Effect of Organic Co-blowing Agents on the Morphology of CO2 Blown Microcellular Polystyrene Foams.

Czech Academy of Sciences Publication Activity Database

Nistor, A.; Topiař, Martin; Sovová, Helena; Kosek, J.

2017-01-01

Roč. 130, DEC 2017 (2017), s. 30-39 ISSN 0896-8446 R&D Projects: GA ČR(CZ) GA14-18938S Institutional support: RVO:67985858 Keywords : polystyrene * closed-cell microcellular foam * co-blowing agent Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 2.991, year: 2016

New ways to produce porous polymeric membranes by carbon dioxide foaming

NARCIS (Netherlands)

Krause, B.; van der Vegt, N.F.A.; Wessling, Matthias

2002-01-01

As a new solvent free method for membrane formation, we have investigated the foaming of high-Tg polymers. We report two different routes for the formation of open-microcellular and open-nanoporous membrane morphologies. Porosity is introduced by expansion of carbon dioxide saturated films and

The effect of pore size and porosity on thermal management performance of phase change material infiltrated microcellular metal foams

International Nuclear Information System (INIS)

Sundarram, Sriharsha S.; Li, Wei

2014-01-01

The effect of pore size and porosity on the performance of phase change material (PCM) infiltrated metal foams, especially when the pore size reduces to less than 100 μm, is investigated in this study. A three dimensional finite element model was developed to consider both the metal and PCM domains, with heat exchange between them. The pore size and porosity effects were studied along with other system variables including heat generation and dissipation of the PCM-based thermal management system. It is shown that both porosity and pore size have strong effects on the heating of PCM. At a fixed porosity, a smaller pore size results in a lower temperature at the heat source for a longer period of time. The effects of pore size and porosity were more pronounced at high heat generation and low convective cooling conditions, representing the situation of portable electronics. There is an optimal porosity for the PCM-metal foam system; however, the optimal value only occurs at high cooling conditions. The net effective thermal conductivity of a PCM-microcellular metal foam system could be doubled by reducing the pore size from 100 μm to 25 μm. - Highlights: •Pore size and porosity of phase change material-microcellular metal foam were investigated. •A smaller pore size results in a lower temperature at the heat source for a longer period of time. •The effects were more pronounced at high heating and low cooling conditions. •Net thermal conductivity doubled by reducing the pore size from 100 μm to 25 μm

Study of microcellular injection-molded polypropylene/waste ground rubber tire powder blend

International Nuclear Information System (INIS)

Xin, Zhen Xiang; Zhang, Zhen Xiu; Pal, Kaushik; Byeon, Jong Ung; Lee, Sung Hyo; Kim, Jin Kuk

2010-01-01

Microcellular polypropylene/waste ground rubber tire powder blend processing was performed on an injection-molding machine with a chemical foaming agent. The molded samples produced based on the design of experiments (DOE) matrices were subjected to tensile testing and scanning electron microscope (SEM) analyses. Molding conditions and waste ground rubber tire (WGRT) powder have been found to have profound effects on the cell structures and mechanical properties of polypropylene (PP) and waste ground rubber tire powder composite samples. The result shows that microcellular PP/WGRT blend samples exhibit smaller cell size and higher cell density compare with polypropylene resin. Among the molding parameters studied, chemical foaming agent weight percentage has the most significant effect on cell size, cell density, and tensile strength. The results also suggest that tensile strength of microcellular PP/WGRT composites is sensitive to weight reduction, and skin thickness.

Preparation of multishell ICF target plastic-foam cushion materials by thermally induced phase-inversion processes

International Nuclear Information System (INIS)

Young, A.T.; Moreno, D.K.; Marsters, R.G.

1981-01-01

Homogenous, low-density plastic foams for ICF targets have been prepared by thermally induced phase inversion processes. Uniform, open cell foams have been obtained by the rapid freezing of water solutions of modified cellulose polymers with densities in the range of 5 mg/cm 3 to 0.7 mg/cm 3 and respective average cell sizes of 2 to 40 micrometers. In addition, low-density, microcellular foams have been prepared from the hydrocarbon polymer poly(4-methyl-l-pentene) via a similar phase inversion process using homogenous solutions in organic solvents. These foams have densities from 2 to 5 mg/cm 3 and average cell sizes of 20 micrometers. The physical-chemical aspects of the thermally induced phase inversion process is presented

Characterization of low density carbon foams by x-ray computed tomography (CT) and ion microtomography (IMF)

International Nuclear Information System (INIS)

Moddeman, W.E.; Kramer, D.P.; Firsich, D.W.; Trainer, P.D.; Yancy, R.N.; Weirup, D.L.; Logan, C.M.; Pontau, A.E.; Antolak, A.J.; Morse, D.H.

1990-01-01

Two NDT techniques were used to characterize low-density, microcellular, carbon foams fabricated from a salt replica process. In this paper the two techniques are x-ray computed tomography (CT) and ion microtomography (IMT); data are presented on carbon foams that contain high-density regions. The data show that densities which differ by 3 ) materials. The data reveal that the carbon foams produced by this replica process have small density variations; the density being ∼30% greater at the outer edges than when compared to the interior of the foam. In addition, the density gradient is found to be rather sharp, that is the density drops-off rapidly from the outer edges to a uniform one in the interior of the foam. This edge build-up in carbon density was explained in terms of polymer concentrating on the foam exterior during drying which immediately followed a polymer infusion processing step. Supporting analytical data from other techniques show the foam material to be >88.8% carbon

Polymer foam comprising a polymer and nanoparticles, and nanoparticles for the manufacture of such foam.

NARCIS (Netherlands)

Vancso, Gyula J.; Duvigneau, Joost; Nederkoorn, P.H.J.; Wassing, T.

2014-01-01

A polymer foam is produced comprising a polymer and nanoparticles having a maximum dimensionof 750 nm, which foam has cells with an average cell size of at most 1 µm and a cell density of at least 1012 cells/ml, wherein polymeric grafts have been attached to the nanoparticles. The nanoparticles may

Effect of Stabilization on Morphology Polystyrene and Supercritical Carbon Dioxide Thermoplastic Foams

Directory of Open Access Journals (Sweden)

Mozafar Mokhtari Motameni Shirvan

2016-01-01

Full Text Available Microcellular thermoplastic foams can be usually produced in a one-step batch system using a physical foaming agent which is dissolved in a polymer system under specific pressure and temperature, higher than the critical condition of solvent and the glass transition temperature of polymer and solvent mixture. By application of a sudden pressure drop the foam structure is formed through stages of nucleation, growth and coalescence. After pressure drop, if the foam temperature is reduced below the glass transition of the gas-polymer mixture, the cells stop growing which results in a foam with stabilized morphology. This stabilization stage has not been thoroughly focused in previous studies. In this work, polystyrene as a polymer system and supercritical carbon dioxide as a solvent were used at 18.5 MPa pressure and different temperatures. The stabilization process took place within milliseconds and helped to a better understanding of cellular structure in thermoplastic foams. In this mechanism, the nucleation takes place in the phase transition of solvent molecules at supercritical state to the gas state and the formation of very small nuclei containing gas molecules between polymer chains. The energy originated from the nuclei growth is in competition with the elastic energy of polymer chains, and the predominance of one type of energy over another determines the final cell size. The results showed that the effect of stabilization process on the structure of the foam depended on the foaming temperature. Stabilization at 110°C resulted in a 50% cell size reduction and a 60% cell density promotion, while at lower temperatures, the stabilization led to greater cell size and reduced cell density.

Amorphous microcellular polytetrafluoroethylene foam film

Science.gov (United States)

Tang, Chongzheng

1991-11-01

We report herein the preparation of novel low-density ultramicrocellular fluorocarbon foams and their application. These fluorocarbon foams are of interest for the biochemistry arena in numerous applications including foodstuff, pharmacy, wine making, beer brewery, fermentation medical laboratory, and other processing factories. All of those require good quality processing programs in which, after eliminating bacterium and virus, compressed air is needed. Ordinarily, compressed air contains bacterium and virus, its size is 0.01 - 2 micrometers fluorocarbon foam films. Having average porous diameter 0.04 - 0.1 micrometers , these are stable to high temperature (280 degree(s)C) and chemical environments, and generally have good engineering and mechanical properties (e.g., low coefficient of thermal expansion, high modulus, and good dimensional stability). Our new process for preparing low density fluorocarbon foams provides materials with unique properties. As such, they offer the possibility for being superior to earlier materials for a number of the filter applications mentioned.

Microcellular injection molding process for producing lightweight thermoplastic polyurethane with customizable properties

Science.gov (United States)

Ellingham, Thomas; Kharbas, Hrishikesh; Manitiu, Mihai; Scholz, Guenter; Turng, Lih-Sheng

2018-03-01

A three-stage molding process involving microcellular injection molding with core retraction and an "out-of-mold" expansion was developed to manufacture thermoplastic polyurethane into lightweight foams of varying local densities, microstructures, and mechanical properties in the same microcellular injection molded part. Two stages of cavity expansion through sequential core retractions and a third expansion in a separate mold at an elevated temperature were carried out. The densities varied from 0.25 to 0.42 g/cm3 (77% to 62% weight reduction). The mechanical properties varied as well. Cyclic compressive strengths and hysteresis loss ratios, together with the microstructures, were characterized and reported.

Tensile and fracture behavior of polymer foams

International Nuclear Information System (INIS)

Kabir, Md. E.; Saha, M.C.; Jeelani, S.

2006-01-01

Tensile and mode-I fracture behavior of cross-linked polyvinyl chloride (PVC) and rigid polyurethane (PUR) foams are examined. Tension tests are performed using prismatic bar specimens and mode-I fracture tests are performed using single edge notched bend (SENB) specimens under three-point bending. Test specimens are prepared from PVC foams with three densities and two different levels of cross-linking, and PUR foam with one density. Tension and quasi-static fracture tests are performed using a Zwick/Rowell test machine. Dynamic fracture tests are performed using a DYNATUP model 8210 instrumented drop-tower test set up at three different impact energy levels. Various parameters such as specimen size, loading rate, foam density, cross-linking, crack length, cell orientation (flow and rise-direction) and solid polymer material are studied. It is found that foam density and solid polymer material have a significant effect on tensile strength, modulus, and fracture toughness of polymer foams. Level of polymer cross-linking is also found to have a significant effect on fracture toughness. The presence of cracks in the rise- and flow direction as well as loading rate has minimal effect. Dynamic fracture behavior is found to be different as compared to quasi-static fracture behavior. Dynamic fracture toughness (K d ) increases with impact energy. Examination of fracture surfaces reveals that the fracture occurs in fairly brittle manner for all foam materials

Electrically conductive composite material

Science.gov (United States)

Clough, Roger L.; Sylwester, Alan P.

1989-01-01

An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistant pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like.

Sorption and vapor transmission properties of uncompressed and compressed microcellular starch foam.

Science.gov (United States)

Glenn, Gregory M; Klamczynski, Artur P; Takeoka, Gary; Orts, William J; Wood, Delilah; Widmaier, Robert

2002-11-20

Microcellular starch foams (MCFs) are made by a solvent-exchange process and consist of a porous matrix with pores generally ranging from approximately 2 microm to submicrometer size. MCF may potentially be useful as a slow-release agent for volatile compounds because of its ability to sorb chemicals from the atmosphere and to absorb liquids into its porous structure, and because it can be compressed to form a starch plastic. MCF made of high-amylose corn and wheat starches was prepared with or without 2% (w/w) silicone oil (SO) or palmitic acid (PA). The MCF was loaded with 1% of various volatile compounds with vapor pressures ranging from 0.02 to 28 mm. The MCF depressed the vapor pressure from 0.37 to 37% compared to a control containing no MCF. Incorporating SO or PA in the matrix of the MCF had little effect on sorption of volatiles. Compressing MCF at 1.4, 6.9, and 69 MPa made a starch plastic with varying porosity. The vapor transmission rate of various volatile compounds through MCF was positively correlated to the vapor pressure of the test compound but was inversely proportional to the compression force used to form the starch plastic. The results indicate that uncompressed and compressed MCFs could be effective slow-release agents for a variety of volatile compounds, especially if used together.

High strain rate behaviour of polypropylene microfoams

Science.gov (United States)

Gómez-del Río, T.; Garrido, M. A.; Rodríguez, J.; Arencón, D.; Martínez, A. B.

2012-08-01

Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc.) or personal safety (helmets, knee-pads, etc.). In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry) is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s-1) in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB). Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

Electrical conductivity and electromagnetic interference shielding of epoxy nanocomposite foams containing functionalized multi-wall carbon nanotubes

Science.gov (United States)

Li, Jiantong; Zhang, Guangcheng; Zhang, Hongming; Fan, Xun; Zhou, Lisheng; Shang, Zhengyang; Shi, Xuetao

2018-01-01

Epoxy/functionalized multi-wall carbon nanotube (EP/F-MWCNT) microcellular foams were fabricated through a supercritical CO2 (scCO2) foaming method. MWCNTs with carboxylation treatment were disentangled by using alpha-zirconium phosphate (ZrP) assisting dispersion method and functionalized with sulfanilamide. The F-MWCNTs were redispersed in acetone for mixing with epoxy resins to prepare nanocomposites. It was found that the dispersion of MWCNTs could be improved, thus heterogeneous nucleation effect of F-MWCNTs took place effectively during the foaming process, resulting in the formation of microcellular structure with larger cell density and smaller cell size. The volume conductivity and electromagnetic interference shielding performance of foamed EP/F-MWCNT nanocomposites were studied. When the F-MWCNT addition was 5 wt%, the conductivity of the foamed EP/F-MWCNT nanocomposites was 3.02 × 10-4 S/cm and the EMI shielding effectiveness (SE) reached 20.5 dB, significantly higher than the corresponding results of nanocomposite counterparts, indicating that introducing microcellular structure in EP/F-MWCNT nanocomposites would beneficial to improve their electrical conductivity and electromagnetic interference shielding performance.

High strain rate behaviour of polypropylene microfoams

Directory of Open Access Journals (Sweden)

Martínez A.B.

2012-08-01

Full Text Available Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc. or personal safety (helmets, knee-pads, etc.. In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s−1 in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB. Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

Foaming behaviour of polymer-surfactant solutions

International Nuclear Information System (INIS)

Cervantes-MartInez, Alfredo; Maldonado, Amir

2007-01-01

We study the effect of a non-ionic amphiphilic polymer (PEG-100 stearate also called Myrj 59) on the foaming behaviour of aqueous solutions of an anionic surfactant (sodium dodecyl sulfate or SDS). The SDS concentration was kept fixed while the Myrj 59 concentration was varied. Measurements of foamability, surface tension and electrical conductivity were carried out. The results show two opposite effects depending on the polymer concentration: foamability is higher when the Myrj 59 concentration is low; however, it decreases considerably when the polymer concentration is increased. This behaviour is due to the polymer adsorption at the air/liquid interface at lower polymer concentrations, and to the formation of a polymer-surfactant complex in the bulk at higher concentrations. The results are confirmed by surface tension and electrical conductivity measurements, which are interpreted in terms of the microstructure of the polymer-surfactant solutions. The observed behaviour is due to the amphiphilic nature of the studied polymer. The increased hydrophobicity of Myrj 59, compared to that of water-soluble polymers like PEG or PEO, increases its 'reactivity' towards SDS, i.e. the strength of its interaction with this anionic surfactant. Our results show that hydrophobically modified polymers have potential applications as additives in order to control the foaming properties of surfactant solutions

Synthesis of Foam-Shaped Nanoporous Zeolite Material: A Simple Template-Based Method

Science.gov (United States)

Saini, Vipin K.; Pires, Joao

2012-01-01

Nanoporous zeolite foam is an interesting crystalline material with an open-cell microcellular structure, similar to polyurethane foam (PUF). The aluminosilicate structure of this material has a large surface area, extended porosity, and mechanical strength. Owing to these properties, this material is suitable for industrial applications such as…

Crosslinked Poly(2-Hydroxyethyl Methacrylate) by Emulsion Templating: Influence of Crosslinker on Microcellular Structure

Czech Academy of Sciences Publication Activity Database

Paljevac, M.; Jeřábek, Karel; Krajnc, P.

2012-01-01

Roč. 20, č. 4 (2012), s. 1095-1102 ISSN 1566-2543 Institutional support: RVO:67985858 Keywords : high internal phase emulsion * polyHIPE * microcellular porous polymers Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.495, year: 2012

Applications of Polymer Matrix Syntactic Foams

Science.gov (United States)

Gupta, Nikhil; Zeltmann, Steven E.; Shunmugasamy, Vasanth Chakravarthy; Pinisetty, Dinesh

2013-11-01

A collection of applications of polymer matrix syntactic foams is presented in this article. Syntactic foams are lightweight porous composites that found their early applications in marine structures due to their naturally buoyant behavior and low moisture absorption. Their light weight has been beneficial in weight sensitive aerospace structures. Syntactic foams have pushed the performance boundaries for composites and have enabled the development of vehicles for traveling to the deepest parts of the ocean and to other planets. The high volume fraction of porosity in syntactic foams also enabled their applications in thermal insulation of pipelines in oil and gas industry. The possibility of tailoring the mechanical and thermal properties of syntactic foams through a combination of material selection, hollow particle volume fraction, and hollow particle wall thickness has helped in rapidly growing these applications. The low coefficient of thermal expansion and dimensional stability at high temperatures are now leading their use in electronic packaging, composite tooling, and thermoforming plug assists. Methods have been developed to tailor the mechanical and thermal properties of syntactic foams independent of each other over a wide range, which is a significant advantage over other traditional particulate and fibrous composites.

Liquid foam templating - A route to tailor-made polymer foams.

Science.gov (United States)

Andrieux, Sébastien; Quell, Aggeliki; Stubenrauch, Cosima; Drenckhan, Wiebke

2018-06-01

Solid foams with pore sizes between a few micrometres and a few millimetres are heavily exploited in a wide range of established and emerging applications. While the optimisation of foam applications requires a fine control over their structural properties (pore size distribution, pore opening, foam density, …), the great complexity of most foaming processes still defies a sound scientific understanding and therefore explicit control and prediction of these parameters. We therefore need to improve our understanding of existing processes and also develop new fabrication routes which we understand and which we can exploit to tailor-make new porous materials. One of these new routes is liquid templating in general and liquid foam templating in particular, to which this review article is dedicated. While all solid foams are generated from an initially liquid(-like) state, the particular notion of liquid foam templating implies the specific condition that the liquid foam has time to find its "equilibrium structure" before it is solidified. In other words, the characteristic time scales of the liquid foam's stability and its solidification are well separated, allowing to build on the vast know-how on liquid foams established over the last 20 years. The dispersed phase of the liquid foam determines the final pore size and pore size distribution, while the continuous phase contains the precursors of the desired porous scaffold. We review here the three key challenges which need to be addressed by this approach: (1) the control of the structure of the liquid template, (2) the matching of the time scales between the stability of the liquid template and solidification, and (3) the preservation of the structure of the template throughout the process. Focusing on the field of polymer foams, this review gives an overview of recent research on the properties of liquid foam templates and summarises a key set of studies in the emerging field of liquid foam templating. It

Fire-Retardant, Self-Extinguishing Inorganic/Polymer Composite Memory Foams.

Science.gov (United States)

Chatterjee, Soumyajyoti; Shanmuganathan, Kadhiravan; Kumaraswamy, Guruswamy

2017-12-27

Polymeric foams used in furniture and automotive and aircraft seating applications rely on the incorporation of environmentally hazardous fire-retardant additives to meet fire safety norms. This has occasioned significant interest in novel approaches to the elimination of fire-retardant additives. Foams based on polymer nanocomposites or based on fire-retardant coatings show compromised mechanical performance and require additional processing steps. Here, we demonstrate a one-step preparation of a fire-retardant ice-templated inorganic/polymer hybrid that does not incorporate fire-retardant additives. The hybrid foams exhibit excellent mechanical properties. They are elastic to large compressional strain, despite the high inorganic content. They also exhibit tunable mechanical recovery, including viscoelastic "memory". These hybrid foams are prepared using ice-templating that relies on a green solvent, water, as a porogen. Because these foams are predominantly comprised of inorganic components, they exhibit exceptional fire retardance in torch burn tests and are self-extinguishing. After being subjected to a flame, the foam retains its porous structure and does not drip or collapse. In micro-combustion calorimetry, the hybrid foams show a peak heat release rate that is only 25% that of a commercial fire-retardant polyurethanes. Finally, we demonstrate that we can use ice-templating to prepare hybrid foams with different inorganic colloids, including cheap commercial materials. We also demonstrate that ice-templating is amenable to scale up, without loss of mechanical performance or fire-retardant properties.

Shape-memory polymer foam device for treating aneurysms

Energy Technology Data Exchange (ETDEWEB)

Ortega, Jason M.; Benett, William J.; Small, Ward; Wilson, Thomas S.; Maitland, Duncan J; Hartman, Jonathan

2017-05-30

A system for treating an aneurysm in a blood vessel or vein, wherein the aneurysm has a dome, an interior, and a neck. The system includes a shape memory polymer foam in the interior of the aneurysm between the dome and the neck. The shape memory polymer foam has pores that include a first multiplicity of pores having a first pore size and a second multiplicity of pores having a second pore size. The second pore size is larger than said first pore size. The first multiplicity of pores are located in the neck of the aneurysm. The second multiplicity of pores are located in the dome of the aneurysm.

A Novel Method for Preparing Auxetic Foam from Closed-cell Polymer Foam Based on Steam Penetration and Condensation (SPC) Process.

Science.gov (United States)

Fan, Donglei; Li, Minggang; Qiu, Jian; Xing, Haiping; Jiang, Zhiwei; Tang, Tao

2018-05-31

Auxetic materials are a class of materials possessing negative Poisson's ratio. Here we establish a novel method for preparing auxetic foam from closed-cell polymer foam based on steam penetration and condensation (SPC) process. Using polyethylene (PE) closed-cell foam as an example, the resultant foams treated by SPC process present negative Poisson's ratio during stretching and compression testing. The effect of steam-treated temperature and time on the conversion efficiency of negative Poisson's ratio foam is investigated, and the mechanism of SPC method for forming re-entrant structure is discussed. The results indicate that the presence of enough steam within the cells is a critical factor for the negative Poisson's ratio conversion in the SPC process. The pressure difference caused by steam condensation is the driving force for the conversion from conventional closed-cell foam to the negative Poisson's ratio foam. Furthermore, the applicability of SPC process for fabricating auxetic foam is studied by replacing PE foam by polyvinyl chloride (PVC) foam with closed-cell structure or replacing water steam by ethanol steam. The results verify the universality of SPC process for fabricating auxetic foams from conventional foams with closed-cell structure. In addition, we explored potential application of the obtained auxetic foams by SPC process in the fabrication of shape memory polymer materials.

Hybrid waste filler filled bio-polymer foam composites for sound absorbent materials

Science.gov (United States)

Rus, Anika Zafiah M.; Azahari, M. Shafiq M.; Kormin, Shaharuddin; Soon, Leong Bong; Zaliran, M. Taufiq; Ahraz Sadrina M. F., L.

2017-09-01

Sound absorption materials are one of the major requirements in many industries with regards to the sound insulation developed should be efficient to reduce sound. This is also important to contribute in economically ways of producing sound absorbing materials which is cheaper and user friendly. Thus, in this research, the sound absorbent properties of bio-polymer foam filled with hybrid fillers of wood dust and waste tire rubber has been investigated. Waste cooking oil from crisp industries was converted into bio-monomer, filled with different proportion ratio of fillers and fabricated into bio-polymer foam composite. Two fabrication methods is applied which is the Close Mold Method (CMM) and Open Mold Method (OMM). A total of four bio-polymer foam composite samples were produce for each method used. The percentage of hybrid fillers; mixture of wood dust and waste tire rubber of 2.5 %, 5.0%, 7.5% and 10% weight to weight ration with bio-monomer. The sound absorption of the bio-polymer foam composites samples were tested by using the impedance tube test according to the ASTM E-1050 and Scanning Electron Microscope to determine the morphology and porosity of the samples. The sound absorption coefficient (α) at different frequency range revealed that the polymer foam of 10.0 % hybrid fillers shows highest α of 0.963. The highest hybrid filler loading contributing to smallest pore sizes but highest interconnected pores. This also revealed that when highly porous material is exposed to incident sound waves, the air molecules at the surface of the material and within the pores of the material are forced to vibrate and loses some of their original energy. This is concluded that the suitability of bio-polymer foam filled with hybrid fillers to be used in acoustic application of automotive components such as dashboards, door panels, cushion and etc.

Microcellular injection-molding of polylactide with chain-extender

International Nuclear Information System (INIS)

Pilla, Srikanth; Kramschuster, Adam; Yang Liqiang; Lee, Junghoo; Gong Shaoqin; Turng, Lih-Sheng

2009-01-01

The effects of adding an epoxy-based chain-extender (CE) on the properties of injection-molded solid and microcellular polylactide (PLA) were studied. PLA and PLA with 8 wt.% CE (PLA-CE) were melt-compounded using a twin-screw extruder. Solid and microcellular specimens were produced via a conventional and microcellular injection-molding process, respectively. Various characterization techniques including gel permeation chromatography, tensile testing and dynamic mechanical analysis, scanning electron microscopy and differential scanning calorimetry were applied to study the molecular weight, static and dynamic mechanical properties, cell morphology, and crystallization behavior, respectively. The addition of CE enhanced the molecular weight but decreased the crystallinity of PLA. The addition of CE also reduced the cell size and increased the cell density. Furthermore, the decomposition temperatures and several tensile properties, including specific strength, specific toughness, and strain-at-break of both solid and microcellular PLA specimens, increased with the addition of CE.

Polymers for nuclear materials processing

International Nuclear Information System (INIS)

Jarvinen, G.; Benicewicz, B.; Duke, J.

1996-01-01

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The use of open-celled microcellular foams as solid sorbents for metal ions and other solutes could provide a revolutionary development in separation science. Macroreticular and gel-bead materials are the current state-of-the-art for solid sorbents to separate metal ions and other solutes from solution. The new polymer materials examined in this effort offer a number of advantages over the older materials that can have a large impact on industrial separations. The advantages include larger usable surface area in contact with the solution, faster sorption kinetics, ability to tailor the uniform cell size to a specific application, and elimination of channeling and packing instability

Multifunctional Polymer-Based Graphene Foams with Buckled Structure and Negative Poisson’s Ratio

Science.gov (United States)

Dai, Zhaohe; Weng, Chuanxin; Liu, Luqi; Hou, Yuan; Zhao, Xuanliang; Kuang, Jun; Shi, Jidong; Wei, Yueguang; Lou, Jun; Zhang, Zhong

2016-01-01

In this study, we report the polymer-based graphene foams through combination of bottom-up assembly and simple triaxially buckled structure design. The resulting polymer-based graphene foams not only effectively transfer the functional properties of graphene, but also exhibit novel negative Poisson’s ratio (NPR) behaviors due to the presence of buckled structure. Our results show that after the introduction of buckled structure, improvement in stretchability, toughness, flexibility, energy absorbing ability, hydrophobicity, conductivity, piezoresistive sensitivity and crack resistance could be achieved simultaneously. The combination of mechanical properties, multifunctional performance and unusual deformation behavior would lead to the use of our polymer-based graphene foams for a variety of novel applications in future such as stretchable capacitors or conductors, sensors and oil/water separators and so on. PMID:27608928

Catalytic hydrodechlorination of dioxins over palladium nanoparticles in supercritical CO2 swollen microcellular polymers

International Nuclear Information System (INIS)

Wu, Ben-Zen; Chen, Hsiang-Yu; Wang, Joanna S.; Tan, Chung-Sung; Wai, Chien M.; Liao, Weisheng; Chiu, KongHwa

2012-01-01

Highlights: ► Pd nanoparticles are embedded in microcellular high density polyethylene (Pd/m-HDPE). ► Pd/m-HDPE is used as heterogeneous catalysts in supercritical carbon dioxide (sc-CO 2 ). ► Dioxins are remedied via hydrodechlorination and hydrogenation over Pd/m-HDPE in sc-CO 2 . ► The final products are dechlorinated and benzene-ring-saturated dioxins. ► Pd/m-HDPE can be recyclable and reusable without complicated cleaning procedures. - Abstract: In this study, palladium nanoparticles embedded in monolithic microcellular high density polyethylene supports are synthesized as heterogeneous catalysts for remediation of 1,6-dichlorodibenzo-p-dioxin and 2,8-dichlorodibenzofuran in 200 atm of supercritical carbon dioxide containing 10 atm of hydrogen gas and at 50–90 °C. Stepwise removal of chlorine atoms takes place first, followed by saturation of two benzene rings with slower reaction rates. The pseudo first order rate constant of initial hydrodechlorination for 2,8-dichlorodibenzofuran is 4.3 times greater than that for 1,6-dichlorodibenzo-p-dioxin at 78 °C. The catalysts are easily separated from products and can be recyclable and reusable without complicated recovery and cleaning procedures.

MmWave Vehicle-to-Infrastructure Communication :Analysis of Urban Microcellular Networks

Science.gov (United States)

2017-05-01

Vehicle-to-infrastructure (V2I) communication may provide high data rates to vehicles via millimeterwave (mmWave) microcellular networks. This report uses stochastic geometry to analyze the coverage of urban mmWave microcellular networks. Prior work ...

Virtual Treatment of Basilar Aneurysms Using Shape Memory Polymer Foam

Science.gov (United States)

Ortega, J.M.; Hartman, J.; Rodriguez, J.N.; Maitland, D.J.

2013-01-01

Numerical simulations are performed on patient-specific basilar aneurysms that are treated with shape memory polymer (SMP) foam. In order to assess the post-treatment hemodynamics, two modeling approaches are employed. In the first, the foam geometry is obtained from a micro-CT scan and the pulsatile blood flow within the foam is simulated for both Newtonian and non-Newtonian viscosity models. In the second, the foam is represented as a porous media continuum, which has permeability properties that are determined by computing the pressure gradient through the foam geometry over a range of flow speeds comparable to those of in vivo conditions. Virtual angiography and additional post-processing demonstrate that the SMP foam significantly reduces the blood flow speed within the treated aneurysms, while eliminating the high-frequency velocity fluctuations that are present within the pre-treatment aneurysms. An estimation of the initial locations of thrombus formation throughout the SMP foam is obtained by means of a low fidelity thrombosis model that is based upon the residence time and shear rate of blood. The Newtonian viscosity model and the porous media model capture similar qualitative trends, though both yield a smaller volume of thrombus within the SMP foam. PMID:23329002

Development of partially biodegradable foams from PP/HMSPP blends with natural and synthetic polymers

International Nuclear Information System (INIS)

Cardoso, Elizabeth Carvalho Leite

2014-01-01

Polymers are used in various application and in different industrial areas providing enormous quantities of wastes in environment. Among diverse components of residues in landfills are polymeric materials, including Polypropylene, which contribute with 20 to 30% of total volume of solid residues. As polymeric materials are immune to microbial degradation, they remain in soil and in landfills as a semi-permanent residue. Environmental concerning in litter reduction is being directed to renewable polymers development for manufacturing of polymeric foams. Foamed polymers are considered future materials, with a wide range of applications; high density structural foams are specially used in civil construction, in replacement of metal, woods and concrete with a final purpose of reducing materials costs. At present development, it was possible the incorporation of PP/HMSPP polymeric matrix blends with sugarcane bagasse, PHB and PLA, in structural foams production. Thermal degradation at 100, 120 and 160 deg C temperatures was not enough to induce biodegradability. Gamma irradiation degradation, at 50, 100, 200 and 500 kGy showed effective for biodegradability induction. Irradiated bagasse blends suffered surface erosion, in favor of water uptake and consequently, a higher biodegradation in bulk structure. (author)

Fabrication of tissue engineering scaffolds through solid-state foaming of immiscible polymer blends

International Nuclear Information System (INIS)

Zhou Changchun; Li Wei; Ma Liang; Yao Donggang

2011-01-01

In scaffold-based tissue engineering, the fabrication process is important for producing suitable microstructures for seeded cells to grow and reformulate. In this paper, we present a new approach to scaffold fabrication by combining the solid-state foaming and the immiscible polymer-blending method. The proposed approach has the advantage of being versatile and able to create a wide range of pore size and porosity. The proposed method is studied with polylactic acid (PLA) and polystyrene (PS) blends. The interconnected porous structure was created by first foaming the PLA/PS blend and then extracting the PS phase. The solid-state foaming experiments were conducted under various conditions to achieve the desired pore sizes. It is shown that the PS phase of the PLA/PS blend can be extracted much faster in the foamed samples and the pore size of the scaffolds can be easily controlled with proper gas foaming parameters. The average pore size achieved in the foaming process ranged from 20 to 70 μm. After PS extraction, both pore size and porosity can be further improved. For example, the pore size and porosity increased from 48 μm and 49% to 59 μm and 67%, respectively, after the PS extraction process. The fabricated porous scaffolds were used to culture human osteoblast cells. Cells grew well and gradually formed a fibrous structure. The combined solid-state foaming and immiscible polymer blending method provides a new technique for fabricating tissue-engineering scaffolds.

Preparation and characterization of shape memory composite foams with interpenetrating polymer networks

International Nuclear Information System (INIS)

Yao, Yongtao; Zhou, Tianyang; Yang, Cheng; Leng, Jinsong; Liu, Yanju

2016-01-01

The present study reports a feasible approach of fabricating shape memory composite foams with an interpenetrating polymer network (IPN) based on polyurethane (PU) and shape memory epoxy resin (SMER) via a simultaneous polymerization technique. The PU component is capable of constructing a foam structure and the SMER is grafted on the PU network to offer its shape memory property in the final IPN foams. A series of IPN foams without phase separation were produced due to good compatibility and a tight chemical interaction between PU and SMER components. The relationships of the geometry of the foam cell were investigated via varying compositions of PU and SMER. The physical property and shape memory property were also evaluated. The stimulus temperature of IPN shape memory composite foams, glass temperature (T g ), could be tunable by varying the constituents and T g of PU and SMER. The mechanism of the shape memory effect of IPN foams has been proposed. The shape memory composite foam with IPN developed in this study has the potential to extend its application field. (paper)

A deterministic model for the planning of microcellular mobile radio communication systems

NARCIS (Netherlands)

Klaassen, M.G.J.J.; Mawira, A.

1994-01-01

A ray model for field strength prediction for the planning of microcellular mobile radio communication systems is presented. The software developed at Eindhoven University of Technology for LMSS has been adapted for application in microcellular mobile radio communication systems. The adaption

A novel and facile strategy for highly flame retardant polymer foam composite materials: Transforming silicone resin coating into silica self-extinguishing layer.

Science.gov (United States)

Wu, Qian; Zhang, Qian; Zhao, Li; Li, Shi-Neng; Wu, Lian-Bin; Jiang, Jian-Xiong; Tang, Long-Cheng

2017-08-15

In this study, a novel strategy was developed to fabricate highly flame retardant polymer foam composite materials coated by synthesized silicone resin (SiR) polymer via a facile dip-coating processing. Applying the SiR polymer coating, the mechanical property and thermal stability of SiR-coated polymer foam (PSiR) composites are greatly enhanced without significantly altering their structure and morphology. The minimum oxygen concentration to support the combustion of foam materials is greatly increased, i.e. from LOI 14.6% for pure foam to LOI 26-29% for the PSiR composites studied. Especially, adjusting pendant group to SiOSi group ratio (R/Si ratio) of SiRs produces highly flame retardant PSiR composites with low smoke toxicity. Cone calorimetry results demonstrate that 44-68% reduction in the peak heat release rate for the PSiR composites containing different R/Si ratios over pure foam is achieved by the presence of appropriate SiR coating. Digital and SEM images of post-burn chars indicate that the SiR polymer coating can be transformed into silica self-extinguishing porous layer as effective inorganic barrier effect, thus preserving the polymer foam structure from fire. Our results show that the SiR dip-coating technique is a promising strategy for producing flame retardant polymer foam composite materials with improved mechanical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Catalytic hydrodechlorination of dioxins over palladium nanoparticles in supercritical CO{sub 2} swollen microcellular polymers

Energy Technology Data Exchange (ETDEWEB)

Wu, Ben-Zen [Department of Chemistry, National Dong Hwa University, Hua-Lien 970, Taiwan, ROC (China); Chen, Hsiang-Yu [Department of Chemistry, Chung Yuan Christian University, Chung-Li, Tao-Yuan 320, Taiwan, ROC (China); Wang, Joanna S. [Department of Chemistry, University of Idaho, Moscow, ID 83844m (United States); Tan, Chung-Sung [Department of Chemical Engineering, National Tsing Hua University, HsinChu 300, Taiwan, ROC (China); Wai, Chien M. [Department of Chemistry, University of Idaho, Moscow, ID 83844m (United States); Liao, Weisheng, E-mail: liao1427@vandals.uidaho.edu [Department of Chemistry, National Dong Hwa University, Hua-Lien 970, Taiwan, ROC (China); Chiu, KongHwa, E-mail: ckh@mail.ndhu.edu.tw [Department of Chemistry, National Dong Hwa University, Hua-Lien 970, Taiwan, ROC (China)

2012-08-15

Highlights: Black-Right-Pointing-Pointer Pd nanoparticles are embedded in microcellular high density polyethylene (Pd/m-HDPE). Black-Right-Pointing-Pointer Pd/m-HDPE is used as heterogeneous catalysts in supercritical carbon dioxide (sc-CO{sub 2}). Black-Right-Pointing-Pointer Dioxins are remedied via hydrodechlorination and hydrogenation over Pd/m-HDPE in sc-CO{sub 2}. Black-Right-Pointing-Pointer The final products are dechlorinated and benzene-ring-saturated dioxins. Black-Right-Pointing-Pointer Pd/m-HDPE can be recyclable and reusable without complicated cleaning procedures. - Abstract: In this study, palladium nanoparticles embedded in monolithic microcellular high density polyethylene supports are synthesized as heterogeneous catalysts for remediation of 1,6-dichlorodibenzo-p-dioxin and 2,8-dichlorodibenzofuran in 200 atm of supercritical carbon dioxide containing 10 atm of hydrogen gas and at 50-90 Degree-Sign C. Stepwise removal of chlorine atoms takes place first, followed by saturation of two benzene rings with slower reaction rates. The pseudo first order rate constant of initial hydrodechlorination for 2,8-dichlorodibenzofuran is 4.3 times greater than that for 1,6-dichlorodibenzo-p-dioxin at 78 Degree-Sign C. The catalysts are easily separated from products and can be recyclable and reusable without complicated recovery and cleaning procedures.

Mechanical and thermal property characterization of poly-L-lactide (PLLA) scaffold developed using pressure-controllable green foaming technology

International Nuclear Information System (INIS)

Sheng, Shen-Jun; Hu, Xiao; Wang, Fang; Ma, Qing-Yu; Gu, Min-Fen

2015-01-01

Poly-L-lactide (PLLA) is one of the most promising biological materials used for tissue engineering scaffolds (TES) because of their excellent biodegradability and tenability. Here, microcellular PLLA foams were fabricated by pressure-controllable green foaming technology. Scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), wide angle X-ray diffraction measurement (WAXRD), thermogravimetric (TG) analysis, reflection-Fourier transform infrared (FTIR) analysis, enzymatic degradation study and MTT assay were used to analyze the scaffolds' morphologies, structures and crystallinities, mechanical and biodegradation properties, as well as their cytotoxicity. The results showed that PLLA foams with pore sizes from 8 to 103 μm diameters were produced when the saturation pressure decreased from 7.0 to 4.0 MPa. Through a combination of StepScan DSC (SSDSC) and WAXRD approaches, it was observed in PLLA foams that the crystallinity, highly-oriented metastable state and rigid amorphous phase increased with the increasing foaming pressure. It was also found that both the glass transition temperature and apparent enthalpy of PLLA significantly increased after the foaming process, which suggested that the changes of microcellular structure could provide PLLA scaffolds better thermal stability and elasticity. Moreover, MTT assessments suggested that the smaller pore size should benefit cell attachment and growth in the scaffold. The results of current work will give us better understanding of the mechanisms involved in structure and property changes of PLLA at the molecular level, which enables more possibilities for the design of PLLA scaffold to satisfy various requirements in biomedical and green chemical applications. - Highlights: • Pressure-controllable green foaming technology is used. • The crystallinity and rigid amorphous fraction is calculated by using DSC and XRD. • We examine the changes of

Mechanical and thermal property characterization of poly-L-lactide (PLLA) scaffold developed using pressure-controllable green foaming technology

Energy Technology Data Exchange (ETDEWEB)

Sheng, Shen-Jun [Center of Analysis and Testing, Nanjing Normal University, Nanjing 210023 (China); School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Hu, Xiao [Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028 (United States); Department of Biomedical and Translational Sciences, Rowan University, Glassboro, NJ 08028 (United States); Wang, Fang, E-mail: wangfang@njnu.edu.cn [Center of Analysis and Testing, Nanjing Normal University, Nanjing 210023 (China); Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028 (United States); Ma, Qing-Yu [Key Laboratory of Optoelectronics of Jiangsu Province, School of Physics and Technology, Nanjing Normal University, Nanjing 210023 (China); Gu, Min-Fen [Center of Analysis and Testing, Nanjing Normal University, Nanjing 210023 (China)

2015-04-01

Poly-L-lactide (PLLA) is one of the most promising biological materials used for tissue engineering scaffolds (TES) because of their excellent biodegradability and tenability. Here, microcellular PLLA foams were fabricated by pressure-controllable green foaming technology. Scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), wide angle X-ray diffraction measurement (WAXRD), thermogravimetric (TG) analysis, reflection-Fourier transform infrared (FTIR) analysis, enzymatic degradation study and MTT assay were used to analyze the scaffolds' morphologies, structures and crystallinities, mechanical and biodegradation properties, as well as their cytotoxicity. The results showed that PLLA foams with pore sizes from 8 to 103 μm diameters were produced when the saturation pressure decreased from 7.0 to 4.0 MPa. Through a combination of StepScan DSC (SSDSC) and WAXRD approaches, it was observed in PLLA foams that the crystallinity, highly-oriented metastable state and rigid amorphous phase increased with the increasing foaming pressure. It was also found that both the glass transition temperature and apparent enthalpy of PLLA significantly increased after the foaming process, which suggested that the changes of microcellular structure could provide PLLA scaffolds better thermal stability and elasticity. Moreover, MTT assessments suggested that the smaller pore size should benefit cell attachment and growth in the scaffold. The results of current work will give us better understanding of the mechanisms involved in structure and property changes of PLLA at the molecular level, which enables more possibilities for the design of PLLA scaffold to satisfy various requirements in biomedical and green chemical applications. - Highlights: • Pressure-controllable green foaming technology is used. • The crystallinity and rigid amorphous fraction is calculated by using DSC and XRD. • We examine the changes of

Studies on a Foam System of Ultralow Interfacial Tension Applied in Daqing Oilfield after Polymer Flooding

Directory of Open Access Journals (Sweden)

Hong-sheng Liu

2013-01-01

Full Text Available In order to study the effects of oil displacement by a foam system of ultralow interfacial tension, the interfacial activities and foam properties of a nonionic gemini surfactant (DWS were investigated under Daqing Oilfield reservoir conditions. Injection methods and alternate cycle of the foam system were discussed here on the basis of results from core flow experiments. It was obtained that the surface tension of DWS was approximately 25 mN/m, and ultralow interfacial tension was reached between oil and DWS with a surfactant concentration between 0.05wt% and 0.4wt%. The binary system showed splendid foam performances, and the preferential surfactant concentration was 0.3wt% with a polymer concentration of 0.2wt%. When gas and liquid were injected simultaneously, flow control capability of the foam reached its peak at the gas-liquid ratio of 3 : 1. Enhanced oil recovery factor of the binary foam system exceeded 10% in a parallel natural cores displacement after polymer flooding.

Simple gases to replace non-environmentally friendly polymer foaming agents. A thermodynamic investigation

International Nuclear Information System (INIS)

Grolier, Jean-Pierre E.; Randzio, Stanislaw L.

2012-01-01

Highlights: ► The PVT-vibrating wire technique and PVT-scanning transitiometry. ► Polymer swelling with measured gas sorption and gas–polymer interaction energies. ► Experimental measurements up to 373 K and 100 MPa. ► Hydrostatic and plasticization effects under high pressure gas and induced T g -shifts. ► Thermodynamic study of the (gas + polymer) systems polystyrene with CO 2 , N 2 , and freons. - Abstract: Foaming constitutes one of the most important industrial activities in polymer engineering to produce efficient thermal insulating materials. In particular, rigid insulating boards are produced worldwide on a large scale using blowing agents which eventually are released in the environment where they adversely impact the natural friendly stratospheric ozone layer. Concomitantly, the chemicals used as blowing agents contribute to the creation of the unfriendly tropospheric ozone layer generating the disastrous green house effect around our planet. The traditional foaming intermediates currently named freons, like chlorofluorocarbons (CFCs) currently used as blowing agents as well as the hydrochlorofluorocarbons (HCFCs) often considered as alternative blowing agents, must be banned from industrial processes and new (friendly) foaming agents have to be suggested and evaluated in terms of both easy engineering and environmental neutrality. Undoubtedly thermodynamics plays a major role in assessing the effective capability of those chemicals. Some CFCs still accepted and other possible simple gases like carbon dioxide and nitrogen have been considered. The in-depth thermodynamic investigation has been made possible thanks to new experimental developments to determine gas solubility in polymers and associated swelling as well as the thermodynamic properties of (gas + polymer) systems, including the thermophysical properties of polymers under gas sorption. Pertinent data have been generated for such properties over extended T and p ranges.

The influence of supercritical foaming conditions on properties of polymer scaffolds for tissue engineering

Directory of Open Access Journals (Sweden)

Kosowska Katarzyna

2017-12-01

Full Text Available The results of experimental investigations into foaming process of poly(ε-caprolactone using supercritical CO2 are presented. The objective of the study was to explore the aspects of fabrication of biodegradable and biocompatible scaffolds that can be applied as a temporary three-dimensional extracellular matrix analog for cells to grow into a new tissue. The influence of foaming process parameters, which have been proven previously to affect significantly scaffold bioactivity, such as pressure (8-18 MPa, temperature (323-373 K and time of saturation (1-6 h on microstructure and mechanical properties of produced polymer porous structures is presented. The morphology and mechanical properties of considered materials were analyzed using a scanning electron microscope (SEM, x-ray microtomography (μ-CT and a static compression test. A precise control over porosity and morphology of obtained polymer porous structures by adjusting the foaming process parameters has been proved. The obtained poly(ε-caprolactone solid foams prepared using scCO2 have demonstrated sufficient mechanical strength to be applied as scaffolds in tissue engineering.

Bioactive Wollastonite-Diopside Foams from Preceramic Polymers and Reactive Oxide Fillers

Directory of Open Access Journals (Sweden)

Laura Fiocco

2015-05-01

Full Text Available Wollastonite (CaSiO3 and diopside (CaMgSi2O6 silicate ceramics have been widely investigated as highly bioactive materials, suitable for bone tissue engineering applications. In the present paper, highly porous glass-ceramic foams, with both wollastonite and diopside as crystal phases, were developed from the thermal treatment of silicone polymers filled with CaO and MgO precursors, in the form of micro-sized particles. The foaming was due to water release, at low temperature, in the polymeric matrix before ceramic conversion, mainly operated by hydrated sodium phosphate, used as a secondary filler. This additive proved to be “multifunctional”, since it additionally favored the phase development, by the formation of a liquid phase upon firing, in turn promoting the ionic interdiffusion. The liquid phase was promoted also by the incorporation of powders of a glass crystallizing itself in wollastonite and diopside, with significant improvements in both structural integrity and crushing strength. The biological characterization of polymer-derived wollastonite-diopside foams, to assess the bioactivity of the samples, was performed by means of a cell culture test. The MTT assay and LDH activity tests gave positive results in terms of cell viability.

Analysis of the Influence of Microcellular Injection Molding on the Environmental Impact of an Industrial Component

Directory of Open Access Journals (Sweden)

Daniel Elduque

2014-09-01

Full Text Available Microcellular injection molding is a process that offers numerous benefits due to the internal structure generated; thus, many applications are currently being developed in different fields, especially home appliances. In spite of the advantages, when changing the manufacturing process from conventional to microcellular injection molding, it is necessary to analyze its new mechanical properties and the environmental impact of the component. This paper presents a deep study of the environmental behavior of a manufactured component by both conventional and microcellular injection molding. Environmental impact will be evaluated performing a life cycle assessment. Functionality of the component will be also evaluated with samples obtained from manufactured components, to make sure that the mechanical requirements are fulfilled when using microcellular injection molding. For this purpose a special device has been developed to measure the flexural modulus. With a 16% weight reduction, the variation of flexural properties in the microcellular injected components is only 6.8%. Although the energy consumption of the microcellular injection process slightly increases, there is an overall reduction of the environmental burden of 14.9% in ReCiPe and 15% in carbon footprint. Therefore, MuCell technology can be considered as a green manufacturing technology for components working mainly under flexural load.

Flame-retardant copolymers of dialkyl (meth)acryloyloxyalkyl phosphate or dialkyl (meth)acryloyloxyalkyl phosphonate monomers and polymer foams based made therefrom

Energy Technology Data Exchange (ETDEWEB)

Qi, Yudong; Li, Yan; Bunker, Shana P.; Costeux, Stephane; Morgan, Ted A.

2017-12-12

Polymer foam bodies are made from phosphorus-containing thermoplastic random copolymers of a dialkyl (meth)acryloyloxyalkyl phosph(on)ate. Foam bodies made from these copolymers exhibit increased limiting oxygen indices and surprisingly have good properties. In certain embodiments, the phosphorus-containing thermoplastic copolymer is blended with one or more other polymers and formed into nanofoams.

In situ production of microporous foams in sub-millimeter cylindrical gold targets

International Nuclear Information System (INIS)

Fan Yongheng; Luo Xuan; Fang Yu; Ren Hongbo; Yuan Guanghui; Wang Honglian; Zhou Lan; Zhang Lin; Du Kai

2009-01-01

The preparation of microcellular foam in sub-millimeter cylindrical gold targets is described. Small, open-ended, gold cylinders of 400 μm diameter, 700 μm length, and 20 μm wall thickness were fabricated by electroplating gold onto a silicon bronze mandrel and leaching the mandrel with concentrated nitric acid. After several rinsing and cleaning steps, the cylinders were filled with a solution containing acrylate monomers. The solution was polymerized in situ with ultraviolet light to produce a gel. Precipitation of these gels in a non-solvent such as methanol and subsequent drying by means of a critical point drying apparatus produced cylinders filled with microporous foams. The foams have densities of 50 mg · cm -3 and cell sizes on more than 1 μm. They fill the cylinders completely without shrinkage during the drying process, and need no subsequent machining. (authors)

Biodegradable poly (lactic acid)/Cellulose nanocrystals (CNCs) composite microcellular foam: Effect of nanofillers on foam cellular morphology, thermal and wettability behavior.

Science.gov (United States)

Borkotoky, Shasanka Sekhar; Dhar, Prodyut; Katiyar, Vimal

2018-01-01

This article addresses the elegant and green approach for fabrication of bio-based poly (lactic acid) (PLA)/cellulose nanocrystal (CNCs) bionanocomposite foam (PLA/CNC) with cellular morphology and hydrophobic surface behavior. Highly porous (porosity >80%) structure is obtained with interconnected pores and the effect of CNCs in the cell density (N f ) and cell size of foams are thoroughly investigated by morphological analysis. The thermo-mechanical investigations are performed for the foam samples and almost ∼1.7 and ∼2.2 fold increase in storage modulus is observed for the compressive and tensile mode respectively. PLA/CNC based bionanocomposite foams displayed similar thermal stability as base PLA foam. Detailed investigations of decomposition behavior are studied by using hyphenated thermogravimetric analysis-fourier transmission infrared spectroscopy (TGA-FTIR) system. Almost ∼13% increment is observed in crystallinity at highest loading of CNCs compared to neat counterpart. To investigate the splitting and spreading phenomenon of the wettability of the samples, linear model is used to find the Young's contact angle and contact angle hysteresis (CAH). Besides, ∼6.1 folds reduction in the density of PLA and the nanocomposite foams compared to PLA carries much significance in specialized application areas where weight is an important concern. Copyright © 2017 Elsevier B.V. All rights reserved.

Electromagnetic interference shielding effectiveness of microcellular polyimide/in situ thermally reduced graphene oxide/carbon nanotubes nanocomposites

Science.gov (United States)

Yang, Hongli; Yu, Zhi; Wu, Peng; Zou, Huawei; Liu, Pengbo

2018-03-01

A simple and effective method was adopted to fabricate microcellular polyimide (PI)/reduced graphene oxide (GO)/multi-walled carbon nanotubes (MWCNTs) nanocomposites. Firstly, microcellular poly (amic acid) (PAA)/GO/MWCNTs nanocomposites were prepared through solvent evaporation induced phase separation. In this process, PAA and dibutyl phthalate (DBP) co-dissolved in N,N-dimethylacetamide (DMAc) underwent phase separation with DMAc evaporating, and DBP microdomains were formed in continuous PAA phase. Subsequently, PAA was thermally imidized and simultaneously GO was in situ reduced. After DBP was removed, the microcellular PI/reduced GO (RGO)/MWCNTs nanocomposites were finally obtained. When the initial filler loading was 8 wt%, the electrical conductivity of microcellular PI/RGO, PI/MWCNTs and PI/RGO/MWCNTs nanocomposites were 0.05, 0.02 and 1.87 S·m-1, respectively, and the electromagnetic interference (EMI) shielding efficiency (SE) of microcellular PI/RGO, PI/MWCNTs and PI/RGO/MWCNTs nanocomposites were 13.7-15.1, 13.0-14.3 and 16.6-18.2 dB, respectively. The synergistic effect between RGO and MWCNTs enhanced both the electrical conductivity and EMI shielding performance of the microcellular PI/RGO/MWCNTs nanocomposites. The dominating EMI shielding mechanism for these materials was microwave absorption. While the initial loading of GO and MWCNT was 8 wt%, the microcellular PI/RGO/MWCNTs nanocomposite (500 μm thickness) had extremely high specific EMI SE value of 755-823 dB·cm2·g-1. Its thermal stability was also obviously improved, the 5% weight loss temperature in nitrogen was 548 °C. In addition, it also possessed a high Young's modulus of 789 MPa.

