Application Of Foam Research Articles

Production, thermal recycling, and application of cardanol-based polyurethane foam with phenol-carbamate bonds

The economic processing, sustainable recycling, and environmentally friendly application of polyurethane (PU) foams are important issues that need to be addressed urgently. In this study, we propose a strategy for the comprehensive utilization of cardanol and cashew shells to design cardanol-based PU (CPU) foams and wood-plastic films that can be recycled and reused. Firstly, cardanol-based polyphenols (CBPs) with a phenolic hydroxyl content of 3.29 mmol/g were prepared by Friedel-Crafts alkylation reaction using cardanol and guaiacol as raw materials. Subsequently, CPU foams were prepared by reacting CBPs with isocyanate, and the vertical and parallel compressive strengths could reach up to 0.27 MPa and 0.32 MPa, respectively, when the addition of CBPs was 80 %. These CPU foams, containing dynamic phenol-carbamate bonds, could be hot-pressed into transparent and smooth CPU films with tensile strengths of up to 30.5 MPa and could be re-formed at least three times. Finally, CPU foam and cashew shell waste were mixed and hot-pressed to produce a green wood-plastic composite with a tensile strength of up to 38.8 MPa. The resulting CPU-Wood films could be repaired or reshaped at least five times (38.0 MPa and 38.1 MPa) and could be formed into various shapes. This research paves the way for large-scale industrial production of recyclable and regenerative bio-based foams, making effective use of waste materials to achieve environmentally friendly production processes.

Development of polyamide foam by supercritical CO2: Low density, anti-shrinkage and thermal insulation

Saving energy and reducing environmental harmful emissions have become a global concern, so the foam thermal insulation materials are of great significance for saving energy, reducing greenhouse effect and ensuring the comfort and safety requirements of buildings. Polyamide12 (PA12) has outstanding weather resistance, mechanical stability and termite resistance, which is a promising building material. Herein, we prepared a series of PA12 foams by using supercritical carbon dioxide (Sc-CO2) as foaming agent, polymethyl methacrylate (PMMA) as a blend modification material, tridehydroglycerol isocyanurate (TGIC) as chain extender improved the cells wall strength and stability. When the PA12 and PMMA blending ratio was 70:30 and TGIC content was 0.2 phr, the foam density was 0.02 g/cm3, and the thermal conductivity of the foam was as low as 0.0302 W/m·K. Moreover, the influence of viscosity gradually increased with the increase of PMMA as shown by tanδ; at the same time, as an amorphous material, PMMA enlarged the melting range of the blends and reduced the enthalpy of melting. Therefore, the introduction of PMMA increased the temperature range of the foaming window to170–190 °C. This study provided an effective method for the design of foams with low density, low shrinkage, excellent mechanical properties and high thermal insulation properties, which has broad PA12 foam application prospects in the fields of buildings, such as wall or roof insulation.

Evaluation of the dynamics of oral pathogenic microbiota in COVID-19 patients by genomic sequencing after application of foam with antimicrobial action

Relevance. The COVID-19 pandemic caused by the SARS-CoV-2 virus has demonstrated the critical importance of understanding the mechanisms of transmission and finding effective methods of prevention. Particular attention has been paid to the role of oral hygiene, as the oral cavity serves as a major route of transmission. Studies show that the composition of the oral microbiota can influence the course and outcome of COVID-19 disease. Therefore, there is a need to study the effects of oral antiseptics on the microbiome, which may offer new opportunities for the prevention and treatment of this disease.Objective. The aim of this study is to evaluate the effectiveness of the oral cleansing foam «Parodontol PROF» in reducing the pathogenic microflora of the oral cavity in patients with COVID-19 and to assess its effect on the risk of secondary infections.Materials and methods. The study was conducted on the basis of the Clinical Medical Centre «Kuskovo» of Russian University of Medicine. It included 450 patients with a confirmed diagnosis of COVID-19. The participants were divided into two groups: the test group used oral cleansing foam, while the control group used no additional oral hygiene. Comparative analyses of the taxonomic composition of the oropharyngeal microbiota and dental plaque before and after the use of the cleansing foam were performed.Results. The study showed that patients who regularly used the cleansing foam «Parodontol PROF» had a significant decrease in the representation of pathogens, including Mycoplasma, and an increase in the number of beneficial commensals such as Lactococcus and Lactobacillus. These changes indicate the potential efficacy of this product to improve oral hygiene and reduce the risk of secondary infections.Conclusion. The study supports the hypothesis that improving oral hygiene with specialised antiseptic agents, such as a cleansing foam, may help to reduce pathogenic microflora in the oral cavity in patients with COVID-19. This, in turn, may reduce the risk of pathogen migration into the lower respiratory tract and the development of secondary infections. The findings emphasise the importance of further research in this area and the development of comprehensive approaches to oral hygiene management in the context of infectious diseases.

