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Foaming Volume and Foam Stability

Description: "A method of measuring foaming volume is described and investigated to establish the critical factors in its operation. Data on foaming volumes and foam stabilities are given for a series of hydrocarbons and for a range of concentrations of aqueous ethylene-glycol solutions. It is shown that the amount of foam formed depends on the machinery of its production as well as on properties of the liquid, whereas the stability of the foam produced, within specified mechanical limitations, is primarily a function of the liquid" (p. 1).
Date: February 1947
Creator: Ross, Sydney
Partner: UNT Libraries Government Documents Department

A General Method of Selecting Foam Inhibitors

Description: Note presenting a criterion for selecting foam inhibitors from insoluble liquids that form emulsions with the foaming liquid. By determining the surface tensions of the foaming liquid and of the additive saturated with that liquid and the interfacial tension between them, spreading and entering coefficients may be calculated. A mechanism of foam inhibition is also described.
Date: May 1946
Creator: Robinson, J. V. & Woods, W. W.
Partner: UNT Libraries Government Documents Department

Nanohybrids Based on Solid and Foam Polyurethanes

Description: 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.
Date: May 2015
Creator: Bo, Chong
Partner: UNT Libraries

A Very Approximate Theory for Gas Transport in a Polymer Foam

Description: The author is involved with a project that requires calculation of the flow of gas through thin sheets of a flexible polymer foam. Essentially, the foam is a collection of interconnected spherical holes in the polymer matrix. When the material is made, its porosity is in the range of 60-70%. Initially, the sheets are roughly a millimeter thick. In the application, the sheets are compressed between solid surfaces so that their thickness is reduced to approximately 50-75% of the original (thereby reducing the porosity to as low as 20%). The project requires calculating gas transport in the longitudinal direction (in other words, parallel to the thin section of the sheets and perpendicular to the direction of compression). The transport calculations must be done in three different flow regimes. First, with gas pressures high enough so that the gas in the pores is in the continuum regime and thus the transport is governed by the usual equations for flow of a compressible gas in a porous medium. Second, with gas pressures low enough so that the flow is in the free molecular region. In the third regime, the foam is filled with a carrier gas (with pressure high enough to be in continuum) and the flow of interest is that of a small amount of an additional gas. In this third regime, the driving force is diffusion of the trace gas in the carrier.
Date: December 1, 1999
Creator: Kirkpatrick, J.R.
Partner: UNT Libraries Government Documents Department

Processing and Characterization of Polycarbonate Foams with Supercritical Co2 and 5-Phenyl-1H-tetrazole

Description: Since their discovery in the 1930s, polymeric foams have been widely used in the industry for a variety of applications such as acoustical and thermal insulation, filters, absorbents etc. The reason for this ascending trend can be attributed to factors such as cost, ease of processing and a high strength to weight ratio compared to non-foamed polymers. The purpose of this project was to develop an “indestructible” material made of polycarbonate (PC) for industrial applications. Due to the high price of polycarbonate, two foaming methods were investigated to reduce the amount of material used. Samples were foamed physically in supercritical CO2 or chemically with 5-phenyl-1H-tetrazole. After thermal characterization of the foams in differential scanning calorimetry (DSC), we saw that none of the foaming methods had an influence on the glass transition of polycarbonate. Micrographs taken in scanning electron microscopy (SEM) showed that foams obtained in physical and chemical foaming had different structures. Indeed, samples foamed in supercritical CO2 exhibited a microcellular opened-cell structure with a high cell density and a homogeneous cell distribution. On the other hand, samples foamed with 5-phenyl-1H-tetrazole had a macrocellular closed-cell structure with a much smaller cell density and a random cell distribution. Compression testing showed that polycarbonate foamed physically had a compression modulus a lot greater. Then, XLPE mesh 35 or 50 and wollastonite were added to the polymeric matrices to enhance the foaming process and the mechanical properties. DSC experiments showed that the addition of fillers changed the thermal properties of polycarbonate for both foaming methods by inducing a shift in glass transition. SEM revealed that fillers lowered the average cell diameter and increased the cell density. This phenomenon increased the compression modulus for polycarbonate foamed in supercritical CO2. However, mechanical properties decreased for samples foamed with 5-phenyl-1H-tetrazole due to their relative brittleness and ...
Date: May 2015
Creator: Cloarec, Thomas
Partner: UNT Libraries

Foam process models.