Biopolymer foams - Relationship between material characteristics and foaming behavior of cellulose based foams

International Nuclear Information System (INIS)

Rapp, F.; Schneider, A.; Elsner, P.

2014-01-01

Biopolymers are becoming increasingly important to both industry and consumers. With regard to waste management, CO 2 balance and the conservation of petrochemical resources, increasing efforts are being made to replace standard plastics with bio-based polymers. Nowadays biopolymers can be built for example of cellulose, lactic acid, starch, lignin or bio mass. The paper will present material properties of selected cellulose based polymers (cellulose propionate [CP], cellulose acetate butyrate [CAB]) and corresponding processing conditions for particle foams as well as characterization of produced parts. Special focus is given to the raw material properties by analyzing thermal behavior (differential scanning calorimetry), melt strength (Rheotens test) and molecular weight distribution (gel-permeation chromatography). These results will be correlated with the foaming behavior in a continuous extrusion process with physical blowing agents and underwater pelletizer. Process set-up regarding particle foam technology, including extrusion foaming and pre-foaming, will be shown. The characteristics of the resulting foam beads will be analyzed regarding part density, cell morphology and geometry. The molded parts will be tested on thermal conductivity as well as compression behavior (E-modulus, compression strength)

Biopolymer foams - Relationship between material characteristics and foaming behavior of cellulose based foams

Science.gov (United States)

Rapp, F.; Schneider, A.; Elsner, P.

2014-05-01

Biopolymers are becoming increasingly important to both industry and consumers. With regard to waste management, CO2 balance and the conservation of petrochemical resources, increasing efforts are being made to replace standard plastics with bio-based polymers. Nowadays biopolymers can be built for example of cellulose, lactic acid, starch, lignin or bio mass. The paper will present material properties of selected cellulose based polymers (cellulose propionate [CP], cellulose acetate butyrate [CAB]) and corresponding processing conditions for particle foams as well as characterization of produced parts. Special focus is given to the raw material properties by analyzing thermal behavior (differential scanning calorimetry), melt strength (Rheotens test) and molecular weight distribution (gel-permeation chromatography). These results will be correlated with the foaming behavior in a continuous extrusion process with physical blowing agents and underwater pelletizer. Process set-up regarding particle foam technology, including extrusion foaming and pre-foaming, will be shown. The characteristics of the resulting foam beads will be analyzed regarding part density, cell morphology and geometry. The molded parts will be tested on thermal conductivity as well as compression behavior (E-modulus, compression strength).

Bio-based Polymer Foam from Soyoil

Science.gov (United States)

Bonnaillie, Laetitia M.; Wool, Richard P.

2006-03-01

The growing bio-based polymeric foam industry is presently lead by plant oil-based polyols for polyurethanes and starch foams. We developed a new resilient, thermosetting foam system with a bio-based content higher than 80%. The acrylated epoxidized soybean oil and its fatty acid monomers is foamed with pressurized carbon dioxide and cured with free-radical initiators. The foam structure and pore dynamics are highly dependent on the temperature, viscosity and extent of reaction. Low-temperature cure hinds the destructive pore coalescence and the application of a controlled vacuum results in foams with lower densities ˜ 0.1 g/cc, but larger cells. We analyze the physics of foam formation and stability, as well as the structure and mechanical properties of the cured foam using rigidity percolation theory. The parameters studied include temperature, vacuum applied, and cross-link density. Additives bring additional improvements: nucleating agents and surfactants help produce foams with a high concentration of small cells and low bulk density. Hard and soft thermosetting foams with a bio content superior to 80% are successfully produced and tested. Potential applications include foam-core composites for hurricane-resistant housing, structural reinforcement for windmill blades, and tissue scaffolds.

Interventional Application of Shape Memory Polymer Foam Final Report CRADA No. TC-02067-03

Energy Technology Data Exchange (ETDEWEB)

Maitland, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Metzger, M. F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-09-27

This was a collaborative effort between The Regents of the University of California, Lawrence Livermore National Laboratory (LLNL) and Sierra Interventions, LLC, to develop shape memory polymer foam devices for treating hemorrhagic stroke.

A numerical model to simulate foams during devolatilization of polymers

Science.gov (United States)

Khan, Irfan; Dixit, Ravindra

2014-11-01

Customers often demand that the polymers sold in the market have low levels of volatile organic compounds (VOC). Some of the processes for making polymers involve the removal of volatiles to the levels of parts per million (devolatilization). During this step the volatiles are phase separated out of the polymer through a combination of heating and applying lower pressure, creating foam with the pure polymer in liquid phase and the volatiles in the gas phase. The efficiency of the devolatilization process depends on predicting the onset of solvent phase change in the polymer and volatiles mixture accurately based on the processing conditions. However due to the complex relationship between the polymer properties and the processing conditions this is not trivial. In this work, a bubble scale model is coupled with a bulk scale transport model to simulate the processing conditions of polymer devolatilization. The bubble scale model simulates the nucleation and bubble growth based on the classical nucleation theory and the popular ``influence volume approach.'' As such it provides the information of bubble size distribution and number density inside the polymer at any given time and position. This information is used to predict the bulk properties of the polymer and its behavior under the applied processing conditions. Initial results of this modeling approach will be presented.

Processing and characterization of solid and microcellular PHBV/PBAT blend and its RWF/nanoclay composites

Science.gov (United States)

Alireza Javadi; Yottha Srithep; Jungjoo Lee; Srikanth Pilla; Craig Clemons; Shaoqin Gong; Lih-Sheng Turng

2010-01-01

Solid and microcellular components made of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/ poly (butylenes adipate-co-terephthalate) (PBAT) blend (weight ration of PHBV:PBAT = 30:70), recycled wood fiber (RWF), and nanoclay (NC) were prepared via a conventional and microcellular-injection molding process, respectively. Morphology, thermal properties, and...

Biomass derived novel functional foamy materials - BIO-FOAM

Energy Technology Data Exchange (ETDEWEB)

Suurnaekki, A.; Boer, H.; Forssell, P. (and others) (VTT Technical Research Centre of Finland, Espoo (Finland)), Email: anna.suurnakki@vtt.fi

2010-10-15

BIO-FOAM has aimed at exploiting the potential of biomaterials in replacing synthetic polymers in solid foamy materials. The target applications have been various, including food, packaging, construction and insulation. The project activities during the second project year have focused on characterisation of the solid model foams and on modeling the behaviour of polymers at liquid- liquid interfaces. In the modelling study the intrinsic consistence of the applied thermodynamic approach was confirmed. The experimentally obtained solubility parameters of polymers were in good agreement with the calculated solubility parameters. The polymers were, however, found to posses too little surface activity to alone provide stable foams, but they were able to act as co-surfactants. In the model polymer foam work both expanded polymer foams and wood fibre based foams were prepared. Supercritical CO{sub 2}-gas chamber was found to be a useful tool to prepare expanded polymer foams in small scale. Only partial replacement of synthetic polymers could, however, be obtained with native biomaterials indicating the need of tailoring of biopolymer properties and suitable formulations including surfactants or stabilizing particles. In wood fibre-based foams both nanocellulose and lignin showed potential as additives or reinforcing components.The outcome of the extruded food snacks study was that the processing parameters were related with the equipmentvariables. Furthermore, glycerol was shown to facilitate greatly extrusion processing. In foam concrete work concrete pore structure was shown to correlate with its strength and stability. At optimum concentration wood fibres affected positively the concrete processing performance. (orig.)

Polyethylene ionomer-based nano-composite foams prepared by a batch process and MuCell injection molding

International Nuclear Information System (INIS)

Hayashi, Hidetomo; Mori, Tomoki; Okamoto, Masami; Yamasaki, Satoshi; Hayami, Hiroshi

2010-01-01

To understand the correlation between foamability and melt rheology of polyethylene-based ionomers having different degrees of the neutralization and corresponding nano-composites, we have conducted the foam processing via a batch process in an autoclave and microcellular foam injection molding (FIM) process using the MuCell technology. We have discussed the obtainable morphological properties in both foaming processes. All cellular structures were investigated by using field emission scanning electron microscopy. The competitive phenomenon between the cell nucleation and the cell growth including the coalescence of cell was discussed in light of the interfacial energy and the relaxation rate as revealed by the modified classical nucleation theory and rheological measurement, respectively. The FIM process led to the opposite behavior in the cell growth and coalescence of cell as compared with that of the batch process, where the ionic cross-linked structure has significant contribution to retard the cell growth and coalescence of cell. The mechanical properties of the structural foams obtained by FIM process were discussed.

Coated foams, preparation, uses and articles

Science.gov (United States)

Duchane, D.V.; Barthell, B.L.

1982-10-21

Hydrophobic cellular material is coated with a thin hydrophilic polymer skin which stretches tightly over the foam but which does not fill the cells of the foam, thus resulting in a polymer-coated foam structure having a smoothness which was not possible in the prior art. In particular, when the hydrophobic cellular material is a specially chosen hydrophobic polymer foam and is formed into arbitrarily chosen shapes prior to the coating with hydrophilic polymer, inertial confinement fusion (ICF) targets of arbitrary shapes can be produced by subsequently coating the shapes with metal or with any other suitable material. New articles of manufacture are produced, including improved ICF targets, improved integrated circuits, and improved solar reflectors and solar collectors. In the coating method, the cell size of the hydrophobic cellular material, the viscosity of the polymer solution used to coat, and the surface tension of the polymer solution used to coat are all very important to the coating.

A polymer foam conduit seeded with Schwann cells promotes guided peripheral nerve regeneration.

Science.gov (United States)

Hadlock, T; Sundback, C; Hunter, D; Cheney, M; Vacanti, J P

2000-04-01

Alternatives to autografts have long been sought for use in bridging neural gaps. Many entubulation materials have been studied, although with generally disappointing results in comparison with autografts. The purpose of this study was to design a more effective neural guidance conduit, to introduce Schwann cells into the conduit, and to determine regenerative capability through it in an in vivo model. A novel, fully biodegradable polymer conduit was designed and fabricated for use in peripheral nerve repair, which approximates the macro- and microarchitecture of native peripheral nerves. It comprised a series of longitudinally aligned channels, with diameters ranging from 60 to 550 microns. The lumenal surfaces promoted the adherence of Schwann cells, whose presence is known to play a key role in nerve regeneration. This unique channel architecture increased the surface area available for Schwann cell adherence up to five-fold over that available through a simple hollow conduit. The conduit was composed of a high-molecular-weight copolymer of lactic and glycolic acids (PLGA) (MW 130,000) in an 85:15 monomer ratio. A novel foam-processing technique, employing low-pressure injection molding, was used to create highly porous conduits (approximately 90% pore volume) with continuous longitudinal channels. Using this technique, conduits were constructed containing 1, 5, 16, 45, or more longitudinally aligned channels. Prior to cellular seeding of these conduits, the foams were prewet with 50% ethanol, flushed with physiologic saline, and coated with laminin solution (10 microg/mL). A Schwann cell suspension was dynamically introduced into these processed foams at a concentration of 5 X 10(5) cells/mL, using a simple bioreactor flow loop. In vivo regeneration studies were carried out in which cell-laden five-channel polymer conduits (individual channel ID 500 microm, total conduit OD 2.3 mm) were implanted across a 7-mm gap in the rat sciatic nerve (n = 4), and midgraft

Technology of foamed propellants

Energy Technology Data Exchange (ETDEWEB)

Boehnlein-Mauss, Jutta; Kroeber, Hartmut [Fraunhofer Institut fuer Chemische Technologie ICT, Pfinztal (Germany)

2009-06-15

Foamed propellants are based on crystalline explosives bonded in energetic reaction polymers. Due to their porous structures they are distinguished by high burning rates. Energy content and material characteristics can be varied by using different energetic fillers, energetic polymers and porous structures. Foamed charges can be produced easily by the reaction injection moulding process. For the manufacturing of foamed propellants a semi-continuous remote controlled production plant in pilot scale was set up and a modified reaction injection moulding process was applied. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Self-fitting shape memory polymer foam inducing bone regeneration: A rabbit femoral defect study.

Science.gov (United States)

Xie, Ruiqi; Hu, Jinlian; Hoffmann, Oskar; Zhang, Yuanchi; Ng, Frankie; Qin, Tingwu; Guo, Xia

2018-04-01

Although tissue engineering has been attracted greatly for healing of critical-sized bone defects, great efforts for improvement are still being made in scaffold design. In particular, bone regeneration would be enhanced if a scaffold precisely matches the contour of bone defects, especially if it could be implanted into the human body conveniently and safely. In this study, polyurethane/hydroxyapatite-based shape memory polymer (SMP) foam was fabricated as a scaffold substrate to facilitate bone regeneration. The minimally invasive delivery and the self-fitting behavior of the SMP foam were systematically evaluated to demonstrate its feasibility in the treatment of bone defects in vivo. Results showed that the SMP foam could be conveniently implanted into bone defects with a compact shape. Subsequently, it self-matched the boundary of bone defects upon shape-recovery activation in vivo. Micro-computed tomography determined that bone ingrowth initiated at the periphery of the SMP foam with a constant decrease towards the inside. Successful vascularization and bone remodeling were also demonstrated by histological analysis. Thus, our results indicate that the SMP foam demonstrated great potential for bone regeneration. Copyright © 2018 Elsevier B.V. All rights reserved.

Fire retardant polyisocyanurate foam

Science.gov (United States)

Riccitiello, S. R.; Parker, J. A.

1972-01-01

Fire retardant properties of low density polymer foam are increased. Foam has pendant nitrile groups which form thermally-stable heterocyclic structures at temperature below degradation temperature of urethane linkages.

The effect of moisture absorption on the physical properties of polyurethane shape memory polymer foams

International Nuclear Information System (INIS)

Yu, Ya-Jen; Hearon, Keith; Maitland, Duncan J; Wilson, Thomas S

2011-01-01

The effect of moisture absorption on the glass transition temperature (T g ) and the stress/strain behavior of network polyurethane shape memory polymer (SMP) foams has been investigated. With our ultimate goal of engineering polyurethane SMP foams for use in blood-contacting environments, we have investigated the effects of moisture exposure on the physical properties of polyurethane foams. To the best of our knowledge, this study is the first to investigate the effects of moisture absorption at varying humidity levels (non-immersion and immersion) on the physical properties of polyurethane SMP foams. The SMP foams were exposed to differing humidity levels for varying lengths of time, and they exhibited a maximum water uptake of 8.0% (by mass) after exposure to 100% relative humidity for 96 h. Differential scanning calorimetry results demonstrated that water absorption significantly decreased the T g of the foam, with a maximum water uptake shifting the T g from 67 to 5 °C. Samples that were immersed in water for 96 h and immediately subjected to tensile testing exhibited 100% increases in failure strains and 500% decreases in failure stresses; however, in all cases of time and humidity exposure, the plasticization effect was reversible upon placing moisture-saturated samples in 40% humidity environments for 24 h

INFLUENCE OF THE CEMENT TYPE ON THE CHARACTERISTICS OF THE MINERAL FOAM APPLICABLE IN FOAMED CERAMIC TECHNOLOGIES

Directory of Open Access Journals (Sweden)

Korolev Evgeniy Valer'evich

2012-10-01

Full Text Available The subject of the research is the influence of the type of Portland cement, as well as the nature and concentration of additives that represent electrolytes and polymers, onto the foam stability. The project is implemented within the framework of the research of foamed ceramic. Detailed explanation of the influence pattern is provided. The research performed by the authors has generated the following findings. Besides the rheological properties of the solution, chemical interaction between the mix components must be taken into account in the course of development of the best foamed ceramic mix composition, as chemical processes produce a substantial influence onto the foam stability. Polymer additives based on liquid carbamyde-formaldehyde and polyacrylamide substantially improve the quality of the foam mineralized by the particles of the cement binder. They also assure the foam stability rate sufficient for the formation of a high-quality foamed material.

Preparation and characterization of starch-based loose-fill packaging foams

Science.gov (United States)

Fang, Qi

Regular and waxy corn starches were blended in various ratios with biodegradable polymers including polylactic acid (PLA), Eastar Bio Copolyester 14766 (EBC) and Mater-Bi ZF03U (MBI) and extruded with a C. W. Brabender laboratory twin screw extruder using a 3-mm die nozzle at 150°C and 150 rev/min. Physical characteristics including radial expansion, unit density and bulk density and water solubility index, water absorption characteristics, mechanical properties including compressibility, Young's modulus, spring index, bulk compressibility and bulk spring index and abrasion resistance were investigated as affected by the ingredient formulations, i.e. type of polymers, type of starches, polymer to starch ratio and starch moisture content. A completely randomized factorial blocking experimental design was used. Fifty-four treatments resulted. Each treatment was replicated three times. SAS statistical software package was used to analyze the data. Foams made of waxy starch had better radial expansion, lower unit density and bulk density than did foams made of regular starch. Regular starch foams had significantly lower water solubility index than did the waxy starch foams. PLA-starch foams had the lowest compressibility and Young's modulus. MBI-starch foams were the most rigid. All foams had excellent spring indices and bulk spring indices which were comparable to the spring index of commercial expanded polystyrene foam. Correlations were established between the foam mechanical properties and the physical characteristics. Foam compressibility and Young's modulus decreased as increases in radial expansion and decreases in unit and bulk densities. Their relationships were modeled with power law equations. No correlation was observed between spring index and bulk spring index and foam physical characteristics. MBI-starch foams had the highest equilibrium moisture content. EBC-starch and PLA-starch foams had similar water absorption characteristics. No significant

Preparation and characterization of PMMA graded microporous foams via one-step supercritical carbon dioxide foaming

International Nuclear Information System (INIS)

Yuan Huan; Li Junguo; Xiong Yuanlu; Luo Guoqiang; Shen Qiang; Zhang Lianmeng

2013-01-01

Supercritical carbon dioxide (ScCO 2 ) foaming which is inexpensive and environmental friendly has been widely used to prepare polymer-based microporous materials. In this paper, PMMA graded microporous materials were foamed by PMMA matrix after an unstable saturation process which was done under supercritical condition of 28MPa and 50 °C. The scanning electron microscopy (SEM) was utilized to observe the morphology of the graded foam. A gas adsorption model was proposed to predict the graded gas concentration in the different region of the polymer matrix. The SEM results showed that the solid and foam region of the graded foam can be connected without laminated layers. With the increasing thickness position of the graded microporous foam, the cell size increased from 3.4 to 27.5 μm, while the cell density decreased from 1.04 × 10 9 to 1.96 × 10 7 cells/cm 3 . It also found that the gradient microporous structure of the foam came from graded gas concentration which was obtained in the initial saturation process.

Magnetic Resonance Flow Velocity and Temperature Mapping of a Shape Memory Polymer Foam Device

Energy Technology Data Exchange (ETDEWEB)

Small IV, W; Gjersing, E; Herberg, J L; Wilson, T S; Maitland, D J

2008-10-29

Interventional medical devices based on thermally responsive shape memory polymer (SMP) are under development to treat stroke victims. The goals of these catheter-delivered devices include re-establishing blood flow in occluded arteries and preventing aneurysm rupture. Because these devices alter the hemodynamics and dissipate thermal energy during the therapeutic procedure, a first step in the device development process is to investigate fluid velocity and temperature changes following device deployment. A laser-heated SMP foam device was deployed in a simplified in vitro vascular model. Magnetic resonance imaging (MRI) techniques were used to assess the fluid dynamics and thermal changes associated with device deployment. Spatial maps of the steady-state fluid velocity and temperature change inside and outside the laser-heated SMP foam device were acquired. Though non-physiological conditions were used in this initial study, the utility of MRI in the development of a thermally-activated SMP foam device has been demonstrated.

Preparation And Characterization Of Silicon Carbide Foam By Using In-Situ Generated Polyurethane Foam

Directory of Open Access Journals (Sweden)

Shalini Saxena

2015-08-01

Full Text Available Abstract The open cell silicon carbide SiC foam was prepared using highly crosslinked hybrid organic- inorganic polymer resin matrix. As inorganic polymer polycarbosilane was taken and organic resin was taken as a mixture of epoxy resin and diisocyanates. The resultant highly crosslinked hybrid resin matrix on heating and subsequently on pyrolysis yielded open cell silicon carbide foam. The hybrid resin matrix was characterized by Fourier transform Infrared Spectroscopy FT-IR and thermal properties i.e. Thermogravimetric analysis TGA amp Differential Scanning Calorimetry DSC were also studied. The morphological studies of silicon carbide ceramic foam were carried out using X-ray Spectroscopy XRD amp Scanning Electron Microscopy SEM.

Progress in development of low density polymer foams for the ICF Program

International Nuclear Information System (INIS)

Letts, S.A.; Lucht, L.M.; Morgan, R.J.; Cook, R.C.; Tillotson, T.M.; Mercer, M.B.; Miller, D.E.

1985-01-01

This report describes the status of CH foam development with densities of 50 mg/ccs and cell sizes of 1 μm for the ICF Program. Two approaches that both involve polymer phase separation are being investigated. The first involves a gelation-crystallization of high molecular weight polyethylene from solution, whereas the second approach involves the modification of the phase separation morphology of water-styrene emulsions by molecularly-tailored surfactants followed by polymerization of the continuous styrene phase

Fire-retardant foams

Science.gov (United States)

Gagliani, J.

1978-01-01

Family of polyimide resins are being developed as foams with exceptional fire-retardant properties. Foams are potentially useful for seat cushions in aircraft and ground vehicles and for applications such as home furnishings and building-construction materials. Basic formulations can be modified with reinforcing fibers or fillers to produce celular materials for variety of applications. By selecting reactants, polymer structure can be modified to give foams with properties ranging from high resiliency and flexibility to brittleness and rigidity.

New Approaches to Aluminum Integral Foam Production with Casting Methods

Directory of Open Access Journals (Sweden)

Ahmet Güner

2015-08-01

Full Text Available Integral foam has been used in the production of polymer materials for a long time. Metal integral foam casting systems are obtained by transferring and adapting polymer injection technology. Metal integral foam produced by casting has a solid skin at the surface and a foam core. Producing near-net shape reduces production expenses. Insurance companies nowadays want the automotive industry to use metallic foam parts because of their higher impact energy absorption properties. In this paper, manufacturing processes of aluminum integral foam with casting methods will be discussed.

Effect of slurries density on the properties of ceramic foam produced via polymer replication method

International Nuclear Information System (INIS)

Mohd Al Amin Muhammad Nor; Lee Chain Hong; Hazizan Md Akil; Zainal Ariffin Ahmad

2007-01-01

Ceramic foams are a class of high porosity materials that are used or being considered for a wide range of technological applications. Ceramic foam was produce by polymer replication method. In this process, commercial polymeric sponge was use as template, dipping with ceramic particles slurry, drying and then sintered to yield a replica of the original foams. The study was focus on the fabrication of different density of ceramic foams by varying the density of ceramic slurries (1.1876, 1.2687, 1.3653 and 1.5295 g/cm?3). Properties of ceramic foam produced such as density was characterized accordingly to ASTM C 271-94 and porosity were characterized using Archimedes methods. Compressive and bending strength was performed accordingly to ASTM C1161-94 and C773-88 (1999), respectively. The morphological study was performed using Scanning Electron Microscopy (SEM) and EDX. Density of ceramic foams produced was about 0.5588 and 1.1852 g/cm 3 , where as porosity was around 26.28 and 70.59 %. Compressive and bending strength was increase from strength also increases from 2.60 to 23.07 MPa and 1.20 to 11.10 MPa, respectively, with increasing of slurries density from 1.1876 to 1.3653 g/cm 3 . The SEM micrographs show that the cells structure become denser as the slurries density increased. EDX proved that the ceramic used is porcelain. As conclusion, increasing in slurries density produced ceramic foams with good mechanical properties such as compressive and bending strength and denser body. (Author)

Nonlinear Thermo-mechanical Finite Element Analysis of Polymer Foam Cored Sandwich Structures including Geometrical and Material Nonlinearity

DEFF Research Database (Denmark)

Palleti, Hara Naga Krishna Teja; Thomsen, Ole Thybo; Taher, Siavash Talebi

In this paper, polymer foam cored sandwich structures with fibre reinforced composite face sheets subjected to combined mechanical and thermal loads will be analysed using the commercial FE code ABAQUS® incorporating both material and geometrical nonlinearity. Large displacements and rotations...

Ultra Low Density Shape Memory Polymer Foams With Tunable Physicochemical Properties for Treatment of intracranial Aneurysms

Energy Technology Data Exchange (ETDEWEB)

Singhal, Pooja [Texas A & M Univ., College Station, TX (United States)

2013-12-01

Shape memory polymers (SMPs) are a rapidly emerging class of smart materials that can be stored in a deformed temporary shape, and can actively return to their original shape upon application of an external stimulus such as heat, pH or light. This behavior is particularly advantageous for minimally invasive biomedical applications comprising embolic/regenerative scaffolds, as it enables a transcatheter delivery of the device to the target site. The focus of this work was to exploit this shape memory behavior of polyurethanes, and develop an efficient embolic SMP foam device for the treatment of intracranial aneurysms.In summary, this work reports a novel family of ultra low density polymer foams which can be delivered via a minimally invasive surgery to the aneurysm site, actuated in a controlled manner to efficiently embolize the aneurysm while promoting physiological fluid/blood flow through the reticulated/open porous structure, and eventually biodegrade leading to complete healing of the vasculature.

Fluid flow through replicated microcellular materials in the Darcy-Forchheimer regime

International Nuclear Information System (INIS)

Weber, L.; Ingram, D.; Guardia, S.; Athanasiou-Ioannou, A.; Mortensen, A.

2017-01-01

We extend here a “bottleneck” flow model derived earlier for incompressible fluids flowing under creeping flow conditions [Despois, J. and Mortensen, A: Acta Materialia 53 (2005) 1381] to flow regimes where inertial losses are no longer negligible, causing the governing flow law to deviate from Darcy's law and become the Darcy-Forchheimer law. The proposed law is compared with measurements of the Darcian permeability K_D and of the Forchheimer coefficient C in forced-flow of air through microcellular aluminium made by the replication process. The geometrical features of the cellular medium are varied in terms of volume fraction of porosity (in the range of 0.66–0.86) and the average cell diameter from (108–425 μm). As found previously in measurements with water, the Darcy permeability of the foams for airflow is also reasonably well captured by the model. In the Forchheimer-regime the model gives good quantitative agreement with data if one assumes that the amount of air kinetic energy that is dissipated when passing across each bottleneck linking one pore to its neighbour along the fluid flow path corresponds to the difference, in a stream of constant cross-sectional area, between a uniform fluid velocity profile and the non-uniform profile that is created by the no-slip condition along the window boundary.

Ultra low density biodegradable shape memory polymer foams with tunable physical properties

Science.gov (United States)

Singhal, Pooja; Wilson, Thomas S.; Cosgriff-Hernandez, Elizabeth; Maitland, Duncan J.

2017-12-12

Compositions and/or structures of degradable shape memory polymers (SMPs) ranging in form from neat/unfoamed to ultra low density materials of down to 0.005 g/cc density. These materials show controllable degradation rate, actuation temperature and breadth of transitions along with high modulus and excellent shape memory behavior. A method of m ly low density foams (up to 0.005 g/cc) via use of combined chemical and physical aking extreme blowing agents, where the physical blowing agents may be a single compound or mixtures of two or more compounds, and other related methods, including of using multiple co-blowing agents of successively higher boiling points in order to achieve a large range of densities for a fixed net chemical composition. Methods of optimization of the physical properties of the foams such as porosity, cell size and distribution, cell openness etc. of these materials, to further expand their uses and improve their performance.

Data characterizing tensile behavior of cenosphere/HDPE syntactic foam.

Science.gov (United States)

Kumar, B R Bharath; Doddamani, Mrityunjay; Zeltmann, Steven E; Gupta, Nikhil; Ramakrishna, Seeram

2016-03-01

The data set presented is related to the tensile behavior of cenosphere reinforced high density polyethylene syntactic foam composites "Processing of cenosphere/HDPE syntactic foams using an industrial scale polymer injection molding machine" (Bharath et al., 2016) [1]. The focus of the work is on determining the feasibility of using an industrial scale polymer injection molding (PIM) machine for fabricating syntactic foams. The fabricated syntactic foams are investigated for microstructure and tensile properties. The data presented in this article is related to optimization of the PIM process for syntactic foam manufacture, equations and procedures to develop theoretical estimates for properties of cenospheres, and microstructure of syntactic foams before and after failure. Included dataset contains values obtained from the theoretical model.

Results of radiotherapy and chemotherapy in microcellular bronchial carcinoma

International Nuclear Information System (INIS)

Topuz, E.; Aldemir, O.; Toere, G.; Bilge, N.; Kural, N.

1986-01-01

At the Radiotherapeutic Department of the Faculty of Medicine in Istanbul, 35 masculine patients with microcellular bronchial carcinoma, limited disease, were treated for two years, i.e. between 1980 and 1981, with a combination of radiotherapy and chemotherapy. Nine out of these patients are tumor-free after at least 46 months, i.e. about four years. This corresponds to a tumor-free survival rate of 25.7%. (orig.) [de

Three-Dimensional Graphene Foam-Polymer Composite with Superior Deicing Efficiency and Strength.

Science.gov (United States)

Bustillos, Jenniffer; Zhang, Cheng; Boesl, Benjamin; Agarwal, Arvind

2018-02-07

The adhesion of ice severely compromises the aerodynamic performance of aircrafts operating under critically low-temperature conditions to their surfaces. In this study, highly thermally and electrically conductive graphene foam (GrF) polymer composite is fabricated. GrF-polydimethylsiloxane (PDMS) deicing composite exhibits superior deicing efficiency of 477% and electrical conductivities of 500 S m -1 with only 0.1 vol % graphene foam addition as compared to other nanocarbon-based deicing systems. The three-dimensional interconnected architecture of GrF allows the effective deicing of surfaces by employing low power densities (0.2 W cm -2 ). Electrothermal stability of the GrF-PDMS composite was proven after enduring 100 cycles of the dc loading-unloading current. Moreover, multifunctional GrF-PDMS deicing composite provides simultaneous mechanical reinforcement by the effective transfer and absorption of loads resulting in a 23% and 18% increase in elastic modulus and tensile strength, respectively, as compared to pure PDMS. The enhanced efficiency of the GrF-PDMS deicing composite is a novel alternative to current high-power consumption deicing systems.

Method of forming a continuous polymeric skin on a cellular foam material

Science.gov (United States)

Duchane, David V.; Barthell, Barry L.

1985-01-01

Hydrophobic cellular material is coated with a thin hydrophilic polymer skin which stretches tightly over the outer surface of the foam but which does not fill the cells of the foam, thus resulting in a polymer-coated foam structure having a smoothness which was not possible in the prior art. In particular, when the hydrophobic cellular material is a specially chosen hydrophobic polymer foam and is formed into arbitrarily chosen shapes prior to the coating with hydrophilic polymer, inertial confinement fusion (ICF) targets of arbitrary shapes can be produced by subsequently coating the shapes with metal or with any other suitable material. New articles of manufacture are produced, including improved ICF targets, improved integrated circuits, and improved solar reflectors and solar collectors. In the coating method, the cell size of the hydrophobic cellular material, the viscosity of the polymer solution used to coat, and the surface tensin of the polymer solution used to coat are all very important to the coating.

Characterization of thermoplastic polyurethane/polylactic acid (TPU/PLA) tissue engineering scaffolds fabricated by microcellular injection molding

International Nuclear Information System (INIS)

Mi, Hao-Yang; Salick, Max R.; Jing, Xin; Jacques, Brianna R.; Crone, Wendy C.; Peng, Xiang-Fang; Turng, Lih-Sheng

2013-01-01

Polylactic acid (PLA) and thermoplastic polyurethane (TPU) are two kinds of biocompatible and biodegradable polymers that can be used in biomedical applications. PLA has rigid mechanical properties while TPU possesses flexible mechanical properties. Blended TPU/PLA tissue engineering scaffolds at different ratios for tunable properties were fabricated via twin screw extrusion and microcellular injection molding techniques for the first time. Multiple test methods were used to characterize these materials. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of the two components in the blends; differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirmed the immiscibility between the TPU and PLA. Scanning electron microscopy (SEM) images verified that, at the composition ratios studied, PLA was dispersed as spheres or islands inside the TPU matrix and that this phase morphology further influenced the scaffold's microstructure and surface roughness. The blends exhibited a large range of mechanical properties that covered several human tissue requirements. 3T3 fibroblast cell culture showed that the scaffolds supported cell proliferation and migration properly. Most importantly, this study demonstrated the feasibility of mass producing biocompatible PLA/TPU scaffolds with tunable microstructures, surface roughnesses, and mechanical properties that have the potential to be used as artificial scaffolds in multiple tissue engineering applications. - Highlights: • Microcellular injection molding was used to fabricate tissue engineering scaffolds. • TPU/PLA tissue engineering scaffolds with tunable properties were fabricated. • Multiple test methods were used to characterize the scaffolds. • The biocompatibility of the scaffolds was confirmed by fibroblast cell culture. • Scaffolds produced have the potential to be used in multiple tissue applications

Polymer-Derived Silicoboron Carbonitride Foams for CO2 Capture: From Design to Application as Scaffolds for the in Situ Growth of Metal-Organic Frameworks.

Science.gov (United States)

Sandra, Fabien; Depardieu, Martin; Mouline, Zineb; Vignoles, Gérard L; Iwamoto, Yuji; Miele, Philippe; Backov, Rénal; Bernard, Samuel

2016-06-06

A template-assisted polymer-derived ceramic route is investigated for preparing a series of silicoboron carbonitride (Si/B/C/N) foams with a hierarchical pore size distribution and tailorable interconnected porosity. A boron-modified polycarbosilazane was selected to impregnate monolithic silica and carbonaceous templates and form after pyrolysis and template removal Si/B/C/N foams. By changing the hard template nature and controlling the quantity of polymer to be impregnated, controlled micropore/macropore distributions with mesoscopic cell windows are generated. Specific surface areas from 29 to 239 m(2)  g(-1) and porosities from 51 to 77 % are achieved. These foams combine a low density with a thermal insulation and a relatively good thermostructural stability. Their particular structure allowed the in situ growth of metal-organic frameworks (MOFs) directly within the open-cell structure. MOFs offered a microporosity feature to the resulting Si/B/C/N@MOF composite foams that allowed increasing the specific surface area to provide CO2 uptake of 2.2 %. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Supercritical Carbon Dioxide Assisted Processing of Silica/PMMA Nanocomposite Foams

Science.gov (United States)

Rende, Deniz; Schadler, Linda S.; Ozisik, Rahmi

2012-02-01

Polymer nanocomposite foams receive considerable attention in both scientific and industrial communities. These structures are defined as closed or open cells (pores) surrounded by bulk material and are widely observed in nature in the form of bone structure, sponge, corals and natural cork. Inspired by these materials, polymer nanocomposite foams are widely used in advanced applications, such as bone scaffolds, food packaging and transportation materials due to their lightweight and enhanced mechanical, thermal, and electrical properties compared to bulk polymer foams. The presence of the nanosized fillers facilitates heterogeneous bubble nucleation as a result, the number of bubbles increases while the average bubble size decreases. Therefore, the foam morphology can be controlled by the size, concentration, and surface chemistry of the nanofiller. In the current study, we used supercritical carbon dioxide as a foaming agent for silica/poly(methyl methacrylate), PMMA, foams. The silica nanoparticles were chemically modified by fluoroalkane chains to make them CO2-philic. The surface coverage was controlled via tethering density, and the effect of silica surface coverage and concentration on foam morphology was investigated through scanning electron microscopy and image processing. Results indicated that nanofiller concentration and filler surface chemistry (CO2-philicity) had tremendous effect on foam morphology but surface coverage did not have any effect.

Biodegradable polymeric foam with food waste; Shokumotsu zansa wo mochiita seibunkai kobunshi hahhotai

Energy Technology Data Exchange (ETDEWEB)

Mishima, Kenji; Matsuyama, Kiyoshi; Yamauchi, Satoru; Takarabe, Shin' ichi

1999-09-01

A huge amount of food waste such as tea and beer dregs becomes a serious problem because of the lack of industrial waste space in Japan. On the other hand, the new polymeric foam is expected to be developed since the dangerous pollution of endorphin disrupters from industrial polymer foam is pointed out. In this work, we try to develop the biodegradable polymeric foam using the tea and beer dregs as secondary resources. And we examined the degradability of biodegradable polymer in the hydrothermal water for fundamental knowledge of polymeric foam production. We used an extruder equipped with a high pressure device to make the polymeric foam. And we examined the effect of the component ratio on the foam properties, foaming rate, strength, shrinkage rate, water-resistant. As a result, it was found that the amount of polymer is effective of quality of form and the biodegradability can be controlled by the amount of water and temperature. (author)

Foam-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

Science.gov (United States)

Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

2015-06-02

Foam-based adsorbents and a related method of manufacture are provided. The foam-based adsorbents include polymer foam with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the foam-based adsorbents includes irradiating polymer foam, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Foam-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

Mechanical and thermal properties of conventional and microcellular injection molded poly (lactic acid)/poly (ε-caprolactone) blends.

Science.gov (United States)

Zhao, Haibin; Zhao, Guoqun

2016-01-01

In view of their complementary properties, blending polylactide (PLA) with poly (ε-caprolactone) (PCL) becomes a good choice to improve PLA's properties without compromising its biodegradability. A series of blends of biodegradable PLA and PCL with different mass fraction were prepared by melt mixing. Standard tensile bars were produced by both conventional and microcellular injection molding to study their mechanical and thermal properties. With the increase in PCL content, the blend showed decreased tensile strength and modulus; however, elongation was dramatically increased. With the addition of PCL, the failure mode changed from brittle fracture of the neat PLA to ductile fracture of the blend as demonstrated by tensile test. Various theoretical models based on dispersion and interface adhesion were used to predict the Young's modulus and the results shows the experimental data are consistent with the predictions of the foam model and Kerner-Uemura-Takayangi model. The thermal behavior of the blends was investigated by DSC and TGA. The melting temperature and the degree of crystallinity of PCL in the PLA/PCL did not significantly change with the PCL content increasing in the whole range of blends composition. Copyright © 2015 Elsevier Ltd. All rights reserved.

Applications of polyamide/cellulose fiber/wollastonite composites for microcellular injection molding

Science.gov (United States)

Herman Winata; Lih-Sheng Turng; Daniel F. Caulfield; Tom Kuster; Rick Spindler; Rod Jacobson

2003-01-01

In this study, a cellulose-fiber-reinforced Polyamide-6 (PA-6) composite, a hybrid composite (PA-6/cellulose/Wollastonite), and the neat PA-6 resin were injection molded into ASTM test–bar samples with conventional and microcellular injection molding. The impact and tensile strengths of molded samples were measured and the Scanning Electron Microscopy (SEM) images were...

Preparation and properties of polymer foams for ICF targets

International Nuclear Information System (INIS)

Letts, S.A.; Lucht, L.M.

1986-09-01

Low density small cell sized foams were developed to localize the liquid DT layer in a direct drive wetted foam laser fusion target. We have developed foams made from ultrahigh molecular weight polyethylene gels and polystyrene inverse emulsions. Materials in the density range of from 0.020 to 0.300 g/cc were prepared and characterized for cell size, mechanical properties, machinability, specific surface area, and wetting. Foams with a density of 0.05 g/cc were made with a cell size of less than 5 μm. A cell structure model was developed which relates the density and specific surface area to cell size and cell wall thickness. Wetting tests in organic solvents and in liquid hydrogen were used to characterize the capillary pressure, pore structure and uniformity of the foams. 13 refs., 9 figs., 2 tabs

CO2 Induced Foaming Behavior of Polystyrene near the Glass Transition

Directory of Open Access Journals (Sweden)

Salah Al-Enezi

2017-01-01

Full Text Available This paper examines the effect of high-pressure carbon dioxide on the foaming process in polystyrene near the glass transition temperature and the foaming was studied using cylindrical high-pressure view cell with two optical windows. This technique has potential applications in the shape foaming of polymers at lower temperatures, dye impregnation, and the foaming of polystyrene. Three sets of experiments were carried out at operating temperatures of 50, 70, and 100°C, each over a range of pressures from 24 to 120 bar. Foaming was not observed when the polymer was initially at conditions below Tg but was observed above Tg. The nucleation appeared to occur randomly leading to subsequent bubble growth from these sites, with maximum radius of 0.02–0.83 mm. Three models were applied on the foaming experimental data. Variable diffusivity and viscosity model (Model C was applied to assess the experimental data with the WLF equation. The model shows very good agreement by using realistic parameter values. The expansion occurs by diffusion of a dissolved gas from the supersaturated polymer envelope into the bubble.

Application of metal foam heat exchangers for a high-performance liquefied natural gas regasification system

International Nuclear Information System (INIS)

Kim, Dae Yeon; Sung, Tae Hong; Kim, Kyung Chun

2016-01-01

The intermediate fluid vaporizer has wide applications in the regasification of LNG (liquefied natural gas). The heat exchanger performance is one of the main contributors to the thermodynamic and cost effectiveness of the entire LNG regasification system. Within the paper, the authors discuss a new concept for a compact heat exchanger with a micro-cellular structure medium to minimize volume and mass and to increase thermal efficiency. Numerical calculations have been conducted to design a metal-foam filled plate heat exchanger and a shell-and-tube heat exchanger using published experimental correlations. The geometry of both heat exchangers was optimized using the conditions of thermolators in LNG regasification systems. The heat transfer and pressure drop performance was predicted to compare the heat exchangers. The results show that the metal-foam plate heat exchanger has the best performance at different channel heights and mass flow rates of fluid. In the optimized configurations, the metal-foam plate heat exchanger has a higher heat transfer rate and lower pressure drop than the shell-and-tube heat exchanger as the mass flow rate of natural gas is increased. - Highlights: • A metal foam heat exchanger is proposed for LNG regasification system. • Comparison was made with a shell and tube heat exchanger. • Heat transfer and pressure drop characteristics were estimated. • The geometry of both heat exchangers is optimized for thermolators. • It can be used as a compact and high performance thermolators.

Polymer microcapsules with "foamed" membranes.

Science.gov (United States)

Lavergne, Fleur-Marie; Cot, Didier; Ganachaud, François

2007-06-05

This article describes the preparation of capsules displaying craters at their surfaces and independent holes inside their membranes. These poly(methylmethacrylate) capsules of 20 to 200 microm diameter are prepared by a solvent evaporation process and typically contain a dispersant, polyvinyl alcohol, and an excipient, namely, a fatty acid triglyceride (miglyol 812). Spectroscopic methods showed that, depending on the miglyol content, the craters at the surface exhibited sizes of about 1 to 2 microm, whereas the core structure of the membrane changed significantly, typically from "soft-part-of-bread" up to "foamed"-like aspects. Among several spectroscopy techniques, confocal fluorescence microscopy confirmed that the capsules retained the miglyol in their core and not in the craters or holes, even after centrifugation and handling. This technique also showed that holes in the membrane are filled with water. A possible analysis of the "foaming" phenomenon based on the surface tensions of different oils, as well as their optimal hydrophile-lipophile balance (HLBO), is added to generalize the concept.

Supercapacitors based on carbon foams

Science.gov (United States)

Kaschmitter, James L.; Mayer, Steven T.; Pekala, Richard W.

1993-01-01

A high energy density capacitor incorporating a variety of carbon foam electrodes is described. The foams, derived from the pyrolysis of resorcinol-formaldehyde and related polymers, are high density (0.1 g/cc-1.0 g/cc) electrically conductive and have high surface areas (400 m.sup.2 /g-1000 m.sup.2 /g). Capacitances on the order of several tens of farad per gram of electrode are achieved.

Development of partially biodegradable foams from PP/HMSPP blends with natural and synthetic polymers; Desenvolvimento de espumas parcialmente biodegradaveis a partir de blendas de PP/HMSPP com polimeros naturais e sinteticos

Energy Technology Data Exchange (ETDEWEB)

Cardoso, Elizabeth Carvalho Leite

2014-07-01

Polymers are used in various application and in different industrial areas providing enormous quantities of wastes in environment. Among diverse components of residues in landfills are polymeric materials, including Polypropylene, which contribute with 20 to 30% of total volume of solid residues. As polymeric materials are immune to microbial degradation, they remain in soil and in landfills as a semi-permanent residue. Environmental concerning in litter reduction is being directed to renewable polymers development for manufacturing of polymeric foams. Foamed polymers are considered future materials, with a wide range of applications; high density structural foams are specially used in civil construction, in replacement of metal, woods and concrete with a final purpose of reducing materials costs. At present development, it was possible the incorporation of PP/HMSPP polymeric matrix blends with sugarcane bagasse, PHB and PLA, in structural foams production. Thermal degradation at 100, 120 and 160 deg C temperatures was not enough to induce biodegradability. Gamma irradiation degradation, at 50, 100, 200 and 500 kGy showed effective for biodegradability induction. Irradiated bagasse blends suffered surface erosion, in favor of water uptake and consequently, a higher biodegradation in bulk structure. (author)

Comparison of shape memory polymer foam versus bare metal coil treatments in an in vivo porcine sidewall aneurysm model.

Science.gov (United States)

Horn, John; Hwang, Wonjun; Jessen, Staci L; Keller, Brandis K; Miller, Matthew W; Tuzun, Egemen; Hartman, Jonathan; Clubb, Fred J; Maitland, Duncan J

2017-10-01

The endovascular delivery of platinum alloy bare metal coils has been widely adapted to treat intracranial aneurysms. Despite the widespread clinical use of this technique, numerous suboptimal outcomes are possible. These may include chronic inflammation, low volume filling, coil compaction, and recanalization, all of which can lead to aneurysm recurrence, need for retreatment, and/or potential rupture. This study evaluates a treatment alternative in which polyurethane shape memory polymer (SMP) foam is used as an embolic aneurysm filler. The performance of this treatment method was compared to that of bare metal coils in a head-to-head in vivo study utilizing a porcine vein pouch aneurysm model. After 90 and 180 days post-treatment, gross and histological observations were used to assess aneurysm healing. At 90 days, the foam-treated aneurysms were at an advanced stage of healing compared to the coil-treated aneurysms and showed no signs of chronic inflammation. At 180 days, the foam-treated aneurysms exhibited an 89-93% reduction in cross-sectional area; whereas coiled aneurysms displayed an 18-34% area reduction. The superior healing in the foam-treated aneurysms at earlier stages suggests that SMP foam may be a viable alternative to current treatment methods. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1892-1905, 2017. © 2016 Wiley Periodicals, Inc.

Influence of material non-linearity on the thermo-mechanical response of polymer foam cored sandwich structures - FE modelling and preliminary experiemntal results

DEFF Research Database (Denmark)

Palleti, Hara Naga Krishna Teja; Thomsen, Ole Thybo; Fruehmann, Richard.K

In this paper, the polymer foam cored sandwich structures with fibre reinforced composite face sheets will be analyzed using the commercial FE code ABAQUS/Standard® incorporating the material and geometrical non-linearity. Large deformations are allowed which attributes geometric non linearity...

Structural Foams of Biobased Isosorbide-Containing Copolycarbonate

Directory of Open Access Journals (Sweden)

Stefan Zepnik

2017-01-01

Full Text Available Isosorbide-containing copolycarbonate (Bio-PC is a partly biobased alternative to conventional bisphenol A (BPA based polycarbonate (PC. Conventional PC is widely used in polymer processing technologies including thermoplastic foaming such as foam injection molding. At present, no detailed data is available concerning the foam injection molding behavior and foam properties of Bio-PC. This contribution provides first results on injection-molded foams based on isosorbide-containing PC. The structural foams were produced by using an endothermic chemical blowing agent (CBA masterbatch and the low pressure foam injection molding method. The influence of weight reduction and blowing agent concentration on general foam properties such as density, morphology, and mechanical properties was studied. The test specimens consist of a foam core in the center and compact symmetrical shell layers on the sides. The thickness of the foam core increases with increasing weight reduction irrespective of the CBA concentration. The specific (mechanical bending properties are significantly improved and the specific tensile properties can almost be maintained while reducing the density of the injection-molded parts.

Foam shell project: Progress report

International Nuclear Information System (INIS)

Overturf, G.; Reibold, B.; Cook, B.; Schroen-Carey, D.

1994-01-01

The authors report on their work to produce a foam shell target for two possible applications: (1) as liquid-layered cryogenic target on Omega Upgrade, and (2) as a back-up design for the NIF. This target consists of a roughly 1 mm diameter and 100 μm thick spherical low-density foam shell surrounding a central void. The foam will be slightly overfilled with liquid D 2 or DT, the overfilled excess being symmetrically distributed on the inside of the shell and supported by thermal gradient techniques. The outside of the foam is overcoated with full density polymer which must be topologically smooth. The technology for manufacturing this style of foam shell involves microencapsulation techniques and has been developed by the Japanese at ILE. Their goal is to determine whether this technology can be successfully adapted to meet US ICF objectives. To this end a program of foam shell development has been initiated at LLNL in collaboration with both the General Atomics DOE Target Fabrication Contract Corporation and the Target Fabrication Group at LLE

The effect of crystallinity on cell growth in semi-crystalline microcellular foams by solid-state process: modeling and numerical simulation

Science.gov (United States)

Rezvanpanah, Elham; Ghaffarian Anbaran, S. Reza

2017-11-01

This study establishes a model and simulation scheme to describe the effect of crystallinity as one of the most effective parameters on cell growth phenomena in a solid batch foaming process. The governing model of cell growth dynamics, based on the well-known ‘Cell model’, is attained in details. To include the effect of crystallinity in the model, the properties of the polymer/gas mixtures (i.e. solubility, diffusivity, surface tension and viscosity) are estimated by modifying relations to consider the effect of crystallinity. A finite element-finite difference (FEFD) method is employed to solve the highly nonlinear and coupled equations of cell growth dynamics. The proposed simulation is able to evaluate all properties of the system at the given process condition and uses them to calculate the cell size, pressure and gas concentration gradient with time. A high-density polyethylene/nitrogen (HDPE/N2) system is used herein as a case study. Comparing the simulation results with the others works and experimental results verify the accuracy of the simulation scheme. The cell growth is a complicated combination of several phenomena. This study attempted to reach a better understanding of cell growth trend, driving and retarding forces and the effect of crystallinity on them.

Dynamics of poroelastic foams

Science.gov (United States)

Forterre, Yoel; Sobac, Benjamin

2010-11-01

Soft poroelastic structures are widespread in biological tissues such as cartilaginous joints in bones, blood-filled placentae or plant organs. Here we investigate the dynamics of open elastic foams immersed in viscous fluids, as model soft poroelastic materials. The experiment consists in slowly compacting blocs of polyurethane solid foam embedded in silicon oil-tanks and studying their relaxation to equilibrium when the confining stress is suddenly released. Measurements of the local fluid pressure and foam velocity field are compared with a simple two-phase flow approach. For small initial compactions, the results show quantitative agreement with the classical diffusion theory of soil consolidation (Terzaghi, Biot). On the other hand, for large initial compactions, the dynamics exhibits long relaxation times and decompaction fronts, which are mainly controlled by the highly non-linear mechanical response of the foam. The analogy between this process and the evaporation of a polymer melt close to the glass transition will be briefly discussed.

Robust Vacuum-/Air-Dried Graphene Aerogels and Fast Recoverable Shape-Memory Hybrid Foams.

Science.gov (United States)

Li, Chenwei; Qiu, Ling; Zhang, Baoqing; Li, Dan; Liu, Chen-Yang

2016-02-17

New graphene aerogels can be fabricated by vacuum/air drying, and because of the mechanical robustness of the graphene aerogels, shape-memory polymer/graphene hybrid foams can be fabricated by a simple infiltration-air-drying-crosslinking method. Due to the superelasticity, high strength, and good electrical conductivity of the as-prepared graphene aerogels, the shape-memory hybrid foams exhibit excellent thermotropical and electrical shape-memory properties, outperforming previously reported shape-memory polymer foams. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low-density carbonized composite foams for direct-drive laser ICF targets

International Nuclear Information System (INIS)

Kong, Fung-Ming.

1989-03-01

The design for a direct-drive, high-gain laser inertial confinement fusion target calls for the use of a low-density, low-atomic-number foam to confine and stabilize liquid deuterium-tritium (DT) in a spherical-shell configuration. Over the past two years, we have successfully developed polystyrene foams (PS) and carbonized resorcinol-formaldehyde foams (CRF) for that purpose. Both candidates are promising materials with unique characteristics. PS has superior mechanical strength and machinability, but its relatively large thermal contraction is a significant disadvantage. CRF has outstanding wettability and dimensional stability in liquid DT; yet it is much more fragile than PS. To combine the strengths of both materials, we have recently developed a polymer composite foam which exceeds PS in mechanical strength, but retains the wettability and dimension stability of CRF. This paper will discuss the preparation, structure, and properties of the polymer composite foams. 5 refs., 1 fig., 1 tab

Extraction of uranium from aqueous solution by phosphonic acid-imbedded polyurethane foam

International Nuclear Information System (INIS)

Katragadda, S.; Gesser, H.D.; Chow, A.

1997-01-01

Phenylphosphonic acid was imbedded into the matrix of the polyurethane foam during the fabrication process of the polymer. The extraction of uranium by phosphonic acid-imbedded polyurethane foam and blank polyurethane (i.e., foam without phosphonic acid functional groups) was investigated. Phosphonic acid-imbedded foam showed superior extractability of uranium from solutions with pH = 7.0 ± 1.5 over a wide range of temperatures. (author)

Polyimide-Foam/Aerogel Composites for Thermal Insulation

Science.gov (United States)

Williams, Martha; Fesmire, James; Sass, Jared; Smith, Trent; Weoser. Erol

2009-01-01

Composites of specific types of polymer foams and aerogel particles or blankets have been proposed to obtain thermal insulation performance superior to those of the neat polyimide foams. These composites have potential to also provide enhanced properties for vibration dampening or acoustic attenuation. The specific type of polymer foam is denoted "TEEK-H", signifying a series, denoted H, within a family of polyimide foams that were developed at NASA s Langley Research Center and are collectively denoted TEEK (an acronym of the inventors names). The specific types of aerogels include Nanogel aerogel particles from Cabot Corporation in Billerica, MA. and of Spaceloft aerogel blanket from Aspen Aerogels in Northborough, MA. The composites are inherently flame-retardant and exceptionally thermally stable. There are numerous potential uses for these composites, at temperatures from cryogenic to high temperatures, in diverse applications that include aerospace vehicles, aircraft, ocean vessels, buildings, and industrial process equipment. Some low-temperature applications, for example, include cryogenic storage and transfer or the transport of foods, medicines, and chemicals. Because of thermal cycling, aging, and weathering most polymer foams do not perform well at cryogenic temperatures and will undergo further cracking over time. The TEEK polyimides are among the few exceptions to this pattern, and the proposed composites are intended to have all the desirable properties of TEEK-H foams, plus improved thermal performance along with enhanced vibration or acoustic-attenuation performance. A composite panel as proposed would be fabricated by adding an appropriate amount of TEEK friable balloons into a mold to form a bottom layer. A piece of flexible aerogel blanket material, cut to the desired size and shape, would then be placed on the bottom TEEK layer and sandwiched between another top layer of polyimide friable balloons so that the aerogel blanket would become

Morphologies, Processing and Properties of Ceramic Foams and Their Potential as TPS Materials

Science.gov (United States)

Stackpoole, Mairead; Simoes, Conan R.; Johnson, Sylvia M.