Large-Scale Fire Tests of Battery Electric Vehicle (BEV): Slovak Case Study

Due to the increasing number of battery electric vehicles (BEV) on the roads and the number of BEV accidents with the occurrence of a fire, full-scale fire tests of BEVs were carried out. For initiation, the BEVs were mechanically damaged, forming a gap with a size of 15 cm × 15 cm. The external heat source was a 300 kW propane burner with a maximum power of 54.0 kW and a length of 54 cm. The flame of the propane–butane fuel mixed in air at a temperature of 1970 °C was inserted directly into the battery pack. The increase in the temperature was monitored as a function of time through thermocouples at selected locations of the BEV until the point of initiation. Thermocouples were placed 10, 30, and 50 cm from the place of BEV surface. Accordingly, to obtain the temperature–time curves from the experiment measurement, critical temperatures were subsequently evaluated. The fire tests on BEVs can be described according to the individual phases of the fire. The external heat source started the initiation process at the 25 min time mark. Consequently, the phase of a developed fire with a dynamic course started. A sharp rise in temperature occurred. Within two minutes, the temperature rose to 1056.9 °C. After the initiation source was removed, there was decline in temperature and re-ignition to the stage of a fully developed fire. Thermocouples recorded temperatures in the range of 900 °C. The resulting dynamic process of a BEV fire with a sharp increase in temperature is a problem for the implementation of firefighting works and the liquidation of traffic accidents. Furthermore, foam extinguishing was part of the experiments. In both cases after the foam application, the temperature on the thermocouple T1 (distance was 10 cm from the surface of the BEV) dropped from 486.1 °C to 76 °C after 10 s of application.

Stable aqueous foams containing Nanoparticle-enhanced wormlike micelles as the fracturing fluids

The petroleum industry makes extensive use of aqueous foams; however, their efficacy is constrained considerably by their long-term stability. Polymers are frequently utilized to stabilize the foam stability, but potential formation damages by blocking pores cannot be ignored. In this work, wormlike micelles are employed as an alternative to traditional polymer, while cellulose nanocrystals (CNCs) are added to improve the viscoelasticity under higher temperatures. Our results confirm that CNCs-enhanced viscoelastic micellar dispersions could indeed generate the super-stable foam, which mainly contributed to their synergistic effects in the bulk rheology and interfacial properties of the continuous phase. In accordance with the long-term stability, our foams also exhibit a great sand-carrying capability, i.e., the foam containing 0.5% CNCs was able to retain the sands for over 10 h without visible settlements. Our findings advance the strategies of foam stabilization and provide a strong complement to the subsurface application of aqueous foam.

A comprehensive 3D modelling exploration of a protonic ceramic electrolysis cell stack with metal foam

Protonic ceramic electrolysis cells (PCECs) offer significant potential for large-scale green hydrogen production. The performance of conventional PCEC stacks is notably limited due to the uneven gas distribution. In this research, a new stack design using metal foam as the gas distributor is proposed and numerically evaluated using a 3D Multiphysics model to improve the gas distribution uniformity. At 1.3 V and 600 °C, the current density of the newly designed PCEC with metal foam is 173 % higher than that of the conventional PCEC. Moreover, the hydrogen production capability of metal foam based PCEC is 234 % higher than that of conventional PCEC, due to the improved gas distribution uniformity and faradaic efficiency (FE) of the new PCEC. The application of metal foam increases steam distribution uniformity by 91.2 %. In a conventional PCEC, the FE under the rib is notably lower than that under the channel. In contrast, the FE distribution is more uniform in a metal foam based PCEC. The improved performance in terms of current density, FE, and distribution uniformity highlights the potential of metal foam as a beneficial component in PCEC stacks. These findings contribute to the understanding and further development of PCEC technology.