Description: In this report, we summarize our work on developing a production level foam processing computational model suitable for predicting the self-expansion of foam in complex geometries. The model is based on a finite element representation of the equations of motion, with the movement of the free surface represented using the level set method, and has been implemented in SIERRA/ARIA. An empirically based time- and temperature-dependent density model is used to encapsulate the complex physics of foam nucleation and growth in a numerically tractable model. The change in density with time is at the heart of the foam self-expansion as it creates the motion of the foam. This continuum-level model uses an homogenized description of foam, which does not include the gas explicitly. Results from the model are compared to temperature-instrumented flow visualization experiments giving the location of the foam front as a function of time for our EFAR model system.
Date: September 1, 2008
Creator: Moffat, Harry K.; Noble, David R.; Baer, Thomas A. (Procter & Gamble Co., West Chester, OH); Adolf, Douglas Brian; Rao, Rekha Ranjana & Mondy, Lisa Ann
Partner: UNT Libraries Government Documents Department


Description: Heating and cooling the house is one of the homeowners major expenses. Reducing these costs, saving energy, and creating a healthier, more comfortable indoor environment are good reasons to consider improving the building thermal envelope. Improvements usually consider increasing the amount of insulation, reducing the infiltration of outside air, and controlling moisture in existing buildings. This report describes the use of spray foam materials to insulate, seal, and control moisture. This discussion is limited to treating areas that are accessible. What is accessible, however, can vary depending on the type of renovation. If the building has been gutted or exterior surfaces removed, there are more options. This report will look at areas to consider for spray foam application and discuss the types of spray foams available and their uses. A number of case studies are presented to show the effectiveness of this retrofit in existing houses based on performance data.
Date: December 1, 2013
Creator: Christian, Jeffrey E & Gant, Kathy
Partner: UNT Libraries Government Documents Department

Inflatable Devices for Use in Combating Mine Fires

Description: Abstract: The U.S. Bureau of Mines is conducting full-scale laboratory studies on the development of lightweight inflatable devices that can be used for rapidly isolating mine fire areas to allow for fire suppression and/or personnel escape. These inflatable devices were able to stop airflows of over 1,100 m3/min within several minutes. The remotely installed bag was designed to rapidly isolate the fire zone and to then serve, if necessary, as a containment form for the remote injection of low-dersil organic or inorganic foams. Other inflatable bag concepts that were tested include an inflatable feed-tube seal for high-expansion foam generators and a positive pressure inflatable walk-through escape device. Laboratory studies indicated that a high-expansion foam plug will travel 183 m through an entry with a 4.5 pct rise in elevation before foam leakage from around the inflatable feed-tube seal. Additionally, the positive-pressure, inflatable walk-through escape device with its "pass-through" feature may allow extra time for personnel evacuation. All of these inflatable devices have shown merit during laboratory studies in providing a rapid method for isolation of a mine fire prior to suppressant foam injection or personnel escape.
Date: 1996
Creator: Weiss, E. S.; Conti, R. S.; Bazala, E. M. & Pro, R. W.
Partner: UNT Libraries Government Documents Department

Investigation of a Novel Vapor Chamber for Efficient Heat Spreading and Removal for Power Electronics in Electric Vehicles

Description: This work investigated a novel vapor chamber for efficient heat spreading and heat removal. A vapor chamber acting as a heat spreader enables for more uniform temperature distribution along the surface of the device being cooled. First, a vapor chamber was studied and compared with the traditional copper heat spreader. The thickness of vapor chamber was kept 1.35 mm which was considered to be ultra-thin vapor chamber. Then, a new geometrical model having graphite foam in vapor space was proposed where the graphite foam material was incorporated in vapor space as square cubes. The effects of incorporating graphite foam in vapor space were compared to the vapor chamber without the embedded graphite foam to investigate the heat transfer performance improvements of vapor chamber by the high thermal conductivity graphite foam. Finally, the effects of various vapor chamber thicknesses were studied through numerical simulations. It was found that thinner vapor chamber (1.35 mm thickness) had better heat transfer performance than thicker vapor chamber (5 mm thickness) because of the extreme high effective thermal conductivities of ultra-thin vapor chamber. Furthermore, the effect of graphite foam on thermal performance improvement was very minor for ultra-thin vapor chamber, but significant for thick vapor chamber. The GF could help reduce the junction temperature by 15-30% in the 5-mm thick vapor chamber. Use of GF embedded vapor chamber could achieve 250-400 Watt per Centimeter square local heat removal for power electronics. The application of this is not only limited to electronic devices but actuator and avionics cooling in aircrafts, thermal management of electronics in directed energy weapon systems, battery thermal management for electric and hybrid vehicles, smart phones cooling, thus covering a wide gamut of heat flux applications.
Date: May 2017
Creator: Patel, Anand Kishorbhai
Partner: UNT Libraries