2002-01-01

The current research is focused on processing ceramic foams with compositions that have potential as a thermal protection material. The use of pre-ceramic polymers with the addition of sacrificial blowing agents or sacrificial fillers offers a viable approach to form either open or closed cell insulation. Our work demonstrates that this is a feasible method to form refractory ceramic foams at relatively low processing temperatures. It is possible to foam complex shapes then pyrolize the system to form a ceramic while retaining the shape of the unfired foam. Initial work focused on identifying suitable pre-ceramic polymers with desired properties such as ceramic yield and chemical make up of the pyrolysis product after firing. We focused on making foams in the Si system (Sic, Si02, Si-0-C), which is in use in current acreage TPS systems. Ceramic foams with different architectures were formed from the pyrolysis of pre-ceramic polymers at 1200 C in different atmospheres. In some systems a sacrificial polyurethane was used as the blowing agent. We have also processed foams using sacrificial fillers to introduce controlled cell sizes. Each sacrificial filler or blowing agent leads to a unique morphology. The effect of different fillers on foam morphologies and the characterization of these foams in terms of mechanical and thermal properties are presented. We have conducted preliminary arc jet testing on selected foams with the materials being exposed to typical re-entry conditions for acreage TPS and these results will be discussed. Foams processed using these approaches have bulk densities ranging from 0.15 to 0.9 g/cm3 and cell sizes ranging from 5 to 500 pm. Compression strengths ranged from 2 to 7 MPa for these systems. Finally, preliminary oxidation studies have been conducted on selected systems and will be discussed.

Thermal assault and polyurethane foam-evaluating protective mechanisms

International Nuclear Information System (INIS)

Williamson, C.L.; Iams, Z.L.

2004-01-01

Rigid polyurethane foam utilizes a variety of mechanisms to mitigate the thermal assault of a ''regulatory burn''. Polymer specific heat and foam k-factor are of limited usefulness in predicting payload protection. Properly formulated rigid polyurethane foam provides additional safeguards by employing ablative mechanisms which are effective even when the foam has been crushed or fractured as a result of trauma. The dissociative transitions from polymer to gas and char, and the gas transport of heat from inside the package out into the environment are also thermal mitigators. Additionally, the in-situ production of an intumescent, insulative, carbonaceous char, confers thermal protection even when a package's outer steel skin has been breached. In this test program, 19 liter, ''Five gallon'' steel pails are exposed on one end to the flame of an ''Oil Burner'' as described in the US Federal Aviation Administration (FAA) ''Aircraft Materials Fire Test Handbook''. When burning 2 diesel at a nominal rate of 8.39 kg (18.5 pounds)/hr, the burner generates a high emissivity flame that impinges on the pail face with the thermal intensity of a full scale pool-fire environment. Results of these tests, TGA and MDSC analysis on the subject foams are reported, and their relevance to full size packages and pool fires are discussed

Modification of Foamed Articles Based on Cassava Starch

International Nuclear Information System (INIS)

Ponce, P.

2006-01-01

This work reports the influence of radiation, plasticizers and poly vinyl alcohol (PVA) on the barrier properties [water vapour permeability (WVP)) and mechanical properties (tensile strength and elongation; compression resistance and flexibility) of foamed articles based on cassava starch. The starch foam was obtained by thermopressing process. Poly ethylene glycol (PEG, 300) was selected as plasticizer and water was necessary for the preparation of the foams. The foamed articles based on cassava starch were irradiated at low doses of 2 and 5 kGy, commonly used in food irradiation. The mechanical properties of starch foams are influenced by the plasticizer concentration and by irradiation dose. An increase in PEG content showed a considerable increase in elongation percentage and a decrease in the tensile strength of the foams; also increase the permeability of the foams in water. After irradiation, the barrier properties and mechanical properties of the foams were improved due to chemical reactions among polymer molecules. Irradiated starch cassava foams with poly vinyl alcohol (PVA) have good flexibility and low water permeability. WVP can be reduced by low doses of gamma radiation

Silica-Assisted Nucleation of Polymer Foam Cells with Nanoscopic Dimensions: Impact of Particle Size, Line Tension, and Surface Functionality.

Science.gov (United States)

Liu, Shanqiu; Eijkelenkamp, Rik; Duvigneau, Joost; Vancso, G Julius

2017-11-01

Core-shell nanoparticles consisting of silica as core and surface-grafted poly(dimethylsiloxane) (PDMS) as shell with different diameters were prepared and used as heterogeneous nucleation agents to obtain CO 2 -blown poly(methyl methacrylate) (PMMA) nanocomposite foams. PDMS was selected as the shell material as it possesses a low surface energy and high CO 2 -philicity. The successful synthesis of core-shell nanoparticles was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy. The cell size and cell density of the PMMA micro- and nanocellular materials were determined by scanning electron microscopy. The cell nucleation efficiency using core-shell nanoparticles was significantly enhanced when compared to that of unmodified silica. The highest nucleation efficiency observed had a value of ∼0.5 for nanoparticles with a core diameter of 80 nm. The particle size dependence of cell nucleation efficiency is discussed taking into account line tension effects. Complete engulfment by the polymer matrix of particles with a core diameter below 40 nm at the cell wall interface was observed corresponding to line tension values of approximately 0.42 nN. This line tension significantly increases the energy barrier of heterogeneous nucleation and thus reduces the nucleation efficiency. The increase of the CO 2 saturation pressure to 300 bar prior to batch foaming resulted in an increased line tension length. We observed a decrease of the heterogeneous nucleation efficiency for foaming after saturation with CO 2 at 300 bar, which we attribute to homogenous nucleation becoming more favorable at the expense of heterogeneous nucleation in this case. Overall, it is shown that the contribution of line tension to the free energy barrier of heterogeneous foam cell nucleation must be considered to understand foaming of viscoelastic materials. This finding emphasizes the need for new strategies including the use of

Drainage and Stratification Kinetics of Foam Films

Science.gov (United States)

Zhang, Yiran; Sharma, Vivek

2014-03-01

Baking bread, brewing cappuccino, pouring beer, washing dishes, shaving, shampooing, whipping eggs and blowing bubbles all involve creation of aqueous foam films. Foam lifetime, drainage kinetics and stability are strongly influenced by surfactant type (ionic vs non-ionic), and added proteins, particles or polymers modify typical responses. The rate at which fluid drains out from a foam film, i.e. drainage kinetics, is determined in the last stages primarily by molecular interactions and capillarity. Interestingly, for certain low molecular weight surfactants, colloids and polyelectrolyte-surfactant mixtures, a layered ordering of molecules, micelles or particles inside the foam films leads to a stepwise thinning phenomena called stratification. Though stratification is observed in many confined systems including foam films containing particles or polyelectrolytes, films containing globular proteins seem not to show this behavior. Using a Scheludko-type cell, we experimentally study the drainage and stratification kinetics of horizontal foam films formed by protein-surfactant mixtures, and carefully determine how the presence of proteins influences the hydrodynamics and thermodynamics of foam films.

Hydroxyapatite fiber reinforced poly(alpha-hydroxy ester) foams for bone regeneration

Science.gov (United States)

Thomson, R. C.; Yaszemski, M. J.; Powers, J. M.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

1998-01-01

A process has been developed to manufacture biodegradable composite foams of poly(DL-lactic-co-glycolic acid) (PLGA) and hydroxyapatite short fibers for use in bone regeneration. The processing technique allows the manufacture of three-dimensional foam scaffolds and involves the formation of a composite material consisting of a porogen material (either gelatin microspheres or salt particles) and hydroxyapatite short fibers embedded in a PLGA matrix. After the porogen is leached out, an open-cell composite foam remains which has a pore size and morphology defined by the porogen. By changing the weight fraction of the leachable component it was possible to produce composite foams with controlled porosities ranging from 0.47 +/- 0.02 to 0.85 +/- 0.01 (n = 3). Up to a polymer:fiber ratio of 7:6, short hydroxyapatite fibers served to reinforce low-porosity PLGA foams manufactured using gelatin microspheres as a porogen. Foams with a compressive yield strength up to 2.82 +/- 0.63 MPa (n = 3) and a porosity of 0.47 +/- 0.02 (n = 3) were manufactured using a polymer:fiber weight ratio of 7:6. In contrast, high-porosity composite foams (up to 0.81 +/- 0.02, n = 3) suitable for cell seeding were not reinforced by the introduction of increasing quantities of hydroxyapatite short fibers. We were therefore able to manufacture high-porosity foams which may be seeded with cells but which have minimal compressive yield strength, or low porosity foams with enhanced osteoconductivity and compressive yield strength.

Isocyanurate: safe substitute for urethane in polymer foams for mine roadways

Energy Technology Data Exchange (ETDEWEB)

Eisner, H.S.; Leger, J.P.

1989-02-01

Rigid polyurethane foam (PU) used for lining roadways or insulating cooling pipes has been involved in several large fires in South African mines. Polyisocyanurate foam when applied to continuous surfaces in a ventilated mine roadway and subjected to a sizeable flame, will ignite and rapidly propagate flame over its surface, with considerable evolution of carbon monoxide, in a manner substantially similar to polyurethane foam. 12 refs.

Effect of silica nanoparticles on polyurethane foaming process and foam properties

International Nuclear Information System (INIS)

Francés, A B; Bañón, M V Navarro

2014-01-01

Flexible polyurethane foams (FPUF) are commonly used as cushioning material in upholstered products made on several industrial sectors: furniture, automotive seating, bedding, etc. Polyurethane is a high molecular weight polymer based on the reaction between a hydroxyl group (polyol) and isocyanate. The density, flowability, compressive, tensile or shearing strength, the thermal and dimensional stability, combustibility, and other properties can be adjusted by the addition of several additives. Nanomaterials offer a wide range of possibilities to obtain nanocomposites with specific properties. The combination of FPUF with silica nanoparticles could develop nanocomposite materials with unique properties: improved mechanical and thermal properties, gas permeability, and fire retardancy. However, as silica particles are at least partially surface-terminated with Si-OH groups, it was suspected that the silica could interfere in the reaction of poyurethane formation.The objective of this study was to investigate the enhancement of thermal and mechanical properties of FPUF by the incorporation of different types of silica and determining the influence thereof during the foaming process. Flexible polyurethane foams with different loading mass fraction of silica nanoparticles (0-1% wt) and different types of silica (non treated and modified silica) were synthesized. PU/SiO 2 nanocomposites were characterized by FTIR spectroscopy, TGA, and measurements of apparent density, resilience and determination of compression set. Addition of silica nanoparticles influences negatively in the density and compression set of the foams. However, resilience and thermal stability of the foams are improved. Silica nanoparticles do not affect to the chemical structure of the foams although they interfere in the blowing reaction

METHODS OF REDUCTION OF FREE PHENOL CONTENT IN PHENOLIC FOAM

Directory of Open Access Journals (Sweden)

Bruyako Mikhail Gerasimovich

2012-12-01

method aimed at reduction of toxicity of phenolic foams consists in the introduction of a composite mixture of chelate compounds. Raw materials applied in the production of phenolic foams include polymers FRB-1A and VAG-3. The aforementioned materials are used to produce foams FRP-1. Introduction of 1% aluminum fluoride leads to the 40% reduction of the free phenol content in the foam. Introduction of crystalline zinc chloride accelerates the foaming and curing of phenolic foams. The technology that contemplates the introduction of zeolites into the mixture includes pre-mixing with FRB -1A and subsequent mixing with VAG-3; thereafter, the composition is poured into the form, in which the process of foaming is initiated. The content of free phenol was identified using the method of UV spectroscopy. The objective of the research was to develop methods of reduction of the free phenol content in the phenolic foam.

Polymer-Reinforced, Non-Brittle, Lightweight Cryogenic Insulation

Science.gov (United States)

Hess, David M.

2013-01-01

The primary application for cryogenic insulating foams will be fuel tank applications for fueling systems. It is crucial for this insulation to be incorporated into systems that survive vacuum and terrestrial environments. It is hypothesized that by forming an open-cell silica-reinforced polymer structure, the foam structures will exhibit the necessary strength to maintain shape. This will, in turn, maintain the insulating capabilities of the foam insulation. Besides mechanical stability in the form of crush resistance, it is important for these insulating materials to exhibit water penetration resistance. Hydrocarbon-terminated foam surfaces were implemented to impart hydrophobic functionality that apparently limits moisture penetration through the foam. During the freezing process, water accumulates on the surfaces of the foams. However, when hydrocarbon-terminated surfaces are present, water apparently beads and forms crystals, leading to less apparent accumulation. The object of this work is to develop inexpensive structural cryogenic insulation foam that has increased impact resistance for launch and ground-based cryogenic systems. Two parallel approaches will be pursued: a silica-polymer co-foaming technique and a post foam coating technique. Insulation characteristics, flexibility, and water uptake can be fine-tuned through the manipulation of the polyurethane foam scaffold. Silicate coatings for polyurethane foams and aerogel-impregnated polyurethane foams have been developed and tested. A highly porous aerogel-like material may be fabricated using a co-foam and coated foam techniques, and can insulate at liquid temperatures using the composite foam

Floating matrix tablets based on low density foam powder: effects of formulation and processing parameters on drug release.

Science.gov (United States)

Streubel, A; Siepmann, J; Bodmeier, R

2003-01-01

The aim of this study was to develop and physicochemically characterize single unit, floating controlled drug delivery systems consisting of (i). polypropylene foam powder, (ii). matrix-forming polymer(s), (iii). drug, and (iv). filler (optional). The highly porous foam powder provided low density and, thus, excellent in vitro floating behavior of the tablets. All foam powder-containing tablets remained floating for at least 8 h in 0.1 N HCl at 37 degrees C. Different types of matrix-forming polymers were studied: hydroxypropyl methylcellulose (HPMC), polyacrylates, sodium alginate, corn starch, carrageenan, gum guar and gum arabic. The tablets eroded upon contact with the release medium, and the relative importance of drug diffusion, polymer swelling and tablet erosion for the resulting release patterns varied significantly with the type of matrix former. The release rate could effectively be modified by varying the "matrix-forming polymer/foam powder" ratio, the initial drug loading, the tablet geometry (radius and height), the type of matrix-forming polymer, the use of polymer blends and the addition of water-soluble or water-insoluble fillers (such as lactose or microcrystalline cellulose). The floating behavior of the low density drug delivery systems could successfully be combined with accurate control of the drug release patterns.

Dip TIPS as a facile and versatile method for fabrication of polymer foams with controlled shape, size and pore architecture for bioengineering applications

Czech Academy of Sciences Publication Activity Database

Kasoju, Naresh; Kubies, Dana; Kumorek, Marta M.; Kříž, J.; Fabryová, E.; Machová, Luďka; Kovářová, Jana; Rypáček, František

2014-01-01

Roč. 9, č. 10 (2014), e108792_1-e108792_16 E-ISSN 1932-6203 R&D Projects: GA MŠk(CZ) EE2.3.30.0029; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : polymer foams * anisotropy * Dip TIPS Subject RIV: CE - Biochemistry Impact factor: 3.234, year: 2014

Vegetable-origin foam employed in dye extraction in tanning and leather processing facilities

Directory of Open Access Journals (Sweden)

José M. Cangemi

2009-01-01

Full Text Available This study addressed the use of conventional and vegetable origin polyurethane foams to extract C. I. Acid Orange 61 dye. The quantitative determination of the residual dye was carried out with an UV/Vis absorption spectrophotometer. The extraction of the dye was found to depend on various factors such as pH of the solution, foam cell structure, contact time and dye and foam interactions. After 45 days, better results were obtained for conventional foam when compared to vegetable foam. Despite presenting a lower percentage of extraction, vegetable foam is advantageous as it is considered a polymer with biodegradable characteristics.

Polyimide Foams Offer Superior Insulation

Science.gov (United States)

2012-01-01

At Langley Research Center, Erik Weiser and his colleagues in the Advanced Materials and Processing Branch were working with a new substance for fabricating composites for use in supersonic aircraft. The team, however, was experiencing some frustration. Every time they tried to create a solid composite from the polyimide (an advanced polymer) material, it bubbled and foamed. It seemed like the team had reached a dead end in their research - until they had another idea. "We said, This isn t going to work for composites, but maybe we could make a foam out of it," Weiser says. "That was kind of our eureka moment, to see if we could go in a whole other direction. And it worked." Weiser and his colleagues invented a new kind of polyimide foam insulation they named TEEK. The innovation displayed a host of advantages over existing insulation options. Compared to other commercial foams, Weiser explains, polyimide foams perform well across a broad range of temperatures, noting that the NASA TEEK foams provide effective structural insulation up to 600 F and down to cryogenic temperatures. The foam does not burn or off-gas toxic fumes, and even at -423 F - the temperature of liquid hydrogen - the material stays flexible. The inventors could produce the TEEK foam at a range of densities, from 0.5 pounds per cubic foot up to 20 pounds per cubic foot, making the foam ideal for a range of applications, including as insulation for reusable launch vehicles and for cryogenic tanks and lines. They also developed a unique, friable balloon format for manufacturing the foam, producing it as hollow microspheres that allowed the foam to be molded and then cured into any desired shape - perfect for insulating pipes of different sizes and configurations. The team s originally unplanned invention won an "R&D 100" award, and a later form of the foam, called LaRC FPF-44 (Spinoff 2009), was named "NASA Invention of the Year" in 2007.

The compressive behaviour and constitutive equation of polyimide foam in wide strain rate and temperature

Directory of Open Access Journals (Sweden)

Yoshimoto Akifumi

2015-01-01

Full Text Available These days, polymer foams, such as polyurethane foam and polystyrene foam, are used in various situations as a thermal insulator or shock absorber. In general, however, their strength is insufficient in high temperature environments because of their low glass transition temperature. Polyimide is a polymer which has a higher glass transition temperature and high strength. Its mechanical properties do not vary greatly, even in low temperature environments. Therefore, polyimide foam is expected to be used in the aerospace industry. Thus, the constitutive equation of polyimide foam that can be applied across a wide range of strain rates and ambient temperature is very useful. In this study, a series of compression tests at various strain rates, from 10−3 to 103 s−1 were carried out in order to examine the effect of strain rate on the compressive properties of polyimide foam. The flow stress of polyimide foam increased rapidly at dynamic strain rates. The effect of ambient temperature on the properties of polyimide foam was also investigated at temperature from − 190 °C to 270°∘C. The flow stress decreased with increasing temperature.

Flammability of Gas-Filled Polymers

Directory of Open Access Journals (Sweden)

Ushkov Valentin Anatol'evich

2017-09-01

Full Text Available The regularities of flame propagation on the horizontal surface of gas-filled polymers are considered depending on the concentration of oxygen in the oxidizer flow. The values of the coefficients in the expression describing relationship between the rate of flame propagation on the surface of foams and oxygen concentration are obtained. It was shown that with the mass content of reactive organophosphorus compounds reaching 4.0...5.9%, non-smoldering resole foam plastics with high performance characteristics are obtained. It was found that in order to obtain moderately combustible polyurethane foams based on oxyethylated phosphorus-containing polyols, the phosphorus concentration should not exceed 3 % of mass. To obtain flame-retardant urea-formaldehyde foam cellular plastics, the concentration of phosphorus should not exceed 0.3 % of mass. Physical-mechanical properties and flammability indices of developed gas-filled polymers based on reactive oligomers are presented.

Small cell foams and blends and a process for their preparation

Science.gov (United States)

Hedstrand, D.M.; Tomalia, D.A.

1995-02-07

Dense star polymers or dendrimers, modified by capping with a hydrophobic group capable of providing a hydrophobic outer shell, act as molecular nucleating agents. These modified dense star polymers or dendrimers are particularly effective for the production of small cell foams.

Numerical modeling of foam flows

International Nuclear Information System (INIS)

Cheddadi, Ibrahim

2010-01-01

Liquid foam flows are involved in numerous applications, e.g. food and cosmetics industries, oil extraction, nuclear decontamination. Moreover, their study leads to fundamental knowledge: as it is easier to manipulate and analyse, foam is used as a model material to understand the flow of emulsions, polymers, pastes, or cell aggregates, all of which display both solid and liquid behaviour. Systematic experiments performed by Francois Graner et al. provide precise data that emphasize the non Newtonian properties of the foam. Meanwhile, Pierre Saramito proposed a visco-elasto-plastic continuous tensorial model, akin to predict the behaviour of the foam. The goal of this thesis is to understand this complex behaviour, using these two elements. We have built and validated a resolution algorithm based on a bidimensional finite elements methods. The numerical solutions are in excellent agreement with the spatial distribution of all measured quantities, and confirm the predictive capabilities of the model. The dominant parameters have been identified and we evidenced the fact that the viscous, elastic, and plastic contributions to the flow have to be treated simultaneously in a tensorial formalism. We provide a substantial contribution to the understanding of foams and open the path to realistic simulations of complex VEP flows for industrial applications. (author)

Nanocellular foam with solid flame retardant

Science.gov (United States)

Chen, Liang; Kelly-Rowley, Anne M.; Bunker, Shana P.; Costeux, Stephane

2017-11-21

Prepare nanofoam by (a) providing an aqueous solution of a flame retardant dissolved in an aqueous solvent, wherein the flame retardant is a solid at 23.degree. C. and 101 kiloPascals pressure when in neat form; (b) providing a fluid polymer composition selected from a solution of polymer dissolved in a water-miscible solvent or a latex of polymer particles in a continuous aqueous phase; (c) mixing the aqueous solution of flame retardant with the fluid polymer composition to form a mixture; (d) removing water and, if present, solvent from the mixture to produce a polymeric composition having less than 74 weight-percent flame retardant based on total polymeric composition weight; (e) compound the polymeric composition with a matrix polymer to form a matrix polymer composition; and (f) foam the matrix polymer composition into nanofoam having a porosity of at least 60 percent.

A Polymer "Pollution Solution" Classroom Activity.

Science.gov (United States)

Helser, Terry L.

1996-01-01

Explains an approach to presenting polymer chemistry to nonmajors that employs polystyrene foam, foam peanuts made from water soluble starch, and water soluble plastic bags. Students are presented with a pollution scenario and are guided to the discovery of solutions. (DDR)

Validation of Heat Transfer Thermal Decomposition and Container Pressurization of Polyurethane Foam.

Energy Technology Data Exchange (ETDEWEB)

Scott, Sarah Nicole; Dodd, Amanda B.; Larsen, Marvin E.; Suo-Anttila, Jill M.; Erickson, Kenneth L

2014-09-01

Polymer foam encapsulants provide mechanical, electrical, and thermal isolation in engineered systems. In fire environments, gas pressure from thermal decomposition of polymers can cause mechanical failure of sealed systems. In this work, a detailed uncertainty quantification study of PMDI-based polyurethane foam is presented to assess the validity of the computational model. Both experimental measurement uncertainty and model prediction uncertainty are examined and compared. Both the mean value method and Latin hypercube sampling approach are used to propagate the uncertainty through the model. In addition to comparing computational and experimental results, the importance of each input parameter on the simulation result is also investigated. These results show that further development in the physics model of the foam and appropriate associated material testing are necessary to improve model accuracy.

A cement based syntactic foam

International Nuclear Information System (INIS)

Li Guoqiang; Muthyala, Venkata D.

2008-01-01

In this study, a cement based syntactic foam core was proposed and experimentally investigated for composite sandwich structures. This was a multi-phase composite material with microballoon dispersed in a rubber latex toughened cement paste matrix. A trace amount of microfiber was also incorporated to increase the number of mechanisms for energy absorption and a small amount of nanoclay was added to improve the crystal structure of the hydrates. Three groups of cement based syntactic foams with varying cement content were investigated. A fourth group of specimens containing pure cement paste were also prepared as control. Each group contained 24 beam specimens. The total number of beam specimens was 96. The dimension of each beam was 30.5 cm x 5.1 cm x 1.5 cm. Twelve foam specimens from each group were wrapped with plain woven 7715 style glass fabric reinforced epoxy to prepare sandwich beams. Twelve cubic foam specimens, three from each group, with a side length of 5.1 cm, were also prepared. Three types of testing, low velocity impact test and four-point bending test on the beam specimens and compression test on the cubic specimens, were conducted to evaluate the impact energy dissipation, stress-strain behavior, and residual strength. Scanning electron microscope (SEM) was also used to examine the energy dissipation mechanisms in the micro-length scale. It was found that the cement based syntactic foam has a higher capacity for dissipating impact energy with an insignificant reduction in strength as compared to the control cement paste core. When compared to a polymer based foam core having similar compositions, it was found that the cement based foam has a comparable energy dissipation capacity. The developed cement based syntactic foam would be a viable alternative for core materials in impact-tolerant composite sandwich structures

Dynamics of the rupture precursors for heterogeneous materials: application to vitreous polymers foams

International Nuclear Information System (INIS)

Deschanel, St.

2005-12-01

New physical approaches concerning the damage mechanisms consist to consider the rupture phenomenon as the critical point of a phase transition. Rupture can then result for some materials by a percolation of microcracks. This multi-crack implies the choice of heterogeneous materials. Mechanical tests on solid polymer foams have been carried out until rupture and have been coupled to the follow-up of the acoustic activity. The energies distributions reveal power laws independently of the material density, of the load mode or of the behaviour laws. On the other hand, the agreement with a power law of time periods seems to require a quasi constant stress on the most part of the test. The trend of the cumulated energy in the case of creep experiments seems to present a power law on a narrow period of time. On the other hand, for tensile tests, no power law has been observed. (O.M.)

Polling-Based High-Bit-Rate Packet Transfer in a Microcellular Network to Allow Fast Terminals

Science.gov (United States)

Hoa, Phan Thanh; Lambertsen, Gaute; Yamada, Takahiko

A microcellular network will be a good candidate for the future broadband mobile network. It is expected to support high-bit-rate connection for many fast mobile users if the handover is processed fast enough to lessen its impact on QoS requirements. One of the promising techniques is believed to use for the wireless interface in such a microcellular network is the WLAN (Wireless LAN) technique due to its very high wireless channel rate. However, the less capability of mobility support of this technique must be improved to be able to expand its utilization for the microcellular environment. The reason of its less support mobility is large handover latency delay caused by contention-based handover to the new BS (base station) and delay of re-forwarding data from the old to new BS. This paper presents a proposal of multi-polling and dynamic LMC (Logical Macro Cell) to reduce mentioned above delays. Polling frame for an MT (Mobile Terminal) is sent from every BS belonging to the same LMC — a virtual single macro cell that is a multicast group of several adjacent micro-cells in which an MT is communicating. Instead of contending for the medium of a new BS during handover, the MT responds to the polling sent from that new BS to enable the transition. Because only one BS of the LMC receives the polling ACK (acknowledgement) directly from the MT, this ACK frame has to be multicast to all BSs of the same LMC through the terrestrial network to continue sending the next polling cycle at each BS. Moreover, when an MT hands over to a new cell, its current LMC is switched over to a newly corresponding LMC to prevent the future contending for a new LMC. By this way, an MT can do handover between micro-cells of an LMC smoothly because the redundant resource is reserved for it at neighboring cells, no need to contend with others. Our simulation results using the OMNeT++ simulator illustrate the performance achievements of the multi-polling and dynamic LMC scheme in eliminating

Heating of low-density CHO-foam layers by means of soft X-rays

Energy Technology Data Exchange (ETDEWEB)

Rosmej, O.N., E-mail: o.rosmej@gsi.de [GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, 164291 Darmstadt (Germany); Bagnoud, V.; Eisenbarth, U. [GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, 164291 Darmstadt (Germany); Vatulin, V.; Zhidkov, N.; Suslov, N.; Kunin, A.; Pinegin, A. [All Russian Scientific Research Institute of Experimental Physics, RFNC-VNIIEF, Mira St. 37, Sarov (Russian Federation); Schaefer, D.; Nisius, Th.; Wilhein, Th. [RheinAhrCampus Remagen, Institute for X-optics, Suedallee 2, 53424 Remagen (Germany); Rienecker, T.; Wiechula, J.; Jacoby, J. [Goethe University, Frankfurt am Main (Germany); Zhao, Y. [Institute of Modern Physics, CAS, Nanchang Road 509, 730000 Lanzhou (China); Vergunova, G.; Borisenko, N. [Lebedev Physical Institute, Leninskii Prospekt, 65 Moscow (Russian Federation); Orlov, N. [Joint Institute for High Temperatures RAS, Institute for High Energy Density, Izhorskaya. 13, building 2, 125412 Moscow (Russian Federation)

2011-10-11

Interaction of soft X-ray thermal radiation with polymer foam layers has been studied experimentally. Indirectly heated CHO-foams were used to create a plasma target for applications in combined heavy ion beam-laser experiments that are aimed at investigation of the heavy ion energy loss in ionized matter. In this work, we report experimental results on heating of low Z foams by means of the Planckian radiation generated in gold hohlraums. The experimental goal was to study the hohlraum radiation field, duration of the soft X-ray pulse, the conversion efficiency of the laser energy into soft X-rays, measurements of the absorption properties of foam layers and parameters of the foam targets heated by the Plankian radiation.

Heating of low-density CHO-foam layers by means of soft X-rays

International Nuclear Information System (INIS)

Rosmej, O.N.; Bagnoud, V.; Eisenbarth, U.; Vatulin, V.; Zhidkov, N.; Suslov, N.; Kunin, A.; Pinegin, A.; Schaefer, D.; Nisius, Th.; Wilhein, Th.; Rienecker, T.; Wiechula, J.; Jacoby, J.; Zhao, Y.; Vergunova, G.; Borisenko, N.; Orlov, N.

2011-01-01

Interaction of soft X-ray thermal radiation with polymer foam layers has been studied experimentally. Indirectly heated CHO-foams were used to create a plasma target for applications in combined heavy ion beam-laser experiments that are aimed at investigation of the heavy ion energy loss in ionized matter. In this work, we report experimental results on heating of low Z foams by means of the Planckian radiation generated in gold hohlraums. The experimental goal was to study the hohlraum radiation field, duration of the soft X-ray pulse, the conversion efficiency of the laser energy into soft X-rays, measurements of the absorption properties of foam layers and parameters of the foam targets heated by the Plankian radiation.

Electrical and dielectric properties of foam injection-molded polypropylene/multiwalled carbon nanotube composites

Energy Technology Data Exchange (ETDEWEB)

Ameli, A.; Nofar, M.; Saniei, M.; Hossieny, N.; Park, C. B. [Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King’s College Road, Toronto, Ontario, Canada M5S 3G8 (Canada); Pötschke, P. [Leibniz-Institut für Polymerforschung Dresden e.V. (IPF), Hohe Strasse 6, D-01069 Dresden (Germany)

2015-05-22

A combination of high dielectric permittivity (ε′) and low dielectric loss (tan δ) is required for charge storage applications. In percolative systems such as conductive polymer composites, however, obtaining high ε′ and low tan δ is very challenging due to the sharp insulation-conduction transition near the threshold region. Due to the particular arrangement of conductive fillers induced by both foaming and injection molding processes, they may address this issue. Therefore, this work evaluates the application of foam injection molding process in fabricating polymer nanocomposites for energy storage. Polypropylene-multiwalled carbon nanotubes (PP-MWCNT) composites were prepared by melt mixing and foamed in an injection molding process. Electrical conductivity (σ), ε′ and tan δ were then characterized. Also, scanning and transmission electron microscopy (SEM and TEM) was used to investigate the carbon nanotube’s arrangement as well as cellular morphology. The results showed that foam injection-molded composites exhibited highly superior dielectric properties to those of solid counterparts. For instance, foamed samples had ε′=68.3 and tan δ =0.05 (at 1.25 vol.% MWCNT), as opposed to ε′=17.8 and tan δ=0.04 in solid samples (at 2.56 vol.% MWCNT). The results of this work reveal that high performance dielectric nanocomposites can be developed using foam injection molding technologies for charge storage applications.

Review of Synthetic Methods to Form Hollow Polymer Nanocapsules

Energy Technology Data Exchange (ETDEWEB)

Barker, Madeline T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-03-13

Syntactic foams have grown in interest due to the widened range of applications because of their mechanical strength and high damage tolerance. In the past, hollow glass or ceramic particles were used to create the pores. This paper reviews literature focused on the controlled synthesis of hollow polymer spheres with diameters ranging from 100 –200 nm. By using hollow polymer spheres, syntactic foams could reach ultra-low densities.

Metal-doped organic foam and method of making same. [Patent application

Science.gov (United States)

Rinde, J.A.

Organic foams having a low density and very small cell size and method for producing same in either a metal-loaded or unloaded (nonmetal loaded) form are described. Metal-doped foams are produced by soaking a polymer gel in an aqueous solution of desired metal salt, soaking the gel successively in a solvent series of decreasing polarity to remove water from the gel and replace it with a solvent of lower polarity with each successive solvent in the series being miscible with the solvents on each side and being saturated with the desired metal salt, and removing the last of the solvents from the gel to produce the desired metal-doped foam having desired density cell size, and metal loading. The unloaded or metal-doped foams can be utilized in a variety of applications requiring low density, small cell size foam. For example, rubidium-doped foam made in accordance with the invention has utility in special applications, such as in x-ray lasers.

Testing and modeling the dynamic response of foam materials for blast protection

Science.gov (United States)

Fitek, John H.

The pressure wave released from an explosion can cause injury to the lungs. A personal armor system concept for blast lung injury protection consists of a polymer foam layer behind a rigid armor plate to be worn over the chest. This research develops a method for testing and modeling the dynamic response of foam materials to be used for down-selection of materials for this application. Constitutive equations for foam materials are incorporated into a lumped parameter model of the combined armor plate and foam system. Impact testing and shock tube testing are used to measure the foam model parameters and validate the model response to a pressure wave load. The plate and foam armor model is then coupled to a model of the human thorax. With a blast pressure wave input, the armor model is evaluated based on how it affects the injury-causing mechanism of chest wall motion. Results show that to reduce chest wall motion, the foam must compress at a relatively constant stress level, which requires a sufficient foam thickness.

Preparation of novel magnetic polyurethane foam nanocomposites by using core-shell nanoparticles

Directory of Open Access Journals (Sweden)

Mir Mohammad Alavi Nikje

Full Text Available Abstract Iron oxide magnetic nanoparticles (NP's converted to the core- shell structres by reacting with by n-(2-aminoethyl-3-aminopropyl trimethoxysilane (AEAP incorporated in polyurethane flexible (PUF foam formulations. Fourier transform spectra, thermal gravimetric analysis, scanning electron images, thermo-mechanical analysis and magnetic properties of the prepared nanocomposites were studied. Obtained data shown that by the increasing of the amine modified magnetic iron oxide NP's up to 3% in the polymer matrix, thermal and magnetic properties improved in comparison with pristine foams. In addition, due to the presence of functional groups on the magnetic NP's surface, hard phases formation decrease in the bulk polymer and cause decreasing of glass transition temperature.

Shape memory polymers

Energy Technology Data Exchange (ETDEWEB)

Wilson, Thomas S.; Bearinger, Jane P.

2017-08-29

New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

Shape memory polymers

Science.gov (United States)

Wilson, Thomas S.; Bearinger, Jane P.

2015-06-09

New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxyl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

Optimisation of multi-layer rotationally moulded foamed structures

Science.gov (United States)

Pritchard, A. J.; McCourt, M. P.; Kearns, M. P.; Martin, P. J.; Cunningham, E.

2018-05-01

Multi-layer skin-foam and skin-foam-skin sandwich constructions are of increasing interest in the rotational moulding process for two reasons. Firstly, multi-layer constructions can improve the thermal insulation properties of a part. Secondly, foamed polyethylene sandwiched between solid polyethylene skins can increase the mechanical properties of rotationally moulded structural components, in particular increasing flexural properties and impact strength (IS). The processing of multiple layers of polyethylene and polyethylene foam presents unique challenges such as the control of chemical blowing agent decomposition temperature, and the optimisation of cooling rates to prevent destruction of the foam core; therefore, precise temperature control is paramount to success. Long cooling cycle times are associated with the creation of multi-layer foam parts due to their insulative nature; consequently, often making the costs of production prohibitive. Devices such as Rotocooler®, a rapid internal mould water spray cooling system, have been shown to have the potential to significantly decrease cooling times in rotational moulding. It is essential to monitor and control such devices to minimise the warpage associated with the rapid cooling of a moulding from only one side. The work presented here demonstrates the use of threaded thermocouples to monitor the polymer melt in multi-layer sandwich constructions, in order to analyse the cooling cycle of multi-layer foamed structures. A series of polyethylene skin-foam test mouldings were produced, and the effect of cooling medium on foam characteristics, mechanical properties, and process cycle time were investigated. Cooling cycle time reductions of 45%, 26%, and 29% were found for increasing (1%, 2%, and 3%) chemical blowing agent (CBA) amount when using internal water cooling technology from ˜123°C compared with forced air cooling (FAC). Subsequently, a reduction of IS for the same skin-foam parts was found to be 1%, 4

A general synthesis strategy for the multifunctional 3D polypyrrole foam of thin 2D nanosheets

Science.gov (United States)

Xue, Jiangli; Mo, Maosong; Liu, Zhuming; Ye, Dapeng; Cheng, Zhihua; Xu, Tong; Qu, Liangti

2018-05-01

A 3D macroporous conductive polymer foam of thin 2D polypyrrole (PPy) nanosheets is developed by adopting a novel intercalation of guest (monomer Py) between the layers of the lamellar host (3D vanadium oxide foam) template-replication strategy. The 3D PPy foam of thin 2D nanosheets exhibits diverse functions including reversible compressibility, shape memory, absorption/adsorption and mechanically deformable supercapacitor characteristics. The as-prepared 3D PPy foam of thin nanosheets is highly light weight with a density of 12 mg·cm-3 which can bear the large compressive strain up to 80% whether in wet or dry states; and can absorb organic solutions or extract dye molecules fast and efficiently. In particular, the PPy nanosheet-based foamas a mechanically deformable electrode material for supercapacitors exhibits high specific capacitance of 70 F·g-1 at a fast charge-discharge rate of 50 mA·g-1, superior to that of any other typical pure PPy-based capacitor. We envision that the strategy presented here should be applicable to fabrication of a wide variety of organic polymer foams and hydrogels of low-dimensional nanostructures and even inorganic foams and hydrogels of low-dimensional nanostructures, and thus allow for exploration of their advanced physical and chemical properties.

Self-healing of sandwich structures with a grid stiffened shape memory polymer syntactic foam core

Science.gov (United States)

John, Manu; Li, Guoqiang

2010-07-01

In this paper, a new sandwich with an orthogrid stiffened shape memory polymer (SMP) based syntactic foam core was proposed, fabricated, programmed, impacted, healed (sealed), and compression tested, for the purposes of healing impact damage repeatedly and almost autonomously. Two prestrain levels (3% and 20%), two impact energy levels (30.0 and 53.3 J), and two recovery (healing) conditions (2D confined and 3D confined) were employed in this paper. Up to seven impact-healing cycles were conducted. Macroscopic and microscopic damage-healing observation and analysis were implemented. Residual strength was evaluated using an anti-buckling compression test fixture. It was found that the healing efficiency was over 100% for almost all the impact-healing cycles; programming using 20% prestrain led to higher residual strength than that with 3% prestrain; 3D confined recovery resulted in higher residual strength than 2D confined recovery; and as the impact energy increased, the healing efficiency slightly decreased.

Bitumen modified with recycled polyurethane foam for employment in hot mix asphalt

Directory of Open Access Journals (Sweden)

Miguel Ángel Salas

2018-01-01

Full Text Available A wide variety of modifiers have been applied to bitumen in order to enhance their properties and performance. Among them, polymers have been mainly used. The aim of this paper is to assess the use of polyurethane foam waste as a bitumen modifier for hot mix asphalts. The polyurethane foam is a by-product of the manufacturing of polyurethane for thermal insulation. From a bitumen with a penetration grade of 50/70, various samples with percentages of waste material in weight ranging from 1% to 5% were produced and tested. Samples with 5% of waste material or more became rough and were refused due to their poor workability. A bituminous mixture with modified bitumen with a 4% of polyurethane was manufactured and compared with a sample with the same aggregates and original bitumen. Results in Marshall test showed that a mix with polymer modified bitumen yielded improvements in stability and a lower deformability. This result suggests that the employment of polyurethane foam waste is a promising bitumen modifier, contributing also to recycle waste materials.

Improving Water Repellence and Friability of Tannin-Furanic Foams by Oil-Grafted Flavonoid Tannins

Directory of Open Access Journals (Sweden)

Géraldine Rangel

2016-08-01

Full Text Available Tannin-furanic biobased foams, based on the co-reaction of bark-derived condensed tannins and thermoset furanic polymers, have low thermal conductivity, are self-extinguishing, and have high fire resistance, which allows their development for several industrial uses. One of their main drawbacks, however, is the absorption of water within the foam itself. Another problem is the rather friable surface, which is a definite drawback for some potential applications. In this work, these two problems are minimized or eliminated by introducing a component of oil-grafted tannin in the foam formulation. The incorporation of fatty chains markedly decreased foam friability and increased water repellency in the body of the foams. These properties and the compounds formed by fatty acids grafting onto the tannin flavonoids were extensively tested.

Three-Dimensional Graphene Foam Induces Multifunctionality in Epoxy Nanocomposites by Simultaneous Improvement in Mechanical, Thermal, and Electrical Properties.

Science.gov (United States)

Embrey, Leslie; Nautiyal, Pranjal; Loganathan, Archana; Idowu, Adeyinka; Boesl, Benjamin; Agarwal, Arvind

2017-11-15

Three-dimensional (3D) macroporous graphene foam based multifunctional epoxy composites are developed in this study. Facile dip-coating and mold-casting techniques are employed to engineer microstructures with tailorable thermal, mechanical, and electrical properties. These processing techniques allow capillarity-induced equilibrium filling of graphene foam branches, creating epoxy/graphene interfaces with minimal separation. Addition of 2 wt % graphene foam enhances the glass transition temperature of epoxy from 106 to 162 °C, improving the thermal stability of the polymer composite. Graphene foam aids in load-bearing, increasing the ultimate tensile strength by 12% by merely 0.13 wt % graphene foam in an epoxy matrix. Digital image correlation (DIC) analysis revealed that the graphene foam cells restrict and confine the deformation of the polymer matrix, thereby enhancing the load-bearing capability of the composite. Addition of 0.6 wt % graphene foam also enhances the flexural strength of the pure epoxy by 10%. A 3D network of graphene branches is found to suppress and deflect the cracks, arresting mechanical failure. Dynamic mechanical analysis (DMA) of the composites demonstrated their vibration damping capability, as the loss tangent (tan δ) jumps from 0.1 for the pure epoxy to 0.24 for ∼2 wt % graphene foam-epoxy composite. Graphene foam branches also provide seamless pathways for electron transfer, which induces electrical conductivity exceeding 450 S/m in an otherwise insulator epoxy matrix. The epoxy-graphene foam composite exhibits a gauge factor as high as 4.1, which is twice the typical gauge factor for the most common metals. Simultaneous improvement in thermal, mechanical, and electrical properties of epoxy due to 3D graphene foam makes epoxy-graphene foam composite a promising lightweight and multifunctional material for aiding load-bearing, electrical transport, and motion sensing in aerospace, automotive, robotics, and smart device structures.

Study on a Novel Gelled Foam for Conformance Control in High Temperature and High Salinity Reservoirs

Directory of Open Access Journals (Sweden)

Tong Li

2018-05-01

Full Text Available A novel gelled foam for conformance control was investigated for its ability to enhance oil recovery (EOR in high temperature and high salinity reservoirs. The formulation optimization, foaming performance, and core flooding performance of the gelled foam were systematically evaluated under harsh reservoir conditions. The gelled foam formulation was optimized with 0.4% polymer (hydrolyzed polyacrylamide; HPAM, 0.06% cross-linker (phenolic and 0.2% foaming agent (sulphobetaine; SB. The addition of the gel improved the stability of the foam system by 3.8 times that of traditional foam. A stabilization mechanism in the gelled foam was proposed to describe the stabilization process of the foam film. The uniformly distributed three-dimensional network structure of the gel provided a thick protective layer for the foam system that maintained the stability of the foam and improved the strength and thickness of the liquid film. The gelled foam exhibited good formation adaptability, profile control, and EOR performance. The foam flowed into the high permeability layer, plugged the dominant channel, and increased the swept volume. Oil recovery was enhanced by 29.4% under harsh high -temperature and high salinity conditions.

Development of foams from linear polypropylene (PP) and high melt strength polypropylene (HMSPP) polymeric blends

International Nuclear Information System (INIS)

Cardoso, Elisabeth Carvalho Leite

2009-01-01

Foamed polymers are future materials, with a comprehensive application field. They can be used in order to improve appearance of insulation structures, for example, or to reduce costs involving materials. This work address to Isotactic Polypropylene / High Melt Strength Polypropylene blends, for foams production. Rheological behavior of polymer melt, especially referring to viscosity in processing temperature, plays a decisive role in applications where dominates extensional flow, as in case of foaming. If the viscosity is very low, it will correspond to a low melt strength, as in case of linear homopolymer (Isotact PP), and the foam will be prejudiced, due to the impossibility of expansion. Otherwise, if the viscosity is very high, with a high melt strength, the foam will collapse immediately after its formation. In order to get foams with an homogeneous and defined cellular structure, there were accomplished blends, 50% in weight, between linear homopolymer (isotactic PP) and HMSPP, from PP modified as per gamma radiation, in acetylene environment and at a 12.5 kGy doses. Extrusion process used a soluble foaming methodology, according to a processing/dissolution principle, which involves the dissolution of a Physical Blowing Agent (PBA), under 30 bar pressure, homogeneously mixed with polymeric melt. Extrusion conditions, that generally involve temperature, pressure and viscoelastic material flow control were experimentally investigated to define prevalent characteristics for producing foams. Nitrogen was the used PBA and process extrusion parameters were adapted to PP, HMSPP and their 50% in weight mixtures thereof. Major PP and HMSPP characteristics were obtained via melt Index and melt strength and thermal analyses (DSC/TGA), in order to make viable and to reproduce foaming as per extrusion process. Foams cellular morphology of PP, HMSPP and their 50% in weight mixtures thereof was investigated, with and without talc addition, as nucleating agent, by using

Forming foam structures with carbon foam substrates

Science.gov (United States)

Landingham, Richard L.; Satcher, Jr., Joe H.; Coronado, Paul R.; Baumann, Theodore F.

2012-11-06

The invention provides foams of desired cell sizes formed from metal or ceramic materials that coat the surfaces of carbon foams which are subsequently removed. For example, metal is located over a sol-gel foam monolith. The metal is melted to produce a metal/sol-gel composition. The sol-gel foam monolith is removed, leaving a metal foam.

Mechanisms of nanoclay-enhanced plastic foaming processes: effects of nanoclay intercalation and exfoliation

Energy Technology Data Exchange (ETDEWEB)

Wong, Anson; Wijnands, Stephan F. L.; Kuboki, Takashi; Park, Chul B., E-mail: park@mie.utoronto.ca [University of Toronto, Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering (Canada)

2013-08-15

The foaming behaviors of high-density polypropylene-nanoclay composites with intercalated and exfoliated nanoclay particles blown with carbon dioxide were examined via in situ observation of the foaming processes in a high-temperature/high-pressure view-cell. The intercalated nanoclay particles were 300-600 nm in length and 50-200 nm in thickness, while the exfoliated nanoclay particles were 100-200 nm in length and 1 nm in thickness. Contrary to common belief, it was discovered that intercalated nanoclay yielded higher cell density than exfoliated nanoclay despite its lower particle density. This was attributed to the higher tensile stresses generated around the larger and stiffer intercalated nanoclay particles, which led to increase in supersaturation level for cell nucleation. Also, the coupling agent used to exfoliate nanoclay would increase the affinity between polymer and surface of nanoclay particles. Consequently, the critical work needed for cell nucleation would be increased; pre-existing microvoids, which could act as seeds for cell nucleation, were also less likely to exist. Meanwhile, exfoliated nanoclay had better cell stabilization ability to prevent cell coalescence and cell coarsening. This investigation clarifies the roles of nanoclay in plastic foaming processes and provides guidance for the advancement of polymer nanocomposite foaming technology.

Foam, Foam-resin composite and method of making a foam-resin composite

Science.gov (United States)

Cranston, John A. (Inventor); MacArthur, Doug E. (Inventor)

1995-01-01

This invention relates to a foam, a foam-resin composite and a method of making foam-resin composites. The foam set forth in this invention comprises a urethane modified polyisocyanurate derived from an aromatic amino polyol and a polyether polyol. In addition to the polyisocyanurate foam, the composite of this invention further contains a resin layer, wherein the resin may be epoxy, bismaleimide, or phenolic resin. Such resins generally require cure or post-cure temperatures of at least 350.degree. F.

Channel Measurement and Modeling for 5G Urban Microcellular Scenarios

Directory of Open Access Journals (Sweden)

Michael Peter

2016-08-01

Full Text Available In order to support the development of channel models for higher frequency bands, multiple urban microcellular measurement campaigns have been carried out in Berlin, Germany, at 60 and 10 GHz. In this paper, the collected data is uniformly analyzed with focus on the path loss (PL and the delay spread (DS. It reveals that the ground reflection has a dominant impact on the fading behavior. For line-of-sight conditions, the PL exponents are close to free space propagation at 60 GHz, but slightly smaller (1.62 for the street canyon at 10 GHz. The DS shows a clear dependence on the scenario (median values between 16 and 38 ns and a strong distance dependence for the open square and the wide street canyon. The dependence is less distinct for the narrow street canyon with residential buildings. This behavior is consistent with complementary ray tracing simulations, though the simplified model tends to overestimate the DS.

mdFoam+: Advanced molecular dynamics in OpenFOAM

Science.gov (United States)

Longshaw, S. M.; Borg, M. K.; Ramisetti, S. B.; Zhang, J.; Lockerby, D. A.; Emerson, D. R.; Reese, J. M.

2018-03-01

This paper introduces mdFoam+, which is an MPI parallelised molecular dynamics (MD) solver implemented entirely within the OpenFOAM software framework. It is open-source and released under the same GNU General Public License (GPL) as OpenFOAM. The source code is released as a publicly open software repository that includes detailed documentation and tutorial cases. Since mdFoam+ is designed entirely within the OpenFOAM C++ object-oriented framework, it inherits a number of key features. The code is designed for extensibility and flexibility, so it is aimed first and foremost as an MD research tool, in which new models and test cases can be developed and tested rapidly. Implementing mdFoam+ in OpenFOAM also enables easier development of hybrid methods that couple MD with continuum-based solvers. Setting up MD cases follows the standard OpenFOAM format, as mdFoam+ also relies upon the OpenFOAM dictionary-based directory structure. This ensures that useful pre- and post-processing capabilities provided by OpenFOAM remain available even though the fully Lagrangian nature of an MD simulation is not typical of most OpenFOAM applications. Results show that mdFoam+ compares well to another well-known MD code (e.g. LAMMPS) in terms of benchmark problems, although it also has additional functionality that does not exist in other open-source MD codes.

Application to the radiation processing of polymer

Energy Technology Data Exchange (ETDEWEB)

Yoshii, Fumio [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

2003-02-01

Polypropylene (PP) and biodegradable polymer (blend of poly ({epsilon}-caploracton) 30/polybutylenesuccynate 70), PHB02 were irradiated with an electron beam to improve processability for production of thin film and foam. The processability of the polymer was improved due to enhancement of melt strength with irradiation at the dose range between 10 and 100 kGy. Increase of melt strength is due to entanglement of branch structure formed by irradiation. Possibility of high-speed production of thin film and production of foam have been achieved by this process. The soil degradation test showed that biodegradable polymer film buried in the soil was almost entirely degraded (97%) after two months and completely degraded after two and a half months. In the case of foam samples, 65% degradation was achieved after four months. Radiation crosslinked water-soluble polymer form hydrogel, which absorb much water. The hydrogel prepared by irradiation of polymer in aqueous solution was applied as dressing for healing of wound. In order to evaluate the healing effect of the polyethylene oxide (PEO) hydrogel dressing, wounds formed on the back of marmots were covered by the hydrogel. The healing under the wet environment of the hydrogel dressing had three advantages, compared with that of gauze dressing, which gives a dry environment: (1) enhancement of healing rate, (2) facilitation for changing the dressing, i.e. the hydrogel can be peeled off without any damage to the regenerated skin surface, and (3) hydrogel dressing material does not remain stuck on the wound. (author)

Application to the radiation processing of polymer

International Nuclear Information System (INIS)

Yoshii, Fumio

2003-01-01

Polypropylene (PP) and biodegradable polymer (blend of poly (ε-caploracton) 30/polybutylenesuccynate 70), PHB02 were irradiated with an electron beam to improve processability for production of thin film and foam. The processability of the polymer was improved due to enhancement of melt strength with irradiation at the dose range between 10 and 100 kGy. Increase of melt strength is due to entanglement of branch structure formed by irradiation. Possibility of high-speed production of thin film and production of foam have been achieved by this process. The soil degradation test showed that biodegradable polymer film buried in the soil was almost entirely degraded (97%) after two months and completely degraded after two and a half months. In the case of foam samples, 65% degradation was achieved after four months. Radiation crosslinked water-soluble polymer form hydrogel, which absorb much water. The hydrogel prepared by irradiation of polymer in aqueous solution was applied as dressing for healing of wound. In order to evaluate the healing effect of the polyethylene oxide (PEO) hydrogel dressing, wounds formed on the back of marmots were covered by the hydrogel. The healing under the wet environment of the hydrogel dressing had three advantages, compared with that of gauze dressing, which gives a dry environment: (1) enhancement of healing rate, (2) facilitation for changing the dressing, i.e. the hydrogel can be peeled off without any damage to the regenerated skin surface, and (3) hydrogel dressing material does not remain stuck on the wound. (author)

Initial development and testing of a novel foam-based pressure sensor for wearable sensing

Directory of Open Access Journals (Sweden)

Smyth Barry

2005-03-01

Full Text Available Abstract Background This paper provides an overview of initial research conducted in the development of pressure-sensitive foam and its application in wearable sensing. The foam sensor is composed of polypyrrole-coated polyurethane foam, which exhibits a piezo-resistive reaction when exposed to electrical current. The use of this polymer-coated foam is attractive for wearable sensing due to the sensor's retention of desirable mechanical properties similar to those exhibited by textile structures. Methods The development of the foam sensor is described, as well as the development of a prototype sensing garment with sensors in several areas on the torso to measure breathing, shoulder movement, neck movement, and scapula pressure. Sensor properties were characterized, and data from pilot tests was examined visually. Results The foam exhibits a positive linear conductance response to increased pressure. Torso tests show that it responds in a predictable and measurable manner to breathing, shoulder movement, neck movement, and scapula pressure. Conclusion The polypyrrole foam shows considerable promise as a sensor for medical, wearable, and ubiquitous computing applications. Further investigation of the foam's consistency of response, durability over time, and specificity of response is necessary.