Stochastic microstructure modeling and thermal conductivity of coal-based carbon foam

The mechanical, thermal and electrical properties and applications of coal-based carbon foam (CCF) are based on its porous structure. In the present study, a 3-D stochastic numerical program was used to model the microstructure of CCF considering its non-uniformly distributed elliptical pores (i.e., pore dispersity). The heuristic program derived from the foaming process reflected the heterogeneity of foam. Stochastic seeding was used to regulate the pore location dispersity caused by material unevenness and impurities, while the pore size dispersity was revealed by assigning dissolved gas to adjacent pores during pore growth. The structural similarity was confirmed by comparison between the established model and the actual foam in geometrical features, including ligament edge/wall thickness, pore size and ligament cross-section shape etc. The effective thermal conductivity (ETC) of the stochastic model is more sensitive to changes in porosity, compared to that of uniform model of previous literatures. The reason was suspected to be the longer heat transfer path and less cross-section variation of the ligaments of heterogeneous foam. Pore location and size dispersities were regulated in a stable range by program parameters, which indicated that the stochastic model accurately simulated the microstructural complexity of CCF.

Bio-based P–N flame retardant with ZIF-67 in-situ growth on flexible polyurethane foam with excellent fire safety performance

The wide application of flexible polyurethane foam (FPUF) poses a giant challenge to human society in terms of fire prevention and environmental pollution. To solve this problem, the lignocellulose-based P–N flame retardant (LFPN) has been developed using mechanochemical methods. It was found that FPUF treated using LFPN exhibited good flame retardancy, but suffered from high smoke generation and toxicity. The hollow dodecahedral ZIF-67 has been used for smoke suppression catalysis, but the agglomeration phenomenon makes it inefficient. Hence, in this study, the adhesive properties of polydopamine (PDA) were utilized to assist the in-situ growth of ZIF-67. The results showed that the total smoke release rate of the treated FPUF was reduced by 40.5%. The toxic gases, such as carbon monoxide (CO), hydrogen cyanide, etc., also showed the same decreasing trend. What's more, the catalytic effect of ZIF-67 itself and the synergistic effect with LFPN gave FPUF great flame retardant and smoke inhibition properties. This novel FPUF provides a new reference for achieving smoke suppression and toxicity reduction.

Experimental and data-driven analysis for predicting nanofluid performance in improving foam stability and reducing mobility at critical micelle concentration

Application of surfactant-based foam flooding is an effective approach to reduce mobility and control early breakthrough. Despite the proper performance of surfactant-based foams in decreasing the channeling of the flooded gas and water, high pressure, high temperature, and high salinity of the reservoirs put some limitations on the foam flooding efficiency. Nanoparticles are used to improve the quality of the foams, enhance stability, and transcend the limitations. Although there are many benefits of using nanoparticles in foam flooding, their performance at surfactant critical micelle concentration (CMC) is not fully investigated and the optimum nanoparticle concentration is not specified. In this study, an experimental investigation using nanosilica with surfactants at CMC to improve the stability (half-life) and mobility reduction factor (MRF) has been conducted. Furthermore, data from the literature were collected and analyzed to evaluate the change in MRF and stability for a nanofluid-based foam at CMC. Both experimental results and literature data showed that application of nanofluid-based foam is a successful approach to develop a more stable foam with lower mobility. Nanoparticle (NP) concentration is the dominant parameter at different salinities and temperatures that affects foam flow through porous media. The range of 0.2–0.4 wt% is the optimum nanoparticle concentration to develop a strong foam with acceptable performance in controlling mobility.

Experimental study of ultra-low IFT foam flooding for low permeability reservoirs

Foam flooding is an effective oil displacement technique to improve fluid sweep efficiency and increase oil recovery. The objective of this paper is to investigate the applicability of ultra-low IFT foam flooding for low permeability oil recovery under the conditions of WX reservoir block in Tuha oilfield (84°C, 86,072 mg/L). A modified amphoteric hydroxy sulfobetaine surfactant (Cn-HSB) was formulated as a foaming agent based on the principle of compatibility with crude oil that could achieve the ultra-low interfacial tension (IFT) and strong foamability simultaneously. This is shown to reduce the oil/water dynamic IFT (DIFT) to an ultra-low value of the order of 10−5 mN/m (0.10wt%), as well as produce a foam volume and half-life of 448 mL and 2567 s, respectively. In addition, results of IFT and foam quality tests indicate that the modified Cn-HSB has good thermal stability and excellent salinity-resistance. Moreover, the ultra-low IFT foam flooding has an ideal injectivity and oil displacement efficiency in low permeability porous media that can mobilize the trapped oil in k = 1.50 × 10−3μm2 with a threshold pressure gradient of 0.115 MPa/m. This improves oil displacement efficiency about 15%OOIP. Fundamental knowledge gained from this research gives insight into the application of ultra-low IFT foam flooding in low-permeability reservoirs under a combination of specific reservoir conditions.