Thermal, Electrical, and Structural Analysis of Graphite Foam

Description: A graphite foam was developed at Oak Ridge National Laboratory (ORNL) by Dr. James Klett and license was granted to POCO Graphite, Inc. to manufacture and market the product as PocoFoam™. Unlike many processes currently used to manufacture carbon foams, this process yields a highly graphitic structure and overcomes many limitations, such as oxidation stabilization, that are routinely encountered in the development of carbon foam materials. The structure, thermal properties, electrical resistivity, isotropy, and density uniformity of PocoFoam™ were evaluated. These properties and characteristics of PocoFoam™ are compared with natural and synthetic graphite in order to show that, albeit similar, it is unique. Thermal diffusivity and thermal conductivity were derived from Fourier's energy equation. It was determined that PocoFoam™ has the equivalent thermal conductivity of metals routinely used as heat sinks and that thermal diffusivity is as much as four times greater than pure copper and pure aluminum. SEM and XRD results indicate that PocoFoam™ has a high degree of crystalline alignment and near theoretical d spacing that is more typical of natural flake graphite than synthetic graphite. PocoFoam™ is anisotropic, indicating an isotropy factor of 0.5, and may yield higher thermal conductivity at cryogenic temperatures than is observed in polycrystalline graphite.
Access: This item is restricted to UNT Community Members. Login required if off-campus.
Date: August 2001
Creator: Morgan, Dwayne Russell
Partner: UNT Libraries

Mechanical Properties of a Metal Powder-Loaded Polyurethane Foam

Description: Quasi-static compression tests have been performed on polyurethane foam specimens. The modulus of the foam exhibited a power-law dependence with respect to density of the form: E* {proportional_to} {rho}*{sup n}, where n = 1.7. The modulus data is well described by a simple geometric model (attributed to the work of Gibson and Ashby) for closed-cell foam in which the stiffness of the foam is governed by the flexure of the cell struts and cell walls. The compressive strength of the foam is also found to follow a power-law behavior with respect to foam density. In this instance, Euler buckling is used to rationalize the density dependence. The modulus of the polyurethane foam was modified by addition of a gas atomized, spherical aluminum powder. Additions of 30 and 50 weight percent of the powder significantly increased the foam modulus. However, there were only slight increases in modulus with 5 and 10 weight percent additions of the metal powder. Strength was also slightly increased at high loading fractions of powder. This increase in modulus and strength could be predicted by combining the above geometric model with a well-known model describing the effect on modulus of a rigid dispersoid in a compliant matrix.
Date: April 1, 1999
Creator: Neuschwanger, C. L.; Whinnery, L. L. & Goods, S. H.
Partner: UNT Libraries Government Documents Department

Project Overcoat - An Exploration of Exterior Insulation Strategies for 1-1/2-Story Roof Applications in Cold Climates

Description: The development of an alternative method to interior-applied insulation strategies or exterior applied 'band-aids' such as heat tapes and ice belts may help reduce energy needs of millions of 1-1/2 story homes while reducing the risk of ice dam formation. A potential strategy for energy improvement of the roof is borrowed from new construction best practices: Here an 'overcoat' of a continuous air, moisture, and thermal barrier is applied on the outside of the roof structure for improved overall performance. The continuous insulation of this approach facilitates a reduction in thermal bridging which could further reduce energy consumption and bring existing homes closer to meeting the Building America goals for energy reduction. Research favors an exterior approach to deep energy retrofits and ice dam prevention in existing homes. The greatest amount of research focuses on whole house deep energy retrofits leaving a void in roof-only applications. The research is also void of data supporting the hygrothermal performance, durability, constructability, and cost of roof-only exterior overcoat strategies. Yet, contractors interviewed for this report indicate an understanding that exterior approaches are most promising for mitigating ice dams and energy loss and are able to sell these strategies to homeowners.
Date: April 1, 2013
Creator: Ojczyk, C.; Mosiman, G.; Huelman, P.; Schirber, T.; Yost, P. & Murry, T.
Partner: UNT Libraries Government Documents Department