Measurement of Mechanical Properties of PVC Foam Using a Modified Arcan Fixture

DEFF Research Database (Denmark)

Taher, Siavash Talebi; Thomsen, Ole Thybo; M. Dulieu-Barton, Janice

, compressive and shear properties. The MAF enables the realization of unidirectional tensile, compressive and shear loading states, as well as high compression or tension to shear ratio bidirectional loading conditions. The MAF is attached to a standard universal test machine using specially designed grips......Previously, the Arcan test rig has been used to measure bidirectional properties of polymer foams used for sandwich core materials, especially in the tensile-shear stress region [1]. In this work, a modified Arcan fixture (MAF) is used to load polymer foam specimens to obtain their tensile...... that do not constrain the specimen either in-plane or out-of-plane and hence eliminate any paristic effects due to test machine misalignment. The focus of this paper is to compare and validate the accuracy of the material properties measured using the proposed MAF, by comparing with results obtained using...

The effect of gamma-radiation on biodegradability of natural FIBER/PP-HMSPP foams: A study of thermal stability and biodegradability

International Nuclear Information System (INIS)

Cardoso, Elizabeth C.L.; Scagliusi, Sandra R.; Lugao, Ademar B.

2015-01-01

This research was carried out to evaluate how gamma-radiation affected PP/HMSPP structural foams reinforced with sugarcane bagasse, in terms of thermal properties, biodegradability and infrared spectrum. Polymers are used in various applications and in different industrial areas providing enormous quantities of wastes in environment, contributing with 20 to 30% of total volume of solid residues. Besides, shortage of plastics resins obtained from oil and natural gas is addressing research and development toward alternative materials; environmental concerning in litter reduction is being directed to renewable polymers for manufacturing of polymeric foams. Biodegradable polymers, a new generation of polymers produced from various natural resources, environmentally safe and friendly, can contribute for pollution reduction, at a low cost. High density structural foams are specially used in civil construction, in replacement of metals, woods and concrete, but contribute for environmental pollution, due to components nature. In this study, it was incorporated sugarcane bagasse in PP/HMSPP polymeric matrix blends. Gamma radiation applied at 50, 100, 150, 200 and 500 kGy doses showed effective for biodegradability induction. TGA analyses pointed toward stability around 205 deg C; decomposition of both cellulose and hemicellulose took place at 310 deg C and above, whereas the degradation of reinforced fibers composites took place above 430 deg C. Infrared spectrum of foams were studied using FTIR, showing no sensitivity to the presence of C = C and C =O functional groups. (author)

The effect of gamma-radiation on biodegradability of natural FIBER/PP-HMSPP foams: A study of thermal stability and biodegradability

Energy Technology Data Exchange (ETDEWEB)

Cardoso, Elizabeth C.L.; Scagliusi, Sandra R.; Lugao, Ademar B., E-mail: eclcardo@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

This research was carried out to evaluate how gamma-radiation affected PP/HMSPP structural foams reinforced with sugarcane bagasse, in terms of thermal properties, biodegradability and infrared spectrum. Polymers are used in various applications and in different industrial areas providing enormous quantities of wastes in environment, contributing with 20 to 30% of total volume of solid residues. Besides, shortage of plastics resins obtained from oil and natural gas is addressing research and development toward alternative materials; environmental concerning in litter reduction is being directed to renewable polymers for manufacturing of polymeric foams. Biodegradable polymers, a new generation of polymers produced from various natural resources, environmentally safe and friendly, can contribute for pollution reduction, at a low cost. High density structural foams are specially used in civil construction, in replacement of metals, woods and concrete, but contribute for environmental pollution, due to components nature. In this study, it was incorporated sugarcane bagasse in PP/HMSPP polymeric matrix blends. Gamma radiation applied at 50, 100, 150, 200 and 500 kGy doses showed effective for biodegradability induction. TGA analyses pointed toward stability around 205 deg C; decomposition of both cellulose and hemicellulose took place at 310 deg C and above, whereas the degradation of reinforced fibers composites took place above 430 deg C. Infrared spectrum of foams were studied using FTIR, showing no sensitivity to the presence of C = C and C =O functional groups. (author)

A phenomenological constitutive model for low density polyurethane foams

International Nuclear Information System (INIS)

Neilsen, M.K.; Morgan, H.S.; Krieg, R.D.

1987-04-01

Results from a series of hydrostatic and triaxial compression tests which were performed on polyurethane foams are presented in this report. These tests indicate that the volumetric and deviatoric parts of the foam behavior are strongly coupled. This coupling behavior could not be captured with any of several commonly used plasticity models. Thus, a new constitutive model was developed. This new model was based on a decomposition of the foam response into two parts: (1) response of the polymer skeleton, and (2) response of the air inside the cells. The air contribution was completely volumetric. The new constitutive model was implemented in two finite element codes, SANCHO and PRONTO. Results from a series of analyses completed with these codes indicated that the new constitutive model captured all of the foam behaviors that had been observed in the experiments. Finally, a typical dynamic problem was analyzed using the new constitutive model and other constitutive models to demonstrate differences between the models. Results from this series of analyses indicated that the new constitutive model generated displacement and acceleration predictions that were between predictions obtained using the other models. This result was expected. 9 refs., 45 figs., 4 tabs

Polymer Microstructures: Modification and Characterization by Fluid Sorption

Science.gov (United States)

Boyer, S. A. E.; Baba, M.; Nedelec, J.-M.; Grolier, Jean-Pierre E.

2008-12-01

Polymer micro-organization can be modified by a combination of three constraints, thermal, hydrostatic, and fluid sorption. In selecting the fluid’s nature, chemically active or inert, and its physical state, liquid or supercritical, new “materials” can be generated. In addition, the interplay of temperature and pressure allows tailoring the obtained material structure for specific applications. Several complementary techniques have been developed to modify, analyze, and characterize the end products: scanning transitiometry, vibrating-wire (VW)-PVT coupling, thermoporosimetry, and temperature-modulated DSC (TMDSC). The great variety of possible applications in materials science is illustrated with different polymers which can produce materials from soft gel to rigid foams when submitted to fluid sorption, typical fluids being methane or a simple gas (CO2 or N2). Absorption of an appropriate fluid in a cross-linked polymer leads to a swelling phenomenon. Thermoporosimetry is a calorimetric technique developed to measure the shift by confinement of thermal-transition temperatures of the swelling fluids, which can be currently used solvents or mercury. Application of thermoporosimetry to a swollen cross-linked polymer allows calculation of the mesh size distribution and evaluation of the degree of reticulation of the polymer. The same technique can be applied to characterize the pore size distribution in a foamed polymer.

Gas-Foamed Scaffold Gradients for Combinatorial Screening in 3D

Directory of Open Access Journals (Sweden)

Joachim Kohn

2012-03-01

Full Text Available Current methods for screening cell-material interactions typically utilize a two-dimensional (2D culture format where cells are cultured on flat surfaces. However, there is a need for combinatorial and high-throughput screening methods to systematically screen cell-biomaterial interactions in three-dimensional (3D tissue scaffolds for tissue engineering. Previously, we developed a two-syringe pump approach for making 3D scaffold gradients for use in combinatorial screening of salt-leached scaffolds. Herein, we demonstrate that the two-syringe pump approach can also be used to create scaffold gradients using a gas-foaming approach. Macroporous foams prepared by a gas-foaming technique are commonly used for fabrication of tissue engineering scaffolds due to their high interconnectivity and good mechanical properties. Gas-foamed scaffold gradient libraries were fabricated from two biodegradable tyrosine-derived polycarbonates: poly(desaminotyrosyl-tyrosine ethyl ester carbonate (pDTEc and poly(desaminotyrosyl-tyrosine octyl ester carbonate (pDTOc. The composition of the libraries was assessed with Fourier transform infrared spectroscopy (FTIR and showed that pDTEc/pDTOc gas-foamed scaffold gradients could be repeatably fabricated. Scanning electron microscopy showed that scaffold morphology was similar between the pDTEc-rich ends and the pDTOc-rich ends of the gradient. These results introduce a method for fabricating gas-foamed polymer scaffold gradients that can be used for combinatorial screening of cell-material interactions in 3D.

Impact of foamed matrix components on foamed concrete properties

Science.gov (United States)

Tarasenko, V. N.

2018-03-01

The improvement of the matrix foam structure by means of foam stabilizing additives is aimed at solving the technology-oriented problems as well as at the further improvement of physical and mechanical properties of cellular-concrete composites. The dry foam mineralization is the mainstream of this research. Adding the concrete densifiers, foam stabilizers and mineral powders reduces the drying shrinkage, which makes the foam concrete products technologically effective.

Thermo-mechanical characterisation of low density carbon foams and composite materials for the ATLAS upgrade

CERN Document Server

Isaac, Bonad

As a result of the need to increase the luminosity of the Large Hadron Collider (LHC) at CERN-Geneva by 2020, the ATLAS detector requires an upgraded inner tracker. Up- grading the ATLAS experiment is essential due to higher radiation levels and high particle occupancies. The design of this improved inner tracker detector involves development of silicon sensors and their support structures. These support structures need to have well un- derstood thermal properties and be dimensionally stable in order to allow efficient cooling of the silicon and accurate track reconstruction. The work presented in this thesis is an in- vestigation which aims to qualitatively characterise the thermal and mechanical properties of the materials involved in the design of the inner tracker of the ATLAS upgrade. These materials are silicon carbide foam (SiC foam), low density carbon foams such as PocoFoam and Allcomp foam, Thermal Pyrolytic Graphite (TPG), carbon/carbon and Carbon Fibre Re- inforced Polymer (CFRP). The work involve...

Post-processing of polymer foam tissue scaffolds with high power ultrasound: A route to increased pore interconnectivity, pore size and fluid transport

International Nuclear Information System (INIS)

Watson, N.J.; Johal, R.K.; Glover, Z.; Reinwald, Y.; White, L.J.; Ghaemmaghami, A.M.; Morgan, S.P.; Rose, F.R.A.J.; Povey, M.J.W.; Parker, N.G.

2013-01-01

The aim of this work is to demonstrate that the structural and fluidic properties of polymer foam tissue scaffolds, post-fabrication but prior to the introduction of cells, can be engineered via exposure to high power ultrasound. Our analysis is supported by measurements of fluid uptake during insonification and imaging of the scaffold microstructure via X-ray computed tomography, scanning electron microscopy and acoustic microscopy. The ultrasonic treatment is performed with a frequency of 30 kHz, average intensities up to 80,000 Wm −2 and exposure times up to 20 h. The treatment is found to increase the mean pore size by over 10%. More striking is the improvement in fluid uptake: for scaffolds with only 40% water uptake via standard immersion techniques, we can routinely achieve full saturation of the scaffold over approximately one hour of exposure. These desirable modifications occur with negligible loss of scaffold integrity and mass, and are optimized when the ultrasound treatment is coupled to a pre-wetting stage with ethanol. Our findings suggest that high power ultrasound is highly targeted towards flow obstructions in the scaffold architecture, thereby providing an efficient means to promote pore interconnectivity and fluid transport in thick foam tissue scaffolds. - Highlights: • We expose thick PLA foam tissue scaffolds to high power ultrasound. • This treatment both accelerates and enhances the uptake of fluid into the scaffold. • It leads to significant increases in the mean pore size, pore interconnectivity and porosity. • The ultrasonic treatment is most effective when the scaffold is pre-wet with ethanol. • We demonstrate the use of acoustic microscopy to characterize the scaffold microstructure

FoamVis, A Visualization System for Foam Research: Design and Implementation

OpenAIRE

Lipsa, Dan; Roberts, Richard; Laramee, Robert

2015-01-01

Liquid foams are used in areas such as mineral separation, oil recovery, food and beverage production, sanitation and fire fighting. To improve the quality of products and the efficiency of processes in these areas, foam scientists wish to understand and control foam behaviour. To this end, foam scientists have used foam simulations to model foam behaviour; however, analysing these simulations presents difficult challenges. We describe the main foam research challenges and present the design ...

Polyurethane Foams for Thermal Insulation Uses Produced from Castor Oil and Crude Glycerol Biopolyols.

Science.gov (United States)

Carriço, Camila S; Fraga, Thaís; Carvalho, Vagner E; Pasa, Vânya M D

2017-07-02

Rigid polyurethane foams were synthesized using a renewable polyol from the simple physical mixture of castor oil and crude glycerol. The effect of the catalyst (DBTDL) content and blowing agents in the foams' properties were evaluated. The use of physical blowing agents (cyclopentane and n-pentane) allowed foams with smaller cells to be obtained in comparison with the foams produced with a chemical blowing agent (water). The increase of the water content caused a decrease in density, thermal conductivity, compressive strength, and Young's modulus, which indicates that the increment of CO₂ production contributes to the formation of larger cells. Higher amounts of catalyst in the foam formulations caused a slight density decrease and a small increase of thermal conductivity, compressive strength, and Young's modulus values. These green foams presented properties that indicate a great potential to be used as thermal insulation: density (23-41 kg·m -3 ), thermal conductivity (0.0128-0.0207 W·m -1 ·K -1 ), compressive strength (45-188 kPa), and Young's modulus (3-28 kPa). These biofoams are also environmentally friendly polymers and can aggregate revenue to the biodiesel industry, contributing to a reduction in fuel prices.

Blending Novatein{sup ®} thermoplastic protein with PLA for carbon dioxide assisted batch foaming

Energy Technology Data Exchange (ETDEWEB)

Walallavita, Anuradha, E-mail: asw15@students.waikato.ac.nz; Verbeek, Casparus J. R., E-mail: jverbeek@waikato.ac.nz; Lay, Mark, E-mail: mclay@waikato.ac.nz [University of Waikato, Hamilton 3240 (New Zealand)

2016-03-09

The convenience of polymeric foams has led to their widespread utilisation in everyday life. However, disposal of synthetic petroleum-derived foams has had a detrimental effect on the environment which needs to be addressed. This study uses a clean and sustainable approach to investigate the foaming capability of a blend of two biodegradable polymers, polylactic acid (PLA) and Novatein® Thermoplastic Protein (NTP). PLA, derived from corn starch, can successfully be foamed using a batch technique developed by the Biopolymer Network Ltd. NTP is a patented formulation of bloodmeal and chemical additives which can be extruded and injection moulded similar to other thermoplastics. However, foaming NTP is a new area of study and its interaction with blowing agents in the batch process is entirely unknown. Subcritical and supercritical carbon dioxide have been examined individually in two uniquely designed pressure vessels to foam various compositions of NTP-PLA blends. Foamed material were characterised in terms of expansion ratio, cell size, and cellular morphology in order to study how the composition of NTP-PLA affects foaming with carbon dioxide. It was found that blends with 5 wt. % NTP foamed using subcritical CO{sub 2} expanded up to 11 times due to heterogeneous nucleation. Morphology analysis using scanning electron microscopy showed that foams blown with supercritical CO{sub 2} had a finer cell structure with consistent cell size, whereas, foams blown with subcritical CO{sub 2} ranged in cell size and showed cell wall rupture. Ultimately, this research would contribute to the production of a biodegradable foam material to be used in packaging applications, thereby adding to the application potential of NTP.

Foam/Aerogel Composite Materials for Thermal and Acoustic Insulation and Cryogen Storage

Science.gov (United States)

Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Weiser, Erik S. (Inventor); Sass, Jared P. (Inventor)

2011-01-01

The invention involves composite materials containing a polymer foam and an aerogel. The composite materials have improved thermal insulation ability, good acoustic insulation, and excellent physical mechanical properties. The composite materials can be used, for instance, for heat and acoustic insulation on aircraft, spacecraft, and maritime ships in place of currently used foam panels and other foam products. The materials of the invention can also be used in building construction with their combination of light weight, strength, elasticity, ability to be formed into desired shapes, and superior thermal and acoustic insulation power. The materials have also been found to have utility for storage of cryogens. A cryogenic liquid or gas, such as N.sub.2 or H.sub.2, adsorbs to the surfaces in aerogel particles. Thus, another embodiment of the invention provides a storage vessel for a cryogen.

Improving the Strength of ZTA Foams with Different Strategies: Immersion Infiltration and Recoating

Directory of Open Access Journals (Sweden)

Xiaodong Chen

2017-07-01

Full Text Available The combination of high strength and toughness, excellent wear resistance and moderate density makes zirconia-toughened alumina (ZTA a favorable ceramic, and the foam version of it may also exhibit excellent properties. Here, ZTA foams were prepared by the polymer sponge replication method. We developed an immersion infiltration approach with simple equipment and operations to fill the hollow struts in as-prepared ZTA foams, and also adopted a multiple recoating method (up to four cycles to strengthen them. The solid load of the slurry imposed a significant influence on the properties of the ZTA foams. Immersion infiltration gave ZTA foams an improvement of 1.5 MPa in compressive strength to 2.6 MPa at 87% porosity, only resulting in a moderate reduction of porosity (2–3%. The Weibull modulus of the infiltrated foams was in the range of 6–9. The recoating method generated an increase in compression strength to 3.3–11.4 MPa with the reduced porosity of 58–83%. The recoating cycle dependency of porosity and compression strength is nearly linear. The immersion infiltration strategy is comparable to the industrially-established recoating method and can be applied to other reticulated porous ceramics (RPCs.

Radiation synthesis of polymer polyol

International Nuclear Information System (INIS)

Guo Jianmei; Zeng Xinmiao; Zhou Chengfei; Cao Wei; Zhai Tong; Wu Dezhen

2010-01-01

The polymer polyol was synthesized by γ irradiation. The properties of polymer polyol synthesized with different radiation dose were studied. The experiment result showed the radiation dose hadn't significant influence on the hydroxyl value of polymer polyol. The sample with different solid content had different hydroxyl value. When the radiation dose is between 1 to 12 kGy, the viscosity and hydroxyl value of polymer polyol were increased with the increment of radiation dose. When radiation dose is between 1 to 12 kGy, with the increment of radiation dose, viscosity of polymer polyol was rapidly increased, and the content solid of sample has few change. When radiation dose is higher than 20 kGy, the viscosity and hydroxyl value of polymer polyol have gradually increase with the increment of radiation dose. The size of polymer particles is 0.1-0.6 μm. The value of 150 mesh filter was 100%. The polymer polyol may be used as PU foam and elastomer. (authors)

Role of foam drainage in producing protein aggregates in foam fractionation.

Science.gov (United States)

Li, Rui; Zhang, Yuran; Chang, Yunkang; Wu, Zhaoliang; Wang, Yanji; Chen, Xiang'e; Wang, Tao

2017-10-01

It is essential to obtain a clear understanding of the foam-induced protein aggregation to reduce the loss of protein functionality in foam fractionation. The major effort of this work is to explore the roles of foam drainage in protein aggregation in the entire process of foam fractionation with bovine serum albumin (BSA) as a model protein. The results show that enhancing foam drainage increased the desorption of BSA molecules from the gas-liquid interface and the local concentration of desorbed molecules in foam. Therefore, it intensified the aggregation of BSA in foam fractionation. Simultaneously, it also accelerated the flow of BSA aggregates from rising foam into the residual solution along with the drained liquid. Because enhancing foam drainage increased the relative content of BSA molecules adsorbed at the gas-liquid interface, it also intensified the aggregation of BSA during both the defoaming process and the storage of the foamate. Furthermore, enhancing foam drainage more readily resulted in the formation of insoluble BSA aggregates. The results are highly important for a better understanding of foam-induced protein aggregation in foam fractionation. Copyright © 2017 Elsevier B.V. All rights reserved.

Generation of sclerosant foams by mechanical methods increases the foam temperature.

Science.gov (United States)

Tan, Lulu; Wong, Kaichung; Connor, David; Fakhim, Babak; Behnia, Masud; Parsi, Kurosh

2017-08-01

Objective To investigate the effect of agitation on foam temperature. Methods Sodium tetradecyl sulphate and polidocanol were used. Prior to foam generation, the sclerosant and all constituent equipment were cooled to 4-25℃ and compared with cooling the sclerosant only. Foam was generated using a modified Tessari method. During foam agitation, the temperature change was measured using a thermocouple for 120 s. Results Pre-cooling all the constituent equipment resulted in a cooler foam in comparison with only cooling the sclerosant. A starting temperature of 4℃ produced average foam temperatures of 12.5 and 13.2℃ for sodium tetradecyl sulphate and polidocanol, respectively. It was also found that only cooling the liquid sclerosant provided minimal cooling to the final foam temperature, with the temperature 20 and 20.5℃ for sodium tetradecyl sulphate and polidocanol, respectively. Conclusion The foam generation process has a noticeable impact on final foam temperature and needs to be taken into consideration when creating foam.

FoamVis, A Visualization System for Foam Research: Design and Implementation

Directory of Open Access Journals (Sweden)

Dan R. Lipsa

2015-03-01

Full Text Available Liquid foams are used in areas such as mineral separation, oil recovery, food and beverage production, sanitation and fire fighting. To improve the quality of products and the efficiency of processes in these areas, foam scientists wish to understand and control foam behaviour. To this end, foam scientists have used foam simulations to model foam behaviour; however, analysing these simulations presents difficult challenges. We describe the main foam research challenges and present the design of FoamVis, the only existing visualization, exploration and analysis application created to address them. We describe FoamVis’ main features, together with relevant design and implementation notes. Our goal is to provide a global overview and individual feature implementation details that would allow a visualization scientist to extend the FoamVis system with new algorithms and adapt it to new requirements. The result is a detailed presentation of the software that is not provided in previous visualization research papers.

Simulation of UMTS Capacity and Quality of Coverage in Urban Macro- and Microcellular Environment

Directory of Open Access Journals (Sweden)

P. Pechac

2005-12-01

Full Text Available This paper deals with simulations of a radio interface of thirdgeneration (3G mobile systems operating in the WCDMA FDD modeincluding propagation predictions in macro and microcells. In the radionetwork planning of 3G mobile systems, the quality of coverage and thesystem capacity present a common problem. Both macro and microcellularconcepts are very important for implementing wireless communicationsystems, such as Universal Mobile Telecommunication Systems (UMTS indense urban areas. The aim of this paper is to introduce differentimpacts - selected bit rate, uplink (UL loading, allocation and numberof Nodes B, selected propagation prediction models, macro andmicrocellular environment - on system capacity and quality of coveragein UMTS networks. Both separated and composite simulation scenarios ofmacro and microcellular environments are presented. The necessity of aniteration-based simulation approach and site-specific propagationmodeling in microcells is proven.

MICROCT AND PREPARATION OF ß-TCP GRANULAR MATERIAL BY THE POLYURETHANE FOAM METHOD

Directory of Open Access Journals (Sweden)

Robert Filmon

2011-05-01

Full Text Available Commercial ß-tricalcium phosphate (ß-TCP is commercialy available in granules manufactured by sintering of powders. We have evaluated the different steps of the manufacturing process of ß-TCP ceramics granules prepared from blocks obtained with the polyurethane foam technology. Three types of slurry were prepared with 10, 15 and 25 g of ß-TCP per gram of polyurethane foam. Analysis was done by scanning electron microscopy, EDX, Raman spectroscopy and microcomputed tomography combined with image analysis. A special algorithm was used to identify the internal microporosity (created by the calcination of the foam from the internal macroporosity due to the spatial repartition of the material. The low ß-TCP dosages readily infiltrated the foam and the slurry was deposited along the polymer rods. On the contrary, the highest concentration produced inhomogeneous infiltrated blocks and foam cavities appeared completely filled in some areas. 2D microcomputed sections and reconstructed 3D models evidenced this phenomenon and the frequency distribution of the thickness and separation of material trabeculae confirmed the heterogeneity of the distribution. When crushed, blocks prepared with the 25 g slurry provided the largest and irregular granulates.

A new method to make poly acrylate foam shells

International Nuclear Information System (INIS)

Fan Yongheng; Luo Xuan; Fang Yu; Ren Hongbo; Zhang Lin; Cui Yi

2009-01-01

A triple-orifice droplet generator was designed and developed for the size-controllable continuous fabrication of hollow foam micro-shells. Solutions of an internal water phase, an oil phase (trimethylpropane triacrylate monomer, dibutyl phthalate solvent, and benzoin ethyl ether initiator), and an external water phase were used to prepare micro-shells whose diameters are between 1.5 mm and 4.0 mm successfully. Characterization of the foam shells was carried out using a scanning electron microscope and X-ray radiography. The results show that cell diameters of the shells are not above 1 um. The refractive index of the polymer framework is around 1.50. Furthermore, the shells fabricated through the triple-orifice droplet generator have a high survival probability of 93% and exhibit narrow size distribution. (authors)

Helium ion microscopy based wall thickness and surface roughness analysis of polymer foams obtained from high internal phase emulsion

International Nuclear Information System (INIS)

Rodenburg, C.; Viswanathan, P.; Jepson, M.A.E.; Liu, X.; Battaglia, G.

2014-01-01

Due to their wide range of applications, porous polymers obtained from high internal phase emulsions have been widely studied using scanning electron microscopy. However, due to their lack of electrical conductivity, quantitative information of wall thicknesses and surface roughness, which are of particular interest to tissue engineering, has not been obtained. Here, Helium Ion Microscopy is used to examine uncoated polymer foams and some very strong but unexpected contrast is observed, the origin of which is established here. Based on this analysis, a method for the measurement of wall thickness variations and wall roughness measurements has been developed, based on the modeling of Helium ion transmission. The results presented here indicate that within the walls of the void structure there exist small features with height variations of ∼30 nm and wall thickness variations from ∼100 nm to larger 340 nm in regions surrounding interconnecting windows within the structure. The suggested imaging method is applicable to other porous carbon based structures with wall thicknesses in the range of 40–340 nm. - Highlights: • The first helium ion microscopy image of uncoated structures formed from HIPEs is presented. • Unusually high contrast features that change with accelerating voltage are observed. • The origin of the observed contrast is determined to be mass thickness contrast. • A new method for quantitative wall thickness variation/roughness measurements is demonstrated

Helium ion microscopy based wall thickness and surface roughness analysis of polymer foams obtained from high internal phase emulsion

Energy Technology Data Exchange (ETDEWEB)

Rodenburg, C., E-mail: c.rodenburg@sheffield.ac.uk [Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Viswanathan, P. [Department of Biomedical Sciences, University of Sheffield, Firth Court, Western Bank Sheffield, Sheffield S10 2 TN (United Kingdom); Jepson, M.A.E. [Department of Materials, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom); Liu, X. [Carl Zeiss Microscopy GmbH, Carl-Zeiss-Strasse 22, 73447 Oberkochen (Germany); Battaglia, G. [Department of Chemistry University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); The MRC/UCL Centre for Medical Molecular Virology, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

2014-04-01

Due to their wide range of applications, porous polymers obtained from high internal phase emulsions have been widely studied using scanning electron microscopy. However, due to their lack of electrical conductivity, quantitative information of wall thicknesses and surface roughness, which are of particular interest to tissue engineering, has not been obtained. Here, Helium Ion Microscopy is used to examine uncoated polymer foams and some very strong but unexpected contrast is observed, the origin of which is established here. Based on this analysis, a method for the measurement of wall thickness variations and wall roughness measurements has been developed, based on the modeling of Helium ion transmission. The results presented here indicate that within the walls of the void structure there exist small features with height variations of ∼30 nm and wall thickness variations from ∼100 nm to larger 340 nm in regions surrounding interconnecting windows within the structure. The suggested imaging method is applicable to other porous carbon based structures with wall thicknesses in the range of 40–340 nm. - Highlights: • The first helium ion microscopy image of uncoated structures formed from HIPEs is presented. • Unusually high contrast features that change with accelerating voltage are observed. • The origin of the observed contrast is determined to be mass thickness contrast. • A new method for quantitative wall thickness variation/roughness measurements is demonstrated.

Toxicity of pyrolysis gases from some cellular polymers

Science.gov (United States)

Hilado, C. J.; Machado, A. M.

1978-01-01

Various samples of cellular polymers were evaluated for toxicity of pyrolysis gases, using the screening test method developed at the University of San Francisco. The cellular polymer samples included polyimide, polymethacrylimide, polybismaleimide, polyurethane, polyisocyanurate, polyethylene, polychloroprene, polyvinyl chloride, polystyrene, polysiloxane, and polyphosphazene. The cellular polymers exhibited varying levels of toxicity under these test conditions. Among the rigid cellular polymers, times to death were shortest with the imide type foams and longest with polyvinyl chloride and polystyrene. Among the flexible cellular polymers, times to death were shortest with polyimide and polyester, and longest with polychloroprene and polysiloxane. Increased char yield was not necessarily associated with reduced toxicity.

A kinetic approach to modeling the manufacture of high density strucutral foam: Foaming and polymerization

Energy Technology Data Exchange (ETDEWEB)

Rao, Rekha R. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, Livermore, CA (United States); Mondy, Lisa Ann [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, Livermore, CA (United States); Noble, David R. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, Livermore, CA (United States); Brunini, Victor [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, Livermore, CA (United States); Roberts, Christine Cardinal [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, Livermore, CA (United States); Long, Kevin Nicholas [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, Livermore, CA (United States); Soehnel, Melissa Marie [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, Livermore, CA (United States); Celina, Mathias C. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, Livermore, CA (United States); Wyatt, Nicholas B. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, Livermore, CA (United States); Thompson, Kyle R. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, Livermore, CA (United States); Tinsley, James

2015-09-01

We are studying PMDI polyurethane with a fast catalyst, such that filling and polymerization occur simultaneously. The foam is over-packed to tw ice or more of its free rise density to reach the density of interest. Our approach is to co mbine model development closely with experiments to discover new physics, to parameterize models and to validate the models once they have been developed. The model must be able to repres ent the expansion, filling, curing, and final foam properties. PMDI is chemically blown foam, wh ere carbon dioxide is pr oduced via the reaction of water and isocyanate. The isocyanate also re acts with polyol in a competing reaction, which produces the polymer. A new kinetic model is developed and implemented, which follows a simplified mathematical formalism that decouple s these two reactions. The model predicts the polymerization reaction via condensation chemis try, where vitrification and glass transition temperature evolution must be included to correctly predict this quantity. The foam gas generation kinetics are determined by tracking the molar concentration of both water and carbon dioxide. Understanding the therma l history and loads on the foam due to exothermicity and oven heating is very important to the results, since the kinetics and ma terial properties are all very sensitive to temperature. The conservation eq uations, including the e quations of motion, an energy balance, and thr ee rate equations are solved via a stabilized finite element method. We assume generalized-Newtonian rheology that is dependent on the cure, gas fraction, and temperature. The conservation equations are comb ined with a level set method to determine the location of the free surface over time. Results from the model are compared to experimental flow visualization data and post-te st CT data for the density. Seve ral geometries are investigated including a mock encapsulation part, two configur ations of a mock stru ctural part, and a bar geometry to

Foam Microrheology

International Nuclear Information System (INIS)

KRAYNIK, ANDREW M.; LOEWENBERG, MICHAEL; REINELT, DOUGLAS A.

1999-01-01

The microrheology of liquid foams is discussed for two different regimes: static equilibrium where the capillary number Ca is zero, and the viscous regime where viscosity and surface tension are important and Ca is finite. The Surface Evolver is used to calculate the equilibrium structure of wet Kelvin foams and dry soap froths with random structure, i.e., topological disorder. The distributions of polyhedra and faces are compared with the experimental data of Matzke. Simple shearing flow of a random foam under quasistatic conditions is also described. Viscous phenomena are explored in the context of uniform expansion of 2D and 3D foams at low Reynolds number. Boundary integral methods are used to calculate the influence of Ca on the evolution of foam microstructure, which includes bubble shape and the distribution of liquid between films, Plateau borders, and (in 3D) the nodes where Plateau borders meet. The micromechanical point of view guides the development of structure-property-processing relationships for foams

dsmcFoam+: An OpenFOAM based direct simulation Monte Carlo solver

Science.gov (United States)

White, C.; Borg, M. K.; Scanlon, T. J.; Longshaw, S. M.; John, B.; Emerson, D. R.; Reese, J. M.

2018-03-01

dsmcFoam+ is a direct simulation Monte Carlo (DSMC) solver for rarefied gas dynamics, implemented within the OpenFOAM software framework, and parallelised with MPI. It is open-source and released under the GNU General Public License in a publicly available software repository that includes detailed documentation and tutorial DSMC gas flow cases. This release of the code includes many features not found in standard dsmcFoam, such as molecular vibrational and electronic energy modes, chemical reactions, and subsonic pressure boundary conditions. Since dsmcFoam+ is designed entirely within OpenFOAM's C++ object-oriented framework, it benefits from a number of key features: the code emphasises extensibility and flexibility so it is aimed first and foremost as a research tool for DSMC, allowing new models and test cases to be developed and tested rapidly. All DSMC cases are as straightforward as setting up any standard OpenFOAM case, as dsmcFoam+ relies upon the standard OpenFOAM dictionary based directory structure. This ensures that useful pre- and post-processing capabilities provided by OpenFOAM remain available even though the fully Lagrangian nature of a DSMC simulation is not typical of most OpenFOAM applications. We show that dsmcFoam+ compares well to other well-known DSMC codes and to analytical solutions in terms of benchmark results.

The influence of the parameters of lost foam process on the quality of aluminum alloys castings

Directory of Open Access Journals (Sweden)

Aćimović-Pavlović Zagorka

2010-01-01

Full Text Available This paper presents the research results of application of Lost foam process for aluminum alloys castings of a simple geometry. The process characteristic is that patterns and gating of moulds, made of polymers, stay in the mould till the liquid metal inflow. In contact with the liquid metal, pattern intensely and in relatively short time decomposes and evaporates, which is accompanied by casting crystallization. As a consequence of polymer pattern decomposition and evaporation a great quantity of liquid and gaseous products are produced, which is often the cause of different types of casting errors. This paper presents the results of a research with a special consideration given to detecting and analyzing the errors of castings. In most cases the cause of these errors are defects of polymer materials used for evaporable patterns production, as well as defects of materials for refractory coatings production for polymer patterns. The researches have shown that different types of coatings determine properties of the obtained castings. Also, the critical processing parameters (polymer pattern density, casting temperature, permeability of refractory coating and sand, construction of patterns and gating of moulds significantly affect on castings quality. During the research a special consideration was given to control and optimization of these parameters with the goal of achieving applicable castings properties. The study of surface and internal error of castings was performed systematically in order to carry out preventive measures to avoid errors and minimize production costs. In order to achieve qualitative and profitable castings production by the method of Lost foam it is necessary to reach the balance in the system: evaporable polymer pattern - liquid metal - refractory coating - sandy cast in the phase of metal inflow, decomposition and evaporation of polymer pattern, formation and solidification of castings. By optimizing the processing

Thermal, crystallinity and morphological studies of the filled RBD palm kernel oil polyurethane foam

International Nuclear Information System (INIS)

Khairiah Badri; Sahrim Ahmad; Sarani Zakaria

2000-01-01

The synthesis of RBD palm kernel oil (PKO) polyurethane polyol and the polyurethane foam has well been documented. However, less study has been put in discovering the thermal properties and crystallinity of the foam. It is also an initiative to investigate the effect of oil palm empty fruit bunch (EFB) and sorbitol as fillers in the polyurethane (PU) foam to these properties. Thermogravimetric (TGA) investigation of the PKO PU foam was performed to study their decompositions. The semi-crystalline nature of EFB-filled PU was confirmed by x-ray diffratogram and DSC thermogram of glass transition temperature, T g . The x-ray diffraction (XRD) study of the unfilled PU showed a broad amorphous halo, indicative of absence of crystallinity in the polymer, which has been explained as due to strong hydrogen bonding in the hard phase. Overall crystallinity decreases with an increase in the polyester content in agreement with the XRD results. The crystallinity however, increases with the inclusion of EFB in the polyurethane system. This study was followed by the observation of the surface morphologies of the PKO PU foam with and without fillers. The scanning electron micrographs verified the finding on the improved k-factor values. (Author)

Flexible Foam Model.

Energy Technology Data Exchange (ETDEWEB)

Neilsen, Michael K.; Lu, Wei-Yang; Werner, Brian T.; Scherzinger, William M.; Lo, Chi S.

2018-03-01

Experiments were performed to characterize the mechanical response of a 15 pcf flexible polyurethane foam to large deformation at different strain rates and temperatures. Results from these experiments indicated that at room temperature, flexible polyurethane foams exhibit significant nonlinear elastic deformation and nearly return to their original undeformed shape when unloaded. However, when these foams are cooled to temperatures below their glass transition temperature of approximately -35 o C, they behave like rigid polyurethane foams and exhibit significant permanent deformation when compressed. Thus, a new model which captures this dramatic change in behavior with temperature was developed and implemented into SIERRA with the name Flex_Foam to describe the mechanical response of both flexible and rigid foams to large deformation at a variety of temperatures and strain rates. This report includes a description of recent experiments. Next, development of the Flex Foam model for flexible polyurethane and other flexible foams is described. Selection of material parameters are discussed and finite element simulations with the new Flex Foam model are compared with experimental results to show behavior that can be captured with this new model.

Using Sodium Hydrogen Carbonate for Foaming Polymers

Directory of Open Access Journals (Sweden)

Satin Lukáš

2016-09-01

Full Text Available All plastics products are made of the essential polymer mixed with a complex blend of materials known collectively as additives. Without additives, plastics would not work, but with them, they can be made safer, cleaner, tougher and more colourful. Additives cost money, but by reducing production costs and making products live longer, they help us save money and conserve the world's precious raw material reserves. In fact, our world would be a lot less safe, a lot more expensive and a great deal duller without the additives that turn basic polymers into useful plastics. One of these additives is sodium bicarbonate. Influence of sodium bicarbonate on properties of the product made of polystyrene was observed in the research described in this paper. Since polystyrene is typically used as a material for electrical components, the mechanical properties of tensile strength and inflammability were measured as a priority. Inflammability parameters were measured using a cone calorimeter.

Corrosion-resistant Foamed Cements for Carbon Steels

Energy Technology Data Exchange (ETDEWEB)

Sugama T.; Gill, S.; Pyatina, T., Muraca, A.; Keese, R.; Khan, A.; Bour, D.

2012-12-01

The cementitious material consisting of Secar #80, Class F fly ash, and sodium silicate designed as an alternative thermal-shock resistant cement for the Enhanced Geothermal System (EGS) wells was treated with cocamidopropyl dimethylamine oxide-based compound as foaming agent (FA) to prepare numerous air bubble-dispersed low density cement slurries of and #61603;1.3 g/cm3. Then, the foamed slurry was modified with acrylic emulsion (AE) as corrosion inhibitor. We detailed the positive effects of the acrylic polymer (AP) in this emulsion on the five different properties of the foamed cement: 1) The hydrothermal stability of the AP in 200 and #61616;C-autoclaved cements; 2) the hydrolysis-hydration reactions of the slurry at 85 and #61616;C; 3) the composition of crystalline phases assembled and the microstructure developed in autoclaved cements; 4) the mechanical behaviors of the autoclaved cements; and, 5) the corrosion mitigation of carbon steel (CS) by the polymer. For the first property, the hydrothermal-catalyzed acid-base interactions between the AP and cement resulted in Ca-or Na-complexed carboxylate derivatives, which led to the improvement of thermal stability of the AP. This interaction also stimulated the cement hydration reactions, enhancing the total heat evolved during cement’s curing. Addition of AP did not alter any of the crystalline phase compositions responsible for the strength of the cement. Furthermore, the AP-modified cement developed the porous microstructure with numerous defect-free cavities of disconnected voids. These effects together contributed to the improvement of compressive-strength and –toughness of the cured cement. AP modification of the cement also offered an improved protection of CS against brine-caused corrosion. There were three major factors governing the corrosion protection: 1) Reducing the extents of infiltration and transportation of corrosive electrolytes through the cement layer deposited on the underlying CS

Modeling Heat Transfer and Pressurization of Polymeric Methylene Diisocyanate (PMDI) Polyurethane Foam in a Sealed Container.

Energy Technology Data Exchange (ETDEWEB)

Scott, Sarah Nicole

2018-01-01

Polymer foam encapsulants provide mechanical, electrical, and thermal isolation in engineered systems. It can be advantageous to surround objects of interest, such as electronics, with foams in a hermetically sealed container to protect the electronics from hostile en vironments, such as a crash that produces a fire. However, i n fire environments, gas pressure from thermal decomposition of foams can cause mechanical failure of the sealed system . In this work, a detailed study of thermally decomposing polymeric methylene diisocyanate (PMDI) - polyether - polyol based polyurethane foam in a sealed container is presented . Both experimental and computational work is discussed. Three models of increasing physics fidelity are presented: No Flow, Porous Media, and Porous Media with VLE. Each model us described in detail, compared to experiment , and uncertainty quantification is performed. While the Porous Media with VLE model matches has the best agreement with experiment, it also requires the most computational resources.

Combining mechanical foaming and thermally induced phase separation to generate chitosan scaffolds for soft tissue engineering.

Science.gov (United States)

Biswas, D P; Tran, P A; Tallon, C; O'Connor, A J

2017-02-01

In this paper, a novel foaming methodology consisting of turbulent mixing and thermally induced phase separation (TIPS) was used to generate scaffolds for tissue engineering. Air bubbles were mechanically introduced into a chitosan solution which forms the continuous polymer/liquid phase in the foam created. The air bubbles entrained in the foam act as a template for the macroporous architecture of the final scaffolds. Wet foams were crosslinked via glutaraldehyde and frozen at -20 °C to induce TIPS in order to limit film drainage, bubble coalescence and Ostwald ripening. The effects of production parameters, including mixing speed, surfactant concentration and chitosan concentration, on foaming are explored. Using this method, hydrogel scaffolds were successfully produced with up to 80% porosity, average pore sizes of 120 μm and readily tuneable compressive modulus in the range of 2.6 to 25 kPa relevant to soft tissue engineering applications. These scaffolds supported 3T3 fibroblast cell proliferation and penetration and therefore show significant potential for application in soft tissue engineering.

Green waste cooking oil-based rigid polyurethane foam

Science.gov (United States)

Enderus, N. F.; Tahir, S. M.

2017-11-01

Polyurethane is a versatile polymer traditionally prepared using petroleum-based raw material. Petroleum, however, is a non-renewable material and polyurethane produced was found to be non-biodegradable. In quest for a more environmentally friendly alternative, wastecooking oil, a highly abundant domestic waste with easily derivatized structure, is a viable candidate to replace petroleum. In this study,an investigation to determine physical and chemical properties of rigid polyurethane (PU) foam from waste cooking oil (WCO) was carried out. WCO was first adsorbed by using coconut husk activated carbon adsorbent prior to be used for polyol synthesis. The purified WCO was then used to synthesize polyol via transesterification reaction to yield alcohol groups in the WCO chains structure. Finally, the WCO-based polyol was used to prepare rigid PU foam. The optimum formulation for PU formation was found to be 90 polyol: 60 glycerol: 54 water: 40 diethanolamine: 23 diisocyanate. The rigid PU foam has density of 208.4 kg/m3 with maximum compressive strength and capability to receive load at 0.03 MPa and 0.09 kN, respectively. WCO-based PU can potentially be used to replace petroleum-based PU as house construction materials such as insulation panels.

Study on combined chemotherapy and radiotherapy of the microcellular bronchial carcinoma (CCR study): chemo-/radiotherapy opposed to radio-/chemotherapy

International Nuclear Information System (INIS)

Heilmann, H.P.; Buenemann, H.; Arnal, M.L.; Calavrezos, A.; Engel, J.; Hain, E.; Koschel, G.; Seysen, U.; Allgemeines Krankenhaus Harburg, Hamburg; Franke, H.D.; Juengst, G.; Kohl, F.V.; Wichert, P. v.

1983-01-01

The authors studied the effect of a chemo-/radiotherapy or radio-/chemotherapy on 52 cases of microcellular bronchial carcinoma, classification ''limited disease''. The survival curves were slightly better for the patients submitted to primary chemotherapy, but the difference was not statistically significant, and the curves coincided again after 18 months. 60 to 80% of the patients had no complaints or only unimportant complaints during more than half of their survival time. In 23 patients with ''extensive disease'' who received only a symptomatic therapy or a combined palliative chemotherapy, chemotherapy had a slightly better effect, but this was not statistically significant. (orig.) [de

PUR-PIR foam produced based on poly(hydroxybutyl citrate foamed founded with different factories

Directory of Open Access Journals (Sweden)

Liszkowska Joanna

2018-03-01

Full Text Available A poly(hydroxybutyl citrate p(HBC was obtained. The product compound produced in the solution during esterification, was added to rigid polyurethane-polyisocyanurate foams (PUR-PIR. The amount of petrochemical polyol in the foams was decreased in favor of the p(HBC from 0.1 to 0.5 equivalent. The foams were foamed in two ways: with distilled water (W foams and with Solkane 365/227 (S foams. The examination results of both foam series were compared. They showed that the foams foamed with water have higher softening temperature than the foams foamed with solkane. The retention values for both foam series are around 91–95%, and water absorption in the range of 0.7–3.2%. The anisotropy coefficient did not exceed 1.08 (the lowest value being 1.01.

Infiltrated carbon foam composites

Science.gov (United States)

Lucas, Rick D. (Inventor); Danford, Harry E. (Inventor); Plucinski, Janusz W. (Inventor); Merriman, Douglas J. (Inventor); Blacker, Jesse M. (Inventor)

2012-01-01

An infiltrated carbon foam composite and method for making the composite is described. The infiltrated carbon foam composite may include a carbonized carbon aerogel in cells of a carbon foam body and a resin is infiltrated into the carbon foam body filling the cells of the carbon foam body and spaces around the carbonized carbon aerogel. The infiltrated carbon foam composites may be useful for mid-density ablative thermal protection systems.

Thermally insulating and fire-retardant lightweight anisotropic foams based on nanocellulose and graphene oxide

Science.gov (United States)

Wicklein, Bernd; Kocjan, Andraž; Salazar-Alvarez, German; Carosio, Federico; Camino, Giovanni; Antonietti, Markus; Bergström, Lennart

2015-03-01

High-performance thermally insulating materials from renewable resources are needed to improve the energy efficiency of buildings. Traditional fossil-fuel-derived insulation materials such as expanded polystyrene and polyurethane have thermal conductivities that are too high for retrofitting or for building new, surface-efficient passive houses. Tailored materials such as aerogels and vacuum insulating panels are fragile and susceptible to perforation. Here, we show that freeze-casting suspensions of cellulose nanofibres, graphene oxide and sepiolite nanorods produces super-insulating, fire-retardant and strong anisotropic foams that perform better than traditional polymer-based insulating materials. The foams are ultralight, show excellent combustion resistance and exhibit a thermal conductivity of 15 mW m-1 K-1, which is about half that of expanded polystyrene. At 30 °C and 85% relative humidity, the foams retained more than half of their initial strength. Our results show that nanoscale engineering is a promising strategy for producing foams with excellent properties using cellulose and other renewable nanosized fibrous materials.

Dielectric and Radiative Properties of Sea Foam at Microwave Frequencies: Conceptual Understanding of Foam Emissivity

OpenAIRE

Peter W. Gaiser; Magdalena D. Anguelova

2012-01-01

Foam fraction can be retrieved from space-based microwave radiometric data at frequencies from 1 to 37 GHz. The retrievals require modeling of ocean surface emissivity fully covered with sea foam. To model foam emissivity well, knowledge of foam properties, both mechanical and dielectric, is necessary because these control the radiative processes in foam. We present a physical description of foam dielectric properties obtained from the foam dielectric constant including foam skin depth; foam ...

Operator spin foam models

International Nuclear Information System (INIS)

Bahr, Benjamin; Hellmann, Frank; Kaminski, Wojciech; Kisielowski, Marcin; Lewandowski, Jerzy

2011-01-01

The goal of this paper is to introduce a systematic approach to spin foams. We define operator spin foams, that is foams labelled by group representations and operators, as our main tool. A set of moves we define in the set of the operator spin foams (among other operations) allows us to split the faces and the edges of the foams. We assign to each operator spin foam a contracted operator, by using the contractions at the vertices and suitably adjusted face amplitudes. The emergence of the face amplitudes is the consequence of assuming the invariance of the contracted operator with respect to the moves. Next, we define spin foam models and consider the class of models assumed to be symmetric with respect to the moves we have introduced, and assuming their partition functions (state sums) are defined by the contracted operators. Briefly speaking, those operator spin foam models are invariant with respect to the cellular decomposition, and are sensitive only to the topology and colouring of the foam. Imposing an extra symmetry leads to a family we call natural operator spin foam models. This symmetry, combined with assumed invariance with respect to the edge splitting move, determines a complete characterization of a general natural model. It can be obtained by applying arbitrary (quantum) constraints on an arbitrary BF spin foam model. In particular, imposing suitable constraints on a spin(4) BF spin foam model is exactly the way we tend to view 4D quantum gravity, starting with the BC model and continuing with the Engle-Pereira-Rovelli-Livine (EPRL) or Freidel-Krasnov (FK) models. That makes our framework directly applicable to those models. Specifically, our operator spin foam framework can be translated into the language of spin foams and partition functions. Among our natural spin foam models there are the BF spin foam model, the BC model, and a model corresponding to the EPRL intertwiners. Our operator spin foam framework can also be used for more general spin

Bubble and foam chemistry

CERN Document Server

Pugh, Robert J

2016-01-01

This indispensable guide will equip the reader with a thorough understanding of the field of foaming chemistry. Assuming only basic theoretical background knowledge, the book provides a straightforward introduction to the principles and properties of foams and foaming surfactants. It discusses the key ideas that underpin why foaming occurs, how it can be avoided and how different degrees of antifoaming can be achieved, and covers the latest test methods, including laboratory and industrial developed techniques. Detailing a variety of different kinds of foams, from wet detergents and food foams, to polymeric, material and metal foams, it connects theory to real-world applications and recent developments in foam research. Combining academic and industrial viewpoints, this book is the definitive stand-alone resource for researchers, students and industrialists working on foam technology, colloidal systems in the field of chemical engineering, fluid mechanics, physical chemistry, and applied physics.

Foam engineering fundamentals and applications

CERN Document Server

2012-01-01

Containing contributions from leading academic and industrial researchers, this book provides a much needed update of foam science research. The first section of the book presents an accessible summary of the theory and fundamentals of foams. This includes chapters on morphology, drainage, Ostwald ripening, coalescence, rheology, and pneumatic foams. The second section demonstrates how this theory is used in a wide range of industrial applications, including foam fractionation, froth flotation and foam mitigation. It includes chapters on suprafroths, flotation of oil sands, foams in enhancing petroleum recovery, Gas-liquid Mass Transfer in foam, foams in glass manufacturing, fire-fighting foam technology and consumer product foams.

Foams theory, measurements, and applications

CERN Document Server

Khan, Saad A

1996-01-01

This volume discusses the physics and physical processes of foam and foaming. It delineates various measurement techniques for characterizing foams and foam properties as well as the chemistry and application of foams. The use of foams in the textile industry, personal care products, enhanced oil recovery, firefighting and mineral floatation are highlighted, and the connection between the microstructure and physical properties of foam are detailed. Coverage includes nonaqueous foams and silicone antifoams, and more.

Structural Foaming at the Nano-, Micro-, and Macro-Scales of Continuous Carbon Fiber Reinforced Polymer Matrix Composites

Science.gov (United States)

2012-10-29

structural porosity at MNM scales could be introduced into the matrix, the carbon fiber reinforcement, and during prepreg lamination processing, without...areas, including fibers. Furthermore, investigate prepreg thickness and resin content effects on the thermomechanical performance of laminated ...Accomplishment 4) 5 Develop constitutive models for nano- foamed and micro- foamed PMC systems from single ply prepreg to multilayer laminated

Influence of the molecular structure on indentation size effect in polymers

International Nuclear Information System (INIS)

Han, Chung-Souk

2010-01-01

Size dependent deformation of polymers has been observed by various researchers in various experimental settings including micro beam bending, foams and indentation testing. Here in this article the indentation size effect in polymers is examined which manifests itself in increased hardness at decreasing indentation depths. Based on previously suggested rationale of size dependent deformation and depth dependent hardness model the depth dependent hardness of various polymers are analyzed. It is found that polymers containing aromatic rings in their molecular structure exhibit depth dependent hardness above the micron length scale. For polymers not containing aromatic rings polymers the indentation size effect starts at smaller indentation depths if they are present at all.

Efficacy of liquid and foam decontamination technologies for chemical warfare agents on indoor surfaces.

Science.gov (United States)

Love, Adam H; Bailey, Christopher G; Hanna, M Leslie; Hok, Saphon; Vu, Alex K; Reutter, Dennis J; Raber, Ellen

2011-11-30

Bench-scale testing was used to evaluate the efficacy of four decontamination formulations on typical indoor surfaces following exposure to the liquid chemical warfare agents sarin (GB), soman (GD), sulfur mustard (HD), and VX. Residual surface contamination on coupons was periodically measured for up to 24h after applying one of four selected decontamination technologies [0.5% bleach solution with trisodium phosphate, Allen Vanguard Surface Decontamination Foam (SDF™), U.S. military Decon Green™, and Modec Inc. and EnviroFoam Technologies Sandia Decontamination Foam (DF-200)]. All decontamination technologies tested, except for the bleach solution, performed well on nonporous and nonpermeable glass and stainless-steel surfaces. However, chemical agent residual contamination typically remained on porous and permeable surfaces, especially for the more persistent agents, HD and VX. Solvent-based Decon Green™ performed better than aqueous-based bleach or foams on polymeric surfaces, possibly because the solvent is able to penetrate the polymer matrix. Bleach and foams out-performed Decon Green for penetrating the highly polar concrete surface. Results suggest that the different characteristics needed for an ideal and universal decontamination technology may be incompatible in a single formulation and a strategy for decontaminating a complex facility will require a range of technologies. Copyright © 2011 Elsevier B.V. All rights reserved.