Fast-curing bio-based thermoset foams produced via the Michael 1,4-addition using fatty acid-based acetoacetate and acrylate

This study introduces an approach for creating bio-based polymer foams exploiting the Michael reaction that could be utilized as thermal insulation. The thermoset foams were developed using a second-generation bio-based feedstock – tall oil. Tall oil is a by-product of wood pulping in paper manufacturing and mainly comprises unsaturated fatty acids like oleic and linoleic acid. The study explores the use of tall oil-based acetoacetates (Michael donor) combined with various acrylates (Michael acceptor), petrochemical-based (bisphenol-A ethoxylate diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate), and bio-based (epoxidized soybean oil acrylate, epoxidized tall oil free fatty acids-based acrylate), to develop polymer foams that meet today's sustainability requirements. The developed polymer foams underwent extensive characterization. Matrix curing parameters were assessed by measuring changes in dielectric polarization during curing. Foaming parameters, including start and rise times, were precisely measured. The chemical composition of the foams was analysed using Fourier-transform infrared spectroscopy. Their thermal, thermo-mechanical, and mechanical properties were evaluated through thermal gravimetric analysis, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and compression tests. Additionally, the content of closed-cell and the coefficient of thermal conductivity were determined, further characterizing the foams as potential thermal insulation materials. Foams from bio-based donors with petrochemical-based acceptors exhibited a range of enhanced properties. They not only achieved high glass transition temperatures (up to 85 °C by DSC and up to 108 °C by DMA) but also displayed a spectrum of mechanical strengths (compression strength ranging from moderate to as high as ∼ 0.40 MPa) and good thermal isolation properties (thermal conductivity coefficient ∼ 31mW/(m·K)). Bio-based foams, derived from renewable resources, were characterized by properties fitting for flexible foam applications, such as low glass transition temperatures (down to −9.7 °C by DSC and down to 9.8 °C by DMA), reduced compression strength (approximately 0.011 MPa), and increased thermal conductivity (up to 46.7mW/(m·K)), indicating their potential utility in applications where flexibility is a key requirement.

Improving the performance of LiNi0.8Co0.15Al0.05O2-δ electrode-based fuel cell through cathode modification

LiNi0.8Co0.15Al0.05O2-δ (NCAL) is reported to provide dual catalytic activities of hydroxide reaction (HOR) and oxygen reduction reaction (ORR) in solid oxide fuel cell. However, it has been observed that the performance of NCAL symmetric electrodes undergoes a gradual decrease during fuel cell operation, especially the cathode, which was found to suffer from severe gas diffusion degradation. In this study, we tried to optimize the NCAL cathode by modifying the microstructure in order to increase the cathode performance under extended operation time. During the fabrication of SOFCs, various mass ratios of poly (methyl methacrylate) (PMMA) microspheres were introduced into the NCAL cathode as pore former. The affection of pore former ratio and its size on cell performance is investigated. Results suggest that properly increasing the porosity of the cathode is of significant importance for improving cathode performance, but additionally increasing the porosity of the anode by pore-former is not a wise choice. Besides, considering the oxidation of nickel foam at the cathode, comparative study on the application of nickel foam is carried out to understand its role. In addition, the performance of the cells over a continuous operation for hours has been studied to evaluate the effectiveness of the optimization method. This study provides reference for improving the performance of SOFC based on NCAL electrodes.