Foam Transport in Porous Media - A Review

Description: Amendment solutions with or without surfactants have been used to remove contaminants from soil. However, it has drawbacks such that the amendment solution often mobilizes the plume, and its movement is controlled by gravity and preferential flow paths. Foam is an emulsion-like, two-phase system in which gas cells are dispersed in a liquid and separated by thin liquid films called lamellae. Potential advantages of using foams in sub-surface remediation include providing better control on the volume of fluids injected, uniformity of contact, and the ability to contain the migration of contaminant laden liquids. It is expected that foam can serve as a carrier of amendments for vadose zone remediation, e.g., at the Hanford Site. As part of the U.S. Department of Energy’s EM-20 program, a numerical simulation capability will be added to the Subsurface Transport Over Multiple Phases (STOMP) flow simulator. The primary purpose of this document is to review the modeling approaches of foam transport in porous media. However, as an aid to understanding the simulation approaches, some experiments under unsaturated conditions and the processes of foam transport are also reviewed. Foam may be formed when the surfactant concentration is above the critical micelle concentration. There are two main types of foams – the ball foam (microfoam) and the polyhedral foam. The characteristics of bulk foam are described by the properties such as foam quality, texture, stability, density, surface tension, disjoining pressure, etc. Foam has been used to flush contaminants such as metals, organics, and nonaqueous phase liquids from unsaturated soil. Ball foam, or colloidal gas aphrons, reportedly have been used for soil flushing in contaminated site remediation and was found to be more efficient than surfactant solutions on the basis of weight of contaminant removed per gram of surfactant. Experiments also indicate that the polyhedral foam can be ...
Date: November 11, 2009
Creator: Zhang, Z. F.; Freedman, Vicky L. & Zhong, Lirong
Partner: UNT Libraries Government Documents Department

CPUF - a chemical-structure-based polyurethane foam decomposition and foam response model.

Description: A Chemical-structure-based PolyUrethane Foam (CPUF) decomposition model has been developed to predict the fire-induced response of rigid, closed-cell polyurethane foam-filled systems. The model, developed for the B-61 and W-80 fireset foam, is based on a cascade of bondbreaking reactions that produce CO2. Percolation theory is used to dynamically quantify polymer fragment populations of the thermally degrading foam. The partition between condensed-phase polymer fragments and gas-phase polymer fragments (i.e. vapor-liquid split) was determined using a vapor-liquid equilibrium model. The CPUF decomposition model was implemented into the finite element (FE) heat conduction codes COYOTE and CALORE, which support chemical kinetics and enclosure radiation. Elements were removed from the computational domain when the calculated solid mass fractions within the individual finite element decrease below a set criterion. Element removal, referred to as ?element death,? creates a radiation enclosure (assumed to be non-participating) as well as a decomposition front, which separates the condensed-phase encapsulant from the gas-filled enclosure. All of the chemistry parameters as well as thermophysical properties for the CPUF model were obtained from small-scale laboratory experiments. The CPUF model was evaluated by comparing predictions to measurements. The validation experiments included several thermogravimetric experiments at pressures ranging from ambient pressure to 30 bars. Larger, component-scale experiments were also used to validate the foam response model. The effects of heat flux, bulk density, orientation, embedded components, confinement and pressure were measured and compared to model predictions. Uncertainties in the model results were evaluated using a mean value approach. The measured mass loss in the TGA experiments and the measured location of the decomposition front were within the 95% prediction limit determined using the CPUF model for all of the experiments where the decomposition gases were vented sufficiently. The CPUF model results were not as good for the partially confined radiant heat experiments where the ...
Date: July 1, 2003
Creator: Fletcher, Thomas H. (Brigham Young University, Provo, UT); Thompson, Kyle Richard; Erickson, Kenneth L.; Dowding, Kevin J.; Clayton, Daniel (Brigham Young University, Provo, UT); Chu, Tze Yao et al.
Partner: UNT Libraries Government Documents Department

Compatibility of Fluorinert, FC-72, with selected materials.