Influence of gamma radiation in the mechanical properties of partially biodegradable foams of PP/HMSP blends with sugar cane bagasse

International Nuclear Information System (INIS)

Cardoso, Elizabeth C.L.; Scagliusi, Sandra R.; Mascarenha, Yago; Lugao, Ademar B.

2015-01-01

Polymers are used in various applications and in different market segments generating enormous amounts of wastes in environment. Among residues components in landfills are polymeric materials, as PP, contributing with 20 to 30% of total solids residues. As polymeric materials are immune to microbial degradation, remain in soil and in landfills as a semi-permanent residue. Environmental concerning toward residues reduction is nowadays directed to the development of renewable polymers for manufacturing of materials that degrade under environment, as biodegradable polymeric foams. High density structural foams are especially used in civil construction, replacing metals, woods and concrete, with a major purpose of materials cost reduction. This work aims to the study of biodegradability in PP/HMSPP blends with sugarcane bagasse at 10, 15, 30 and 50% further irradiated at 50, 100, 150 and 200 kGy doses. The biodegradability was assessed via Soil Burial Test. Tensile strength and elongation at break results proved that natural fibers reinforcement characteristic was not affected by gamma radiation, responsible by degradation and consequent biodegradability acceleration in structural foams. (author)

Starch/fiber/poly(lactic acid) foam and compressed foam composites

Science.gov (United States)

Composites of starch, fiber, and poly(lactic acid) (PLA) were made using a foam substrate formed by dehydrating starch or starch/fiber gels. PLA was infiltrated into the dry foam to provide better moisture resistance. Foam composites were compressed into plastics using force ranging from 4-76MPa. Te...

Sterilized PP/HMSPP cushion foams for medical and food packaging applications

International Nuclear Information System (INIS)

Cardoso, Elisabeth C.L.; Lima, L. Filipe C.P.; Parra, Duclerc F.; Lugao, Ademar B.; Bueno, N.R.; Gasparin, Eleosmar

2009-01-01

Treatment with gamma radiation is becoming a common process for the sterilization of packages, mostly made of natural or synthetic plastics, used in aseptic processing of foods and pharmaceuticals. Packaging materials may be irradiated either prior or after filling; the irradiation prior to filling is usually chosen for dairy products, processed food, beverages, pharmaceuticals and medical devices. Cushion foams are used to help protect fragile items during moving transport. Shock, vibration and damage are avoided by the cushioning effect and chances of product damage are reduced. It is easy to use and perforated for easy tearing. Cushion foams are employed to wrap glasses, plates, crockery, lamps, electronics and other breakable items. This paper presents special cushion foams to be used for medical and food packaging applications; so, these foams will be gamma irradiated before getting in contact with these special articles. Foams were previously produced from a 50% blending Polypropylene homopolymer / High Melt Strength Polypropylene (HMSPP) thereof, that presented following results for properties assessed: melt flow index, 230 deg C - 3.67 g/10 minutes; crystallinity = 47%; melt strength, at 200 deg C = 7.3 cN. This admixture was further fed into the barrel of a single-screw extruder, Rheomex 332 p, equipped with 3:1,33 d screw and 19/33 special screw for foaming, with standard controller and monitored panel, temperature controller (2 channels), melt temperature (2 channels) and melt pressure (4 channels). By using a 175/200/210/220/165/25 (deg C) profile temperature, and after attaining a homogeneous melting, a given amount of physical blowing agent (nitrogen) was injected and mixed with the polymer melt stream to produce the foam. Foamed extrudate was subjected to sterilization radiation doses: 25, 50, 75 and 100 kGy and further evaluated as per: appearance (whiteness / yellowness) and temperature dependent oxidative-induction time (TOIT) tests, by comparing

Preparation and characterization of new biologically active polyurethane foams.

Science.gov (United States)

Savelyev, Yuri; Veselov, Vitali; Markovskaya, Ludmila; Savelyeva, Olga; Akhranovich, Elena; Galatenko, Natalya; Robota, Ludmila; Travinskaya, Tamara

2014-12-01

Biologically active polyurethane foams are the fast-developed alternative to many applications of biomedical materials. Due to the polyurethane structure features and foam technology it is possible to incorporate into their structure the biologically active compounds of target purpose via structural-chemical modification of macromolecule. A series of new biologically active polyurethane foams (PUFs) was synthesized with polyethers (MM 2500-5000), polyesters MM (500-2200), 2,4(2,6) toluene diisocyanate, water as a foaming agent, catalysts, foam stabilizers and functional compounds. Different functional compounds: 1,4-di-N-oxy-2,3-bis-(oxymethyl)-quinoxaline (DOMQ), partial sodium salt of poly(acrylic acid) and 2,6-dimethyl-N,N-diethyl aminoacetatanilide hydrochloride were incorporated into the polymer structure/composition due to the chemical and/or physical bonding. Structural peculiarities of PUFs were studied by FTIR spectroscopy and X-ray scattering. Self-adhesion properties of PUFs were estimated by measuring of tensile strength at break of adhesive junction. The optical microscopy method was performed for the PUF morphology studies. Toxicological estimation of the PUFs was carried out in vitro and in vivo. The antibacterial action towards the Gram-positive and Gram-negative bacteria (Escherichia coli ATC 25922, E. coli ATC 2150, Klebsiella pneumoniae 6447, Staphylococcus aureus 180, Pseudomonas aeruginosa 8180, Proteus mirabilis F 403, P. mirabilis 6054, and Proteus vulgaris 8718) was studied by the disc method on the solid nutrient. Physic-chemical properties of the PUFs (density, tensile strength and elongation at break, water absorption and vapor permeability) showed that all studied PUFs are within the operational requirements for such materials and represent fine-cellular foams. Spectral studies confirmed the incorporation of DOMQ into the PUF's macrochain. PUFs are characterized by microheterogeneous structure. They are antibacterially active, non

Investigation of Thermal and Thermomechanical Properties of Biodegradable PLA/PBSA Composites Processed via Supercritical Fluid-Assisted Foam Injection Molding

Directory of Open Access Journals (Sweden)

Sai Aditya Pradeep

2017-01-01

Full Text Available Bio-based polymer foams have been gaining immense attention in recent years due to their positive contribution towards reducing the global carbon footprint, lightweighting, and enhancing sustainability. Currently, polylactic acid (PLA remains the most abundant commercially consumed biopolymer, but suffers from major drawbacks such as slow crystallization rate and poor melt processability. However, blending of PLA with a secondary polymer would enhance the crystallization rate and the thermal properties based on their compatibility. This study investigates the physical and compatibilized blends of PLA/poly (butylene succinate-co-adipate (PBSA processed via supercritical fluid-assisted (ScF injection molding technology using nitrogen (N2 as a facile physical blowing agent. Furthermore, this study aims at understanding the effect of blending and ScF foaming of PLA/PBSA on crystallinity, melting, and viscoelastic behavior. Results show that compatibilization, upon addition of triphenyl phosphite (TPP, led to an increase in molecular weight and a shift in melting temperature. Additionally, the glass transition temperature (Tg obtained from the tanδ curve was observed to be in agreement with the Tg value predicted by the Gordon–Taylor equation, further confirming the compatibility of PLA and PBSA. The compatibilization of ScF-foamed PLA–PBSA was found to have an increased crystallinity and storage modulus compared to their physically foamed counterparts.

Vitrification Conditions and Porosity Prediction of CO2 Blown Polystyrene Foams.

Czech Academy of Sciences Publication Activity Database

Sovová, Helena; Nistor, A.; Topiař, Martin; Kosek, J.

2017-01-01

Roč. 127, SEP 2017 (2017), s. 1-8 ISSN 0896-8446. [Iberoamerican Conference on Supercritical Fluids ProSCiba 2016 /4./. Vina del Mar, 28.03.2016-01.04.2016] R&D Projects: GA ČR(CZ) GA14-18938S Institutional support: RVO:67985858 Keywords : polymer foam * supercritical CO2 * heat transfer Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 2.991, year: 2016

Hemostatic foam from radiation-modified carboxymethyl derivative of chitosan

International Nuclear Information System (INIS)

Barba, Bin Jeremiah D.; Aranilla, Charito T.; Vista, Jeanina Richelle M.; Relleve, Lorna S.; Abad, Lucille V.

2015-01-01

A hemostatic agent or hemostat is intended to accelerate the blood clotting process when applied to a bleeding surface, such as those in military and civilian wound trauma or in surgery. Natural polymers like chitosan (Ch) has been previously used as raw material in developing hemostats owing to their bioavailability and biocompatibility. Hydrogels were made from its carboxymethylated derivate (CMCh) and were crosslinked by gamma irradiation at a dose of 30 kGy. Further processing was done by salt leaching with sodium chloride and lyophilization to produce the foam hemostat. The final products were then radiation-sterilized at 25 kGy. The use of gamma radiation for both the crosslinking and sterilization process preserves the biocompatibility of the product unlike conventional methods that may require the use of harmful and non-biocompatible chemicals. The hemostatic efficacy of the designed foam hemostats was compared to the commercially available foam hemostat, GELFOAM Sterile Compressed Sponge by Pfizer. The results showed a significantly higher efficiency of the designed products using in vitro test to determine blood clotting index and platelet adhesion capacity. Characterization by gel fraction, swelling capacity and SEM imaging indicated a hydrophilic three-dimensional network which can be attributed for the thrombogenicity of the foams produced. The foam structure can act as a physical matrix for platelet adhesion forming the mechanical plug and at the same time, rapidly absorb water thereby locally increasing the concentration of platelets and physiological coagulation factors that will contribute to quick and efficient hemostasis. The designed products will provide the healthcare and military sector with a local alternative to the commercial products which are both expensive (USD 85 per piece) and not readily accessible in the Philippine market. Further animal efficacy and biocompatibility studies are recommended to supplement the positive in vitro

Multifunctional foaming agent to prepare aluminum foam with enhanced mechanical properties

Science.gov (United States)

Li, Xun; Liu, Ying; Ye, Jinwen; An, Xuguang; Ran, Huaying

2018-03-01

In this paper, CuSO4 was used as foaming agent to prepare close cell Aluminum foam(Al foam) at the temperature range of 680 °C ∼ 758 °C for the first time. The results show that CuSO4 has multifunctional such as, foaming, viscosity increasing, reinforcement in Al matrix, it has a wide decomposition temperature range of 641 °C ∼ 816 °C, its sustain-release time is 5.5 min at 758 °C. The compression stress and energy absorption of CuSO4-Al foam is 6.89 Mpa and 4.82 × 106 J m‑3(compression strain 50%), which are 77.12% and 99.17% higher than that of TiH2-Al foam at the same porosity(76% in porosity) due to the reinforcement in Al matrix and uniform pore dispersion.

Foam Glass for Construction Materials

DEFF Research Database (Denmark)

Petersen, Rasmus Rosenlund

2016-01-01

Foaming is commonly achieved by adding foaming agents such as metal oxides or metal carbonates to glass powder. At elevated temperature, the glass melt becomes viscous and the foaming agents decompose or react to form gas, causing a foamy glass melt. Subsequent cooling to room temperature, result...... in a solid foam glass. The foam glass industry employs a range of different melt precursors and foaming agents. Recycle glass is key melt precursors. Many parameters influence the foaming process and optimising the foaming conditions is very time consuming. The most challenging and attractive goal is to make...... low density foam glass for thermal insulation applications. In this thesis, it is argued that the use of metal carbonates as foaming agents is not suitable for low density foam glass. A reaction mechanism is proposed to justify this result. Furthermore, an in situ method is developed to optimise...

Preparation of three-dimensional shaped aluminum alloy foam by two-step foaming

International Nuclear Information System (INIS)

Shang, J.T.; Xuming, Chu; Deping, He

2008-01-01

A novel method, named two-step foaming, was investigated to prepare three-dimensional shaped aluminum alloy foam used in car industry, spaceflight, packaging and related areas. Calculations of thermal decomposition kinetics of titanium hydride showed that there is a considerable amount of hydrogen releasing when the titanium hydride is heated at a relatively high temperature after heated at a lower temperature. The hydrogen mass to sustain aluminum alloy foam, having a high porosity, was also estimated by calculations. Calculations indicated that as-received titanium hydride without any pre-treatment can be used as foaming agents in two-step foaming. The processes of two-step foaming, including preparing precursors and baking, were also studied by experiments. Results showed that, low titanium hydride dispersion temperature, long titanium hydride dispersion time and low precursors porosity are beneficial to prepare three-dimensional shaped aluminum alloy foams with uniform pores

Assisted heterogeneous multinucleation and bubble growth in semicrystalline ethylene-vinyl acetate copolymer/expanded graphite nanocomposite foams: Control of morphology and viscoelastic properties

Directory of Open Access Journals (Sweden)

O. Yousefzade

2015-10-01

Full Text Available Nanocomposite foams of ethylene-vinyl acetate copolymer (EVA reinforced by expanded graphite (EG were prepared using supercritical nitrogen in batch foaming process. Effects of EG particle size, crosslinking of EVA chains and foaming temperature on the cell morphology and foam viscoelastic properties were investigated. EG sheet surface interestingly provide multiple heterogeneous nucleation sites for bubbles. This role is considerably intensified by incorporating lower loadings of EG with higher aspect ratio. The amorphous and non-crosslinked domains of EVA matrix constitute denser bubble areas. Higher void fraction and more uniform cell structure is achieved for non-crosslinked EVA/EG nanocomposites foamed at higher temperatures. With regard to the structural variation, the void fraction of foam samples decreases with increasing the EG content. Storage and loss moduli were analyzed to study the viscoelastic properties of nanocomposite foams. Surprisingly, the foaming process of EVA results in a drastic reduction in loss and storage moduli regardless of whether the thermoplastic matrix contains EG nanofiller or not. For the EVA/EG foams with the same composition, the nanocomposite having higher void fraction shows relatively lower loss modulus and more restricted molecular movements. The study findings have verified that the dynamics of polymer chains varies after foaming EVA matrix in the presence of EG.

Encapsulation of low density plastic foam materials for the fast ignition realization experiment (FIREX). Control of microstructure and density

International Nuclear Information System (INIS)

Nagai, Keiji; Yang, H.; Iwamoto, A.

2008-10-01

Development of foam capsule fabrication for cryogenically cooled fuel targets is overviewed in the present paper. The fabrication development was initiated as a part of the Fast Ignition Realization Experiment (FIREX) Project at the ILE, Osaka University in the way of bilateral collaboration between Osaka University and National Institute for Fusion Science (NIFS). A foam cryogenic target was designed where low-density foam shells with a conical light guide will be cooled down to the cryogenic temperature and will be fueled through a narrow pipe. The required diameter and thickness of the capsule are 500 μm and 20 μm, respectively. The material should be low-density plastics foam. We have prepared such capsules using 1) mixtureing a new material of (phloroglucinolcarboxylic acid)/formalin (PF) linear polymer to control kinematic viscosity of the precursor, 2) phase-transfer-catalyzed gelation process to keep density matching of three phases of the emulsion. 3) non-volatile silicone oil as outer oil of emulsion in order to prevent hazard halogenated hydrocarbon and flammable mineral oil. The obtained foam capsule had fine structure of 180 nm (outer surface) to 220 nm (inner surface) and uniform thickness reaching to resolution limit of optical analysis (∼0.5 μm). A small hole was made before the solvent exchange and the drying process to prevent distortion due to volume changes. The density of dried foam was 0.29 g/cm 3 . After attaching the petawatt laser guiding cone and fueling glass tube, poly([2,2]paracyclophane) was coated on the foam surface and supplied for a fueling test of cryogenic hydrogen. Generally, lower density is from larger pore, then precise control of thickness and its encapsulation becomes more difficult. We have clarified the relation between pore size and preparation conditions using several precursor materials, and revealed how to control pore size of low density foams, where the solvent affinity for the polymer chain plays fundamental

Thermal performance enhancement of erythritol/carbon foam composites via surface modification of carbon foam

Science.gov (United States)

Li, Junfeng; Lu, Wu; Luo, Zhengping; Zeng, Yibing

2017-03-01

The thermal performance of the erythritol/carbon foam composites, including thermal diffusivity, thermal capacity, thermal conductivity and latent heat, were investigated via surface modification of carbon foam using hydrogen peroxide as oxider. It was found that the surface modification enhanced the wetting ability of carbon foam surface to the liquid erythritol of the carbon foam surface and promoted the increase of erythritol content in the erythritol/carbon foam composites. The dense interfaces were formed between erythritol and carbon foam, which is due to that the formation of oxygen functional groups C=O and C-OH on the carbon surface increased the surface polarity and reduced the interface resistance of carbon foam surface to the liquid erythritol. The latent heat of the erythritol/carbon foam composites increased from 202.0 to 217.2 J/g through surface modification of carbon foam. The thermal conductivity of the erythritol/carbon foam composite before and after surface modification further increased from 40.35 to 51.05 W/(m·K). The supercooling degree of erythritol also had a large decrease from 97 to 54 °C. Additionally, the simple and effective surface modification method of carbon foam provided an extendable way to enhance the thermal performances of the composites composed of carbon foams and PCMs.

Foam-oil interaction in porous media: implications for foam assisted enhanced oil recovery.

Science.gov (United States)

Farajzadeh, R; Andrianov, A; Krastev, R; Hirasaki, G J; Rossen, W R

2012-11-15

The efficiency of a foam displacement process in enhanced oil recovery (EOR) depends largely on the stability of foam films in the presence of oil. Experimental studies have demonstrated the detrimental impact of oil on foam stability. This paper reviews the mechanisms and theories (disjoining pressure, coalescence and drainage, entering and spreading of oil, oil emulsification, pinch-off, etc.) suggested in the literature to explain the impact of oil on foam stability in the bulk and porous media. Moreover, we describe the existing approaches to foam modeling in porous media and the ways these models describe the oil effect on foam propagation in porous media. Further, we present various ideas on an improvement of foam stability and longevity in the presence of oil. The outstanding questions regarding foam-oil interactions and modeling of these interactions are pointed out. Copyright © 2012 Elsevier B.V. All rights reserved.

Carbon particle induced foaming of molten sucrose for the preparation of carbon foams

International Nuclear Information System (INIS)

Narasimman, R.; Vijayan, Sujith; Prabhakaran, K.

2014-01-01

Graphical abstract: - Highlights: • An easy method for the preparation of carbon foam from sucrose is presented. • Wood derived activated carbon particles are used to stabilize the molten sucrose foam. • The carbon foams show relatively good mechanical strength. • The carbon foams show excellent CO 2 adsorption and oil absorption properties. • The process could be scaled up for the preparation of large foam bodies. - Abstract: Activated carbon powder was used as a foaming and foam setting agent for the preparation of carbon foams with a hierarchical pore structure from molten sucrose. The rheological measurements revealed the interruption of intermolecular hydrogen bonding in molten sucrose by the carbon particles. The carbon particles stabilized the bubbles in molten sucrose by adsorbing on the molten sucrose–gas interface. The carbon foams obtained at the activated carbon powder to sucrose weight ratios in the range of 0–0.25 had a compressive strength in the range of 1.35–0.31 MPa. The produced carbon foams adsorb 2.59–3.04 mmol/g of CO 2 at 760 mmHg at 273 K and absorb oil from oil–water mixtures and surfactant stabilized oil-in-water emulsions with very good selectivity and recyclability

State-of-the-Art Review on the Characteristics of Surfactants and Foam from Foam Concrete Perspective

Science.gov (United States)

Sahu, Sritam Swapnadarshi; Gandhi, Indu Siva Ranjani; Khwairakpam, Selija

2018-06-01

Foam concrete finds application in many areas, generally as a function of its relatively lightweight and its beneficial properties in terms of reduction in dead load on structure, excellent thermal insulation and contribution to energy conservation. For production of foam concrete with desired properties, stable and good quality foam is the key requirement. It is to be noted that the selection of surfactant and foam production parameters play a vital role in the properties of foam which in turn affects the properties of foam concrete. However, the literature available on the influence of characteristics of foaming agent and foam on the properties of foam concrete are rather limited. Hence, a more systematic research is needed in this direction. The focus of this work is to provide a review on characteristics of surfactant (foaming agent) and foam for use in foam concrete production.

A NEW RENEWABLE POLYMER FROM BIO-OIL - PHASE I

Science.gov (United States)

The vast majority of today’s polymers, plastics, foams, synthetic fibers, adhesives, and coatings are made from oil, which is non-renewable, non-biodegradable, depends in large part on foreign sources, is highly sensitive to regional conflicts, and has a large carbon foo...

Thermo-mechanical interaction effects in foam cored sandwich panels-correlation between High-order models and Finite element analysis results

DEFF Research Database (Denmark)

Palleti, Hara Naga Krishna Teja; Santiuste, Carlos; Thomsen, Ole Thybo

2010-01-01

Thermo-mechanical interaction effects including thermal material degradation in polymer foam cored sandwich structures is investigated using the commercial Finite Element Analysis (FEA) package ABAQUS/Standard. Sandwich panels with different boundary conditions in the form of simply supported...

Analysis of Influence of Foaming Mixture Components on Structure and Properties of Foam Glass

Science.gov (United States)

Karandashova, N. S.; Goltsman, B. M.; Yatsenko, E. A.

2017-11-01

It is recommended to use high-quality thermal insulation materials to increase the energy efficiency of buildings. One of the best thermal insulation materials is foam glass - durable, porous material that is resistant to almost any effect of substance. Glass foaming is a complex process depending on the foaming mode and the initial mixture composition. This paper discusses the influence of all components of the mixture - glass powder, foaming agent, enveloping material and water - on the foam glass structure. It was determined that glass powder is the basis of the future material. A foaming agent forms a gas phase in the process of thermal decomposition. This aforementioned gas foams the viscous glass mass. The unreacted residue thus changes a colour of the material. The enveloping agent slows the foaming agent decomposition preventing its premature burning out and, in addition, helps to accelerate the sintering of glass particles. The introduction of water reduces the viscosity of the foaming mixture making it evenly distributed and also promotes the formation of water gas that additionally foams the glass mass. The optimal composition for producing the foam glass with the density of 150 kg/m3 is defined according to the results of the research.

Review of radiation processing of natural polymer

International Nuclear Information System (INIS)

Khairul Zaman

2007-01-01

In recent years, natural polymers are being investigated with renewed interest because of their abundant quantity and unique characteristics such as inherent biocompatibility, biodegradability and renewable. It is also known as green polymer. Natural polymers such as carrageen, alginate, chitin/chitosan and starch are traditionally used in food-based industry. But now, the applications of natural polymers are being sought in knowledge-driven areas such as healthcare, agro-technology and industry. Radiation degraded alginates, carrangeenan and chitosan as plant growth promoter and protector have been developed. Radiation degraded chitosan, carraneenan and starch have also been used together with synthetic polymers for hydrogel production to be used for wound dressing, skin moisturization and for biodegradable packaging films and foams. Radiation crosslinking of natural polymer derivatives such as carboxymethyl chitosan, carboxymethyl starch have been successfully developed in Japan and used for various applications such as removal of pollutants, removal of waters from liverstock excrete as well as for bedsores protection mat. (author)

THIRD-GENERATION FOAM BLOWING AGENTS FOR FOAM INSULATION

Science.gov (United States)

The report gives results of a study of third-generation blowing agents for foam insulation. (NOTE: the search for third-generation foam blowing agents has led to the realization that, as the number of potential substitutes increases, new concerns, such as their potential to act a...

Development of polylactide (PLA) and PLA nanocomposite foams in injection molding for automotive applications

Science.gov (United States)

Najafi Chaloupli, Naqi

Plastic materials are extensively used in automotive structures since they make cars more energy efficient. Recently, the automotive industry is searching for bio-based and renewable alternatives to petroleum-based plastics to reduce the dependence on fossil fuels. Among polymers originating from renewable sources, polylactide (PLA) has attracted significant interest. The use of this polymer in durable industries is promising. Fuel-efficient automobiles are nowadays demanded due to the increasing concerns about environmental and fuel issues. The automobile fuel efficiency can be improved by using a lightweight material and, thereby, reducing the automobile weight. A potential method to achieve this objective is the use of the foaming technology. Foam is a material where a gas phase is encapsulated by a solid phase. Foaming technology helps to manufacture lightweight parts with superior properties in comparison with their solid counterparts. The basic mechanisms of foaming process normally consists of gas implementation, formation of uniform polymer-gas solution, cell nucleation, cell growth and, finally, cell stabilization. PLA foaming has, however, proved to be difficult mainly due to poor rheological properties, small processing window, and slow crystallization kinetics. The ultimate purpose of this work is to reduce by 30 % the weight of polylactide (PLA)-clay based nanocomposites by manufacturing injection-molded foamed parts. To use standard processing equipment, a chemical blowing agent (CBA) was employed. The injection molding technique was utilized in this project because it is the most widely used fabrication process in industry that can produce complex shaped articles. This process, however, is more challenging than other foaming processes since it deals with many additional controlling parameters. In the first part of this project, we illustrated how long chain branching (LCB) and molecular structure impact the melt rheology, crystallization and batch

Supercritical CO2 Foaming of Thermoplastic Materials Derived from Maize: Proof-of-Concept Use in Mammalian Cell Culture Applications

Science.gov (United States)

Trujillo-de Santiago, Grissel; Portales-Cabrera, Cynthia Guadalupe; Portillo-Lara, Roberto; Araiz-Hernández, Diana; Del Barone, Maria Cristina; García-López, Erika; Rojas-de Gante, Cecilia; de los Angeles De Santiago-Miramontes, María; Segoviano-Ramírez, Juan Carlos; García-Lara, Silverio; Rodríguez-González, Ciro Ángel; Alvarez, Mario Moisés; Di Maio, Ernesto; Iannace, Salvatore

2015-01-01

Background Foams are high porosity and low density materials. In nature, they are a common architecture. Some of their relevant technological applications include heat and sound insulation, lightweight materials, and tissue engineering scaffolds. Foams derived from natural polymers are particularly attractive for tissue culture due to their biodegradability and bio-compatibility. Here, the foaming potential of an extensive list of materials was assayed, including slabs elaborated from whole flour, the starch component only, or the protein fraction only of maize seeds. Methodology/Principal Findings We used supercritical CO2 to produce foams from thermoplasticized maize derived materials. Polyethylene-glycol, sorbitol/glycerol, or urea/formamide were used as plasticizers. We report expansion ratios, porosities, average pore sizes, pore morphologies, and pore size distributions for these materials. High porosity foams were obtained from zein thermoplasticized with polyethylene glycol, and from starch thermoplasticized with urea/formamide. Zein foams had a higher porosity than starch foams (88% and 85%, respectively) and a narrower and more evenly distributed pore size. Starch foams exhibited a wider span of pore sizes and a larger average pore size than zein (208.84 vs. 55.43 μm2, respectively). Proof-of-concept cell culture experiments confirmed that mouse fibroblasts (NIH 3T3) and two different prostate cancer cell lines (22RV1, DU145) attached to and proliferated on zein foams. Conclusions/Significance We conducted screening and proof-of-concept experiments on the fabrication of foams from cereal-based bioplastics. We propose that a key indicator of foamability is the strain at break of the materials to be foamed (as calculated from stress vs. strain rate curves). Zein foams exhibit attractive properties (average pore size, pore size distribution, and porosity) for cell culture applications; we were able to establish and sustain mammalian cell cultures on zein

Supercritical CO2 foaming of thermoplastic materials derived from maize: proof-of-concept use in mammalian cell culture applications.

Science.gov (United States)

Trujillo-de Santiago, Grissel; Portales-Cabrera, Cynthia Guadalupe; Portillo-Lara, Roberto; Araiz-Hernández, Diana; Del Barone, Maria Cristina; García-López, Erika; Rojas-de Gante, Cecilia; de Los Angeles De Santiago-Miramontes, María; Segoviano-Ramírez, Juan Carlos; García-Lara, Silverio; Rodríguez-González, Ciro Ángel; Alvarez, Mario Moisés; Di Maio, Ernesto; Iannace, Salvatore

2015-01-01

Foams are high porosity and low density materials. In nature, they are a common architecture. Some of their relevant technological applications include heat and sound insulation, lightweight materials, and tissue engineering scaffolds. Foams derived from natural polymers are particularly attractive for tissue culture due to their biodegradability and bio-compatibility. Here, the foaming potential of an extensive list of materials was assayed, including slabs elaborated from whole flour, the starch component only, or the protein fraction only of maize seeds. We used supercritical CO2 to produce foams from thermoplasticized maize derived materials. Polyethylene-glycol, sorbitol/glycerol, or urea/formamide were used as plasticizers. We report expansion ratios, porosities, average pore sizes, pore morphologies, and pore size distributions for these materials. High porosity foams were obtained from zein thermoplasticized with polyethylene glycol, and from starch thermoplasticized with urea/formamide. Zein foams had a higher porosity than starch foams (88% and 85%, respectively) and a narrower and more evenly distributed pore size. Starch foams exhibited a wider span of pore sizes and a larger average pore size than zein (208.84 vs. 55.43 μm2, respectively). Proof-of-concept cell culture experiments confirmed that mouse fibroblasts (NIH 3T3) and two different prostate cancer cell lines (22RV1, DU145) attached to and proliferated on zein foams. We conducted screening and proof-of-concept experiments on the fabrication of foams from cereal-based bioplastics. We propose that a key indicator of foamability is the strain at break of the materials to be foamed (as calculated from stress vs. strain rate curves). Zein foams exhibit attractive properties (average pore size, pore size distribution, and porosity) for cell culture applications; we were able to establish and sustain mammalian cell cultures on zein foams for extended time periods.

Supercritical CO2 foaming of thermoplastic materials derived from maize: proof-of-concept use in mammalian cell culture applications.

Directory of Open Access Journals (Sweden)

Grissel Trujillo-de Santiago

Full Text Available Foams are high porosity and low density materials. In nature, they are a common architecture. Some of their relevant technological applications include heat and sound insulation, lightweight materials, and tissue engineering scaffolds. Foams derived from natural polymers are particularly attractive for tissue culture due to their biodegradability and bio-compatibility. Here, the foaming potential of an extensive list of materials was assayed, including slabs elaborated from whole flour, the starch component only, or the protein fraction only of maize seeds.We used supercritical CO2 to produce foams from thermoplasticized maize derived materials. Polyethylene-glycol, sorbitol/glycerol, or urea/formamide were used as plasticizers. We report expansion ratios, porosities, average pore sizes, pore morphologies, and pore size distributions for these materials. High porosity foams were obtained from zein thermoplasticized with polyethylene glycol, and from starch thermoplasticized with urea/formamide. Zein foams had a higher porosity than starch foams (88% and 85%, respectively and a narrower and more evenly distributed pore size. Starch foams exhibited a wider span of pore sizes and a larger average pore size than zein (208.84 vs. 55.43 μm2, respectively. Proof-of-concept cell culture experiments confirmed that mouse fibroblasts (NIH 3T3 and two different prostate cancer cell lines (22RV1, DU145 attached to and proliferated on zein foams.We conducted screening and proof-of-concept experiments on the fabrication of foams from cereal-based bioplastics. We propose that a key indicator of foamability is the strain at break of the materials to be foamed (as calculated from stress vs. strain rate curves. Zein foams exhibit attractive properties (average pore size, pore size distribution, and porosity for cell culture applications; we were able to establish and sustain mammalian cell cultures on zein foams for extended time periods.

Low-density carbonized resorcinol-formaldehyde foams

International Nuclear Information System (INIS)

Kong, F.M.; Buckley, S.R.; Giles, C.L. Jr.; Haendler, B.L.; Hair, L.M.; Letts, S.A.; Overturf, G.E. III; Price, C.W.; Cook, R.C.

1991-01-01

This report documents research and development on resorcinol- formaldehyde-based foam materials conducted between 1986 and June 1990, when the effort was discontinued. The foams discussed are resorcinol-formaldehyde (RF) foam, carbonized RF (CRF) foam, and two composite foams, a polystyrene/RF (PS/RF) foam and its carbonized derivative (CPR). The RF foams are synthesized by the polycondensation of resorcinol with formaldehyde in a slightly basic solution. Their structure and density depend strongly on the concentration of the sodium carbonate catalyst. The have an interconnected bead structure similar to that of silica aerogels; bead sizes range from 30 to 130 Angstrom, and cell sizes are less than 0.1 μm. We have achieved densities of 16 to 200 mg/cm 3 . The RF foams can be pyrolyzed in an inert atmosphere to form a vitreous carbon foam (CRF), which has a similar microstructure but much higher mechanical strength. The PS/RF foams are obtained by filling the 2- to 3-μm cells of PS foam (a low-density hydrocarbon foam we have developed) with RF. The resultant foams have the outstanding handling and machinability of the PS foam matrix and the small cell size of RF. Pyrolyzing PS/RF foams causes depolymerization and loss of the PS; the resulting CPR foams have a structure similar to the PS foams in which CRF both replicates and fills the PS cells

In vitro evaluation of borate-based bioactive glass scaffolds prepared by a polymer foam replication method

International Nuclear Information System (INIS)

Fu Hailuo; Fu Qiang; Zhou Nai; Huang Wenhai; Rahaman, Mohamed N.; Wang Deping; Liu Xin

2009-01-01

Borate-based bioactive glass scaffolds with a microstructure similar to that of human trabecular bone were prepared using a polymer foam replication method, and evaluated in vitro for potential bone repair applications. The scaffolds (porosity = 72 ± 3%; pore size = 250-500 μm) had a compressive strength of 6.4 ± 1.0 MPa. The bioactivity of the scaffolds was confirmed by the formation of a hydroxyapatite (HA) layer on the surface of the glass within 7 days in 0.02 M K 2 HPO 4 solution at 37 deg. C. The biocompatibility of the scaffolds was assessed from the response of cells to extracts of the dissolution products of the scaffolds, using assays of MTT hydrolysis, cell viability, and alkaline phosphatase activity. For boron concentrations below a threshold value (0.65 mM), extracts of the glass dissolution products supported the proliferation of bone marrow stromal cells, as well as the proliferation and function of murine MLO-A5 cells, an osteogenic cell line. Scanning electron microscopy showed attachment and continuous increase in the density of MLO-A5 cells cultured on the surface of the glass scaffolds. The results indicate that borate-based bioactive glass could be a potential scaffold material for bone tissue engineering provided that the boron released from the glass could be controlled below a threshold value.

Thermal Conductivity of Foam Glass

DEFF Research Database (Denmark)

Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

Due to the increased focus on energy savings and waste recycling foam glass materials have gained increased attention. The production process of foam glass is a potential low-cost recycle option for challenging waste, e.g. CRT glass and industrial waste (fly ash and slags). Foam glass is used...... as thermal insulating material in building and chemical industry. The large volume of gas (porosity 90 – 95%) is the main reason of the low thermal conductivity of the foam glass. If gases with lower thermal conductivity compared to air are entrapped in the glass melt, the derived foam glass will contain...... only closed pores and its overall thermal conductivity will be much lower than that of the foam glass with open pores. In this work we have prepared foam glass using different types of recycled glasses and different kinds of foaming agents. This enabled the formation of foam glasses having gas cells...

Controlling Foam Morphology of Poly(methyl methacrylate via Surface Chemistry and Concentration of Silica Nanoparticles and Supercritical Carbon Dioxide Process Parameters

Directory of Open Access Journals (Sweden)

Deniz Rende

2013-01-01

Full Text Available Polymer nanocomposite foams have received considerable attention because of their potential use in advanced applications such as bone scaffolds, food packaging, and transportation materials due to their low density and enhanced mechanical, thermal, and electrical properties compared to traditional polymer foams. In this study, silica nanofillers were used as nucleating agents and supercritical carbon dioxide as the foaming agent. The use of nanofillers provides an interface upon which CO2 nucleates and leads to remarkably low average cell sizes while improving cell density (number of cells per unit volume. In this study, the effect of concentration, the extent of surface modification of silica nanofillers with CO2-philic chemical groups, and supercritical carbon dioxide process conditions on the foam morphology of poly(methyl methacrylate, PMMA, were systematically investigated to shed light on the relative importance of material and process parameters. The silica nanoparticles were chemically modified with tridecafluoro-1,1,2,2-tetrahydrooctyl triethoxysilane leading to three different surface chemistries. The silica concentration was varied from 0.85 to 3.2% (by weight. The supercritical CO2 foaming was performed at four different temperatures (40, 65, 75, and 85°C and between 8.97 and 17.93 MPa. By altering the surface chemistry of the silica nanofiller and manipulating the process conditions, the average cell diameter was decreased from 9.62±5.22 to 1.06±0.32 μm, whereas, the cell density was increased from 7.5±0.5×108 to 4.8±0.3×1011 cells/cm3. Our findings indicate that surface modification of silica nanoparticles with CO2-philic surfactants has the strongest effect on foam morphology.

Aerosol-foam interaction experiments

International Nuclear Information System (INIS)

Ball, M.H.E.; Luscombe, C.DeM.; Mitchell, J.P.

1990-03-01

Foam treatment offers the potential to clean gas streams containing radioactive particles. A large decontamination factor has been claimed for the removal of airborne plutonium dust when spraying a commercially available foam on the walls and horizontal surfaces of an alpha-active room. Experiments have been designed and undertaken to reproduce these conditions with a non-radioactive simulant aerosol. Careful measurements of aerosol concentrations with and without foam treatment failed to provide convincing evidence to support the earlier observation. The foam may not have been as well mixed with the aerosol in the present studies. Further work is required to explore more efficient mixing methods, including systems in which the aerosol steam is passed through the foam, rather than merely spraying foam into the path of the aerosol. (author)

Foam patterns

Science.gov (United States)

Chaudhry, Anil R; Dzugan, Robert; Harrington, Richard M; Neece, Faurice D; Singh, Nipendra P; Westendorf, Travis

2013-11-26

A method of creating a foam pattern comprises mixing a polyol component and an isocyanate component to form a liquid mixture. The method further comprises placing a temporary core having a shape corresponding to a desired internal feature in a cavity of a mold and inserting the mixture into the cavity of the mold so that the mixture surrounds a portion of the temporary core. The method optionally further comprises using supporting pins made of foam to support the core in the mold cavity, with such pins becoming integral part of the pattern material simplifying subsequent processing. The method further comprises waiting for a predetermined time sufficient for a reaction from the mixture to form a foam pattern structure corresponding to the cavity of the mold, wherein the foam pattern structure encloses a portion of the temporary core and removing the temporary core from the pattern independent of chemical leaching.

Thermosetting Fluoropolymer Foams

Science.gov (United States)

Lee, Sheng Yen

1987-01-01

New process makes fluoropolymer foams with controllable amounts of inert-gas fillings in foam cells. Thermosetting fluoropolymers do not require foaming additives leaving undesirable residues and do not have to be molded and sintered at temperatures of about 240 to 400 degree C. Consequently, better for use with electronic or other parts sensitive to high temperatures or residues. Uses include coatings, electrical insulation, and structural parts.

Pipe Decontamination Involving String-Foam Circulation

International Nuclear Information System (INIS)

Turchet, J.P.; Estienne, G.; Fournel, B.

2002-01-01

Foam applications number for nuclear decontamination purposes has recently increased. The major advantage of foam decontamination is the reduction of secondary liquid wastes volumes. Among foam applications, we focus on foam circulation in contaminated equipment. Dynamic properties of the system ensures an homogeneous and rapid effect of the foam bed-drifted chemical reagents present in the liquid phase. This paper describes a new approach of foam decontamination for pipes. It is based on an alternated air and foam injections. We called it 'string-foam circulation'. A further reduction of liquid wastes is achieved compared to continuous foam. Secondly, total pressure loss along the pipe is controlled by the total foam length in the pipe. It is thus possible to clean longer pipes keeping the pressure under atmospheric pressure value. This ensures the non dispersion of contamination. This study describes experimental results obtained with a neutral foam as well with an acid foam on a 130 m long loop. Finally, the decontamination of a 44 meters pipe is presented. (authors)

A finite element/level set model of polyurethane foam expansion and polymerization

Energy Technology Data Exchange (ETDEWEB)

Rao, Rekha R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Long, Kevin Nicholas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Roberts, Christine Cardinal [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Celina, Mathias C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brunini, Victor [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Soehnel, Melissa Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Noble, David R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tinsley, James [Honeywell Federal Manufacturing & Technologies, Kansas City, MO (United States); Mondy, Lisa [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-12-01

Polyurethane foams are used widely for encapsulation and structural purposes because they are inexpensive, straightforward to process, amenable to a wide range of density variations (1 lb/ft3 - 50 lb/ft3), and able to fill complex molds quickly and effectively. Computational model of the filling and curing process are needed to reduce defects such as voids, out-of-specification density, density gradients, foam decomposition from high temperatures due to exotherms, and incomplete filling. This paper details the development of a computational fluid dynamics model of a moderate density PMDI structural foam, PMDI-10. PMDI is an isocyanate-based polyurethane foam, which is chemically blown with water. The polyol reacts with isocyanate to produces the polymer. PMDI- 10 is catalyzed giving it a short pot life: it foams and polymerizes to a solid within 5 minutes during normal processing. To achieve a higher density, the foam is over-packed to twice or more of its free rise density of 10 lb/ft3. The goal for modeling is to represent the expansion, filling of molds, and the polymerization of the foam. This will be used to reduce defects, optimize the mold design, troubleshoot the processed, and predict the final foam properties. A homogenized continuum model foaming and curing was developed based on reaction kinetics, documented in a recent paper; it uses a simplified mathematical formalism that decouples these two reactions. The chemo-rheology of PMDI is measured experimentally and fit to a generalized- Newtonian viscosity model that is dependent on the extent of cure, gas fraction, and temperature. The conservation equations, including the equations of motion, an energy balance, and three rate equations are solved via a stabilized finite element method. The equations are combined with a level set method to determine the location of the foam-gas interface as it evolves to fill the mold. Understanding the thermal history and loads on the foam due to exothermicity and oven

Additive manufacturing of polymer-derived ceramics

Science.gov (United States)

Eckel, Zak C.; Zhou, Chaoyin; Martin, John H.; Jacobsen, Alan J.; Carter, William B.; Schaedler, Tobias A.

2016-01-01

The extremely high melting point of many ceramics adds challenges to additive manufacturing as compared with metals and polymers. Because ceramics cannot be cast or machined easily, three-dimensional (3D) printing enables a big leap in geometrical flexibility. We report preceramic monomers that are cured with ultraviolet light in a stereolithography 3D printer or through a patterned mask, forming 3D polymer structures that can have complex shape and cellular architecture. These polymer structures can be pyrolyzed to a ceramic with uniform shrinkage and virtually no porosity. Silicon oxycarbide microlattice and honeycomb cellular materials fabricated with this approach exhibit higher strength than ceramic foams of similar density. Additive manufacturing of such materials is of interest for propulsion components, thermal protection systems, porous burners, microelectromechanical systems, and electronic device packaging.

Influence of foaming agents on solid thermal conductivity of foam glasses prepared from CRT panel glass

DEFF Research Database (Denmark)

Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob

2017-01-01

The understanding of the thermal transport mechanism of foam glass is still lacking. The contribution of solid- and gas conduction to the total thermal conductivity remains to be reported. In many foam glasses, the solid phase consist of a mix of an amorphous and a crystalline part where foaming...... containing glass and crystalline foaming agents and amorphous samples where the foaming agents are completely dissolved in the glass structure, respectively. Results show that the samples prepared by sintering have a higher thermal conductivity than the samples prepared by melt-quenching. The thermal...... conductivities of the sintered and the melt-quenched samples represent an upper and lower limit of the solid phase thermal conductivity of foam glasses prepared with these foaming agents. The content of foaming agents dissolved in the glass structure has a major impact on the solid thermal conductivity of foam...

The effect of roughness, floor polish, water, oil and ice on underfoot friction: current safety footwear solings are less slip resistant than microcellular polyurethane.

Science.gov (United States)

Manning, D P; Jones, C

2001-04-01

Research over a period of about 18 years has shown that a microcellular polyurethane known as AP66033 is the most slip-resistant safety footwear soling material on oily and wet surfaces. In recent years it has been replaced in commercially available footwear by a dual density polyurethane (DDP) which has a dense outer layer and a soft microcellular backing. This research programme has compared the slip resistance of AP66033 with DDP and some rubber solings. In addition, data were obtained on the effects of soling and floor roughness, and floor polish on slip resistance. Some data were also obtained for walking on ice. The coefficient of friction (CoF) of the solings was measured on 19 water wet surfaces in three conditions: (I) when the solings were new, (II) following abrasion to create maximum roughness and (III) after polishing. The CoF was measured on four oily surfaces after each of 11 abrasion or polishing treatments. The profound effects of the roughening of all soles and of floor roughness on the CoF were demonstrated for both wet and oily surfaces. The superior slip resistance of AP66033 was confirmed for oily and wet conditions; however, some rubbers not suitable for safety footwear achieved higher CoF values on wet floors. All of the floor polishes reduced the CoF of all floors when contaminated with water. The mean CoF of DDP solings was lower than the mean for AP66033 on wet and oily surfaces. No safety footwear soling provided adequate grip on dry ice and the CoF was reduced by water on the ice. A rubber used for rock climbing footwear was one of the most slip-resistant solings on wet surfaces in the laboratory but recorded the lowest CoF on ice. It is concluded that the incidence of occupational injuries caused by slipping could be reduced by the following: (A) returning to safety footwear soled with the microcellular polyurethane AP66033; (B) abrading all new and smooth footwear solings with a belt sanding machine coated with P100 grit; (C) avoiding

Literature Review: An Overview of Epoxy Resin Syntactic Foams with Glass Microballoons

Energy Technology Data Exchange (ETDEWEB)

Keller, Jennie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-03-12

Syntactic foams are an important category of composite materials that have abundant applications in a wide variety of fields. The bulk phase of syntactic foams is a three-part epoxy resin formulation that consists of a base resin, a curative (curing agent) and a modifier (diluent and/or accelerator) [12]. These thermoset materials [12] are used frequently for their thermal stability [9], low moisture absorption and high compressive strength [10]. The characteristic feature of a syntactic foam is a network of beads that forms pores within the epoxy matrix [3]. In this review, hollow glass beads (known as glass microballoons) are considered, however, solid beads or microballoons made from materials such as ceramic, polymer or metal can also be used [3M, Peter]. The network of hollow beads forms a closed-cell foam; the term closed-cell comes from the fact that the microspheres used in the resin matrix are completely closed and filled with gas (termed hollow). In contrast, the microspheres used in open-cell foams are either not completely closed or broken so that matrix material can fill the spheres [11]. Although closed foams have been found to possess higher densities than open cell foams, their rigid structures give them superior mechanical properties [12]. Past research has extensively studied the effects that changing the volume fraction of microballoons to epoxy will have on the resulting syntactic foam [3,4,9]. In addition, published literature also explores how the microballoon wall thickness affects the final product [4,9,10]. Findings detail that indeed both the mechanical and some thermal properties of syntactic foams can be tailored to a specific application by varying either the volume fraction or the wall thickness of the microballoons used [10]. The major trends in syntactic foam research show that microballoon volume fraction has an inversely proportionate relationship to dynamic properties, while microballoon wall thickness is proportional to those

Foam-mat drying technology: A review.

Science.gov (United States)

Hardy, Z; Jideani, V A

2017-08-13

This article reviews various aspects of foam-mat drying such as foam-mat drying processing technique, main additives used for foam-mat drying, foam-mat drying of liquid and solid foods, quality characteristics of foam-mat dried foods, and economic and technical benefits for employing foam-mat drying. Foam-mat drying process is an alternative method that allows the removal of water from liquid materials and pureed materials. In this drying process, a liquid material is converted into foam that is stable by being whipped after adding an edible foaming agent. The stable foam is then spread out in sheet or mat and dried by using hot air (40-90°C) at atmospheric pressure. Methyl cellulose (0.25-2%), egg white (3-20%), maltodextrin (0.5-05%), and gum Arabic (2-9%) are the commonly utilized additives for the foam-mat drying process at the given range, either combined together for their effectiveness or individual effect. The foam-mat drying process is suitable for heat sensitive, viscous, and sticky products that cannot be dried using other forms of drying methods such as spray drying because of the state of product. More interest has developed for foam-mat drying because of the simplicity, cost effectiveness, high speed drying, and improved product quality it provides.

Production of lightweight foam glass (invited talk)

DEFF Research Database (Denmark)

Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

The foam glass production allows low cost recycling of postconsumer glass and industrial waste materials as foaming agent or as melt resource. Foam glass is commonly produced by utilising milled glass mixed with a foaming agent. The powder mixture is heat-treated to around 10^3.7 – 10^6 Pa s, which...... result in viscous sintering and subsequent foaming of the glass melt. The porous glass melt is cooled down to room temperature to freeze-in the foam structure. The resulting foam glass is applied in constructions as a light weight material to reduce load bearing capacity and as heat insulating material...... in buildings and industry. We foam panel glass from old televisions with different foaming agents. We discuss the foaming ability and the foaming mechanism of different foaming systems. We compare several studies to define a viscous window for preparing low density foam glass. However, preparing foam glass...

Polyurethane-Foam Maskant

Science.gov (United States)

Bodemeijer, R.

1985-01-01

Brown wax previously used to mask hardware replaced with polyurethane foam in electroplating and electroforming operations. Foam easier to apply and remove than wax and does not contaminate electrolytes.

Improving Ballistic Performance of Polyurethane Foam by Nanoparticle Reinforcement

Directory of Open Access Journals (Sweden)

M. F. Uddin

2009-01-01

Full Text Available We report improving ballistic performance of polyurethane foam by reinforcing it with nanoscale TiO2 particles. Particles were dispersed through a sonic cavitation process and the loading of particles was 3 wt% of the total polymer. Once foams were reinforced, sandwich panels were made and impacted with fragment simulating projectiles (FSPs in a 1.5-inch gas gun. Projectile speed was set up to have complete penetration of the target in each experiment. Test results have indicated that sandwich with nanophased cores absorbed about 20% more kinetic energy than their neat counterpart. The corresponding increase in ballistic limit was around 12% over the neat control samples. The penetration phenomenon was also monitored using a high-speed camera. Analyses of digital images showed that FSP remained inside the nanophased sandwich for about 7 microseconds longer than that of a neat sandwich demonstrating improved energy absorption capability of the nanoparticle reinforced core. Failure modes for energy absorption have been investigated through a microscope and high-speed images.

Improving Ballistic Performance of Polyurethane Foam by Nanoparticle Reinforcement

International Nuclear Information System (INIS)

Uddin, M.F.; Zainuddin, S.; Mahfuz, H.; Jeelani, S.

2009-01-01

We report improving ballistic performance of polyurethane foam by reinforcing it with nano scale TiO 2 particles. Particles were dispersed through a sonic cavitation process and the loading of particles was 3 wt % of the total polymer. Once foams were reinforced, sandwich panels were made and impacted with fragment simulating projectiles (FSPs) in a 1.5-inch gas gun. Projectile speed was set up to have complete penetration of the target in each experiment. Test results have indicated that sandwich with nano phased cores absorbed about 20% more kinetic energy than their neat counterpart. The corresponding increase in ballistic limit was around 12% over the neat control samples. The penetration phenomenon was also monitored using a high-speed camera. Analyses of digital images showed that FSP remained inside the nano phased sandwich for about 7 microseconds longer than that of a neat sandwich demonstrating improved energy absorption capability of the nanoparticle reinforced core. Failure modes for energy absorption have been investigated through a microscope and high-speed images.

Recovery Act. Advanced Building Insulation by the CO₂ Foaming Process

Energy Technology Data Exchange (ETDEWEB)

Yang, Arthur [Industrial Science and Technology Network, Inc., Lancaster, PA (United States)

2013-12-30

In this project, ISTN proposed to develop a new "3rd" generation of insulation technology. The focus was a cost-effective foaming process that could be used to manufacture XPS and other extruded polymer foams using environmentally clean blowing agents, and ultimately achieve higher R-values than existing products while maintaining the same level of cost-efficiency. In the U.S., state-of-the-art products are primarily manufactured by two companies: Dow and Owens Corning. These products (i.e., STYROFOAM and FOAMULAR) have a starting thermal resistance of R-5.0/inch, which declines over the life of the product as the HFC blowing agents essential to high R-value exchange with air in the environment. In the existing technologies, the substitution of CO2 for HFCs as the primary foaming agent results in a much lower starting R-value, as evidenced in CO2-foamed varieties of XPS in Europe with R-4.2/inch insulation value. The major overarching achievement from this project was ISTN's development of a new process that uses CO2 as a clean blowing agent to achieve up to R-5.2/inch at the manufacturing scale, with a production cost on a per unit basis that is less than the cost of Dow and Owens Corning XPS products.

Effect of Rigid Polyurethane Foam Core Density on Flexural and Compressive Properties of Sandwich Panels with Glass/Epoxy Faces

Directory of Open Access Journals (Sweden)

saeed Nemati

2013-01-01

Full Text Available Sandwich panels as composite materials have two external walls of either metallic or polymer type. The space between these walls is filled by hard foam or other materials and the thickness of different layers is based on the final application of the panel. In the present work, the extent of variation in core density of polyether urethane foam and subsequent flexural and compressive changes in sandwich panels with glass or epoxy face sheets are tested and investigated. A number of hard polyether urethane foams with different middle panel layers density 80-295 kg/m3 are designed to study the effect of foam density on mechanical properties including flexural and compressive properties. Flexural and compressive test resultsshow that increased core density leads to improved mechanical properties. The slope of the curve decreases beyond density of 235 kg/m3. The reason may be explained on the limitation of shear intensity in increasing the mechanical properties. In this respect an optimum density of 235 kg/m3 is obtained for the system under examinations and for reaching higher strength panels, foams of different core materials should be selected.