Technical development and application of supercritical CO2 foaming technology in PCL foam production

Polycaprolactone (PCL) has the advantages of good biocompatibility, appropriate biodegradability, non-toxicity, flexibility, and processability. As a result, PCL-based foams can successfully work in bone tissue engineering, medical patches, drug delivery, reinforcing materials, and other applications. A promising technology for producing PCL foam products is supercritical CO2 (ScCO2) foaming technology, which avoids using organic solvents, is green, and has low foaming agent costs. However, due to the limitations of ScCO2 foaming technology, it is no longer possible to use this technology alone to meet current production requirements. Therefore, ScCO2 foaming technology must combine with other technologies to develop PCL foam products with better performance and matching requirements. This paper systematically reviews the technological development of ScCO2 foaming in producing PCL foams. The molding process of ScCO2 foaming and the conventional preparation process of PCL foam products are discussed comprehensively, including the preparation process, advantages, and disadvantages, challenges faced, etc. Six combined technologies for ScCO2 foaming in the production of PCL foams and the applications of PCL foams are presented. Finally, the future remaining research for producing PCL foams by ScCO2 foaming is analyzed.

Effect of carbon nanotubes content on compressive properties and deformation behaviors of aluminum matrix composite foams

The incorporation of nano carbon reinforcement is a useful strategy to broaden the engineering applications of metal foams. In this work, carbon nanotubes (CNTs) reinforced aluminum (Al) matrix composite foams (CNTs/Al composite foams) with different CNTs content are prepared by combining ball-milling technique with powder metallurgy method. The result shows that the appropriate content of CNTs can reduce the pore size, improve the circularity, and enhance the compressive properties. Especially, the 1.0 wt% CNTs/Al composite foams possess the optimal compressive properties of yield stress (7.90 MPa), plateau stress (8.75 MPa) and energy absorption capacity (5.19 MJ/m3), which have an enhancement of 23.24%, 98.41% and 84.70%, respectively. Composite foams undergo shear deformation throughout the quasi-static compression process, and the failure mode performs as the brittle mode combined with ductile mode. Meanwhile, the incorporation of CNTs can contribute to the inhomogeneous distribution of the Si phase, provide more nucleation sites, and significantly refine the pore size. It is confirmed that the CNTs in composite foams contribute the grain refinement and the formation of micro stacking faults, making the mechanical properties of CNTs/Al composite foams outperform the counterpart of Al-Si foams. Moreover, due to the weak interfacial reaction, the low content of aluminum carbide is formed, which can promote the load transfer between CNTs and Al. The present finding provides a theoretical and practical design strategy to the future preparation of CNTs/Al composite foams.

Ceramic Based Foam Filters and Applications: A Brief Review

Yüksek oranda gözeneklilik içeren metal, seramik ve polimerler günümüzde giderek artarak yaygın bir şekilde kullanılmaktadır. Metalik ve polimerik gözenekli yapıların zıttına, kırılganlıkları sebebiyle seramik malzemelerde gözenekler tercih edilmez. Buna rağmen, son yıllarda bilhassa yüksek sıcaklık, aşındırıcı ve korozif şartların olduğu ortamlarda gözenekli seramiğin tercih edildiği uygulamalarda artma söz konusudur. Gözenekli seramikler, metal ve polimerlerle kıyaslandığında yüksek sıcaklık dayanımına ve çevresel kararlılığa ihtiyaç duyulan uygulamalarda avantajlara sahiptir. Gözenekli seramikler, son zamanlarda kemik yerine kullanılan biyo-malzemelerde, termal yalıtım malzemelerinde, polimer ve metal matriksli kompozit malzemeler gibi dikkat çekici uygulama alanlarında kullanılmaktadır. Uygulama alanları açık ve kapalı gözenek yapılarına göre farklılık arz etmektedir. Açık gözenekli seramik malzemeler sıvı metal ve gaz filtrelerinde kullanılırken, termal yalıtım malzemeleri, kapalı gözenekli seramikler refrakter astarları ve hafif yapı malzemelerinde kullanılır. Temel gözenekli seramik üretim metodları kısmi sinterleme, replikasyon yöntemi, doğrudan köpükleştirme yöntemi ve karbon preformlarının CVD yöntemiyle kaplanmasıdır. Gözenekli seramikleri köpük, içi boş küreler, bal peteği ve fiberler gibi pek çok farklı formda üretmek mümkündür. Bu çeşitli formların içinde köpük filtreler en yüksek gözeneklilik oranına sahiptirler.

