nanocomposites are a going part of Materials Science and Engineering. These new composite materials exhibit dimensional and thermal stability of inorganic materials and toughness and dielectric properties of polymers. Development of nanocomposites become an important approach to create high-performance composite materials. In this study silica, fly ash, silica nanotubes and carbon black particles have been added to modify polyurethane foam and thermoplastic polyurethanes. It has been found that the addition of silica can diminish the size of foam bubbles, resulting in an increased stiffness of the material, increase of the compressive strength, and greater resistance to deformation. However, the uniformity of bubbles is reduced, resulting in increased friction of the material. Fly ash added to the foam can make bubbles smaller and improve uniformity of cells. Therefore, the material stiffness and compressive strength, resistance to deformation, and has little impact on the dynamic friction of the material. Adding nanotubes make bubble size unequal, and the arrangement of the bubble uneven, resulting in decreased strength of the material, while the friction increases. After the addition of carbon black to the polyurethane foam, due to the special surface structure of the carbon black, the foam generates more bubbles during the foaming process changing the foam structure. Therefore, the material becomes soft, we obtain a flexible polyurethane foam. The results of mechanical properties determination of the thermoplastic polyurethane that adding particles may increase the stiffness and wear resistance of the thermoplastic polyurethane, while the tensile properties of the material are reduced. This phenomenon may be due to agglomeration of particles during the mixing process. Possibly the particles cannot be uniformly dispersed in the thermoplastic polyurethane.
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Testouri, Aouatef. "Highly structured polymer foams from liquid foam templates using millifluidic lab-on-a-chip techniques." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00771862.
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Polymer foams belong to the solid foams family which are versatile materials, extensively used for a large number of applications such as automotive, packaging, sport products, thermal and acoustic insulators, tissue engineering or liquid absorbents. Composed of air bubbles entrapped in a continuous solid network, they combine the properties of the polymer with those of the foam to create an intriguing and complex material. Incorporating a foam into a polymer network not only allows one to use the wide range of interesting properties that the polymer offers, but also permits to profit from the advantageous properties of foam including lightness, low density, compressibility and high surface-to-volume ratio. Generally, the properties of polymer foams are strongly related to their density and their structure (bubble size and size distribution, bubble arrangement, open vs closed cells). Having a good control over foam properties is thus achieved by first controlling its density and structure.We developed a technique in which solid foams are generated essentially in a two-step process: a sufficiently stable liquid foam with well-controlled structural properties is generated in a first step, and then solidified in a second one. With such a two-step approach, the generation of solid foams can be divided into a number of well-separated sub-tasks which can be controlled and optimised separately. The transition from liquid to solid state is a sensitive issue of a great importance and therefore needs to be controlled with sufficient accuracy. It is essentially composed of three key steps: foam generation, mixing of reactants and foam solidification and requires the optimisation of foam stability in conjunction with an appropriate choice of both foaming time and solidification time. Furthermore, a good homogeneity of the polymer foam calls for a good mixing of the different reactants involved in the foaming and the polymerisation.A particularly powerful demonstration of the advantages of this approach is given by solidifying monodisperse liquid foams generated using millifluidic technique, in which all bubbles have the same size. In a liquid foam, equal-volume bubbles self-order into periodic, close-packed structures under gravity or confinement. As such, monodisperse foams provide simultaneous control over the size and the organisation of the pores in the final solid with an accuracy which is expected to give rise to a better understanding of the structure-property relationship of porous solids and to the development of new porous materials.We therefore aim to explore the new spectrum of properties, which polymer foams offer when we introduce an ordered structure into them since the most widely used polymer foams nowadays have disordered structures. The goal of our study is to demonstrate the feasibility of this two-step approach for different classes of polymers, including biomolecular hydrogel, superabsorbent polymer and polyurethane.For the generation of the structured polymer foams we use Lab-on-a-Chip technologies which allow the "shrinking" of large-scale set-ups to micro/millimetic scale. It permits also to perform "flow chemistry" in which the various liquid and gaseous ingredients of the foam are injected and mixed in a purpose-designed network of the micro- and millifluidic Lab-on-a-Chip. We adjust this approach according to the requirements of each polymer system, i.e. the foaming and the mixing techniques are chosen to fit the properties of each system, and can be exchanged to fit the properties of the studied systems.