Influence of the glass particle size on the foaming process and physical characteristics of foam glasses

DEFF Research Database (Denmark)

König, Jakob; Petersen, Rasmus Rosenlund; Yue, Yuanzheng

2016-01-01

We have prepared low-density foam glasses from cathode-ray-tube panel glass using carbon and MnO2 as the foaming agents. The effect of the glass particle size on the foaming process, the apparent density and the pore morphology is revealed. The results show that the foaming is mainly caused...... by the reduction of manganese. Foam glasses with a density of

Activated, coal-based carbon foam

Science.gov (United States)

Rogers, Darren Kenneth; Plucinski, Janusz Wladyslaw

2004-12-21

An ablation resistant, monolithic, activated, carbon foam produced by the activation of a coal-based carbon foam through the action of carbon dioxide, ozone or some similar oxidative agent that pits and/or partially oxidizes the carbon foam skeleton, thereby significantly increasing its overall surface area and concurrently increasing its filtering ability. Such activated carbon foams are suitable for application in virtually all areas where particulate or gel form activated carbon materials have been used. Such an activated carbon foam can be fabricated, i.e. sawed, machined and otherwise shaped to fit virtually any required filtering location by simple insertion and without the need for handling the "dirty" and friable particulate activated carbon foam materials of the prior art.

Foam pad of appropriate thickness can improve diagnostic value of foam posturography in detecting postural instability.

Science.gov (United States)

Liu, Bo; Leng, Yangming; Zhou, Renhong; Liu, Jingjing; Liu, Dongdong; Liu, Jia; Zhang, Su-Lin; Kong, Wei-Jia

2018-04-01

The present study investigated the effect of foam thickness on postural stability in patients with unilateral vestibular hypofunction (UVH) during foam posturography. Static and foam posturography were performed in 33 patients (UVH group) and 30 healthy subjects (control group) with eyes open (EO) and closed (EC) on firm surface and on 1-5 foam pad(s). Sway velocity (SV) of center of pressure, standing time before falling (STBF) and falls reaction were recorded and analyzed. (1) SVs had an increasing tendency in both groups as the foam pads were added under EO and EC conditions. (2) STBFs, only in UVH group with EC, decreased with foam thickness increasing. (3) Significant differences in SV were found between the control and UVH group with EO (except for standing on firm surface, on 1 and 2 foam pad(s)) and with EC (all surface conditions). (4) Receiver operating characteristic curve analysis showed that the SV could better reflect the difference in postural stability between the two groups while standing on the 4 foam pads with EC. Our study showed that diagnostic value of foam posturography in detecting postural instability might be enhanced by using foam pad of right thickness.

Comparison of sound absorbing performances of copper foam and iron foam with the same parameters

Science.gov (United States)

Yang, X. C.; Shen, X. M.; Xu, P. J.; Zhang, X. N.; Bai, P. F.; Peng, K.; Yin, Q.; Wang, D.

2018-01-01

Sound absorbing performances of the copper foam and the iron foam with the same parameters were investigated by the AWA6128A detector according to standing wave method. Two modes were investigated, which included the pure metal foam mode and the combination mode with the settled thickness of metal foam. In order to legibly compare the sound absorbing coefficients of the two metal foams, the detected sound frequency points were divided into the low frequency range (100 Hz ~ 1000 Hz), the middle frequency range (1000 Hz ~ 3200 Hz), and the high frequency range (3500 Hz ~ 6000 Hz). Sound absorbing performances of the two metal foams in the two modes were discussed within the three frequency ranges in detail. It would be calculated that the average sound absorbing coefficients of copper foam in the pure metal foam mode were 12.6%, 22.7%, 34.6%, 43.6%, 51.1%, and 56.2% when the thickness was 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, and 30 mm. meanwhile, in the combination mode, the average sound absorbing coefficients of copper foam with the thickness of 10 mm were 30.6%, 34.8%, 36.3%, and 35.8% when the cavity was 5 mm, 10 mm, 15 mm, and 20 mm. In addition, those of iron foam in the pure metal foam mode were 13.4%, 20.1%, 34.4%, 43.1%, 49.6%, and 56.1%, and in the combination mode were 25.6%, 30.5%, 34.3%, and 33.4%.

Les silicates alcalins, matière de base des mousses minérales isolantes. Etude bibliographique Alkaline Silicates, As a Basic Material for Insulating Mineral Foams. Bibliographie Study

Directory of Open Access Journals (Sweden)

Lesage J.

2006-11-01

Full Text Available Dans cette étude bibliographique, on décrit les méthodes d'obtention des silicates alcalins ainsi que leurs propriétés et les propriétés de leurs polymères en insistant sur l'influence du pH, de la concentration et de la température sur la polymérisation et les caractéristiques des polymères obtenus. On présente ensuite le mode d'obtention des mousses à partir de solutions aqueuses de silicates, ainsi que leurs propriétés et l'influence de divers additifs tels que les agents tensioactifs, moussants, gélifiants ou les agents de durcissement sur les propriétés des mousses. II ressort de cette bibliographie que des mousses polysilicates solubles peuvent être obtenues à partir de solutions de silicates à faible rapport molaire SiO2/Na2O. Par ailleurs, en faisant varier la composition des solutions de silicates alcalins et par l'emploi d'additifs, il est possible de produire une gamme très variée de mousses polysilicates dont les propriétés d'isolation, de solubilité et de résistance mécanique, voire de perméabilité, sont très variées, ce qui leur ouvre la voie à de nombreuses possibilités de débouchés industriels. This article gives a bibliographic description of methods for obtaining alkaline silicates as well as their properties and the properties of their polymers. Emphasis is placed on the influence of the pH, and on the influence of the concentration and temperature on the polymerization and the characteristics of the polymers obtained. Then a method is recommended for obtaining foams from aqueous silicate solutions together with the properties of such foams and the influence of different additives such as surfactants, foaming agents, gelling agents and hardening agents on the properties of foams. This bibliographic study shows that soluble polysilicate foams may be obtained from silicate solutions with a low SiO2/Na2O molar ratio. Furthermore, by varying the composition of alkaline silicate solutions and by

Mechanical Characterization of Rigid Polyurethane Foams

Energy Technology Data Exchange (ETDEWEB)

Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Mechanics of Materials

2014-12-01

Foam materials are used to protect sensitive components from impact loading. In order to predict and simulate the foam performance under various loading conditions, a validated foam model is needed and the mechanical properties of foams need to be characterized. Uniaxial compression and tension tests were conducted for different densities of foams under various temperatures and loading rates. Crush stress, tensile strength, and elastic modulus were obtained. A newly developed confined compression experiment provided data for investigating the foam flow direction. A biaxial tension experiment was also developed to explore the damage surface of a rigid polyurethane foam.

The variation in elastic modulus throughout the compression of foam materials

International Nuclear Information System (INIS)

Sun, Yongle; Amirrasouli, B.; Razavi, S.B.; Li, Q.M.; Lowe, T.; Withers, P.J.

2016-01-01

We present a comprehensive experimental study of the variation in apparent unloading elastic modulus of polymer (largely elastic), aluminium (largely plastic) and fibre-reinforced cement (quasi-brittle) closed-cell foams throughout uniaxial compression. The results show a characteristic “zero-yield-stress” response and thereafter a rapid increase in unloading modulus during the supposedly “elastic” regime of the compressive stress–strain curve. The unloading modulus then falls with strain due to the localised cell-wall yielding or failure in the pre-collapse stage and the progressive cell crushing in the plateau stage, before rising sharply during the densification stage which is associated with global cell crushing and foam compaction. A finite element model based on the actual 3D cell structure of the aluminium foam imaged by X-ray computed tomography (CT) predicts an approximately linear fall of elastic modulus from zero strain until a band of collapsed cells forms. It shows that the subsequent gradual decrease in modulus is caused by the progressive collapse of cells. The elastic modulus rises sharply after the densification initiation strain has been reached. However, the elastic modulus is still well below that of the constituent material even when the “fully” dense state is approached. This work highlights the fact that the unloading elastic modulus varies throughout compression and challenges the idea that a constant elastic modulus can be applied in a homogenised foam model. It is suggested that the most representative value of elastic modulus may be obtained by extrapolating the measured unloading modulus to zero strain.

Basic Performance of Fibre Reinforced Asphalt Concrete with Reclaimed Asphalt Pavement Produced In Low Temperatures with Foamed Bitumen

Science.gov (United States)

Chomicz-Kowalska, Anna; Iwański, Mateusz M.; Mrugała, Justyna

2017-10-01

During the reconstruction of road pavements, the reclaimed asphalt pavement (RAP), which is obtained through milling of the worn out existing asphalt, is commonly used for producing new base courses in cold recycling processes. Two of these techniques are most popular: one using mineral-cement-emulsion mixes and one utilizing mineral cement mixes with foamed bitumen. Additionally, some amounts of RAP can be incorporated into traditional hot mix asphalt. The demand for energy efficient and environmentally friendly solutions however, results in a need for development of new techniques that would result in cheaper and more reliable solutions with smaller carbon footprint. The reduction of processing temperatures with simultaneous incorporation of reclaimed material is the most efficient way of obtaining these objectives, but it often results in the overall decrease of bituminous mix quality. The paper presents the possibility of using RAP for producing asphalt concrete in warm mix asphalt (WMA) production process by the use of foamed bitumen modified with Fischer-Tropsch synthetic wax and polymer-basalt fibers. Additionally, a series of reference mixtures were produced to investigate the effects of the additives and of the warm process. The carried out analyses and tests shown that the experimental warm mix asphalt produced with RAP and foamed bitumen returned satisfactory performance. The introduction of synthetic F-T wax in the warm foam bitumen mixes resulted in a significantly improved compaction levels and moisture and frost resistance and the addition of polymer-basalt fibers has further improved the permanent deformation resistance of the mixes. All of the designed and tested mixes have fulfilled the requirements for binding course asphalt concrete with medium traffic loads.

Polyurethane foams obtained from residues of PET manufacturing and modified with carbon nanotubes

International Nuclear Information System (INIS)

Stiebra, L; Cabulis, U; Knite, M

2016-01-01

In this work we report the preparation of rigid microcellular polyurethane/carbon nanotube nanocomposites with different CNT loadings (0.09-0.46%) and various isocyanate indexes (110-260). Water was used as a blowing agent for samples. Density of all obtained samples – 200 ± 10 kg/m 3 . Electrical properties, as well as heat conductivity, cellular structure and mechanical properties of these nanocomposites were investigated. (paper)

Polyurethane foams obtained from residues of PET manufacturing and modified with carbon nanotubes

Science.gov (United States)

Stiebra, L.; Cabulis, U.; Knite, M.

2016-04-01

In this work we report the preparation of rigid microcellular polyurethane/carbon nanotube nanocomposites with different CNT loadings (0.09-0.46%) and various isocyanate indexes (110-260). Water was used as a blowing agent for samples. Density of all obtained samples - 200 ± 10 kg/m3. Electrical properties, as well as heat conductivity, cellular structure and mechanical properties of these nanocomposites were investigated.

Study of two-phase foam flow

Energy Technology Data Exchange (ETDEWEB)

Gurbanov, R S; Guliev, B B; Mekhtiev, K G; Kerimov, R G

1970-01-01

The objectives of this study were to determine characteristics of aqueous foam flow through porous media and to estimate the depth of foam penetration into a formation. Foam was generated by mixing air and 1% solution of surfactant PO-1. Foam density was maintained at 0.14 g/cc in all experiments. The foam was passed through sand columns (800 mm long x 30 mm diam) of permeabilities 26, 39, 80, 111, and 133 darcys. Flow rates were measured at various pressure drops and the relationship between system parameters was expressed analytically and graphically. From the data, distance of foam penetration into a formation as a function of pressure drop and permeability was calculated. The data indicate that under most conditions, foam will penetrate the formation to a negligible distance. This study indicates that when foam is used to remove sand from a well, a negligible loss of foam to the formation occurs.

Experiments to populate and validate a processing model for polyurethane foam. BKC 44306 PMDI-10

Energy Technology Data Exchange (ETDEWEB)

Mondy, Lisa Ann [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rao, Rekha Ranjana [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Shelden, Bion [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Soehnel, Melissa Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); O' Hern, Timothy J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grillet, Anne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Celina, Mathias C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wyatt, Nicholas B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Russick, Edward Mark [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bauer, Stephen J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hileman, Michael Bryan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Urquhart, Alexander [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thompson, Kyle Richard [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Smith, David Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2014-03-01

We are developing computational models to elucidate the expansion and dynamic filling process of a polyurethane foam, PMDI. The polyurethane of interest is chemically blown, where carbon dioxide is produced via the reaction of water, the blowing agent, and isocyanate. The isocyanate also reacts with polyol in a competing reaction, which produces the polymer. Here we detail the experiments needed to populate a processing model and provide parameters for the model based on these experiments. The model entails solving the conservation equations, including the equations of motion, an energy balance, and two rate equations for the polymerization and foaming reactions, following a simplified mathematical formalism that decouples these two reactions. Parameters for the polymerization kinetics model are reported based on infrared spectrophotometry. Parameters describing the gas generating reaction are reported based on measurements of volume, temperature and pressure evolution with time. A foam rheology model is proposed and parameters determined through steady-shear and oscillatory tests. Heat of reaction and heat capacity are determined through differential scanning calorimetry. Thermal conductivity of the foam as a function of density is measured using a transient method based on the theory of the transient plane source technique. Finally, density variations of the resulting solid foam in several simple geometries are directly measured by sectioning and sampling mass, as well as through x-ray computed tomography. These density measurements will be useful for model validation once the complete model is implemented in an engineering code.

Mass transfer measurements in foams

International Nuclear Information System (INIS)

Leblond, J.G.; Fournel, B.

2004-01-01

Full text of publication follows:This study participates to the elaboration of a method for decontamination of the inside surfaces of steel structures (pipes, tanks,...). The solution which has been chosen is to attack the surface of the structure by a dipping solution. In order to reduce the quantity of product to be recovered and treated at the end of the cleaning process, the active solution will be introduced as a foam. During its free or forced drainage the foam supplies an active liquid film along the structure surfaces. It was important to know if the transfers of the dipping liquid inside the foam and between foam and wall film are sufficient to allow a correct supplying of the active liquid at the wall and a correct dragging of the dipped products. The objective of this work is to develop a numerical model which simulates the various transfers. However such a modeling cannot be performed without a thorough knowledge of the different transfer parameters in the foam and in the film. The following study has been performed on a model foam (foaming water + air) held in a smooth vertical glass pipe and submitted to a forced drainage by the foaming water (water + surfactants). The liquid transfer involves the dispersion of the drainage liquid inside the foam and the transfer between the foam and the liquid film flowing down at the wall. The different transfers has been analyzed by NMR using a PFGSE-NMR sequence, which allows to determine the propagator, i.e., the probability density of the liquid particle displacements during a given time interval Δt, along a selected direction. This study allowed to measure, firstly, the mean liquid and the liquid dispersion in the foam along the vertical and horizontal direction, and secondly, the vertical mean velocity in the parietal liquid film. (authors)

Foaming in manure based digesters: Effect of overloading and foam suppression using antifoam agents

OpenAIRE

Kougias, Panagiotis; Tsapekos, Panagiotis; Boe, Kanokwan; Angelidaki, Irini

2013-01-01

Anaerobic digestion foaming is one of the major problems that occasionally occur in full-scale biogas plants, affecting negatively the overall digestion process. The foam is typically created either in the main biogas reactor or/and in the pre-storage tank and the entrapped solids in the foam cause severe operational problems, such as blockage of mixing devices and collapse of pumps. Furthermore, the foaming problem is linked with economic consequences for biogas plants, due to income losses ...

Influence of Rubber Powders on Foaming Behavior and Mechanical Properties of Foamed Polypropylene Composites

Directory of Open Access Journals (Sweden)

HE Yue

2017-02-01

Full Text Available Polypropylene/rubber powders composites with different kinds of rubber powders were foamed by injection molding machine equipped with volume-adjustable cavity. The effect of dispersity of rubber powders and crystallization behavior of composites on the foaming behavior and mechanical properties was investigated. The results show that the addition of rubber powders can improve the cell structure of foamed PP with fine and uniform cell distribution. And cell density and size of PP/PP-MAH/NBR foams are 7.64×106cell/cm3 and 29.78μm respectively, which are the best among these foams. Combining cell structures with mechanical properties, notch impact strength of PP/PP-MAH/CNBR composites increases approximately by 2.2 times while tensile strength is reduced just by 26% compared with those of the pure PP. This indicates that PP/PP-MAH/CNBR composites are ideal foamed materials.

Chaotic bubbling and nonstagnant foams.

Science.gov (United States)

Tufaile, Alberto; Sartorelli, José Carlos; Jeandet, Philippe; Liger-Belair, Gerard

2007-06-01

We present an experimental investigation of the agglomeration of bubbles obtained from a nozzle working in different bubbling regimes. This experiment consists of a continuous production of bubbles from a nozzle at the bottom of a liquid column, and these bubbles create a two-dimensional (2D) foam (or a bubble raft) at the top of this column. The bubbles can assemble in various dynamically stable arrangement, forming different kinds of foams in a liquid mixture of water and glycerol, with the effect that the bubble formation regimes influence the foam obtained from this agglomeration of bubbles. The average number of bubbles in the foam is related to the bubble formation frequency and the bubble mean lifetime. The periodic bubbling can generate regular or irregular foam, while a chaotic bubbling only generates irregular foam.

Determination of Acreage Thermal Protection Foam Loss From Ice and Foam Impacts

Science.gov (United States)

Carney, Kelly S.; Lawrence, Charles

2015-01-01

A parametric study was conducted to establish Thermal Protection System (TPS) loss from foam and ice impact conditions similar to what might occur on the Space Launch System. This study was based upon the large amount of testing and analysis that was conducted with both ice and foam debris impacts on TPS acreage foam for the Space Shuttle Project External Tank. Test verified material models and modeling techniques that resulted from Space Shuttle related testing were utilized for this parametric study. Parameters varied include projectile mass, impact velocity and impact angle (5 degree and 10 degree impacts). The amount of TPS acreage foam loss as a result of the various impact conditions is presented.

Polyurethane foam impregnated with lignin as a filler for the removal of crude oil from contaminated water

Energy Technology Data Exchange (ETDEWEB)

Santos, O.S.H. [Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, CEP: 31.270-901 (Brazil); Coelho da Silva, Mercês [Engenharia de Materiais, Universidade Federal de Itajubá—UNIFEI, Campus Universitário de Itabira. Itabira, Minas Gerais, CEP: 35.903-087 (Brazil); Silva, V.R.; Mussel, W.N. [Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, CEP: 31.270-901 (Brazil); Yoshida, M.I., E-mail: mirene@ufmg.br [Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, CEP: 31.270-901 (Brazil)

2017-02-15

Highlights: • The presence of lignin in polyurethane foams increased oil sorption capacity. • The presence of lignin resulted in a decrease in the hydrophobicity of the foams. • Langmuir isotherm predicted a maximum oil adsorption of 28.9 g g{sup −1} by the PUF-10. • ΔG° (−4.4 kJ mol{sup −1}) indicated that adsorption process by PUF-10 was spontaneous. • The recyclability of the foam showed efficiency greater than 95% after five cycles. - Abstract: The present study describes the influence of the concentration of lignin when used as a filler in polyurethane foam for crude oil sorption. The foams (lignin 0–20 wt%) were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis, contact angle and density. The FTIR analysis confirmed urethane linkage formation, showing that the chemical structure of the polymer was preserved, despite the addition of different lignin concentrations. Thermogravimetric analysis showed that the presence of lignin has altered the onset temperature (T{sub onset}) of the foams, decreasing as the concentration of lignin is increased. The contact angle analysis showed a decrease in the hydrophobicity of the foams with increasing lignin concentration. All modified foams showed an improvement in the oil sorption capacity in a PUF/oil/water system, and the PUF-10 showed an improvement of about 35.5% compared to the PUF-blank. The Langmuir isotherm showed a better fit to the data and predicted a maximum oil adsorption of 28.9 g g{sup −1} by the PUF-10. The ΔG° value of −4.4 kJ mol{sup −1} indicated that crude oil adsorption process by PUF-10 was spontaneous. The results of reuse of the PUF-10 showed that oil removal efficiency remained greater than 95% after five consecutive cycles.

Activity Tests of Macro-Meso Porous Catalysts over Metal Foam Plate for Steam Reforming of Bio-Ethanol.

Science.gov (United States)

Park, No-Kuk; Jeong, Yong Han; Kang, Misook; Lee, Tae Jin

2018-09-01

The catalytic activity of a macro-mesoporous catalyst coated on a metal foam plate in the reforming of bio-ethanol to synthesis gas was investigated. The catalysts were prepared by coating a support with a noble metal and transition metal. The catalytic activity for the production of synthetic gas by the reforming of bio-ethanol was compared according to the support material, reaction temperature, and steam/carbon ratio. The catalysts coated on the metal foams were prepared using a template method, in which macro-pores and meso-pores were formed by mixing polymer beads. In particular, the thermodynamic equilibrium composition of bio-ethanol reforming with the reaction temperature and steam/carbon ratio to produce synthetic gas was examined using the HSC (Enthalpy-Entropy-Heat capacity) chemistry program in this study. The composition of hydrogen and carbon monoxide in the reformate gas produced by steam reforming over the Rh/Ni-Ce-Zr/Al2O3-based pellet type catalysts and metal foam catalysts that had been coated with the Rh/Al-Ce-Zr-based catalysts was investigated by experimental activity tests. The activity of the metal foam catalyst was higher than that of the pellet type catalyst.

A review of aqueous foam in microscale.

Science.gov (United States)

Anazadehsayed, Abdolhamid; Rezaee, Nastaran; Naser, Jamal; Nguyen, Anh V

2018-06-01

In recent years, significant progress has been achieved in the study of aqueous foams. Having said this, a better understanding of foam physics requires a deeper and profound study of foam elements. This paper reviews the studies in the microscale of aqueous foams. The elements of aqueous foams are interior Plateau borders, exterior Plateau borders, nodes, and films. Furthermore, these elements' contribution to the drainage of foam and hydraulic resistance are studied. The Marangoni phenomena that can happen in aqueous foams are listed as Marangoni recirculation in the transition region, Marangoni-driven flow from Plateau border towards the film in the foam fractionation process, and Marangoni flow caused by exposure of foam containing photosurfactants under UV. Then, the flow analysis of combined elements of foam such as PB-film along with Marangoni flow and PB-node are studied. Next, we contrast the behavior of foams in different conditions. These various conditions can be perturbation in the foam structure caused by injected water droplets or waves or using a non-Newtonian fluid to make the foam. Further review is about the effect of oil droplets and particles on the characteristics of foam such as drainage, stability and interfacial mobility. Copyright © 2018 Elsevier B.V. All rights reserved.

Beer foam physics

NARCIS (Netherlands)

Ronteltap, A.D.

1989-01-01

The physical aspects of beer foam behavior were studied in terms of the four physical processes, mainly involved in the formation and breakdown of foam. These processes are, bubble formation, drainage, disproportionation and coalescence. In detail, the processes disproportionation and

Nonlinear Response of Strong Nonlinear System Arisen in Polymer Cushion

Directory of Open Access Journals (Sweden)

Jun Wang

2013-01-01

Full Text Available A dynamic model is proposed for a polymer foam-based nonlinear cushioning system. An accurate analytical solution for the nonlinear free vibration of the system is derived by applying He's variational iteration method, and conditions for resonance are obtained, which should be avoided in the cushioning design.

FOAM3D: A numerical simulator for mechanistic prediciton of foam displacement in multidimensions

Energy Technology Data Exchange (ETDEWEB)

Kovscek, A.R.; Patzek, T.W. [Lawrence Berkeley Laboratory, Berkeley, CA (United States); Radke, C.J. [Univ. of California, Berkeley, CA (United States)

1995-03-01

Field application of foam is a technically viable enhanced oil recovery process (EOR) as demonstrated by recent steam-foam field studies. Traditional gas-displacement processes, such as steam drive, are improved substantially by controlling gas mobility and thereby improving volumetric displacement efficiency. For instance, Patzek and Koinis showed major oil-recovery response after about two years of foam injection in two different pilot studies at the Kern River field. They report increased production of 5.5 to 14% of the original oil in place over a five year period. Because reservoir-scale simulation is a vital component of the engineering and economic evaluation of any EOR project, efficient application of foam as a displacement fluid requires a predictive numerical model of foam displacement. A mechanistic model would also expedite scale-up of the process from the laboratory to the field scale. No general, mechanistic, field-scale model for foam displacement is currently in use.

Anti-foam System design description

International Nuclear Information System (INIS)

White, M.A.

1994-01-01

The Anti-foam System is a sub-system of the 242-A Evaporator facility. The Anti-foam is used within the C-A-1 Vapor-Liquid Separator, to reduce the effect of foaming and reduce fluid bumping while the vapor and liquid are separated within the C-A-1 Vapor-Liquid Separator. Excessive foaming within the vessel may possibly cause the liquid slurry mixture in the evaporator vessel to foul the de-entrainment pads and cause plant shutdown. The Anti-foam System consists of the following primary elements: the Anti-foam Tank and the Metering Pump. The upgrades to Anti-foam System include the following: installation of a new pump, instruments, and valves; and connection of the instruments, pump and agitator associated with the Anti-foam System to the Monitoring and Control System (MCS). The 242-A Evaporator is a waste treatment facility designed to reduce liquid waste volumes currently stored in the Hanford Area double shell Waste Storage Tanks. The evaporator uses evaporative concentration to achieve this volume reduction, returning the concentrated slurry to the double-shell tanks for storage and, at the same time, releasing the process effluent to a retention facilities for eventual treatment and release to the environment

Stability of metallic foams studied under microgravity

CERN Document Server

Wuebben, T; Banhart, J; Odenbach, S

2003-01-01

Metal foams are prepared by mixing a metal powder and a gas-releasing blowing agent, by densifying the mix to a dense precursor and finally foaming by melting the powder compact. The foaming process of aluminium foams is monitored in situ by x-ray radioscopy. One observes that foam evolution is accompanied by film rupture processes which lead to foam coalescence. In order to elucidate the importance of oxides for foam stability, lead foams were manufactured from lead powders having two different oxide contents. The two foam types were generated on Earth and under weightlessness during parabolic flights. The measurements show that the main function of oxide particles is to prevent coalescence, while their influence on bulk viscosity of the melt is of secondary importance.

Efficient removal of perfluorooctane sulfonate from aqueous film-forming foam solution by aeration-foam collection.

Science.gov (United States)

Meng, Pingping; Deng, Shubo; Maimaiti, Ayiguli; Wang, Bin; Huang, Jun; Wang, Yujue; Cousins, Ian T; Yu, Gang

2018-07-01

Aqueous film-forming foams (AFFFs) used in fire-fighting are one of the main contamination sources of perfluorooctane sulfonate (PFOS) to the subterranean environment, requiring high costs for remediation. In this study, a method that combined aeration and foam collection was presented to remove PFOS from a commercially available AFFF solution. The method utilized the strong surfactant properties of PFOS that cause it to be highly enriched at air-water interfaces. With an aeration flow rate of 75 mL/min, PFOS removal percent reached 96% after 2 h, and the PFOS concentration in the collected foam was up to 6.5 mmol/L, beneficial for PFOS recovery and reuse. Increasing the aeration flow rate, ionic strength and concentration of co-existing surfactant, as well as decreasing the initial PFOS concentration, increased the removal percents of PFOS by increasing the foam volume, but reduced the enrichment of PFOS in the foams. With the assistance of a co-existing hydrocarbon surfactant, PFOS removal percent was above 99.9% after aeration-foam collection for 2 h and the enrichment factor exceeded 8400. Aeration-foam collection was less effective for short-chain perfluoroalkyl substances due to their relatively lower surface activity. Aeration-foam collection was found to be effective for the removal of high concentrations of PFOS from AFFF-contaminated wastewater, and the concentrated PFOS in the collected foam can be reused. Copyright © 2018 Elsevier Ltd. All rights reserved.

A theory of electrical conductivity, dielectric constant, and electromagnetic interference shielding for lightweight graphene composite foams

Energy Technology Data Exchange (ETDEWEB)

Xia, Xiaodong [School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092 (China); Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, New Jersey 08903 (United States); Wang, Yang; Weng, George J., E-mail: weng@jove.rutgers.edu [Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, New Jersey 08903 (United States); Zhong, Zheng [School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092 (China)

2016-08-28

This work was driven by the need to understand the electromagnetic interference (EMI) shielding effectiveness (SE) of light weight, flexible, and high performance graphene composite foams, but as EMI SE of a material depends on its electrical conductivity, dielectric permittivity, and magnetic permeability, the investigation of these three properties also became a priority. In this paper, we first present a continuum theory to determine these three electromagnetic properties, and then use the obtained properties to evaluate the EMI SE of the foam. A two-scale composite model is conceived to evaluate these three properties, with the large one being the skeleton-void composite and the small one being the graphene-polymer composite that serves as the skeleton of the foam. To evaluate the properties of the skeleton, the effective-medium approach is taken as the starting point. Subsequently, the effect of an imperfect interface and the contributions of electron tunneling to the interfacial conductivity and Maxwell-Wagner-Sillars polarization mechanism to the dielectric constant are also implemented. The derived skeleton properties are then utilized on the large scale to determine the three properties of the composite foam at a given porosity. Then a uniform plane electromagnetic wave is considered to evaluate the EMI SE of the foam. It is demonstrated that the electrical conductivity, dielectric constant, and EMI SE of the foam calculated from the developed theory are in general agreement with the reported experimental data of graphene/PDMS composite foams. The theory is further proven to be valid for the EMI SE of solid graphene/epoxy and solid carbon nanotube/epoxy nanocomposites. It is also shown that, among the three electromagnetic properties, electrical conductivity has the strongest influence on the EMI shielding effectiveness.

Numerical Modeling of Foam Drilling Hydraulics

Directory of Open Access Journals (Sweden)

Ozcan Baris

2007-12-01

Full Text Available The use of foam as a drilling fluid was developed to meet a special set of conditions under which other common drilling fluids had failed. Foam drilling is defined as the process of making boreholes by utilizing foam as the circulating fluid. When compared with conventional drilling, underbalanced or foam drilling has several advantages. These advantages include: avoidance of lost circulation problems, minimizing damage to pay zones, higher penetration rates and bit life. Foams are usually characterized by the quality, the ratio of the volume of gas, and the total foam volume. Obtaining dependable pressure profiles for aerated (gasified fluids and foam is more difficult than for single phase fluids, since in the former ones the drilling mud contains a gas phase that is entrained within the fluid system. The primary goal of this study is to expand the knowledge-base of the hydrodynamic phenomena that occur in a foam drilling operation. In order to gain a better understanding of foam drilling operations, a hydrodynamic model is developed and run at different operating conditions. For this purpose, the flow of foam through the drilling system is modeled by invoking the basic principles of continuum mechanics and thermodynamics. The model was designed to allow gas and liquid flow at desired volumetric flow rates through the drillstring and annulus. Parametric studies are conducted in order to identify the most influential variables in the hydrodynamic modeling of foam flow.

Applications of Foamed Lightweight Concrete

Directory of Open Access Journals (Sweden)

Mohd Sari Kamarul Aini

2017-01-01

Full Text Available Application of foamed concrete is increasing at present due to high demand on foamed concrete structures with good mechanical and physical properties. This paper discusses on the use of basic raw materials, their characteristics, production process, and their application in foamed lightweight concrete with densities between 300 kg/m3 and 1800 kg/m3. It also discusses the factors that influence the strengths and weaknesses of foamed concrete based on studies that were conducted previously.

Foam Transport in Porous Media - A Review

Energy Technology Data Exchange (ETDEWEB)

Zhang, Z. F.; Freedman, Vicky L.; Zhong, Lirong

2009-11-11

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 used to enhance soil remediation. The

Effect of foam stirrer design on the catalytic performance of rotating foam stirrer reactions

NARCIS (Netherlands)

Leon Matheus, M.A.; Geers, P.; Nijhuis, T.A.; Schaaf, van der J.; Schouten, J.C.

2012-01-01

The liquid–solid mass transfer rate in a rotating foam stirrer reactor and in a slurry reactor is studied using the hydrogenation of styrene as a model reaction. The rotating foam stirrer reactor is a novel type of multi-phase reactor where highly open-celled materials, solid foams, are used as a

Repair of oxidation protection coatings on carbon-carbon using preceramic polymers

Science.gov (United States)

Schwab, Stuart T.; Graef, Renee C.

1991-01-01

The paper describes a field-applicable technique for the repair of damage to SiC protective coatings on carbon/carbon composites, using commercial preceramic polymers, such as perhydropolysilazane developed by the Southwest Research Institute and several commercial polymers (NICALON, PS110, PS116, PS117, NCP-200, and PHPS were tested). After being applied on the damaged panel and oxidized at 1400 C, these polymers form either SiC or Si3N4 (or a mixture of both). It was found that impact damaged carbon/carbon specimens repaired with perhydropolysilazane exhibit substantial oxidation resistance. Many of the other tested preceramic polymer were found to be unsuitable for the purpose of repair due to either low ceramic yield, foaming, or intumescence.

Anaerobic Digestion Foaming Causes

OpenAIRE

Ganidi, Nafsika

2008-01-01

Anaerobic digestion foaming has been encountered in several sewage treatment plants in the UK. Foaming has raised major concerns for the water utilities due to significant impacts on process efficiency and operational costs. Several foaming causes have been suggested over the past few years by researchers. However, the supporting experimental information is limited and in some cases site specific. The present report aimed to provide a better understanding of the anaerobic di...

Foam-forming properties of Ilex paraguariensis (mate saponin: foamability and foam lifetime analysis by Weibull equation

Directory of Open Access Journals (Sweden)

Janine Treter

2010-01-01

Full Text Available Saponins are natural soaplike foam-forming compounds widely used in foods, cosmetic and pharmaceutical preparations. In this work foamability and foam lifetime of foams obtained from Ilex paraguariensis unripe fruits were analyzed. Polysorbate 80 and sodium dodecyl sulfate were used as reference surfactants. Aiming a better data understanding a linearized 4-parameters Weibull function was proposed. The mate hydroethanolic extract (ME and a mate saponin enriched fraction (MSF afforded foamability and foam lifetime comparable to the synthetic surfactants. The linearization of the Weibull equation allowed the statistical comparison of foam decay curves, improving former mathematical approaches.

Foam flow in a model porous medium: I. The effect of foam coarsening.

Science.gov (United States)

Jones, S A; Getrouw, N; Vincent-Bonnieu, S

2018-05-09

Foam structure evolves with time due to gas diffusion between bubbles (coarsening). In a bulk foam, coarsening behaviour is well defined, but there is less understanding of coarsening in confined geometries such as porous media. Previous predictions suggest that coarsening will cause foam lamellae to move to low energy configurations in the pore throats, resulting in greater capillary resistance when restarting flow. Foam coarsening experiments were conducted in both a model-porous-media micromodel and in a sandstone core. In both cases, foam was generated by coinjecting surfactant solution and nitrogen. Once steady state flow had been achieved, the injection was stopped and the system sealed off. In the micromodel, the foam coarsening was recorded using time-lapse photography. In the core flood, the additional driving pressure required to reinitiate flow after coarsening was measured. In the micromodel the bubbles coarsened rapidly to the pore size. At the completion of coarsening the lamellae were located in minimum energy configurations in the pore throats. The wall effect meant that the coarsening did not conform to the unconstricted growth laws. The coreflood tests also showed coarsening to be a rapid process. The additional driving pressure to restart flow reached a maximum after just 2 minutes.

Foaming in manure based digesters: Effect of overloading and foam suppression using antifoam agents

DEFF Research Database (Denmark)

Kougias, Panagiotis; Tsapekos, Panagiotis; Boe, Kanokwan

Anaerobic digestion foaming is one of the major problems that occasionally occur in full-scale biogas plants, affecting negatively the overall digestion process. The foam is typically created either in the main biogas reactor or/and in the pre-storage tank and the entrapped solids in the foam cause...... severe operational problems, such as blockage of mixing devices and collapse of pumps. Furthermore, the foaming problem is linked with economic consequences for biogas plants, due to income losses derived from the reduced biogas production, extra labour work and additional maintenance costs. Moreover....... A continuous stirred tank reactor, operating under thermophilic conditions (55 oC) was fed with cattle manure. In order to investigate the effect of organic overloading on foam formation, a stepwise increase of the organic loading rate was performed by the addition of glucose in the feeding substrate. Biogas...

46 CFR 108.463 - Foam rate: Protein.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Foam rate: Protein. 108.463 Section 108.463 Shipping... EQUIPMENT Fire Extinguishing Systems Foam Extinguishing Systems § 108.463 Foam rate: Protein. (a) If the outlets of a protein foam extinguishing system are in a space, the foam rate at each outlet must be at...

Foaming Glass Using High Pressure Sintering

DEFF Research Database (Denmark)

Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob

Foam glass is a high added value product which contributes to waste recycling and energy efficiency through heat insulation. The foaming can be initiated by a chemical or physical process. Chemical foaming with aid of a foaming agent is the dominant industrial process. Physical foaming has two...... to expand. After heat-treatment foam glass can be obtained with porosities of 80–90 %. In this study we conduct physical foaming of cathode ray tube (CRT) panel glass by sintering under high pressure (5-25 MPa) using helium, nitrogen, or argon at 640 °C (~108 Pa s). Reheating a sample in a heating...... variations. One way is by saturation of glass melts with gas. The other involves sintering of powdered glass under a high gas pressure resulting in glass pellets with high pressure bubbles entrapped. Reheating the glass pellets above the glass transition temperature under ambient pressure allows the bubbles...

Investigation of Chemical-Foam Design as a Novel Approach toward Immiscible Foam Flooding for Enhanced Oil Recovery.

Science.gov (United States)

Hosseini-Nasab, S M; Zitha, P L J

2017-10-19

Strong foam can be generated in porous media containing oil, resulting in incremental oil recovery; however, oil recovery factor is restricted. A large fraction of oil recovered by foam flooding forms an oil-in-water emulsion, so that costly methods may need to be used to separate the oil. Moreover, strong foam could create a large pressure gradient, which may cause fractures in the reservoir. This study presents a novel chemical-foam flooding process for enhanced oil recovery (EOR) from water-flooded reservoirs. The presented method involved the use of chemically designed foam to mobilize the remaining oil after water flooding and then to displace the mobilized oil to the production well. A blend of two anionic surfactant formulations was formulated for this method: (a) IOS, for achieving ultralow interfacial tension (IFT), and (b) AOS, for generating a strong foam. Experiments were performed using Bentheimer sandstone cores, where X-ray CT images were taken during foam generation to find the stability of the advancing front of foam propagation and to map the gas saturation for both the transient and the steady-state flow regimes. Then the proposed chemical-foam strategy for incremental oil recovery was tested through the coinjection of immiscible nitrogen gas and surfactant solutions with three different formulation properties in terms of IFT reduction and foaming strength capability. The discovered optimal formulation contains a foaming agent surfactant, a low IFT surfactant, and a cosolvent, which has a high foam stability and a considerably low IFT (1.6 × 10 -2 mN/m). Coinjection resulted in higher oil recovery and much less MRF than the same process with only using a foaming agent. The oil displacement experiment revealed that coinjection of gas with a blend of surfactants, containing a cosolvent, can recover a significant amount of oil (33% OIIP) over water flooding with a larger amount of clean oil and less emulsion.

Effect of Mesoporous Silica and Hydroxyapatite Nanoparticles on the Tensile and Dynamic Mechanical Thermal Properties of Polypropylene and Polypropylene Foam

Directory of Open Access Journals (Sweden)

Alireza Albooyeh

2014-12-01

Full Text Available The main purpose of this paper is the experimental study on the tensile and dynamic - mechanical thermal properties of polypropylene (PP and polypropylene foam reinforced with mesoporous silica (MCM-41, hydroxyapatite (HA and the composite of mesoporous silica and hydroxyapatite (MCM41-HA nanoparticles. Nanocomposites and nanocomposite foams containing PP, maleic anhydride grafted polypropylene, different nanoparticles and chemical blowing agent (for foam samples are mixed using the melt-compounding technique in a twin-screw extruder. The results of the tests show that at the same nanoparticles content, all the nanofillers cause better mechanical properties than neat PP and PP foam. Also, due to the porous structure of the foam samples, these samples have the higher damping characteristics and lower tensile properties than the solid samples. Because of higher rigidity and higher strength of HA nanoparticles, the greatest increase in modulus and tensile strength occurs by adding these nanoparticles to neat PP and PP foam. The highest damping factor is obtained by adding MCM-41-HA nanoparticles to PP and PP foam, because of the porous nature of the MCM-41 particles which were reinforced by HA particles. The results of differential scanning calorimetry show that the addition of different nanoparticles does not have any significant effect on crystallinity and melting behavior of PP. Scanning electron microscopy images show that the nanomaterials were fine and uniformly dispersed within the polymer matrix. Furthermore, the addition of different nanoparticles to PP foam causes to increase the cell density, to reduce the cell sizes and to improve the cell sizes distribution. In this respect, the lowest cell sizes and the highest cell density are created by adding HA and MCM41-HA  nanopaticles to PP foams.

Foam-on-Tile Damage Model

Science.gov (United States)

Koharchik, Michael; Murphy, Lindsay; Parker, Paul

2012-01-01

An impact model was developed to predict how three specific foam types would damage the Space Shuttle Orbiter insulating tiles. The inputs needed for the model are the foam type, the foam mass, the foam impact velocity, the foam impact incident angle, the type being impacted, and whether the tile is new or aged (has flown at least one mission). The model will determine if the foam impact will cause damage to the tile. If it can cause damage, the model will output the damage cavity dimensions (length, depth, entry angle, exit angle, and sidewall angles). It makes the calculations as soon as the inputs are entered (less than 1 second). The model allows for the rapid calculation of numerous scenarios in a short time. The model was developed from engineering principles coupled with significant impact testing (over 800 foam impact tests). This model is applicable to masses ranging from 0.0002 up to 0.4 pound (0.09 up to 181 g). A prior tool performed a similar function, but was limited to the assessment of a small range of masses and did not have the large test database for verification. In addition, the prior model did not provide outputs of the cavity damage length, entry angle, exit angle, or sidewall angles.

TPX foams for inertial fusion laser experiments: foam preparation, machining, characterization, and discussion of density issues

International Nuclear Information System (INIS)

Grosse, M.; Guillot, L.; Reneaume, B.; Fleury, E.; Hermerel, C.; Choux, A.; Jeannot, L.; Geoffray, I.; Faivre, A.; Breton, O.; Andre, J.; Collier, R.; Legaie, O.

2011-01-01

Low density foams (in this work, foam density refers to apparent density) are materials of interest for fusion experiments. Low density poly(4-methyl-1-pentene)(commercial name TPX) foams have been produced for 30 years. TPX foams have been shown to have densities as low as 3 mg.cm -3 , which is very close to air density (1.2 mg.cm -3 ). Around this density foams are very light and highly fragile. Their fabrication is thus a real technological challenge. However, shrinking always appears in ranges ranking from 25% to almost 200%. As a result, the apparent density of the final foam never matches the expected value given by the precursor solution concentration. Besides, even if the mold dimensions are precisely known, shrinkage is never linear, and foams have to be machined for precise density measurement. In our work we present a fabrication process for TPX foams and discuss machining and density measuring issues. Particularly, we have found that there are volume and weight limits for a determination of density within the range of 3% uncertainty. This raises the question whether density should rather be determined directly on millimeter-sized targets or should be performed on a bigger scale sample prepared from the same batch. (authors)

Porosity and cell size control in alumina foam preparation by thermo-foaming of powder dispersions in molten sucrose

Directory of Open Access Journals (Sweden)

Sujith Vijayan

2016-09-01

Full Text Available The foaming characteristics of alumina powder dispersions in molten sucrose have been studied as a function of alumina powder to sucrose weight ratio (WA/S and foaming temperature. The increase in foaming temperature significantly decreases the foaming and foam setting time and increases the foam volume due to an increase in the rate of OH condensation as well as a decrease in the viscosity of the dispersion. Nevertheless, the foam collapses beyond a critical foaming temperature, which depends on the WA/S. The sintering shrinkage depends mainly on the WA/S and marginally on the foaming temperature. The porosity (83.4–94.6 vol.% and cell size (0.55–1.6 mm increase with an increase in foaming temperature (120–170 °C and a decrease in WA/S (0.8–1.6. The drastic decrease in compressive strength and modulus beyond a WA/S of 1.2 is due to the pores generated on the cell walls and struts as a result of particle agglomeration. Gibson and Ashby plots show large deviation with respect to the model constants ‘C’ and ‘n’, especially at higher alumina powder to sucrose weight ratios.

Development of drilling foams for geothermal applications

Energy Technology Data Exchange (ETDEWEB)

McDonald, W.J.; Remont, L.J.; Rehm, W.A.; Chenevert, M.E.

1980-01-01

The use of foam drilling fluids in geothermal applications is addressed. A description of foams - what they are, how they are used, their properties, equipment required to use them, the advantages and disadvantages of foams, etc. - is presented. Geothermal applications are discussed. Results of industry interviews presented indicate significant potential for foams, but also indicate significant technical problems to be solved to achieve this potential. Testing procedures and results of tests on representative foams provide a basis for work to develop high-temperature foams.

Industrial waste utilization for foam concrete

Science.gov (United States)

Krishnan, Gokul; Anand, K. B.

2018-02-01

Foam concrete is an emerging and useful construction material - basically a cement based slurry with at least 10% of mix volume as foam. The mix usually containing cement, filler (usually sand) and foam, have fresh densities ranging from 400kg/m3 to 1600kg/m3. One of the main drawbacks of foam concrete is the large consumption of fine sand as filler material. Usage of different solid industrial wastes as fillers in foam concrete can reduce the usage of fine river sand significantly and make the work economic and eco-friendly. This paper aims to investigate to what extent industrial wastes such as bottom ash and quarry dust can be utilized for making foam concrete. Foam generated using protein based agent was used for preparing and optimizing (fresh state properties). Investigation to find the influence of design density and air-void characteristics on the foam concrete strength shows higher strength for bottom ash mixes due to finer air void distribution. Setting characteristics of various mix compositions are also studied and adoption of Class C flyash as filler demonstrated capability of faster setting.

The Modification of Polyurethane Foams Using New Boroorganic Polyols (II) Polyurethane Foams from Boron-Modified Hydroxypropyl Urea Derivatives

Science.gov (United States)

2014-01-01

The work focuses on research related to determination of application possibility of new, ecofriendly boroorganic polyols in rigid polyurethane foams production. Polyols were obtained from hydroxypropyl urea derivatives esterified with boric acid and propylene carbonate. The influence of esterification type on properties of polyols and next on polyurethane foams properties was determined. Nitrogen and boron impacts on the foams' properties were discussed, for instance, on their physical, mechanical, and electric properties. Boron presence causes improvement of dimensional stability and thermal stability of polyurethane foams. They can be applied even at temperature 150°C. Unfortunately, introducing boron in polyurethanes foams affects deterioration of their water absorption, which increases as compared to the foams that do not contain boron. However, presence of both boron and nitrogen determines the decrease of the foams combustibility. Main impact on the decrease combustibility of the obtained foams has nitrogen presence, but in case of proper boron and nitrogen ratio their synergic activity on the combustibility decrease can be easily seen. PMID:24587721

Dechlorination of Environmental Contaminants Using a Hybrid Nanocatalyst: Palladium Nanoparticles Supported on Hierarchical Carbon Nanostructures

Directory of Open Access Journals (Sweden)

Hema Vijwani

2012-01-01

Full Text Available This paper demonstrates the effectiveness of a new type of hybrid nanocatalyst material that combines the high surface area of nanoparticles and nanotubes with the structural robustness and ease of handling larger supports. The hybrid material is made by fabricating palladium nanoparticles on two types of carbon supports: as-received microcellular foam (Foam and foam with carbon nanotubes anchored on the pore walls (CNT/Foam. Catalytic reductive dechlorination of carbon tetrachloride with these materials has been investigated using gas chromatography. It is seen that while both palladium-functionalized carbon supports are highly effective in the degradation of carbon tetrachloride, the rate of degradation is significantly increased with palladium on CNT/Foam. However, there is scope to increase this rate further if the wettability of these structures can be enhanced in the future. Microstructural and spectroscopic analyses of the fresh and used catalysts have been compared which indicates that there is no change in density or surface chemical states of the catalyst after prolonged use in dechlorination test. This implies that these materials can be used repeatedly and hence provide a simple, powerful, and cost-effective approach for dechlorination of water.

Evaluation of Canisterized Foams and Evaluation of Radiation Hardened Foams for D&D Activities

Energy Technology Data Exchange (ETDEWEB)

Nicholson, J. C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-09-26

The introduction of polyurethane foams has previously been examined elsewhere within the DOE complex with regards to decontamination and decommissioning (D&D) activities, though its use has been prohibited as a result of excessive heat generation and flammability concerns per the safety basis. Should these foams be found compatible with respect to the facility safety basis requirements, D&D work involving large void containing structures such as gloveboxes could be eased through the fixation of residual contamination after decontamination efforts have concluded. To this end, SRNL embarked on a characterization of commercial epoxy foams to identify the characteristics that would be most important to safety basis requirements. Through SRNL’s efforts, the performance of commercial two-part epoxy foams was evaluated for their foaming characteristics, temperature profiles, loading capability with high-Z (high density) additives, and applicability for shielding gamma emission from isotopes including; Am-241, Cs-137, and Co-60. It was found that these foams are capable of encapsulation of a desired volume, though the ideal and experimental expansion coefficients were found to differ. While heat is generated during the reaction, no samples generated heat above 70 °C. Of the down–selected materials, heating was on the order of 40 °C for the flexible foam and 60 °C for the rigid foam. Both were found to return to room temperature after 20 minutes regardless of the volume of foam cast. It was also found that the direct introduction of high-Z additives were capable of attenuating 98% of Am-241 gamma signal, 16% of Cs-137 signal, and 9.5% of Co-60 signal at 1:1 loading capacities of total liquid constituent weight to additive weight. These efforts are currently being reviewed for the ASTM January 2017 subcommittee discussions to address the lack of test methods and standards regarding these materials with respect to D&D environments.

Electrical conductivity of quasi-two-dimensional foams.

Science.gov (United States)

Yazhgur, Pavel; Honorez, Clément; Drenckhan, Wiebke; Langevin, Dominique; Salonen, Anniina

2015-04-01

Quasi-two-dimensional (quasi-2D) foams consist of monolayers of bubbles squeezed between two narrowly spaced plates. These simplified foams have served successfully in the past to shed light on numerous issues in foam physics. Here we consider the electrical conductivity of such model foams. We compare experiments to a model which we propose, and which successfully relates the structural and the conductive properties of the foam over the full range of the investigated liquid content. We show in particular that in the case of quasi-2D foams the liquid in the nodes needs to be taken into account even at low liquid content. We think that these results may provide different approaches for the characterization of foam properties and for the in situ characterization of the liquid content of foams in confining geometries, such as microfluidics.

ERGO grown on Ni-Cu foam frameworks by constant potential method as high performance electrodes for supercapacitors

Science.gov (United States)

Mirzaee, Majid; Dehghanian, Changiz; Sabet Bokati, Kazem

2018-04-01

This study presents composite electrode materials based on Electrochemically Reduced graphene oxide (ERGO) and Ni-Cu Foam for supercapacitor applications. Constant potential (CP) method was used to form reduced graphene oxide on Ni-Cu foam and characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), X-Ray Photoelectron Spectra (XPS), Raman Spectroscopy and electrochemical measurements. ERGO improves the electrical conduction leading to decrease of the internal resistance of the heterostructure. The ERGO served as a conductive network to facilitate the collection and transportation of electrons during the cycling, improved the conductivity of Ni-Cu foam, and allowed for a larger specific surface area. The irregular porous structure allowed for the easy diffusion of the electrolyte into the inner region of the electrode. Moreover, the nanocomposite directly fabricated on Ni-Cu foam with a better adhesion and avoided the use of polymer binder. This method efficiently reduced ohmic polarization and enhanced the rate capability. As a result, the Ni-Cu foam/ERGO nanocomposite exhibited a specific capacitance of 1259.3 F g-1 at 2 A g-1and about 99.3% of the capacitance retained after 5000 cycles. The capacitance retention was about 3% when the current density increased from 2 A g-1 to 15 A g-1. This two-step process drop cast and GO reduction by potentiostatic method is nontoxic and scalable and holds promise for improved energy density from redox capacitance in comparison with the conventional double layer supercapacitors.

From Foam Rubber to Volcanoes: The Physical Chemistry of Foam Formation

Science.gov (United States)

Hansen, Lee D.; McCarlie, V. Wallace

2004-01-01

The process of foam formation is used for demonstrating the way in which the application of physiochemical principles and knowledge of the physical properties of the materials contributes towards the understanding of a wide range of phenomenon. Solubility of gas and bubble growth should be considered during the development of foamed polymer…

Nanostructured metal foams: synthesis and applications

Energy Technology Data Exchange (ETDEWEB)

Luther, Erik P [Los Alamos National Laboratory; Tappan, Bryce [Los Alamos National Laboratory; Mueller, Alex [Los Alamos National Laboratory; Mihaila, Bogdan [Los Alamos National Laboratory; Volz, Heather [Los Alamos National Laboratory; Cardenas, Andreas [Los Alamos National Laboratory; Papin, Pallas [Los Alamos National Laboratory; Veauthier, Jackie [Los Alamos National Laboratory; Stan, Marius [Los Alamos National Laboratory

2009-01-01

Fabrication of monolithic metallic nanoporous materials is difficult using conventional methodology. Here they report a relatively simple method of synthesizing monolithic, ultralow density, nanostructured metal foams utilizing self-propagating combustion synthesis of novel metal complexes containing high nitrogen energetic ligands. Nanostructured metal foams are formed in a post flame-front dynamic assembly with densities as low as 0.011 g/cc and surface areas as high as 270 m{sup 2}/g. They have produced metal foams via this method of titanium, iron, cobalt, nickel, zirconium, copper, palladium, silver, hafnium, platinum and gold. Microstructural features vary as a function of composition and process parameters. Applications for the metal foams are discussed including hydrogen absorption in palladium foams. A model for the sorption kinetics of hydrogen in the foams is presented.