Description: Removable encapsulants have been developed as replacement materials for electronic encapsulation. They can be removed from an electronic assembly in a fairly benign manner. Encapsulants must satisfy a limited number of criteria to be useful. These include processing ease, certain mechanical, thermal, and electrical properties, adhesion to common clean surfaces, good aging characteristics, and compatibility. This report discusses one aspect of the compatibility of removable blown epoxy foams with electronic components. Of interest is the compatibility of the blowing agent, Fluorinert{trademark} (FC-72) electronic fluid with electronic parts, components, and select materials. Excellent compatibility is found with most of the investigated materials. A few materials, such as Teflon{reg_sign} that are comprised of chemicals very similar to FC-72 show substantial absorption of FC-72. No compatibility issues have yet been identified even for the few materials that show substantial absorption.
Date: February 1, 2006
Creator: Aubert, James Henry & Sawyer, Patricia Sue
Partner: UNT Libraries Government Documents Department

Unconventional Nuclear Warfare Defense (UNWD) containment and mitigation subtask.

Description: The objective of this subtask of the Unconventional Nuclear Warfare Design project was to demonstrate mitigation technologies for radiological material dispersal and to assist planners with incorporation of the technologies into a concept of operations. The High Consequence Assessment and Technology department at Sandia National Laboratories (SNL) has studied aqueous foam's ability to mitigate the effects of an explosively disseminated radiological dispersal device (RDD). These benefits include particle capture of respirable radiological particles, attenuation of blast overpressure, and reduction of plume buoyancy. To better convey the aqueous foam attributes, SNL conducted a study using the Explosive Release Atmospheric Dispersion model, comparing the effects of a mitigated and unmitigated explosive RDD release. Results from this study compared health effects and land contamination between the two scenarios in terms of distances of effect, population exposure, and remediation costs. Incorporating aqueous foam technology, SNL created a conceptual design for a stationary containment area to be located at a facility entrance with equipment that could minimize the effects from the detonation of a vehicle transported RDD. The containment design was evaluated against several criteria, including mitigation ability (both respirable and large fragment particle capture as well as blast overpressure suppression), speed of implementation, cost, simplicity, and required space. A mock-up of the conceptual idea was constructed at SNL's 9920 explosive test site to demonstrate the containment design.
Date: June 1, 2005
Creator: Wente, William Baker
Partner: UNT Libraries Government Documents Department

Advanced Lost Foam Casting Technology

Description: This report describes the research done under the six tasks to improve the process and make it more functional in an industrial environment. Task 1: Pattern Pyrolysis Products and Pattern Properties Task 2: Coating Quality Control Task 3: Fill and Solidification Code Task 4: Alternate Pattern Materials Task 5: Casting Distortion Task 6: Technology Transfer
Date: November 30, 2000
Creator: Bates, Charles E.; Littleton, Harry E.; Askeland, Don; Molibog, Taras; Hopper, Jason & Vatankhah, Ben
Partner: UNT Libraries Government Documents Department

Advanced geothermal foam drilling systems (AFS) -- Phase 1 final report, Part 1

Description: An advanced coiled-tubing foam drilling system is being developed where two concentric strings of coiled tubing are used to convey water and air to the hole bottom where they are mixed together to produce foam for underbalanced drilling. This system has the potential to significantly reduce drilling costs by increasing drilling rates (due to the motor being powered by water), and reducing compressor and nitrogen costs (due to lower gas pressures and volumes).
Date: June 30, 1999
Creator: Maurer, W. C.
Partner: UNT Libraries Government Documents Department

Blast mitigation capabilities of aqueous foam.

Description: A series of tests involving detonation of high explosive blanketed by aqueous foam (conducted from 1982 to 1984) are described in primarily terms of recorded peak pressure, positive phase specific impulse, and time of arrival. The investigation showed that optimal blast mitigation occurs for foams with an expansion ratio of about 60:1. Simple analyses representing the foam as a shocked single phase mixture are presented and shown inadequate. The experimental data demonstrate that foam slows down and broadens the propagated pressure disturbance relative to a shock in air. Shaped charges and flyer plates were evaluated for operation in foam and appreciable degradation was observed for the flyer plates due to drag created by the foam.
Date: February 1, 2006
Creator: Hartman, William Franklin; Larsen, Marvin Elwood & Boughton, Bruce A.
Partner: UNT Libraries Government Documents Department