Polyethoxylated carboxylic surfactant for ion foam flotation: fundamental study from solution to foam

International Nuclear Information System (INIS)

Micheau, Cyril

2013-01-01

Ion foam flotation allows to concentrate ions in a foam phase formed by a soap. For classical systems, the strong interaction between ions and surfactant generally leads to the formation of precipitates and of froth. When the froth collapses, the solid residue thus recovered requires a recycling or conversion. In order to remedy this, the present work uses as collector a polyethoxylated carboxylic surfactant, AKYPO RO 90 VG, which forms soluble ion/surfactant complexes, even with multi-charge ions. This work presents a detailed study of the fundamental mechanisms that govern the extraction of ions by foaming. In the first part, surface activity and acid/base properties of the surfactant in solution are determined by combining numerous independent techniques which are pH-metric dosage, tensiometry and small angle scattering. The evolution of these properties in the presence of different nitrate salts (Nd, Eu, Ca, Sr, Cu, Li, Na, Cs) coupled with electrophoretic measurements give a first approach to selectivity. Finally, all of these data combined with a study of the formation of surfactant/ion complexes allow us to determine the speciation of Nd/AKYPO system as a function of pH. In the second part, the analysis of the foam by conductivity and neutron scattering provides information on the wetness and foam film thickness, parameters governing foam stability. The pH and the nature of the added ions, their number of charge and also their chemical nature thus appear to be major parameters that governed wetness and foam film thickness. The last part is devoted to the understanding of the ion extraction/separation experiments by flotation based on all previous results. It is shown that the flotation of neodymium is strongly related to its speciation, which could lead to its re-extraction or its flotation in precipitated form. It is shown that, neodymium induces a phenomenon of mono-charge ion depletion in the foam. This ionic specificity allows to consider the studied

Foam rheology at large deformation

Science.gov (United States)

Géminard, J.-C.; Pastenes, J. C.; Melo, F.

2018-04-01

Large deformations are prone to cause irreversible changes in materials structure, generally leading to either material hardening or softening. Aqueous foam is a metastable disordered structure of densely packed gas bubbles. We report on the mechanical response of a foam layer subjected to quasistatic periodic shear at large amplitude. We observe that, upon increasing shear, the shear stress follows a universal curve that is nearly exponential and tends to an asymptotic stress value interpreted as the critical yield stress at which the foam structure is completely remodeled. Relevant trends of the foam mechanical response to cycling are mathematically reproduced through a simple law accounting for the amount of plastic deformation upon increasing stress. This view provides a natural interpretation to stress hardening in foams, demonstrating that plastic effects are present in this material even for minute deformation.

Controlling of density uniformity of polyacrylate foams

International Nuclear Information System (INIS)

Shan Wenwen; Yuan Baohe; Wang Yanhong; Xu Jiayun; Zhang Lin

2010-01-01

The density non-uniformity existing in most low-density foams will affect performance of the foams. The trimethylolpropane trimethacrylate (TMPTA) foam targets were prepared and controlling methods of the foams, density uniformity were explored together with its forming mechanism. It has been found that the UV-light with high intensity can improve the distribution uniformity of the free radicals induced by UV photons in the solvents, thus improve the density uniformity of the foams. In addition, container wall would influence the concentration distribution of the solution, which affects the density uniformity of the foams. Thus, the UV-light with high intensity was chosen together with polytetrafluoroethylene molds instead of glass molds to prepare the foams with the density non-uniformity less than 10%. β-ray detection technology was used to measure the density uniformity of the TMPTA foams with the density in the range of 10 to 100 mg · cm -3 , and the results show that the lower the foam density is, the worse the density uniformity is. (authors)

Blast wave protection of aqueous foams

Energy Technology Data Exchange (ETDEWEB)

Britan, Alexander; Ben-Dor, M. Liverts G. [Shock tube Laboratory of Protective Technologies R and D Center, Department of Mechanical Engineering, Faculty of Engineering Sciences, Ben Gurion University, Beer-Sheva (Israel)

2011-07-01

The primary intention of the present study is to present new contribution of shock tube tests to the problem of particle related stabilization and enhanced mitigation action of the wet particulate foams. The experiments reported were designed to examine (i) the reflection of a shock wave from an air/foam face, (ii) the transmission of the shock wave through the air/foam face and (iii) propagation and dispersion of the transmitted shock wave inside the foam column. Because wet aqueous foam of desired specification is difficult to reproduce, handle and quantitatively characterize the fact that experiments on all the above aspects were conducted in a single facility is a potentially important consideration. Moreover vertical position of shock tube simplified the issues since the gradient of the liquid fraction in draining foam coincides with the shock wave propagation. Under these, much simplified test conditions resulted flows could be treated as one-dimensional and the shock wave mitigation depends on three parameters: the intensity of the incident shock wave, s M , the duration of the foam decay, ∆t and on the particle concentration, n.

Tooling Foam for Structural Composite Applications

Science.gov (United States)

DeLay, Tom; Smith, Brett H.; Ely, Kevin; MacArthur, Doug

1998-01-01

Tooling technology applications for composite structures fabrication have been expanded at MSFC's Productivity Enhancement Complex (PEC). Engineers from NASA/MSFC and Lockheed Martin Corporation have developed a tooling foam for use in composite materials processing and manufacturing that exhibits superior thermal and mechanical properties in comparison with other tooling foam materials. This tooling foam is also compatible with most preimpregnated composite resins such as epoxy, bismaleimide, phenolic and their associated cure cycles. MARCORE tooling foam has excellent processability for applications requiring either integral or removable tooling. It can also be tailored to meet the requirements for composite processing of parts with unlimited cross sectional area. A shelf life of at least six months is easily maintained when components are stored between 50F - 70F. The MARCORE tooling foam system is a two component urethane-modified polyisocyanurate, high density rigid foam with zero ozone depletion potential. This readily machineable, lightweight tooling foam is ideal for composite structures fabrication and is dimensionally stable at temperatures up to 350F and pressures of 100 psi.

Covering sources of toxic vapors with foam

International Nuclear Information System (INIS)

Aue, W. P.; Guidetti, F.

2009-01-01

In a case of chemical terrorism, first responders might well be confronted with a liquid source of toxic vapor which keeps spreading out its hazardous contents. With foam as an efficient and simple means, such a source could be covered up in seconds and the spread of vapors mitigated drastically. Once covered, the source could then wait for a longer time to be removed carefully and professionally by a decontamination team. In order to find foams useful for covering up toxic vapor sources, a large set of measurements has been performed in order to answer the following questions: - Which foams could be used for this purpose? - How thick should the foam cover be? - For how long would such a foam cover be effective? - Could the practical application of foam cause a spread of the toxic chemical? The toxic vapors sources included GB, GD and HD. Among the foams were 10 fire fighter foams (e.g. AFFF, protein) and the aqueous decontamination foam CASCAD. Small scale experiments showed that CASCAD is best suited for covering a toxic source; a 10 cm layer of it covers and decontaminates GB. The large scale experiments confirmed that any fire fighter foam is a suitable cover for a longer or shorter period.(author)

Crosslinked polyethylene foams, via eb radiation

International Nuclear Information System (INIS)

Cardoso, E.C.L.; Lugao, A. B.; Andrade e Silva, L. G.

1998-01-01

Polyethylene foams, produced by radio-induced crosslinking, show a smooth and homogeneous surface, when compared to chemical crosslinking method using peroxide as crosslinking agent. This process fosters excellent adhesive and printability properties. Besides that, closed cells, intrinsic to these foams, imparts optimum mechanical, shocks and insulation resistance, indicating these foams to some markets segments as: automotive and transport; buoyancy, flotation and marine; building and insulation; packaging; domestic sports and leisure goods. We were in search of an ideal foam, by adding 5 to 15% of blowing agent in LDPE. A series of preliminary trials defined 203 degree sign C as the right blowing agent decomposition temperature. At a 22.7 kGys/dose ratio, the lowest dose for providing an efficient foam was 30 kGy, for a formulation comprising 10% of azodicarbonamide in LDPE, within a 10 minutes foaming time

Stretching and folding mechanism in foams

International Nuclear Information System (INIS)

Tufaile, Alberto; Pedrosa Biscaia Tufaile, Adriana

2008-01-01

We have described the stretching and folding of foams in a vertical Hele-Shaw cell containing air and a surfactant solution, from a sequence of upside-down flips. Besides the fractal dimension of the foam, we have observed the logistic growth for the soap film length. The stretching and folding mechanism is present during the foam formation, and this mechanism is observed even after the foam has reached its respective maximum fractal dimension. Observing the motion of bubbles inside the foam, large bubbles present power spectrum associated with random walk motion in both directions, while the small bubbles are scattered like balls in a Galton board

Stretching and folding mechanism in foams

Energy Technology Data Exchange (ETDEWEB)

Tufaile, Alberto [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)], E-mail: tufaile@usp.br; Pedrosa Biscaia Tufaile, Adriana [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)

2008-10-13

We have described the stretching and folding of foams in a vertical Hele-Shaw cell containing air and a surfactant solution, from a sequence of upside-down flips. Besides the fractal dimension of the foam, we have observed the logistic growth for the soap film length. The stretching and folding mechanism is present during the foam formation, and this mechanism is observed even after the foam has reached its respective maximum fractal dimension. Observing the motion of bubbles inside the foam, large bubbles present power spectrum associated with random walk motion in both directions, while the small bubbles are scattered like balls in a Galton board.

Some aspects of image processing using foams

International Nuclear Information System (INIS)

Tufaile, A.; Freire, M.V.; Tufaile, A.P.B.

2014-01-01

We have explored some concepts of chaotic dynamics and wave light transport in foams. Using some experiments, we have obtained the main features of light intensity distribution through foams. We are proposing a model for this phenomenon, based on the combination of two processes: a diffusive process and another one derived from chaotic dynamics. We have presented a short outline of the chaotic dynamics involving light scattering in foams. We also have studied the existence of caustics from scattering of light from foams, with typical patterns observed in the light diffraction in transparent films. The nonlinear geometry of the foam structure was explored in order to create optical elements, such as hyperbolic prisms and filters. - Highlights: • We have obtained the light scattering in foams using experiments. • We model the light transport in foams using a chaotic dynamics and a diffusive process. • An optical filter based on foam is proposed

A graphite foam reinforced by graphite particles

Energy Technology Data Exchange (ETDEWEB)

Zhu, J.J.; Wang, X.Y.; Guo, L.F.; Wang, Y.M.; Wang, Y.P.; Yu, M.F.; Lau, K.T.T. [DongHua University, Shanghai (China). College of Material Science and Engineering

2007-11-15

Graphite foam was obtained after carbonization and graphitization of a pitch foam formed by the pyrolysis of coal tar based mesophase pitch mixed with graphite particles in a high pressure and temperature chamber. The graphite foam possessed high mechanical strength and exceptional thermal conductivity after adding the graphite particles. Experimental results showed that the thermal conductivity of modified graphite foam reached 110W/m K, and its compressive strength increased from 3.7 MPa to 12.5 MPa with the addition of 5 wt% graphite particles. Through the microscopic observation, it was also found that fewer micro-cracks were formed in the cell wall of the modified foam as compared with pure graphite foam. The graphitization degree of modified foam reached 84.9% and the ligament of graphite foam exhibited high alignment after carbonization at 1200{sup o}C for 3 h and graphitization at 3000{sup o}C for 10 min.

Foam injection method and system

Energy Technology Data Exchange (ETDEWEB)

Hardy, W C; Parmley, J B; Shepard, J C

1977-05-10

A method is described for more efficiently practicing in situ combustion techniques by generating a gas-water mist or foam adjacent to the combustion formation within the injection well. The mist or foam is forced out of the well into the formation to transport heat away from the burned region of the formation toward the periphery of the combustion region to conserve fuel. Also taught are a method and system for fluid treating a formation while maintaining enhanced conformance of the fluid injection profile by generating a mist or foam down-hole adjacent to the formation and then forcing the mist or foam out into the formation. (19 claims)

Polyurethane Foams with Pyrimidine Rings

Directory of Open Access Journals (Sweden)

Kania Ewelina

2014-09-01

Full Text Available Oligoetherols based on pyrimidine ring were obtained upon reaction of barbituric acid with glycidol and alkylene carbonates. These oligoetherols were then used to obtain polyurethane foams in the reaction of oligoetherols with isocyanates and water. The protocol of foam synthesis was optimized by the choice of proper kind of oligoetherol and synthetic composition. The thermal resistance was studied by dynamic and static methods with concomitant monitoring of compressive strength. The polyurethane foams have similar physical properties as the classic ones except their enhanced thermal resistance. They stand long-time heating even at 200°C. Moreover thermal exposition of foams results generally in increase of their compressive strength.

Electron beam processing of polymers

International Nuclear Information System (INIS)

Silva, Leonardo G. Andrade e; Dias, Djalma B.; Calvo, Wilson A.P.; Miranda, Leila F. de

2011-01-01

The aim of this work is the use of electron beam produced by industrial electron accelerators to process polymers. There are several applications, such as, irradiation of wires and electric cables for automotive, aerospace, household appliance, naval and computing industries. The effect of different radiation doses in low density polyethylene (LDPE) was also studied. After irradiation and crosslinking it was thermally expanded forming LDPE foam. In addition, poly(N-vinyl-2-pyrrolidone) (PVP) hydrogels using electron beam processing were prepared. In all cases studied crosslinking percentages of the samples were determined. (author)

Foam stabilization by solid particle aggregates

Energy Technology Data Exchange (ETDEWEB)

Guignot, S.; Faure, S. [CEA Marcoule, Lab. des Procedes Avances de Decontamination, 30 (France); Pitois, O. [UniversiteParis-Est Marne-La-Valle, Lab. Physique des Materiaux Divises et des Interfaces (LPMDI), 77 - Marne la Vallee (France)

2008-07-01

During the dismantling of nuclear facilities, radioactive deposits on exposed areas are removed and solubilized by successive rinses of reactive liquid. Using this liquid in a foam state reduces the amount of resulting wastes. During the required decontamination time (1 to 5 hours) the foam has to be sufficiently wet (1). In the Laboratory of Advanced Processes for Decontamination, new formulations are currently studied to slow down the drainage kinetics of these foams, by adding colloidal particles of hydrophilic fumed silica into the classical mixtures of well-defined non ionic foaming surfactants previously used (2). The objective of our study is to shed light on the foam surprising stability induced by these particles. The study focuses on drainage of foams generated by air sparging through a suspension lying on a porous glass. The foaming suspensions contain between 0 and 70 g.L-1 of a fumed silica (Aerosil 380) which is well-known to form gels for concentrations above 200 g.L{sup -1}. In the studied solutions this silica builds up into aggregates of dozens of microns, whose volume-averaged mean diameter after sonication is centred around 300 nm. Under gentle stirring, they display no sign of re-aggregation during 24 h. On a free drainage configuration, a foam that contains particles keeps a significant amount of its initial liquid: up to 60 % during up to 5 hours, in contrast to classical foams that drain out all of their liquid in about 20 minutes. From a rheological point of view, the most concentrated suspensions display a yield stress behaviour. This evidences the structuring of the aggregates into a coherent network that might explain the incomplete drainage of the solutions. For the lowest concentrated solutions, such rheological properties have not been observed although the corresponding foams can retain large amount of solution. This suggests that local concentrations of aggregates can rise owing to their retention by foam channels, until they form

Cryogenic foam insulation: Abstracted publications

Science.gov (United States)

Williamson, F. R.

1977-01-01

A group of documents were chosen and abstracted which contain information on the properties of foam materials and on the use of foams as thermal insulation at cryogenic temperatures. The properties include thermal properties, mechanical properties, and compatibility properties with oxygen and other cryogenic fluids. Uses of foams include applications as thermal insulation for spacecraft propellant tanks, and for liquefied natural gas storage tanks and pipelines.

Biocompatibility and bioactivity of porous polymer-derived Ca-Mg silicate ceramics.

Science.gov (United States)

Fiocco, L; Li, S; Stevens, M M; Bernardo, E; Jones, J R

2017-03-01

Magnesium is a trace element in the human body, known to have important effects on cell differentiation and the mineralisation of calcified tissues. This study aimed to synthesise highly porous Ca-Mg silicate foamed scaffolds from preceramic polymers, with analysis of their biological response. Akermanite (Ak) and wollastonite-diopside (WD) ceramic foams were obtained from the pyrolysis of a liquid silicone mixed with reactive fillers. The porous structure was obtained by controlled water release from selected fillers (magnesium hydroxide and borax) at 350°C. The homogeneous distribution of open pores, with interconnects of modal diameters of 160-180μm was obtained and maintained after firing at 1100°C. Foams, with porosity exceeding 80%, exhibited compressive strength values of 1-2MPa. In vitro studies were conducted by immersion in SBF for 21days, showing suitable dissolution rates, pH and ionic concentrations. Cytotoxicity analysis performed in accordance with ISO10993-5 and ISO10993-12 standards confirmed excellent biocompatibility of both Ak and WD foams. In addition, MC3T3-E1 cells cultured on the Mg-containing scaffolds demonstrated enhanced osteogenic differentiation and the expression of osteogenic markers including Collagen Type I, Osteopontin and Osteocalcin, in comparison to Mg-free counterparts. The results suggest that the addition of magnesium can further enhance the bioactivity and the potential for bone regeneration applications of Ca-silicate materials. Here, we show that the incorporation of Mg in Ca-silicates plays a significant role in the enhancement of the osteogenic differentiation and matrix formation of MC3T3-E1 cells, cultured on polymer-derived highly porous scaffolds. Reduced degradation rates and improved mechanical properties are also observed, compared to Mg-free counterparts, suggesting the great potential of Ca-Mg silicates as bone tissue engineering materials. Excellent biocompatibility of the new materials, in accordance to

Mechanical Properties of Electrolyte Jet Electrodeposited Nickel Foam

Directory of Open Access Journals (Sweden)

Jinsong Chen

2013-07-01

Full Text Available Principles of the preparation of nickel foam by electrolyte jet electrodeposition were introduced, Nickel foam samples with different porosity were fabricated. Effect of different porosity on microhardness and uniaxial tensile properties of nickel foam was discussed. The results show that the microhardness of nickel foam is 320~400 HV, lower than entitative metal clearly. The lower the porosity of nickel foam, the higher the microhardness is. During the process of uniaxial tensile, nickel foam is characterized by three distinct regions, e.g. elastic deforming region, plastic plateau region and densification region. The higher the porosity of nickel foam, the lower the plastic plateau and the poorer the strength of nickel foam, accordingly

Utilization of accelerators for development of polymer materials

International Nuclear Information System (INIS)

Omichi, Hideki

1987-01-01

There are two processes in the development of polymer materials using accelerators. One is to induce graft polymerization by irradiating the electron beam of high dose rate, and another is to induce cross-linking or decomposition by irradiating on existing polymer materials. The former is mostly at the stage of research and development, while in the latter, the industrial utilization has advanced as bridged electric wires, foaming materials and thermal contraction materials. In this paper, the results of the basic research are mainly reported. The polymerization of vinyl monomers such as styrene easily advances by the irradiation of gamma ray or electron beam, accordingly, it is widely utilized as the object of basic research. When the plural radicals produced by the irradiation of polymers couple mutually or attach to double bonds, the polymer of large molecular weight arises, on the other hand, when radicals arise by the severance of main chains in polymers, the molecular weight decreases. The utilization of accelerators for the development of polymer materials is diversified. Hereafter, also particle accelerators will be used for this field. Already ion implantation, sputtering, hole-opening and so on for polymer materials began to be studied, and the new development of materials is expected. (Kako, I.)

Shape memory polymer cellular solid design for medical applications

International Nuclear Information System (INIS)

De Nardo, L; Bertoldi, S; Tanzi, M C; Farè, S; Haugen, H J

2011-01-01

Shape memory polymers (SMPs) are an emerging class of active materials whose response can be easily tailored via modifications of the molecular parameters and optimization of the transformation processes. In this work, we originally demonstrated that a correct coupling of polymer transformation processes (co-extrusion with chemical blowing agents, salt co-extrusion/particulate leaching, solvent casting/particulate leaching) and SMPs allows one to obtain porous structures with a broad spectrum of morphological properties resulting in tunable thermo-mechanical and shape recovery properties. Such a wide range of properties could fulfil the specifications of medical applications in which the use of SMP-based foams can be envisaged

Making continuous bubble type polyethylene foam incombustible

International Nuclear Information System (INIS)

Kaji, Kanako; Hatada, Motoyoshi; Yoshizawa, Iwao; Komai, Kuniaki; Kohara, Choji.

1989-01-01

Since continuous bubble type plastic foam has excellent compression characteristics and sound absorption characteristics, it has been widely used as cushion material, sealing material, sound insulating material and so on. However, the most part of plastic foam is taken by air, therefore at the time of fires, it becomes a very dangerous material. At present, the material used mostly as the seat cushions for airliners, railroad coaches, automobiles and others is polyurethane foam, but since it contains C-N couples in its molecules, it is feared to generate cyanic gas according to the condition of combustion. As the plastic foam that does not generate harmful gas at the time of fires, there is continuous bubble type polyethylene which is excellent in its weathering property and chemical resistance. A reactive, phosphorus-containing oligomer has large molecular weight and two or more double couplings in a molecule, therefore, it does not enter the inside of polyethylene, and polymerizes and crosslinks on the surfaces of bubble walls in the foam, accordingly it is expected that the apparent graft polymerization is carried out, and it is very effective for making polyethylene foam incombustible. The method of making graft foam, the properties of graft foam and so on are reported. When the graft polymerization of this oligomer to continuous bubble type polyethylene foam was tried, highly incombustible polyethylene foam was obtained. (K.I.)

Modelling of Churn-Annular foam flows

NARCIS (Netherlands)

Westende, J.M.C. van 't; Shoeibi Omrani, P.; Vercauteren, F.F.; Nennie, E.D.

2016-01-01

Foam assisted lift is a deliquification method in the oil and gas industry, which aims to prevent or postpone countercurrent gas-liquid flow in maturing gas wells or to assist in removing downhole accumulated liquids. According to Nimwegen, who performed experiments with foam flows, foam

Damping of liquid sloshing by foams

Science.gov (United States)

Sauret, A.; Boulogne, F.; Cappello, J.; Dressaire, E.; Stone, H. A.

2015-02-01

When a container is set in motion, the free surface of the liquid starts to oscillate or slosh. Such effects can be observed when a glass of water is handled carelessly and the fluid sloshes or even spills over the rims of the container. However, beer does not slosh as readily as water, which suggests that foam could be used to damp sloshing. In this work, we study experimentally the effect on sloshing of a liquid foam placed on top of a liquid bath. We generate a monodisperse two-dimensional liquid foam in a rectangular container and track the motion of the foam. The influence of the foam on the sloshing dynamics is experimentally characterized: only a few layers of bubbles are sufficient to significantly damp the oscillations. We rationalize our experimental findings with a model that describes the foam contribution to the damping coefficient through viscous dissipation on the walls of the container. Then we extend our study to confined three-dimensional liquid foam and observe that the behavior of 2D and confined 3D systems are very similar. Thus, we conclude that only the bubbles close to the walls have a significant impact on the dissipation of energy. The possibility to damp liquid sloshing using foam is promising in numerous industrial applications such as the transport of liquefied gas in tankers or for propellants in rocket engines.

Method of making a cyanate ester foam

Science.gov (United States)

Celina, Mathias C.; Giron, Nicholas Henry

2014-08-05

A cyanate ester resin mixture with at least one cyanate ester resin, an isocyanate foaming resin, other co-curatives such as polyol or epoxy compounds, a surfactant, and a catalyst/water can react to form a foaming resin that can be cured at a temperature greater than 50.degree. C. to form a cyanate ester foam. The cyanate ester foam can be heated to a temperature greater than 400.degree. C. in a non-oxidative atmosphere to provide a carbonaceous char foam.

Microstructure of high-strength foam concrete

International Nuclear Information System (INIS)

Just, A.; Middendorf, B.

2009-01-01

Foam concretes are divided into two groups: on the one hand the physically foamed concrete is mixed in fast rotating pug mill mixers by using foaming agents. This concrete cures under atmospheric conditions. On the other hand the autoclaved aerated concrete is chemically foamed by adding aluminium powder. Afterwards it is cured in a saturated steam atmosphere. New alternatives for the application of foam concretes arise from the combination of chemical foaming and air curing in manufacturing processes. These foam concretes are new and innovative building materials with interesting properties: low mass density and high strength. Responsible for these properties are the macro-, meso- and microporosity. Macropores are created by adding aluminium powder in different volumes and with different particle size distributions. However, the microstructure of the cement matrix is affected by meso- and micropores. In addition, the matrix of the hardened cement paste can be optimized by the specific use of chemical additives for concrete. The influence of aluminium powder and chemical additives on the properties of the microstructure of the hardened cement matrices were investigated by using petrographic microscopy as well as scanning electron microscopy.

Influence of the glass-calcium carbonate mixture's characteristics on the foaming process and the properties of the foam glass

DEFF Research Database (Denmark)

König, Jakob; Petersen, Rasmus Rosenlund; Yue, Yuanzheng

2014-01-01

We prepared foam glasses from cathode-ray-tube panel glass and CaCO3 as a foaming agent. We investigated the influences of powder preparation, CaCO3 concentration and foaming temperature and time on the density, porosity and homogeneity of the foam glasses. The results show that the decomposition...

Class B Fire-Extinguishing Performance Evaluation of a Compressed Air Foam System at Different Air-to-Aqueous Foam Solution Mixing Ratios

Directory of Open Access Journals (Sweden)

Dong-Ho Rie

2016-06-01

Full Text Available The purpose of this research is to evaluate the fire-extinguishing performance of a compressed air foam system at different mixing ratios of pressurized air. In this system, compressed air is injected into an aqueous solution of foam and then discharged. The experimental device uses an exclusive fire-extinguishing technology with compressed air foam that is produced based on the Canada National Laboratory and UL (Underwriters Laboratories 162 standards, with a 20-unit oil fire model (Class B applied as the fire extinguisher. Compressed air is injected through the air mixture, and results with different air-to-aqueous solution foam ratios of 1:4, 1:7, and 1:10 are studied. In addition, comparison experiments between synthetic surfactant foam and a foam type which forms an aqueous film are carried out at an air-to-aqueous solution foam ratio of 1:4. From the experimental results, at identical discharging flows, it was found that the fire-extinguishing effect of the aqueous film-forming foam is greatest at an air-to-aqueous solution foam ratio of 1:7 and weakest at 1:10. Moreover, the fire-extinguishing effect of the aqueous film-forming foam in the comparison experiments between the aqueous film-forming foam and the synthetic surfactant foam is greatest.

Experiments to Populate and Validate a Processing Model for Polyurethane Foam: Additional Data for Structural Foams

Energy Technology Data Exchange (ETDEWEB)

Rao, Rekha R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Celina, Mathias C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Giron, Nicholas Henry [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Long, Kevin Nicholas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Russick, Edward M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-01-01

We are developing computational models to help understand manufacturing processes, final properties and aging of structural foam, polyurethane PMDI. Th e resulting model predictions of density and cure gradients from the manufacturing process will be used as input to foam heat transfer and mechanical models. BKC 44306 PMDI-10 and BKC 44307 PMDI-18 are the most prevalent foams used in structural parts. Experiments needed to parameterize models of the reaction kinetics and the equations of motion during the foam blowing stages were described for BKC 44306 PMDI-10 in the first of this report series (Mondy et al. 2014). BKC 44307 PMDI-18 is a new foam that will be used to make relatively dense structural supports via over packing. It uses a different catalyst than those in the BKC 44306 family of foams; hence, we expect that the reaction kineti cs models must be modified. Here we detail the experiments needed to characteriz e the reaction kinetics of BKC 44307 PMDI-18 and suggest parameters for the model based on these experiments. In additi on, the second part of this report describes data taken to provide input to the preliminary nonlinear visco elastic structural response model developed for BKC 44306 PMDI-10 foam. We show that the standard cu re schedule used by KCP does not fully cure the material, and, upon temperature elevation above 150°C, oxidation or decomposition reactions occur that alter the composition of the foam. These findings suggest that achieving a fully cured foam part with this formulation may be not be possible through therma l curing. As such, visco elastic characterization procedures developed for curing thermosets can provide only approximate material properties, since the state of the material continuously evolves during tests.

Modyfication of the Rigid Polyurethane-Polyisocyanurate Foams

Directory of Open Access Journals (Sweden)

Bogusław Czupryński

2014-01-01

Full Text Available The effect of polyethylene glycol 1500 on physicomechanical properties of rigid polyurethane-polyisocyanurate (PUR-PIR foams has been studied. It was found that application of polyethylene glycol 1500 for synthesis of foams in amount from 0% to 20% w/w had an effect on reduction of brittleness and softening point, while the greater the increase in compressive strength the higher its content in foam composition was. Wastes from production of these foams were ground and subjected to glycolysis in diethylene glycol with the addition of ethanolamine and zinc stearate. Liquid brown products were obtained. Properties of the resulting products were defined in order to determine their suitability for synthesis of new foams. It was found that glycolysate 6 was the most suitable for reuse and its application in different amounts allowed us to prepare 4 new foams (nos. 25, 26, 27, and 28. Properties of foams prepared in this manner were determined and, on their basis, the suitability of glycolysates for production of rigid PUR-PIR foams was evaluated.

Effect of polyvinyl alcohol content and after synthesis neutralization on structure, mechanical properties and cytotoxicity of sol-gel derived hybrid foams

Directory of Open Access Journals (Sweden)

Agda Aline Rocha de Oliveira

2009-06-01

Full Text Available Bioactive glass/polymer hybrids are promising materials for biomedical applications because they combine the bioactivity of these glasses with the flexibility of polymers. In this work it was evaluated the effect of increasing the PVA content of the on structural characteristics and mechanical properties of hybrid. The hybrids were prepared with 70 wt. (% SiO2-30 wt. (% CaO and PVA fractions of 20 to 60 wt. (% by the sol-gel method. The structural and mechanical characterization was done by FTIR, SEM and compression tests. To reduce the acidic character of the hybrids due to the catalysts added, different neutralization solutions were tested. The calcium acetate alcoholic solution was the best neutralizing method, resulting in foams with final pH of about 7.0 and small sample contraction. The foams presented porosity of 60-85 wt. (% and pore diameters of 100-500 μm with interconnected structure. An increase of PVA fraction in the hybrids improved their mechanical properties. The scaffolds produced provided a good environment for the adhesion and proliferation of osteoblasts.

Nanoparticle-stabilized CO₂ foam for CO₂ EOR application

Energy Technology Data Exchange (ETDEWEB)

Liu, Ning [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Lee, Robert [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Yu, Jianjia [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Li, Liangxiong [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Bustamante, Elizabeth [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Khalil, Munawar [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Mo, Di [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Jia, Bao [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); Wang, Sai [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); San, Jingshan [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States); An, Cheng [New Mexico Petroleum Recovery Research Center, Socorro, NM (United States)

2015-01-31

The purpose of this project was to develop nanoparticle-stabilized CO₂ foam for CO₂ -EOR application, in which nanoparticles instead of surfactants are used for stabilizing CO₂ foam to improve the CO₂ sweep efficiency and increase oil recovery. The studies included: (1) investigation of CO₂ foam generation nanoparticles, such as silica nanoparticles, and the effects of particle concentration and surface properties, CO₂/brine ratio, brine salinity, pressure, and temperature on foam generation and foam stability; (2) coreflooding tests to understand the nanoparticle-stabilized CO₂ foam for waterflooded residual oil recovery, which include: oil-free coreflooding experiments with nanoparticle-stabilized CO₂ foam to understand the transportation of nanoparticles through the core; measurements of foam stability and CO₂ sweep efficiency under reservoir conditions to investigate temperature and pressure effects on the foam performance and oil recovery as well as the sweep efficiency in different core samples with different rock properties; and (3) long-term coreflooding experiments with the nanoparticle- stabilized CO₂ foam for residual oil recovery. Finally, the technical and economical feasibility of this technology was evaluated.

New decontamination process using foams containing particles

International Nuclear Information System (INIS)

Guignot, S.; Faure, S.

2008-01-01

One key point in the dismantling of nuclear facilities is the thorough cleaning of radiation- exposed surfaces on which radioactive deposits have formed. This cleaning step is often achieved by successive liquid rinses with specific solutions containing alkaline, acidic, or even oxidizing species depending on whether the aim is to dissolve greasy deposits (like ter-butylphosphate) or to corrode surfaces on micrometric thicknesses. An alternative process to reduce the amount of chemicals and the volume of the resulting nuclear wastes consists in using the same but foamed solutions (1). Carrying less liquid, the resulting foams still display similar kinetics of dissolution rates and their efficiency is determined by their ability to hold sufficient wetnesses during the time required for the decontamination. Classical foam decontamination process illustrated by foam pulverization or circulation in the 90 turned five years ago into a specific static process using high-lifetime viscosified foam at a steady state. One way to slow down the liquid drainage is to raise liquid viscosity by adding organic viscosifiers like xanthan gum (2). In 2005, new studies started on an innovative process proposed by S. Faure and based on triphasic foams containing particles [3]. The aim is to generate new decontamination foams containing less quantities of organics materials (surfactants and viscosifiers). Silica particles are obviously known to stabilize or destabilize foams (4). In the frame of S. Guignot Ph.D., new fundamental studies are initiated in order to clarify the role of silica solid microparticles in these foams. Our final goal is to determine whether this kind of new foam can be stable for several hours for a decontamination process. The results we will report focus on wet foams used for nuclear decontamination and incorporating fumed silica. The study is conducted on a vertical foam column in a pseudo-free drainage configuration, and aims at investigating the influence of

Viscous Control of the Foam Glass Process

DEFF Research Database (Denmark)

Petersen, Rasmus Rosenlund; König, Jakob; Smedskjær, Morten Mattrup

The production of foam glass as heat insulating material is an important industrial process because it enables low-cost recycling of glass waste from a variety of chemical compositions. Optimization of the foaming process of new glass waste compositions is time consuming, since many factors affect...... the foaming process such as temperature, particle size, type and concentration of foaming agent. The foaming temperature is one of the key factors, because even small temperature changes can affect the melt viscosity by several orders of magnitude. Therefore, it is important to establish the viscosity range...... in which the foaming process should take place, particularly when the type of recycled cullet is changed or several types of cullet are mixed in one batch. According to recent glass literature, the foaming process should occur at viscosity 103 to 105 Pa s. However, no systematic studies have hitherto been...

Oxidation behaviour of metallic glass foams

Energy Technology Data Exchange (ETDEWEB)

Barnard, B.R. [Department of Materials Science and Engineering, 434 Dougherty Hall, University of Tennessee, Knoxville, TN 37996-2200 (United States)], E-mail: bbarnard@utk.edu; Liaw, P.K. [Department of Materials Science and Engineering, 434 Dougherty Hall, University of Tennessee, Knoxville, TN 37996-2200 (United States); Demetriou, M.D.; Johnson, W.L. [Department of Materials Science, Keck Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States)

2008-08-15

In this study, the effects of porosity on the oxidation behaviour of bulk-metallic glasses were investigated. Porous Pd- and Fe-based bulk-metallic glass (BMG) foams and Metglas ribbons were studied. Oxidizing experiments were conducted at 70 deg. C, and around 80 deg. C below glass-transition temperatures, (T{sub g}s). Scanning-electron microscopy/energy-dispersive spectroscopy (SEM/EDS) studies revealed little evidence of oxidation at 70 deg. C. Specimens exhibited greater oxidation at T{sub g} - 80 deg. C. Oxides were copper-based for Pd-based foams, Fe-, Cr-, and Mo-based for Fe-based foams, and Co-based with borosilicates likely for the Metglas. Pd-based foams demonstrated the best oxidation resistance, followed by Metglas ribbons, followed by Fe-based foams.

USING BIOPOLYMERS TO STABILIZE THE PROTEIN OXYGEN FOAM

Directory of Open Access Journals (Sweden)

N. V. Nepovinnyh

2013-01-01

Full Text Available The cottage cheese whey as an oxygen cocktail foaming base and natural juices as a flavoring ingredient are analyzed. The lifetime of foam generated by the serum proteins is not long: foam falls off rapidly; because from the foam liquid is released (syneresis. The effects of plant polysaccharides on the stabilization of the protein foam oxygen cocktail is studied. It was shown that the use of plant polysaccharides (guar gum, high methoxyl citrus pectin, locust been gum prolong the life of the foam up to 20 times, compared with conventional blowing agents. It was found that oxygen foam properties depend on the molecular weight of guar gum.

Numerical simulation of heat transfer in metal foams

Science.gov (United States)

Gangapatnam, Priyatham; Kurian, Renju; Venkateshan, S. P.

2018-02-01

This paper reports a numerical study of forced convection heat transfer in high porosity aluminum foams. Numerical modeling is done considering both local thermal equilibrium and non local thermal equilibrium conditions in ANSYS-Fluent. The results of the numerical model were validated with experimental results, where air was forced through aluminum foams in a vertical duct at different heat fluxes and velocities. It is observed that while the LTE model highly under predicts the heat transfer in these foams, LTNE model predicts the Nusselt number accurately. The novelty of this study is that once hydrodynamic experiments are conducted the permeability and porosity values obtained experimentally can be used to numerically simulate heat transfer in metal foams. The simulation of heat transfer in foams is further extended to find the effect of foam thickness on heat transfer in metal foams. The numerical results indicate that though larger foam thicknesses resulted in higher heat transfer coefficient, this effect weakens with thickness and is negligible in thick foams.

Synthesis of ZSM-5 on the Surface of Foam Type Porous SiC Support

International Nuclear Information System (INIS)

Jung, Eunjin; Lee, Yoon Joo; Won, Ji Yeon; Kim, Younghee; Kim, Soo Ryong; Shin, Dong-Geun; Kwon, Woo Teck; Lee, Hyun Jae

2015-01-01

ZSM-5 crystals grew by hydrothermal synthesis method on the surface of foam type porous silicon carbide ceramics which fabricated by polymer replica method. Oxide layer was developed on the surface of the porous silicon carbide ceramics to induce growth of ZSM-5 from the surface. In this study, hydrothermal synthesis was carried out for 7 h at 150 .deg. C using TEOS, Al(NO 3 )•9H 2 O and TPAOH as raw materials in the presence of the porous silicon carbide ceramics. X-ray Powder Diffraction (XRD) and Scanning Electron Microscope (SEM) analyses were confirmed 1-3 μm sized ZSM-5 crystals have grown on the surface of porous silicon carbide ceramics. BET data shows that small pores about 10Å size drastically enhanced and surface area increased from 0.83 m 2 /g to 30.75 m 2 /g after ZSM-5 synthesis on the surface of foam type porous silicon carbide ceramics.

Mechanical Characterization of Lightweight Foamed Concrete

Directory of Open Access Journals (Sweden)

Marcin Kozłowski

2018-01-01

Full Text Available Foamed concrete shows excellent physical characteristics such as low self weight, relatively high strength and superb thermal and acoustic insulation properties. It allows for minimal consumption of aggregate, and by replacement of a part of cement by fly ash, it contributes to the waste utilization principles. For many years, the application of foamed concrete has been limited to backfill of retaining walls, insulation of foundations and roof tiles sound insulation. However, during the last few years, foamed concrete has become a promising material for structural purposes. A series of tests was carried out to examine mechanical properties of foamed concrete mixes without fly ash and with fly ash content. In addition, the influence of 25 cycles of freezing and thawing on the compressive strength was investigated. The apparent density of hardened foamed concrete is strongly correlated with the foam content in the mix. An increase of the density of foamed concrete results in a decrease of flexural strength. For the same densities, the compressive strength obtained for mixes containing fly ash is approximately 20% lower in comparison to the specimens without fly ash. Specimens subjected to 25 freeze-thaw cycles show approximately 15% lower compressive strengths compared to the untreated specimens.

Determination of mechanical properties of PVC foam using a modified Arcan fixture

DEFF Research Database (Denmark)

Taher, Siavash Talebi; Thomsen, Ole Thybo; M Dulieu-Barton, Janice

2012-01-01

of the fixture and misalignment of the fixture and loading machine are discussed. Thermoelastic stress analysis (TSA) is used to directly examine and validate the uniformity and symmetry of the stress fields obtained for both tensile and shear specimens. To account for the inhomogeneity of the strain field...... conducted using conventional test tensile and shear test fixtures.......The design and development of a modified Arcan fixture (MAF) is described. The purpose of the fixture is to characterize polymer foam materials with respect to their tensile, compressive, shear and bidirectional mechanical properties. The MAF enables the application of pure compression or high...

Application of Auxetic Foam in Sports Helmets

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Leon Foster

2018-03-01

Full Text Available This investigation explored the viability of using open cell polyurethane auxetic foams to augment the conformable layer in a sports helmet and improve its linear impact acceleration attenuation. Foam types were compared by examining the impact severity on an instrumented anthropomorphic headform within a helmet consisting of three layers: a rigid shell, a stiff closed cell foam, and an open cell foam as a conformable layer. Auxetic and conventional foams were interchanged to act as the helmet’s conformable component. Attenuation of linear acceleration was examined by dropping the combined helmet and headform on the front and the side. The helmet with auxetic foam reduced peak linear accelerations (p < 0.05 relative to its conventional counterpart at the highest impact energy in both orientations. Gadd Severity Index reduced by 11% for frontal impacts (38.9 J and 44% for side impacts (24.3 J. The conformable layer within a helmet can influence the overall impact attenuating properties. The helmet fitted with auxetic foam can attenuate impact severity more than when fitted with conventional foam, and warrants further investigation for its potential to reduce the risk of traumatic brain injuries in sport specific impacts.

Successful field application of novel, non-silicone antifoam chemistries for high foaming heavy oil storage tanks in northern Alberta

Energy Technology Data Exchange (ETDEWEB)

Wylde, J.J. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Clariant Oil Services, Montreal, PQ (Canada)

2008-10-15

Heavy oil operators in northern Alberta have experienced production problems associated with foam formation in crude oil storage tanks. The foam could enter the transportation trucks and create separation problems in the process systems. Any antifoam used in the system could not contain silicone based polymers since these compounds affected the catalysts used in upgrading the crude oil and in the manufacture of asphalt. As such, there was a need to change the performance of the antifoam product. A phosphate ester and a salted amine were the previous incumbent antifoam products that did not perform well. Several chemistries were tested, including phosphate based products; ethoxylated and propoxylated esters; polyethylene glycol esters and oleates; alcohols, fatty alcohols and ethoxylated; and propoxylated alcohols. All products had to be freeze protected to -40 degrees C, which influenced the efficacy of antifoam chemicals. This paper described how laboratory testing has evolved to field wide implementation of a combined defoamer/antifoam chemistry. The laboratory tests revealed that foam induced in heavy, aged crude was very challenging and required the addition of heptane to create the foam. A potential follow-up may be to induce the foam without the addition of heptane by using a Seltzer cylinder in a semi-quantitative manner to rank performance of products against one another. The final selection of antifoam will depend on supply chain cost since the performance of the 2 blend products was essentially the same. 12 refs., 7 figs.

Aqueous foam toxicology evaluation and hazard review

Energy Technology Data Exchange (ETDEWEB)

Archuleta, M.M.

1995-10-01

Aqueous foams are aggregates of bubbles mechanically generated by passing air or other gases through a net, screen, or other porous medium that is wetted by an aqueous solution of surface-active foaming agents (surfactants). Aqueous foams are important in modem fire-fighting technology, as well as for military uses for area denial and riot or crowd control. An aqueous foam is currently being developed and evaluated by Sandia National Laboratories (SNL) as a Less-Than-Lethal Weapon for the National Institute of Justice (NIJ). The purpose of this study is to evaluate the toxicity of the aqueous foam developed for the NIJ and to determine whether there are any significant adverse health effects associated with completely immersing individuals without protective equipment in the foam. The toxicity of the aqueous foam formulation developed for NIJ is determined by evaluating the toxicity of the individual components of the foam. The foam is made from a 2--5% solution of Steol CA-330 surfactant in water generated at expansion ratios ranging from 500:1 to 1000:1. SteoI CA-330 is a 35% ammonium laureth sulfate in water and is produced by Stepan Chemical Company and containing trace amounts (<0.1%) of 1,4-dioxane. The results of this study indicate that Steol CA-330 is a non-toxic, mildly irritating, surfactant that is used extensively in the cosmetics industry for hair care and bath products. Inhalation or dermal exposure to this material in aqueous foam is not expected to produce significant irritation or systemic toxicity to exposed individuals, even after prolonged exposure. The amount of 1,4-dioxane in the surfactant, and subsequently in the foam, is negligible and therefore, the toxicity associated with dioxane exposure is not significant. In general, immersion in similar aqueous foams has not resulted in acute, immediately life-threatening effects, or chronic, long-term, non-reversible effects following exposure.

Behaviour of aluminum foam under fire conditions

Directory of Open Access Journals (Sweden)

J. Grabian

2008-07-01

Full Text Available Taking into account fire-protection requirements it is advantageous for aluminum foam, after melting at a temperature considerably exceeding the melting point, to have a structure of discontinuous suspension of solid inclusions to liquid metal instead of liquid consistency. Continuity of the suspension depends on the solid phase content. The boundary value of the phase determined by J. Śleziona, above which the suspension becomes discontinuous, is provided by the formula (1. Figure 1 presents the relationship graphically. Boundary values of the vs content resulting from the above relationship is too low, taking into account the data obtained from the technology of suspension composites [4]. Therefore, based on the structure assumed for the suspension shown in Figure 2 these authors proposed another way of determining the contents, the value of which is determined by the relationship (3 [5].For purposes of the experimental study presented in the paper two foams have been molten: a commercially available one, made by aluminum foaming with titanium hydride, and a foam manufactured in the Marine Materials Plant of the Maritime University of Szczecin by blowing the AlSi7 +20% SiC composite with argon. Macrophotographs of foam cross-sections are shown in Figure 3. The foams have been molten in the atmosphere of air at a temperature of 750ºC. The products of melting are presented in Figure 4. It appears that molten aluminum foam may have no liquid consistency, being unable to flow, which is a desired property from the point of view of fire-protection. The above feature of the molten foam results from the fact that it may be a discontinuous suspension of solid particles in a liquid metal. The suspended particles may be solid particles of the composite that served for making the foam or oxide membranes formed on extended metal surface of the bubbles included in the foam. The desired foam ability to form a discontinuous suspension after melting may be

Materials Applications for Non-Lethal: Aqueous Foams

Energy Technology Data Exchange (ETDEWEB)

GOOLSBY,TOMMY D.; SCOTT,STEVEN H.

1999-09-15

High expansion aqueous foam is an aggregation of bubbles that has the appearance of soap suds and is used to isolate individuals both visually and acoustically. It was developed in the 1920's in England to fight coal mine fires and has been widely used since for fire fighting and dust suppression. It was developed at Sandia National Laboratories (SNL) in the 1970's for nuclear safeguards and security applications. In the mid-1990s, the National Institute of Justice (NIJ), the research arm of the Department of Justice, began a project with SNL to determine the applicability of high expansion aqueous foam for correctional applications. NIJ funded the project as part of its search for new and better less-than-lethal weapons for responding to violent and dangerous individuals, where other means of force could lead to serious injuries. The phase one objectives of the project were to select a low-to-no toxicity foam concentrate (foaming agent) with physical characteristics suited for use in a single cell or large prison disturbances, and to determine if the selected foam concentrate could serve as a carrier for Oleoresin Capsicum (OC) irritant. The phase two objectives were to conduct an extensive toxicology review of the selected foam concentrate and OC irritant, and to conduct respiration simulation experiments in the selected high expansion aqueous foam. The phase three objectives were to build a prototype individual cell aqueous foam system and to study the feasibility of aqueous foams for large prison facility disturbances. The phase four and five objectives were to use the prototype system to do large scale foam physical characteristics testing of the selected foam concentrate, and to have the prototype single cell system further evaluated by correctional representatives. Prison rather than street scenarios were evaluated as the first and most likely place for using the aqueous foam since prisons have recurrent incidents where officers and inmates might

Materials Applications for Non-Lethal: Aqueous Foams

International Nuclear Information System (INIS)

GOOLSBY, TOMMY D.; SCOTT, STEVEN H.

1999-01-01

High expansion aqueous foam is an aggregation of bubbles that has the appearance of soap suds and is used to isolate individuals both visually and acoustically. It was developed in the 1920's in England to fight coal mine fires and has been widely used since for fire fighting and dust suppression. It was developed at Sandia National Laboratories (SNL) in the 1970's for nuclear safeguards and security applications. In the mid-1990s, the National Institute of Justice (NIJ), the research arm of the Department of Justice, began a project with SNL to determine the applicability of high expansion aqueous foam for correctional applications. NIJ funded the project as part of its search for new and better less-than-lethal weapons for responding to violent and dangerous individuals, where other means of force could lead to serious injuries. The phase one objectives of the project were to select a low-to-no toxicity foam concentrate (foaming agent) with physical characteristics suited for use in a single cell or large prison disturbances, and to determine if the selected foam concentrate could serve as a carrier for Oleoresin Capsicum (OC) irritant. The phase two objectives were to conduct an extensive toxicology review of the selected foam concentrate and OC irritant, and to conduct respiration simulation experiments in the selected high expansion aqueous foam. The phase three objectives were to build a prototype individual cell aqueous foam system and to study the feasibility of aqueous foams for large prison facility disturbances. The phase four and five objectives were to use the prototype system to do large scale foam physical characteristics testing of the selected foam concentrate, and to have the prototype single cell system further evaluated by correctional representatives. Prison rather than street scenarios were evaluated as the first and most likely place for using the aqueous foam since prisons have recurrent incidents where officers and inmates might be

Investigation the foam dynamics capacity of SDS in foam generator by affecting the presence of organic and inorganic contaminant

Science.gov (United States)

Haryanto, Bode; Siswarni, M. Z.; Sianipar, Yosef C. H.; Sinaga, Tongam M. A.; Bestari, Imam

2017-05-01

The effect of negative charge SDS monomer on its foam capacity with the presence of contaminants was investigated in foam generator. Generally, surfactant with higher concentration has higher foam capacity. The higher concentration will increase the number of monomer then increase the micelles in liquid phase. Increasing the number of monomer with the negative charge is a potential to increase interaction with metal ion with positive charge in solution. The presence of inorganic compound as metal ion with positive charge and organic compound (colloid) as particle of coffee impacting to generate the foam lamella with monomer is evaluated. Foam dynamic capacity of only SDS with variation of CMC, 1 x; 2 x; 3 x have the height 7.5, 8.0 and 8.3 cm respectively with the different range time were investigated. The Height of foam dynamic capacity with the presence of 20 ppm Cd2+ ion contaminant was 8.0, 8.3 and 8.4 cm at the same CMC variation of SDS. The presence of metal ion contaminant within the foam was confirmed by AAS. The black coffee particles and oil as contaminant decreased the foam capacity significantly in comparing to metal ions.

Structure formation control of foam concrete

Science.gov (United States)

Steshenko, Aleksei; Kudyakov, Aleksander; Konusheva, Viktoriya; Syrkin, Oleg

2017-01-01

The process of predetermined foam concrete structure formation is considered to be a crucial issue from the point of process control and it is currently understudied thus defining the need for additional research. One of the effective ways of structure formation control in naturally hardening foam concrete is reinforcement with dispersed fibers or introduction of plasticizers. The paper aims at studying the patterns of influence of microreinforcing and plasticizing additives on the structure and performance properties of foam concrete. Preparation of foam concrete mix has been conducted using one-step technology. The structure of modified foam concrete has been studied by means of electron microscopy. The cellular structure of foam concrete samples with the additives is homogeneous; the pores are uniformly distributed over the total volume. It has been revealed that introduction of the Neolas 5.2 plasticizer and microreinforcing fibers in the foam concrete mixture in the amount of 0.4 - 0.1 % by weight of cement leads to reduction of the average pore diameter in the range of 45.3 to 30.2 microns and the standard deviation of the pore average diameter from 23.6 to 9.2 in comparison with the sample without additive. Introduction of modifying additives has stimulated formation of a large number of closed pores. Thus porosity of conditionally closed pores has increased from 16.06 % to 34.48 %, which has lead to increase of frost resistance brand of foam concrete from F15 to F50 and to reduction of its water absorption by weight by 20 %.

Chemical characterization and ecotoxicity of three soil foaming agents used in mechanized tunneling

Energy Technology Data Exchange (ETDEWEB)

Baderna, Diego, E-mail: diego.baderna@marionegri.it [Laboratory of Environmental Chemistry and Toxicology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Lomazzi, Eleonora [Laboratory of Environmental Chemistry and Toxicology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Passoni, Alice [Unit of Analytical Instrumentation, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Pogliaghi, Alberto; Petoumenou, Maria Ifigeneia [Laboratory of Environmental Chemistry and Toxicology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Bagnati, Renzo [Unit of Analytical Instrumentation, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Lodi, Marco [Laboratory of Environmental Chemistry and Toxicology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Viarengo, Aldo; Sforzini, Susanna [Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale “A. Avogadro”, 15121 Alessandria (Italy); Benfenati, Emilio [Laboratory of Environmental Chemistry and Toxicology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Fanelli, Roberto [Department of Environmental Health Sciences, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy)

2015-10-15

Highlights: • An integrated approach was applied to study three foaming agents. • Several compounds not reported on the safety data sheets were identified by HRMS. • Environmental impacts were investigated with a battery of biological assays. • An ecotoxicological ranking of the products was obtained. - Abstract: The construction of tunnels and rocks with mechanized drills produces several tons of rocky debris that are today recycled as construction material or as soil replacement for covering rocky areas. The lack of accurate information about the environmental impact of these excavated rocks and foaming agents added during the excavation process has aroused increasing concern for ecosystems and human health. The present study proposes an integrated approach to the assessment of the potential environmental impact of three foaming agents containing different anionic surfactants and other polymers currently on the market and used in tunnel boring machines. The strategy includes chemical characterization with high resolution mass spectrometry techniques to identify the components of each product, the use of in silico tools to perform a similarity comparison among these compounds and some pollutants already listed in regulatory frameworks to identify possible threshold concentrations of contamination, and the application of a battery of ecotoxicological assays to investigate the impact of each foaming mixture on model organisms of soil (higher plants and Eisenia andrei) and water communities (Daphnia magna). The study identified eleven compounds not listed on the material safety data sheets for which we have identified possible concentrations of contamination based on existing regulatory references. The bioassays allowed us to determine the no effect concentrations (NOAECs) of the three mixtures, which were subsequently used as threshold concentration for the product in its entirety. The technical mixtures used in this study have a different degree of toxicity

Chemical characterization and ecotoxicity of three soil foaming agents used in mechanized tunneling

International Nuclear Information System (INIS)

Baderna, Diego; Lomazzi, Eleonora; Passoni, Alice; Pogliaghi, Alberto; Petoumenou, Maria Ifigeneia; Bagnati, Renzo; Lodi, Marco; Viarengo, Aldo; Sforzini, Susanna; Benfenati, Emilio; Fanelli, Roberto

2015-01-01

Highlights: • An integrated approach was applied to study three foaming agents. • Several compounds not reported on the safety data sheets were identified by HRMS. • Environmental impacts were investigated with a battery of biological assays. • An ecotoxicological ranking of the products was obtained. - Abstract: The construction of tunnels and rocks with mechanized drills produces several tons of rocky debris that are today recycled as construction material or as soil replacement for covering rocky areas. The lack of accurate information about the environmental impact of these excavated rocks and foaming agents added during the excavation process has aroused increasing concern for ecosystems and human health. The present study proposes an integrated approach to the assessment of the potential environmental impact of three foaming agents containing different anionic surfactants and other polymers currently on the market and used in tunnel boring machines. The strategy includes chemical characterization with high resolution mass spectrometry techniques to identify the components of each product, the use of in silico tools to perform a similarity comparison among these compounds and some pollutants already listed in regulatory frameworks to identify possible threshold concentrations of contamination, and the application of a battery of ecotoxicological assays to investigate the impact of each foaming mixture on model organisms of soil (higher plants and Eisenia andrei) and water communities (Daphnia magna). The study identified eleven compounds not listed on the material safety data sheets for which we have identified possible concentrations of contamination based on existing regulatory references. The bioassays allowed us to determine the no effect concentrations (NOAECs) of the three mixtures, which were subsequently used as threshold concentration for the product in its entirety. The technical mixtures used in this study have a different degree of toxicity

Faraday instability at foam-water interface.

Science.gov (United States)

Bronfort, A; Caps, H

2012-12-01

A nearly two-dimensional foam is generated inside a Hele-shaw cell and left at rest on its liquid bath. The system is then vertically shaken and, above a well-defined acceleration threshold, surface waves appear at the foam-liquid interface. Those waves are shown to be subharmonic. The acceleration threshold is studied and compared to the common liquid-gas case, emphasizing the energy dissipation inside the foam. An empirical model is proposed for this energy loss, accounting for the foam characteristics such as the bubble size but also the excitation parameter, namely the linear velocity.

Photoactivity of Titanium Dioxide Foams

Directory of Open Access Journals (Sweden)

Maryam Jami

2018-01-01

Full Text Available TiO2 foams have been prepared by a simple mechanical stirring method. Short-chain amphiphilic molecules have been used to stabilize colloidal suspensions of TiO2 nanoparticles. TiO2 foams were characterized by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, UV-vis absorption spectroscopy, and scanning electron microscopy (SEM. The photoassisted oxidation of NO in the gas phase according to ISO 22197-1 has been used to compare the photoactivity of the newly prepared TiO2 foams to that of the original powders. The results showed that the photoactivity is increased up to about 135%. Foam structures seem to be a good means of improving the photoactivity of semiconductor materials and can readily be used for applications such as air purification devices.

Morphological comparison of PVA scaffolds obtained by gas foaming and microfluidic foaming techniques.

Science.gov (United States)

Colosi, Cristina; Costantini, Marco; Barbetta, Andrea; Pecci, Raffaella; Bedini, Rossella; Dentini, Mariella

2013-01-08

In this article, we have exploited a microfluidic foaming technique for the generation of highly monodisperse gas-in-liquid bubbles as a templating system for scaffolds characterized by an ordered and homogeneous porous texture. An aqueous poly(vinyl alcohol) (PVA) solution (containing a surfactant) and a gas (argon) are injected simultaneously at constant flow rates in a flow-focusing device (FFD), in which the gas thread breaks up to form monodisperse bubbles. Immediately after its formation, the foam is collected and frozen in liquid nitrogen, freeze-dried, and cross-linked with glutaraldehyde. In order to highlight the superior morphological quality of the obtained porous material, a comparison between this scaffold and another one, also constituted of PVA but obtained with a traditional gas foaming technique, was carried out. Such a comparison has been conducted by analyzing electron microscopy and X-ray microtomographic images of the two samples. It turned out that the microfluidic produced scaffold was characterized by much more uniform porous texture than the gas-foaming one as witnessed by narrower pore size, interconnection, and wall thickness distributions. On the other side, scarce pore interconnectivity, relatively low pore volume, and limited production rate represent, by now, the principal disadvantages of microfluidic foaming as scaffold fabrication method, emphasizing the kind of improvement that this technique needs to undergo.

Fast and reversible direct CO2 capture from air onto all-polymer nanofibrillated cellulose-polyethylenimine foams.

Science.gov (United States)

Sehaqui, Houssine; Gálvez, María Elena; Becatinni, Viola; cheng Ng, Yi; Steinfeld, Aldo; Zimmermann, Tanja; Tingaut, Philippe

2015-03-03

Fully polymeric and biobased CO2 sorbents composed of oxidized nanofibrillated cellulose (NFC) and a high molar mass polyethylenimine (PEI) have been prepared via a freeze-drying process. This resulted in NFC/PEI foams displaying a sheet structure with porosity above 97% and specific surface area in the range 2.7-8.3 m(2)·g(-1). Systematic studies on the impact of both PEI content and relative humidity on the CO2 capture capacity of the amine functionalized sorbents have been conducted under atmospheric conditions (moist air with ∼400 ppm of CO2). At 80% RH and an optimum PEI content of 44 wt %, a CO2 capacity of 2.22 mmol·g(-1), a stability over five cycles, and an exceptionally low adsorption half time of 10.6 min were achieved. In the 20-80% RH range studied, the increase in relative humidity increased CO2 capacity of NFC/PEI foams at the expense of a high H2O uptake in the range 3.8-28 mmol·g(-1).

DRY MIX FOR OBTAINING FOAM CONCRETE

Directory of Open Access Journals (Sweden)

S. N. Leonovich

2015-01-01

Full Text Available Composition of a dry mix has been developed for production of non-autoclaved foam concrete with natural curing. The mix has been created on the basis of Portland cement, UFAPORE foaming agent, mineral additives (RSAM sulfoaluminate additive, MK-85 micro-silica and basalt fiber, plasticizing and accelerating “Citrate-T” additive and   redispersible Vinnapas-8034 H powder. It has been established that foam concrete with  density of 400–800 kg/m3, durability of 1,1–3,4 MPa, low water absorption (40–50 %, without shrinkable cracks has been formed while adding water of Water/Solid = 0.4–0.6 in the dry mix,  subsequent mechanical swelling and curing of foam mass.Introduction of the accelerating and plasticizing “Citrate-T” additive into composition of the dry mix leads to an increase of rheological properties in expanded foam mass and  time reduction of its drying and curing. An investigation on microstructure of foam-concrete chipping surface carried out with the help of a scanning electron microscope has shown that the introduction of  basalt fiber and redispersible Vinnapas-8034 H powder into the composition of the dry mix promotes formation of more finely-divided crystalline hydrates. Such approach makes it possible to change purposefully morphology of crystalline hydrates and gives the possibility to operate foam concrete structurization process.

Cellulose nanocrystals reinforced foamed nitrile rubber nanocomposites.

Science.gov (United States)

Chen, Yukun; Zhang, Yuanbing; Xu, Chuanhui; Cao, Xiaodong

2015-10-05

Research on foamed nitrile rubber (NBR)/cellulose nanocrystals (CNs) nanocomposites is rarely found in the literatures. In this paper, CNs suspension and NBR latex was mixed to prepared the foamed NBR/CNs nanocomposites. We found that the CNs mainly located in the cell walls, effectively reinforcing the foamed NBR. The strong interaction between the CNs and NBR matrix restricted the mobility of NBR chains surrounding the CNs, hence increasing the crosslink density of the NBR matrix. CNs exhibited excellent reinforcement on the foamed NBR: a remarkable increase nearly 76% in the tensile strength of the foamed nanocomposites was achieved with a load of only 15 phr CNs. Enhanced mechanical properties make the foamed NBR/CNs nanocomposites a promising damping material for industrial applications with a potential to reduce the petroleum consumption. Copyright © 2015 Elsevier Ltd. All rights reserved.

Recycle Glass in Foam Glass Production

DEFF Research Database (Denmark)

Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

The foam glass industry turn recycle glass into heat insulating building materials. The foaming process is relative insensitive to impurities in the recycle glass. It is therefore considered to play an important role in future glass recycling. We show and discuss trends of use of recycled glasses...... in foam glass industry and the supply sources and capacity of recycle glass....

A cooperative positioning with Kalman filters and handover mechanism for indoor microcellular visible light communication network

Science.gov (United States)

Xiong, Jieqing; Huang, Zhitong; Zhuang, Kaiyu; Ji, Yuefeng

2016-08-01

We propose a novel handover scheme for indoor microcellular visible light communication (VLC) network. With such a scheme, the room, which is fully coverage by light, is divided into several microcells according to the layout of light-emitting diodes (LEDs). However, the directionality of light arises new challenges in keeping the connectivity between the mobile devices and light source under the mobile circumstances. The simplest solution is that all LEDs broadcast data of every user simultaneously, but it wastes too much bandwidth resource, especially when the amount of users increases. To solve this key problem, we utilize the optical positioning assisting handover procedure in this paper. In the positioning stage, the network manager obtains the location information of user device via downlink and uplink signal strength information, which is white light and infrared, respectively. After that, a Kalman filter is utilized for improving the tracking performance of a mobile device. Then, the network manager decides how to initiate the handover process by the previous information. Results show that the proposed scheme can achieve low-cost, seamless data communication, and a high probability of successful handover.

EMS providers do not use FOAM for education.

Science.gov (United States)

Bucher, Joshua; Donovan, Colleen; McCoy, Jonathan

2018-05-24

Free open access to medical education (FOAM, #FOAM) is the free availability of educational materials on various medicine topics. We hope to evaluate the use of social media and FOAM by emergency medical services (EMS) providers. We designed an online survey distributed to EMS providers with questions about demographics and social media/FOAM use by providers. The survey was sent to the American College of Emergency Physicians (ACEP) EMS Listserv of medical directors and was asked to be distributed to their respective agencies. The survey was designed to inquire about the providers' knowledge of FOAM and social media and their use of the above for EMS education. There were 169 respondents out of a total of 523 providers yielding a response rate of 32.3%. Fifty-three percent of respondents are paramedics, 37% are EMT-Basic trained, and the remainder (16%) were "other." The minority (20%) of respondents had heard of FOAM. However, 54% of respondents had heard of "free medical education online" regarding pertinent topics. Of the total respondents who used social media for education, 31% used Facebook and 23% used blogs and podcasts as resources for online education. Only 4% of respondents stated they produced FOAM content. Seventy-six percent of respondents said they were "interested" or "very interested" in using FOAM for medical education. If FOAM provided continuing medical education (CME), 83% of respondents would be interested in using it. Social media is not used frequently by EMS providers for the purposes of FOAM. There is interest within EMS providers to use FOAM for education, even if CME was not provided. FOAM can provide a novel area of education for EMS.

Polyurethane foam infill for fiber-reinforced polymer (FRP) bridge deck panels.

Science.gov (United States)

2014-05-01

Although still in their infancy, fiber-reinforced polymer (FRP) bridges have shown great promise in eliminating corrosion : concerns and meeting (or exceeding) FHWAs goal of 100-year life spans for bridges. While FRP bridges are cost-effective in ...

Rigid Polyurethane Foam Reinforced Coconut Coir Fiber Properties

OpenAIRE

Mohd Azham Azmi

2012-01-01

This research work studied the properties of composite foam panels. Coconut coir fibers were used as reinforcement in polyurethane (PU) foam in order to increase the properties of foam. This composite foam panels were fabricated by using polyurethane molded method. The polyurethane foam panels reinforced from 5 to 20wt% coconut coir were produced to investigate the physical and mechanical test via density test and three point bending test respectively. It was found that the density test resul...

Auxetic Polyurethane Foam (Fabrication, Properties and Applications)

International Nuclear Information System (INIS)

Yousif, H.I.Y.

2012-01-01

Modern technology requires new materials of special properties. For the last two decades there has been a great interest in a class of materials known as auxetic materials. An auxetic material is a material that has a negative Poisson's ratio which means that this material expands laterally when they subjected to a tensile force unlike most of the other traditional materials. This material has superior properties over the traditional material such as high shear modulus and high impact resistance, which makes this material a good candidate for many engineering applications. In the present research work, auxetic flexible polyurethane polymeric foams having different densities were fabricated from conventional flexible polyurethane polymeric foam at different compression ratios. The microstructure of conventional and processed foams was examined by optical microscope to compare between the two structures. The microstructure of processed foam was compared with the one presented in the literature and it has shown the auxetic structure configuration. This is the first time to produce auxetic foam in Egypt. Conventional and auxetic foam samples having cylindrical and square cross-sections were produced from foams having different densities (25 kg/m 3 and 30 kg/m 3 ). The compression ratios used to produce the auxetic samples are (5.56, 6.94 and 9.26). Four mechanical tests were carried out to get the mechanical properties for both conventional and auxetic foams. Two quasi-static mechanical tests t ension and compression a nd two dynamic mechanical tests H ysteresis and resilience w ere carried out to compare between the conventional and auxetic foams. The quasi-static tensile test was carried out at speed was adjusted to be position control rate of 0.2 mm/s. The compression and hysteresis tests were carried out at strain control rate of 0.3 S -1 . The data recorded from the machine were stress and strain. The modulus of elasticity and Poisson's ratio of the test

Shrinkage deformation of cement foam concrete

Science.gov (United States)

Kudyakov, A. I.; Steshenko, A. B.

2015-01-01

The article presents the results of research of dispersion-reinforced cement foam concrete with chrysotile asbestos fibers. The goal was to study the patterns of influence of chrysotile asbestos fibers on drying shrinkage deformation of cement foam concrete of natural hardening. The chrysotile asbestos fiber contains cylindrical fiber shaped particles with a diameter of 0.55 micron to 8 microns, which are composed of nanostructures of the same form with diameters up to 55 nm and length up to 22 microns. Taking into account the wall thickness, effective reinforcement can be achieved only by microtube foam materials, the so- called carbon nanotubes, the dimensions of which are of power less that the wall pore diameter. The presence of not reinforced foam concrete pores with perforated walls causes a decrease in its strength, decreases the mechanical properties of the investigated material and increases its shrinkage. The microstructure investigation results have shown that introduction of chrysotile asbestos fibers in an amount of 2 % by weight of cement provides the finely porous foam concrete structure with more uniform size closed pores, which are uniformly distributed over the volume. This reduces the shrinkage deformation of foam concrete by 50%.

Foam for combating mine fires

Energy Technology Data Exchange (ETDEWEB)

1989-09-01

The application of foam in dealing with underground fire is well known due to its smothering action by cutting off air feed to burning fuel as well as acting as coolant. Besides plugging air feed to fire, water could be virtually reached to the fire affected areas much beyond the jet range as underground galleries with low roof restrict jet range of water. This method also enables a closer approach of a fire fighting team by isolating the toxic gases and smoke with a foam plug. The paper describes the development of high expansion foam composition and its application technology in order that foam plug method can be suitably utilized for combating mine fires in India. Three compositions were recommended for generation of high expansion foam: (a) 0.5% sodium/ammonium lauryl sulphate, 0.15 to 0.2% sodium carboxy methyl cellulose, 0.1% booster; (b) 0.5% sodium/ammonium lauryl sulfate, 0.12 to 0.15% alkaline solution of gum arabic, 0.1 to 0.2% ferrous gluconate; and (c) 0.35% sodium/ammonium lauryl sulfate, 0.20% booster, 0.2% xylene sulfonate.

Extra natural gas by foam injection; Extra aardgas door foam-injectie

Energy Technology Data Exchange (ETDEWEB)

De Boer, B.

2008-07-01

The Dutch Petroleum Company (NAM) has further developed an originally American technology for expanding the economic lifespan of gas fields. Injection of environment-friendly foam enables further extraction of natural gas from nearly depleted gas fields. [mk]. [Dutch] De Nederlandse Aardolie Maatschappij (NAM) heeft een van origine Amerikaanse techniek om de economische levensduur van gasvelden te verlengen verder ontwikkeld. Het injecteren van een milieuvriendelijke zeep (foam) maakt het mogelijk om langer aardgas te produceren uit bijna lege gasvelden.

Foaming in manure based digesters

DEFF Research Database (Denmark)

Kougias, Panagiotis; Boe, Kanokwan; Angelidaki, Irini

2012-01-01

Anaerobic digestion foaming is one of the major problems that occasionally occurred in the Danish full-scale biogas plants, affecting negatively the overall digestion process. The foam is typically formatted in the main biogas reactor or in the pre-storage tank and the entrapped solids in the foam...... cause severe operational problems, such as blockage of mixing devices, and collapse of pumps. Furthermore, the foaming problem is linked with economic consequences for biogas plants, due to income losses derived from the reduced biogas production, extra labour work and additional maintenance costs...... was increased by the addition of glucose in the feeding substrate. During the 2nd and 4th period the organic loading rate was maintained constant, but instead of glucose, higher concentration of Na-oleate or gelatine was added in the feeding substrate. The results obtained from the above experiment showed...

Foam-like structure of the Universe

International Nuclear Information System (INIS)

Kirillov, A.A.; Turaev, D.

2007-01-01

On the quantum stage space-time had the foam-like structure. When the Universe cools, the foam structure tempers and does not disappear. We show that effects caused by the foamed structure mimic very well the observed Dark Matter phenomena. Moreover, we show that in a foamed space photons undergo a chaotic scattering and together with every discrete source of radiation we should observe a diffuse halo. We show that the distribution of the diffuse halo of radiation around a point-like source repeats exactly the distribution of dark matter around the same source, i.e., the DM halos are sources of the diffuse radiation

Foam-like structure of the Universe

Energy Technology Data Exchange (ETDEWEB)

Kirillov, A.A. [Institute for Applied Mathematics and Cybernetics, 10 Ulyanova str., Nizhny Novgorod 603005 (Russian Federation)], E-mail: ka98@mail.ru; Turaev, D. [Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 84105 (Israel)

2007-11-15

On the quantum stage space-time had the foam-like structure. When the Universe cools, the foam structure tempers and does not disappear. We show that effects caused by the foamed structure mimic very well the observed Dark Matter phenomena. Moreover, we show that in a foamed space photons undergo a chaotic scattering and together with every discrete source of radiation we should observe a diffuse halo. We show that the distribution of the diffuse halo of radiation around a point-like source repeats exactly the distribution of dark matter around the same source, i.e., the DM halos are sources of the diffuse radiation.

Effectiveness of Flame Retardants in TufFoam.

Energy Technology Data Exchange (ETDEWEB)

Abelow, Alexis Elizabeth [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Nissen, April [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Massey, Lee Taylor [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Whinnery, LeRoy L. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

2017-12-01

An investigation of polyurethane foam filled with known flame retardant fillers including hydroxides, melamine, phosphate-containing compounds, and melamine phosphates was carried out to produce a low-cost material with high flame retardant efficiency. The impact of flame retardant fillers on the physical properties such a s composite foam density, glass transition temperature, storage modulus, and thermal expansion of composite foams was investigated with the goal of synthesizing a robust rigid foam with excellent flame retardant properties.

Modyfication of the Rigid Polyurethane-Polyisocyanurate Foams

OpenAIRE

Bogusław Czupryński; Joanna Liszkowska; Joanna Paciorek-Sadowska

2014-01-01

The effect of polyethylene glycol 1500 on physicomechanical properties of rigid polyurethane-polyisocyanurate (PUR-PIR) foams has been studied. It was found that application of polyethylene glycol 1500 for synthesis of foams in amount from 0% to 20% w/w had an effect on reduction of brittleness and softening point, while the greater the increase in compressive strength the higher its content in foam composition was. Wastes from production of these foams were ground and subjected to glycolysis...

H1259 Container Foams: Performance Data on Aged Materials

International Nuclear Information System (INIS)

Linda Domeier

2002-01-01

Samples of the three cushioning foams used in the H1259 weapon storage container were obtained in 1997, 1998, 2000 and 2001 and tested for density, compression set and compressive strength using the same procedures specified for acceptance testing. Foams from six containers, all about 30 years old and located at Pantex, were evaluated. The bottom cushioning foam is a General Plastics polyurethane foam and the two side pads are rebonded polyurethane foams. All the tests were carried out at room temperature. When compared to the original acceptance requirements the foams were generally in-spec for density and compressive strength at 10% strain and were generally out-of-spec for compression set and compressive strength at 50% strain. Significant variability was noted in the performance of each foam sample and even more in the container-to-container foam performance. The container-to-container variability remains the major unknown in predicting the long-term suitability of these containers for continued use. The performance of the critical bottom cushion foams was generally more uniform and closer to the specified performance than that of the rebonded foams. It was judged that all the foams were adequate for continued use as storage container foams (not shipping) under controlled conditions to mitigate temperature extremes or high impact. This archived information is important in evaluations of the continued suitability for weapon storage use of the H1259 containers and other containers using the same foam cushions

Foam generator and viscometer apparatus and process

Science.gov (United States)

Reed, Troy D.; Pickell, Mark B.; Volk, Leonard J.

2004-10-26

An apparatus and process to generate a liquid-gas-surfactant foam and to measure its viscosity and enable optical and or electronic measurements of physical properties. The process includes the steps of pumping selected and measured liquids and measured gases into a mixing cell. The mixing cell is pressurized to a desired pressure and maintained at a desired pressure. Liquids and gas are mixed in the mixing cell to produce a foam of desired consistency. The temperature of the foam in the mixing cell is controlled. Foam is delivered from the mixing cell through a viscometer under controlled pressure and temperature conditions where the viscous and physical properties of the foam are measured and observed.

Experimental study on foam coverage on simulated longwall roof

Science.gov (United States)

Reed, W.R.; Zheng, Y.; Klima, S.; Shahan, M.R.; Beck, T.W.

2018-01-01

Testing was conducted to determine the ability of foam to maintain roof coverage in a simulated longwall mining environment. Approximately 27 percent of respirable coal mine dust can be attributed to longwall shield movement, and developing controls for this dust source has been difficult. The application of foam is a possible dust control method for this source. Laboratory testing of two foam agents was conducted to determine the ability of the foam to adhere to a simulated longwall face roof surface. Two different foam generation methods were used: compressed air and blower air. Using a new imaging technology, image processing and analysis utilizing ImageJ software produced quantifiable results of foam roof coverage. For compressed air foam in 3.3 m/s (650 fpm) ventilation, 98 percent of agent A was intact while 95 percent of agent B was intact on the roof at three minutes after application. At 30 minutes after application, 94 percent of agent A was intact while only 20 percent of agent B remained. For blower air in 3.3 m/s (650 fpm) ventilation, the results were dependent upon nozzle type. Three different nozzles were tested. At 30 min after application, 74 to 92 percent of foam agent A remained, while 3 to 50 percent of foam agent B remained. Compressed air foam seems to remain intact for longer durations and is easier to apply than blower air foam. However, more water drained from the foam when using compressed air foam, which demonstrates that blower air foam retains more water at the roof surface. Agent A seemed to be the better performer as far as roof application is concerned. This testing demonstrates that roof application of foam is feasible and is able to withstand a typical face ventilation velocity, establishing this technique’s potential for longwall shield dust control. PMID:29563765

Stability analysis of uniform equilibrium foam states for EOR processes

NARCIS (Netherlands)

Ashoori, E.; Marchesin, D.; Rossen, W.R.

2011-01-01

The use of foam for mobility control is a promising mean to improve sweep efficiency in EOR. Experimental studies discovered that foam exhibits three different states (weak foam, intermediate foam, and strong foam). The intermediate-foam state is found to be unstable in the lab whereas the weak- and

Measurement of Aqueous Foam Rheology by Acoustic Levitation

Science.gov (United States)

McDaniel, J. Gregory; Holt, R. Glynn; Rogers, Rich (Technical Monitor)

2000-01-01

An experimental technique is demonstrated for acoustically levitating aqueous foam drops and exciting their spheroidal modes. This allows fundamental studies of foam-drop dynamics that provide an alternative means of estimating the viscoelastic properties of the foam. One unique advantage of the technique is the lack of interactions between the foam and container surfaces, which must be accounted for in other techniques. Results are presented in which a foam drop with gas volume fraction phi = 0.77 is levitated at 30 kHz and excited into its first quadrupole resonance at 63 +/- 3 Hz. By modeling the drop as an elastic sphere, the shear modulus of the foam was estimated at 75 +/- 3 Pa.

AC induction field heating of graphite foam

Science.gov (United States)

Klett, James W.; Rios, Orlando; Kisner, Roger

2017-08-22

A magneto-energy apparatus includes an electromagnetic field source for generating a time-varying electromagnetic field. A graphite foam conductor is disposed within the electromagnetic field. The graphite foam when exposed to the time-varying electromagnetic field conducts an induced electric current, the electric current heating the graphite foam. An energy conversion device utilizes heat energy from the heated graphite foam to perform a heat energy consuming function. A device for heating a fluid and a method of converting energy are also disclosed.

Foam application from a closed system – a study of machine and foam parameters

NARCIS (Netherlands)

Lemmen, Jacques T.E.; Groot Wassink, Jan

1990-01-01

An attempt has been made to gain a greater insight into the interaction between foam and a moving textile substrate. The effects of changing wet pick–up, fabric velocity, liquid viscosity, foam density and mode of application on penetration have been studied. Application from a closed system makes

Chemical characterization and ecotoxicity of three soil foaming agents used in mechanized tunneling.

Science.gov (United States)

Baderna, Diego; Lomazzi, Eleonora; Passoni, Alice; Pogliaghi, Alberto; Petoumenou, Maria Ifigeneia; Bagnati, Renzo; Lodi, Marco; Viarengo, Aldo; Sforzini, Susanna; Benfenati, Emilio; Fanelli, Roberto

2015-10-15

The construction of tunnels and rocks with mechanized drills produces several tons of rocky debris that are today recycled as construction material or as soil replacement for covering rocky areas. The lack of accurate information about the environmental impact of these excavated rocks and foaming agents added during the excavation process has aroused increasing concern for ecosystems and human health. The present study proposes an integrated approach to the assessment of the potential environmental impact of three foaming agents containing different anionic surfactants and other polymers currently on the market and used in tunnel boring machines. The strategy includes chemical characterization with high resolution mass spectrometry techniques to identify the components of each product, the use of in silico tools to perform a similarity comparison among these compounds and some pollutants already listed in regulatory frameworks to identify possible threshold concentrations of contamination, and the application of a battery of ecotoxicological assays to investigate the impact of each foaming mixture on model organisms of soil (higher plants and Eisenia andrei) and water communities (Daphnia magna). The study identified eleven compounds not listed on the material safety data sheets for which we have identified possible concentrations of contamination based on existing regulatory references. The bioassays allowed us to determine the no effect concentrations (NOAECs) of the three mixtures, which were subsequently used as threshold concentration for the product in its entirety. The technical mixtures used in this study have a different degree of toxicity and the predicted environmental concentrations based on the conditions of use are lower than the NOAEC for soils but higher than the NOAEC for water, posing a potential risk to the waters due to the levels of foaming agents in the muck. Copyright © 2015 Elsevier B.V. All rights reserved.

Foam glass obtained through high-pressure sintering

DEFF Research Database (Denmark)

Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob

2018-01-01

Foam glasses are usually prepared through a chemical approach, that is, by mixing glass powder with foaming agents, and heating the mixture to a temperature above the softening point (106.6 Pa s) of the glass. The foaming agents release gas, enabling expansion of the sintered glass. Here, we use...... a physical foaming approach to prepare foam glass. First, closed pores filled with inert gases (He, Ar, or N2) are physically introduced into a glass body by sintering cathode ray tube (CRT) panel glass powder at high gas pressure (5‐25 MPa) at 640°C and, then cooled to room temperature. The sintered bodies...... are subjected to a second heat treatment above the glass transition temperature at atmospheric pressure. This heat treatment causes expansion of the pores due to high internal gas pressure. We found that the foaming ability strongly depends on the gas pressure applied during sintering, and on the kinetic...

Fluoride Rinses, Gels and Foams

DEFF Research Database (Denmark)

Twetman, Svante; Keller, Mette K

2016-01-01

AIM: The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. METHODS: Relevant papers were selected after...... (6 on fluoride mouth rinse, 10 on fluoride gel and 3 on fluoride foam); 6 had a low risk of bias while 2 had a moderate risk. All fluoride measures appeared to be beneficial in preventing crown caries and reversing root caries, but the quality of evidence was graded as low for fluoride mouth rinse......, moderate for fluoride gel and very low for acidulated fluoride foam. No conclusions could be drawn on the cost-effectiveness. CONCLUSIONS: This review, covering the recent decade, has further substantiated the evidence for a caries-preventive effect of fluoride mouth rinse, fluoride gel and foam...

Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance

Science.gov (United States)

Asfaw, Habtom D.; Roberts, Matthew R.; Tai, Cheuk-Wai; Younesi, Reza; Valvo, Mario; Nyholm, Leif; Edström, Kristina

2014-07-01

In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol-gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4 nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm-2 at 0.1 mA cm-2 (lowest rate) and 1.1 mA h cm-2 at 6 mA cm-2 (highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol-gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating

New Spin Foam Models of Quantum Gravity

Science.gov (United States)

Miković, A.

We give a brief and a critical review of the Barret-Crane spin foam models of quantum gravity. Then we describe two new spin foam models which are obtained by direct quantization of General Relativity and do not have some of the drawbacks of the Barret-Crane models. These are the model of spin foam invariants for the embedded spin networks in loop quantum gravity and the spin foam model based on the integration of the tetrads in the path integral for the Palatini action.

Defect generation during solidification of aluminium foams

International Nuclear Information System (INIS)

Mukherjee, M.; Garcia-Moreno, F.; Banhart, J.

2010-01-01

The reason for the frequent occurrence of cell wall defects in metal foams was investigated. Aluminium foams often expand during solidification, a process which is referred as solidification expansion (SE). The effect of SE on the structure of aluminium foams was studied in situ by X-ray radioscopy and ex situ by X-ray tomography. A direct correlation between the magnitude of SE and the number of cell wall ruptures during SE and finally the number of defects in the solidified foams was found.

Foam film permeability: theory and experiment.

Science.gov (United States)

Farajzadeh, R; Krastev, R; Zitha, Pacelli L J

2008-02-28

The mass transfer of gas through foam films is a prototype of various industrial and biological processes. The aim of this paper is to give a perspective and critical overview of studies carried out to date on the mass transfer of gas through foam films. Contemporary experimental data are summarized, and a comprehensive overview of the theoretical models used to explain the observed effects is given. A detailed description of the processes that occur when a gas molecule passes through each layer that forms a foam film is shown. The permeability of the film-building surfactant monolayers plays an important role for the whole permeability process. It can be successfully described by the models used to explain the permeability of surfactant monolayers on aqueous sub-phase. For this reason, the present paper briefly discusses the surfactant-induced resistance to mass transfer of gases through gas-liquid interface. One part of the paper discusses the experimental and theoretical aspects of the foam film permeability in a train of foam films in a matrix or a cylinder. This special case is important to explain the gas transfer in porous media or in foams. Finally, this paper will highlight the gaps and challenges and sketch possible directions for future research.

Investigation into stress wave propagation in metal foams

Directory of Open Access Journals (Sweden)

Li Lang

2015-01-01

Full Text Available The aim of this study is to investigate stress wave propagation in metal foams under high-speed impact loading. Three-dimensional Voronoi model is established to represent real closed-cell foam. Based on the one-dimensional stress wave theory and Voronoi model, a numerical model is developed to calculate the velocity of elastic wave and shock wave in metal foam. The effects of impact velocity and relative density of metal foam on the stress wave propagation in metal foams are explored respectively. The results show that both elastic wave and shock wave propagate faster in metal foams with larger relative density; with increasing the impact velocity, the shock wave propagation velocity increase, but the elastic wave propagation is not sensitive to the impact velocity.

FoAM Kernow Activity Report 2016

OpenAIRE

Griffiths, Amber; Griffiths, David

2016-01-01

This review shows selected projects from the FoAM Kernow studio in 2016. FoAM is a network of transdisciplinary labs at the intersection of art, science, nature and everyday life. FoAM’s members are generalists - people who work across disparate fields in an entangled, speculative culture. Research and creative projects at FoAM combine elements of futurecrafting, citizen science, prototyping, experience design and process facilitation to re-imagine possible futures, and artistic experime...

FoAM Kernow Activity Report 2017

OpenAIRE

Griffiths, Amber; Weatherill, Aidan; Griffiths, David

2017-01-01

This review shows selected projects from the FoAM Kernow studio in 2017. FoAM is a network of transdisciplinary labs at the intersection of art, science, nature and everyday life. FoAM’s members are generalists - people who work across disparate fields in an entangled, speculative culture. Research and creative projects at FoAM combine elements of futurecrafting, citizen science, prototyping, experience design and process facilitation to re-imagine possible futures.

Studies on Foam Decay Trend and Influence of Temperature Jump on Foam Stability in Sclerotherapy.

Science.gov (United States)

Bai, Taoping; Chen, Yu; Jiang, Wentao; Yan, Fei; Fan, Yubo

2018-02-01

This study investigated the influence of temperature jump and liquid-gas ratio on foam stability to derive the foam-decay law. The experimental group conditions were as follows: mutation temperatures (10°C, 16°C, 20°C, 23°C, 25°C, and 27°C to >37°C) and liquid-gas ratios (1:1, 1:2, 1:3, and 1:4). The control group conditions were as follows: temperatures (10°C, 16°C, 20°C, 23°C, 25°C and 27°C) and liquid-gas ratios (1:1, 1:2, 1:3, and 1:4). A homemade device manufactured using the Tessari DSS method was used to prepare the foam. The decay process was videotape recorded. In the drainage rate curve, the temperature rose, and the liquid-gas ratio varied from 1:1 to 1:4, causing faster decay. In the entire process, the foam volume decreased with increasing drainage rate. The relationships were almost linear. Comparison of the experimental and control groups shows that the temperature jump results in a drainage time range of 1 to 15 seconds. The half-life ranges from 10 to 30 seconds. The maximum rate is 18.85%. Changes in the preparation temperature yields a drainage time range of 3 to 30 seconds. The half-life varies from 20 to 60 seconds. Decreasing the temperature jump range and liquid-gas ratio gradually enhances the foam stability. The foam decay time and drainage rate exhibit an exponential function distribution.

Technological parameters influence on the non-autoclaved foam concrete characteristics

Science.gov (United States)

Bartenjeva, Ekaterina; Mashkin, Nikolay

2017-01-01

Foam concretes are used as effective heat-insulating materials. The porous structure of foam concrete provides good insulating and strength properties that make them possible to be used as heat-insulating structural materials. Optimal structure of non-autoclaved foam concrete depends on both technological factors and properties of technical foam. In this connection, the possibility to manufacture heat-insulation structural foam concrete on a high-speed cavity plant with the usage of protein and synthetic foamers was estimated. This experiment was carried out using mathematical planning method, and in this case mathematical models were developed that demonstrated the dependence of operating performance of foam concrete on foaming and rotation speed of laboratory plant. The following material properties were selected for the investigation: average density, compressive strength, bending strength and thermal conductivity. The influence of laboratory equipment technological parameters on technical foam strength and foam stability coefficient in the cement paste was investigated, physical and mechanical properties of non-autoclaved foam concrete were defined based on investigated foam. As a result of investigation, foam concrete samples were developed with performance parameters ensuring their use in production. The mathematical data gathered demonstrated the dependence of foam concrete performance on the technological regime.

Effect of Cerium(IV)-Surfactant Reaction in Foam Decontamination

Energy Technology Data Exchange (ETDEWEB)

Yang, Han Beom; Jung, Chong-Hun; Yoon, In-Ho; Kim, Chorong; Choi, Wang-Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

Using foams allows the decommissioning of complex shaped facilities. The decontamination foam comprises at least one surfactant to generate the foam and one or more chemical reactants to achieve the dissolution of the contaminants at the solid surface. In order to improve the efficiency of decontamination foam, the present study attempts to find the optimum condition of chemical reagents to the foaming solution. The corrosion rate of radioactive nuclides contaminated stainless steel metal is very important factor for the foam decontamination process. The goal of this study is to develop the decontamination process for contaminated stainless steel in medium of nitric acid. Stainless steel needs a strong oxidizing agent such as Ce(IV) ion and the effects of cerium(IV). Surfactant interaction involved in foam decontamination and finally the improvement brought by formulation science. The formulation of foams loaded with strong oxidizing reagents such as Ce(IV) is an important factor. The enhanced decontamination properties of nitric acid with Ce(IV) additive on stainless steel is well known in liquid mediums. stainless steel metal is an important aspect in the foam decontamination process.

Effect of Cerium(IV)-Surfactant Reaction in Foam Decontamination

International Nuclear Information System (INIS)

Yang, Han Beom; Jung, Chong-Hun; Yoon, In-Ho; Kim, Chorong; Choi, Wang-Kyu

2015-01-01

Using foams allows the decommissioning of complex shaped facilities. The decontamination foam comprises at least one surfactant to generate the foam and one or more chemical reactants to achieve the dissolution of the contaminants at the solid surface. In order to improve the efficiency of decontamination foam, the present study attempts to find the optimum condition of chemical reagents to the foaming solution. The corrosion rate of radioactive nuclides contaminated stainless steel metal is very important factor for the foam decontamination process. The goal of this study is to develop the decontamination process for contaminated stainless steel in medium of nitric acid. Stainless steel needs a strong oxidizing agent such as Ce(IV) ion and the effects of cerium(IV). Surfactant interaction involved in foam decontamination and finally the improvement brought by formulation science. The formulation of foams loaded with strong oxidizing reagents such as Ce(IV) is an important factor. The enhanced decontamination properties of nitric acid with Ce(IV) additive on stainless steel is well known in liquid mediums. stainless steel metal is an important aspect in the foam decontamination process

Thermomechanical analyses of phenolic foam reinforced with glass fiber mat

International Nuclear Information System (INIS)

Zhou, Jintang; Yao, Zhengjun; Chen, Yongxin; Wei, Dongbo; Wu, Yibing

2013-01-01

Highlights: • Over 10% glass fiber was used to reinforce phenolic foam in the shape of glass fiber mat. • Nucleating agents were used together with glass fiber mat and improved tensile strength of phenolic foam by 215.6%. • Nucleating agents lead to a smaller bubble size of phenolic foam. • The glass transition temperature of phenolic foam remained unchanged during the reinforcement. - Abstract: In this paper, thermomechanical analysis (TMA) and dynamic mechanical analysis were employed to study the properties of phenolic foam reinforced with glass fiber mat. Unreinforced phenolic foam was taken as the control sample. Mechanical tests and scanning electron microscopy were performed to confirm the results of TMA. The results show that glass fiber mat reinforcement improves the mechanical performance of phenolic foam, and nucleating agents improve it further. Phenolic foam reinforced with glass fiber mat has a smaller thermal expansion coefficient compared with unreinforced foam. The storage modulus of the reinforced phenolic foam is also higher than that in unreinforced foam, whereas the loss modulus of the former is lower than that of the latter. The glass transition temperature of the phenolic foam matrix remains unchanged during the reinforcement

Experimental Study of Hysteresis behavior of Foam Generation in Porous Media.

Science.gov (United States)

Kahrobaei, S; Vincent-Bonnieu, S; Farajzadeh, R

2017-08-21

Foam can be used for gas mobility control in different subsurface applications. The success of foam-injection process depends on foam-generation and propagation rate inside the porous medium. In some cases, foam properties depend on the history of the flow or concentration of the surfactant, i.e., the hysteresis effect. Foam may show hysteresis behavior by exhibiting multiple states at the same injection conditions, where coarse-textured foam is converted into strong foam with fine texture at a critical injection velocity or pressure gradient. This study aims to investigate the effects of injection velocity and surfactant concentration on foam generation and hysteresis behavior as a function of foam quality. We find that the transition from coarse-foam to strong-foam (i.e., the minimum pressure gradient for foam generation) is almost independent of flowrate, surfactant concentration, and foam quality. Moreover, the hysteresis behavior in foam generation occurs only at high-quality regimes and when the pressure gradient is below a certain value regardless of the total flow rate and surfactant concentration. We also observe that the rheological behavior of foam is strongly dependent on liquid velocity.

Electroactive polymers for healthcare and biomedical applications

Science.gov (United States)

Bauer, Siegfried

2017-04-01

Electroactivity was noticed early in biological substances, including proteins, polynucleotides and enzymes, even piezoand pyroelectricity were found in wool, hair, wood, bone and tendon. Recently, ferroelectricity has been identified in a surprisingly large number of biologically relevant materials, including hydroxyapatite, aortic walls and elastin. Inspired by the variety of natural electroactive materials, a wealth of new elastomers and polymers were designed recently, including an all organic elastomer electret and self-healing dielectric elastomers. Let's further draw inspiration from nature and widen the utilization of electroactive polymers towards (mobile) healthcare and biomedical applications. Ferroelectrets, internally charged polymer foams with a strong piezoelectric thickness coefficient are employed in biomedical sensing, for example as blood pressure and pulse sensor, as vital signs monitor or for the detection of tonicclonic seizures. Piezo- and pyroelectric polymers are booming in printed electronics research. They provide electronic skin the ability to "feel" pressure and temperature changes, or to generate electrical energy from vibrations and motions, even from contractile and relaxation motions of the heart and lung. Dielectric elastomers are pioneered by StretchSense as wearable motion capture sensors, monitoring pressure, stretch, bend and shear, quantifying comfort in sports and healthcare. On the cellular level, electroactive polymer arrays are used to study mechanotransduction of individual cells. Ionic electroactive polymers show potential to be used in implantable electroactive biomedical devices. Already with the currently available science and technology, we are at the verge of witnessing the demonstration of truly complex bionic systems.

Graphite Foam Heat Exchangers for Thermal Management

Energy Technology Data Exchange (ETDEWEB)

Klett, J.W.

2004-06-07

Improved thermal management is needed to increase the power density of electronic and more effectively cool electronic enclosures that are envisioned in future aircraft, spacecraft and surface ships. Typically, heat exchanger cores must increase in size to more effectively dissipate increased heat loads, this would be impossible in many cases, thus improved heat exchanger cores will be required. In this Phase I investigation, MRi aimed to demonstrate improved thermal management using graphite foam (Gr-foam) core heat exchangers. The proposed design was to combine Gr-foams from POCO with MRi's innovative low temperature, active metal joining process (S-Bond{trademark}) to bond Gr-foam to aluminum, copper and aluminum/SiC composite faceplates. The results were very favorable, so a Phase II SBIR with the MDA was initiated. This had primarily 5 tasks: (1) bonding, (2) thermal modeling, (3) cooling chip scale packages, (4) evaporative cooling techniques and (5) IGBT cold plate development. The bonding tests showed that the ''reflow'' technique with S-Bond{reg_sign}-220 resulted in the best and most consistent bond. Then, thermal modeling was used to design different chip scale packages and IGBT cold plates. These designs were used to fabricate many finned graphite foam heat sinks specifically for two standard type IC packages, the 423 and 478 pin chips. These results demonstrated several advantages with the foam. First, the heat sinks with the foam were lighter than the copper/aluminum sinks used as standards. The sinks for the 423 design made from foam were not as good as the standard sinks. However, the sinks made from foam for the 478 pin chips were better than the standard heat sinks used today. However, this improvement was marginal (in the 10-20% better regime). However, another important note was that the epoxy bonding technique resulted in heat sinks with similar results as that with the S-bond{reg_sign}, slightly worse than the S

A testing platform for durability studies of polymers and fiber-reinforced polymer composites under concurrent hygrothermo-mechanical stimuli.

Science.gov (United States)

Gomez, Antonio; Pires, Robert; Yambao, Alyssa; La Saponara, Valeria

2014-12-11

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs and condition-based maintenance. These materials are adopted in a wide range of engineering applications, from aircraft and ship structures, to bridges, wind turbine blades, biomaterials and biomedical implants. Polymers are viscoelastic materials, and their response may be highly nonlinear and thus make it challenging to predict and monitor their in-service performance. The laboratory-scale testing platform presented herein assists the investigation of the influence of concurrent mechanical loadings and environmental conditions on these materials. The platform was designed to be low-cost and user-friendly. Its chemically resistant materials make the platform adaptable to studies of chemical degradation due to in-service exposure to fluids. An example of experiment was conducted at RT on closed-cell polyurethane foam samples loaded with a weight corresponding to ~50% of their ultimate static and dry load. Results show that the testing apparatus is appropriate for these studies. Results also highlight the larger vulnerability of the polymer under concurrent loading, based on the higher mid-point displacements and lower residual failure loads. Recommendations are made for additional improvements to the testing apparatus.

A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli

Science.gov (United States)

Gomez, Antonio; Pires, Robert; Yambao, Alyssa; La Saponara, Valeria

2014-01-01

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs and condition-based maintenance. These materials are adopted in a wide range of engineering applications, from aircraft and ship structures, to bridges, wind turbine blades, biomaterials and biomedical implants. Polymers are viscoelastic materials, and their response may be highly nonlinear and thus make it challenging to predict and monitor their in-service performance. The laboratory-scale testing platform presented herein assists the investigation of the influence of concurrent mechanical loadings and environmental conditions on these materials. The platform was designed to be low-cost and user-friendly. Its chemically resistant materials make the platform adaptable to studies of chemical degradation due to in-service exposure to fluids. An example of experiment was conducted at RT on closed-cell polyurethane foam samples loaded with a weight corresponding to ~50% of their ultimate static and dry load. Results show that the testing apparatus is appropriate for these studies. Results also highlight the larger vulnerability of the polymer under concurrent loading, based on the higher mid-point displacements and lower residual failure loads. Recommendations are made for additional improvements to the testing apparatus. PMID:25548950

Fire-Induced Response in Foam Encapsulants

Energy Technology Data Exchange (ETDEWEB)

Borek, T.T.; Chu, T.Y.; Erickson, K.L.; Gill, W.; Hobbs, M.L.; Humphries, L.L.; Renlund, A.M.; Ulibarri, T.A.

1999-04-02

The paper provides a concise overview of a coordinated experimental/theoretical/numerical program at Sandia National Laboratories to develop an experimentally validated model of fire-induced response of foam-filled engineered systems for nuclear and transportation safety applications. Integral experiments are performed to investigate the thermal response of polyurethane foam-filled systems exposed to fire-like heat fluxes. A suite of laboratory experiments is performed to characterize the decomposition chemistry of polyurethane. Mass loss and energy associated with foam decomposition and chemical structures of the virgin and decomposed foam are determined. Decomposition chemistry is modeled as the degradation of macromolecular structures by bond breaking followed by vaporization of small fragments of the macromolecule with high vapor pressures. The chemical decomposition model is validated against the laboratory data. Data from integral experiments is used to assess and validate a FEM foam thermal response model with the chemistry model developed from the decomposition experiments. Good agreement was achieved both in the progression of the decomposition front and the in-depth thermal response.

Time-dependent crashworthiness of polyurethane foam

Science.gov (United States)

Basit, Munshi Mahbubul; Cheon, Seong Sik

2018-05-01

Time-dependent stress-strain relationship as well as crashworthiness of polyurethane foam was investigated under constant impact energy with different velocities, considering inertia and strain-rate effects simultaneously during the impact testing. Even though the impact energies were same, the percentage in increase in densification strain due to higher impact velocities was found, which yielded the wider plateau region, i.e. growth in crashworthiness. This phenomenon is analyzed by the microstructure of polyurethane foam obtained from scanning electron microscopy. The equations, coupled with the Sherwood-Frost model and the impulse-momentum theory, were employed to build the constitutive equation of the polyurethane foam and calculate energy absorption capacity of the foam. The nominal stress-strain curves obtained from the constitutive equation were compared with results from impact tests and were found to be in good agreement. This study is dedicated to guiding designer use polyurethane foam in crashworthiness structures such as an automotive bumper system by providing crashworthiness data, determining the crush mode, and addressing a mathematical model of the crashworthiness.

Investigation of in-situ poly(lactic acid)/soy protein concentrate composites: Composite preparation, properties and foam application development

Science.gov (United States)

Liu, Bo

2011-12-01

In this study, soy protein (SP), the residue of oil crushing, was used for preparation of value-added thermoplastics. Novel poly(lactic acid) (PLA)/soy protein concentrate (SPC) blends were investigated and foaming of the resulting blends was developed. PLA/SPC blends were prepared by twin-screw extrusion and test specimens by injection molding. Unlike the practice elsewhere SP was used as a filler in mixing with other polymers, SPC was processed as a plastic component in blending process in this work. Processing SPC as plastic component, water played an important role in terms of the deformability and the morphology of SP thus the properties of the blends. Plasticization of SP, compatibilization of the blends and structure-property relationship of the PLA/SPC blends were studied. In the literature water and glycerol were often used together in preparing SP plastics or plastic blends, but this study found that this traditional combination did not provide the best results in terms of morphology and mechanical properties. Water is only recommended in plasticizing SP in the blends. This study showed water as a plasticizer was a domain factor on control of morphology and properties of PLA/SPC blends. The due to the evaporation of water after extrusion, SP domain lost its deformability thus resulted in in-situ composites. Interconnected SPC phase structure was achieved by control water content in the pre-formulated SPC and SPC content in the blends. A novel dual compatibilization method was developed to improve the properties of PLA/SPC blends. Poly(2-ethyl-2-oxazoline) was used to improve the dispersion of SPC in the blending stage, and polymeric methylene diphenyl diisocyanate was used to improve the interfacial adhesion between SPC and PLA in the subsequent processing. The result showed excellent mechanical properties and improved thermal properties of PLA/SPC blends. Using processing aids is an effective way to decrease processing temperature and thermal degradation

Synergistic effect of casein glycomacropeptide on sodium caseinate foaming properties.

Science.gov (United States)

Morales, R; Martinez, M J; Pilosof, A M R

2017-11-01

Several strategies to improve the interfacial properties and foaming properties of proteins may be developed; among them, the use of mixtures of biopolymers that exhibit synergistic interactions. The aim of the present work was to evaluate the effect of casein glycomacropeptide (CMP) on foaming and surface properties of sodium caseinate (NaCas) and to establish the role of protein interactions in the aqueous phase. To this end particles size, interfacial and foaming properties of CMP, NaCas and NaCas-CMP mixtures at pH 5.5 and 7 were determined. At both pH, the interaction between CMP and NaCas induced a decrease in the aggregation state of NaCas. Single CMP foams showed the highest and NaCas the lowest foam overrun (FO) and the mixture exhibited intermediate values. CMP foam quickly drained. The drainage profile of mixed foams was closer to NaCas foams; at pH 5.5, mixed foams drained even slower than NaCas foam, exhibiting a synergistic performance. Additionally, a strong synergism was observed on the collapse of mixed foams at pH 5.5. Finally, a model to explain the synergistic effect observed on foaming properties in CMP-NaCas mixtures has been proposed; the reduced aggregation state of NaCas in the presence of CMP, made it more efficient for foam stabilization. Copyright © 2017 Elsevier B.V. All rights reserved.

Cyclic deformation of bidisperse two-dimensional foams

Science.gov (United States)

Fátima Vaz, M.; Cox, S. J.; Teixeira, P. I. C.

2011-12-01

In-plane deformation of foams was studied experimentally by subjecting bidisperse foams to cycles of traction and compression at a prescribed rate. Each foam contained bubbles of two sizes with given area ratio and one of three initial arrangements: sorted perpendicular to the axis of deformation (iso-strain), sorted parallel to the axis of deformation (iso-stress), or randomly mixed. Image analysis was used to measure the characteristics of the foams, including the number of edges separating small from large bubbles N sl , the perimeter (surface energy), the distribution of the number of sides of the bubbles, and the topological disorder μ2(N). Foams that were initially mixed were found to remain mixed after the deformation. The response of sorted foams, however, depended on the initial geometry, including the area fraction of small bubbles and the total number of bubbles. For a given experiment we found that (i) the perimeter of a sorted foam varied little; (ii) each foam tended towards a mixed state, measured through the saturation of N sl ; and (iii) the topological disorder μ2(N) increased up to an "equilibrium" value. The results of different experiments showed that (i) the change in disorder, ? decreased with the area fraction of small bubbles under iso-strain, but was independent of it under iso-stress; and (ii) ? increased with ? under iso-strain, but was again independent of it under iso-stress. We offer explanations for these effects in terms of elementary topological processes induced by the deformations that occur at the bubble scale.

Effect of ageing at 1200 degrees C in oxidative environment on the mechanical response of SiOC foams

Czech Academy of Sciences Publication Activity Database

Chlup, Zdeněk; Černý, Martin; Strachota, Adam; Svítilová, Jaroslava; Halasová, Martina

2015-01-01

Roč. 41, č. 7 (2015), s. 9030-9034 ISSN 0272-8842 R&D Projects: GA ČR GAP107/12/2445; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 ; RVO:61389013 ; RVO:67985891 Keywords : SILICON OXYCARBIDE GLASSES * PARTIALLY PYROLYZED COMPOSITES * PRECERAMIC POLYMER * CERAMIC FOAMS * POLYSILOXANE Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass; CD - Macromolecular Chemistry (UMCH-V); JL - Materials Fatigue, Friction Mechanics (USMH-B) Impact factor: 2.758, year: 2015

Pitch-based carbon foam and composites and use thereof

Science.gov (United States)

Klett, James W.; Burchell, Timothy D.; Choudhury, Ashok

2006-07-04

A thermally conductive carbon foam is provided, normally having a thermal conductivity of at least 40 W/mK. The carbon foam usually has a specific thermal conductivity, defined as the thermal conductivity divided by the density, of at least about 75 Wcm.sup.3/m.degree. Kgm. The foam also has a high specific surface area, typically at least about 6,000 m.sup.2/m.sup.3. The foam is characterized by an x-ray diffraction pattern having "doublet" 100 and 101 peaks characterized by a relative peak split factor no greater than about 0.470. The foam is graphitic and exhibits substantially isotropic thermal conductivity. The foam comprises substantially ellipsoidal pores and the mean pore diameter of such pores is preferably no greater than about 340 microns. Other materials, such as phase change materials, can be impregnated in the pores in order to impart beneficial thermal properties to the foam. Heat exchange devices and evaporatively cooled heat sinks utilizing the foams are also disclosed.

Numerical simulation of anisotropic polymeric foams

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