Polypropylene re-entrant foams with high energy absorption realized by vacuum-counter pressure-assisted supercritical CO2 foaming

Manipulating the cellular microstructure is an important means to alter the mechanical properties and expand the application of polymer foams. Herein, a vacuum-counter pressure-assisted supercritical CO2 foaming (V-CP foaming) process was developed to fabricate polypropylene (PP) foams with closed re-entrant cell structures. The re-entrant cellular structure was realized by the combined effect of the cell over expansion during the vacuum treatment stage right after the depressurization, and the rapid cell contraction under the counter pressure of the refilled air. The morphology of the re-entrant structure could be tuned by adjusting the key processing parameters. By using butanol and scCO2 as the co-blowing agent, the over expansion and rapid contraction of cells were greatly amplified due to the plasticizing, vaporization, and liquidation of the butanol in the V-CP process. The fabricated PP re-entrant foams that have a negative Poisson's ratio possess prominent compressive properties and impact energy absorption performance.

A novel phosphorus-modified silica aerogel for simultaneously improvement of flame retardancy, mechanical and thermal insulation properties in rigid polyurethane foam

Due to the wide application of rigid polyurethane foam (RPUF) in the fields of building structural materials and thermal insulation materials, the development of high-performance RPUF composites with exceptional flame retardancy, smoke suppression, and mechanical properties is of paramount importance. In this study, we present an approach involving the amalgamation of a phosphorus-containing diol with ammonium polyphosphate to fabricate phosphorus-hybridized silica aerogel (P-SiA). The unique dual hydroxyl configuration of DDP exhibits a remarkable reactivity with silica sol, thereby facilitating the effective dispersion of APP within the silica sol. Additionally, the polyhydroxyl structure within the P-SiA enhance its compatibility with the RPUF. The compressive strength of RPUF/P-SiA-5 increased by approximately 46.4% in comparison to pristine RPUF. Furthermore, in contrast to pristine RPUF, the thermal insulation effect of RPUF/P-SiA composites were further enhanced. In addition, the effective integration of two distinct phosphorus-containing compounds in P-SiA effectively enhances the flame retardancy of RPUF composites, as substantiated by the achievement of a limiting oxygen index value of 23.2% for RPUF/P-SiA-15. Besides, relative to RPUF containing pure silica aerogel, both heat release and smoke release of RPUF/P-SiA composites are effectively suppressed. The implications of these findings propose a new strategy of tailoring material interactions and optimizing composite formulations to obtain the high-performance RPUF composites, which has a broad application prospect.

Stabilization and strengthening effects of filamentous nanocellulose in the foam forming of quartz paper

Compared with traditional papermaking, foam forming is a new papermaking technology that uses foam instead of water to disperse fibres, which can effectively solve the problem of poor evenness of ceramic paper, but the instability of foam itself affects the application of foam forming technology. Herein, a highly stable foaming agent for foam forming technology was prepared via physical reaction of lauryl dimethyl amine oxide (OB-2) with filamentous nanocellulose (cellulose nanofiber (CNF-C) and bacterial cellulose (BC)). Then, the quartz paper was prepared by foam forming technology. Firstly, hydrogen bond interactions between hydroxyl groups of the filamentous nanocellulose and hydrophilic moieties on OB-2 enabled the formation of a 3D nanonetwork layer on the surface of the bubble, which extended the half-life of the bubble and effectively prevented the bubble from bursting or coalescing. Then, the foam was extruded and cracked, and the filamentous nanocellulose was retained on the quartz fibres to prepare filamentous nanocellulose/quartz fibre paper by foam forming technology. The quartz paper exhibited excellent evenness and mechanical properties. In conclusion, the research of foam forming technology is of great significance to the application and development of special paper.

Application of foam assisted water-alternating-gas flooding and quantification of resistivity and water saturation by experiment and simulation to determine foam propagation in sandstone

Foam flooding by Foam Assisted Water-Alternating-Gas (FAWAG) is an important enhanced oil recovery method that has proven successful in experimental and pilot studies. The present study is carried out to monitor the movement of the foam front once injected into the porous medium. This study aims to investigate applications of resistivity waves to monitor foam propagation in a sandstone formation. In the present lab-scale experiments and simulations, resistivity measurements were carried out to monitor the progression of foam in a sand pack, and the relationships between foam injection time and resistivity, as well as brine saturation, were studied. The brine saturation from foam simulation using CMG STAR is exported to COMSOL and calculated true formation resistivity. A diagram was produced summarizing the progression of foam through the sand pack in the function of time, which enabled us to establish how foam progressed through a porous medium. A surfactant and brine mixture was injected into the sand pack, followed by nitrogen gas to generate the foam in situ. As foam progressed through the sand pack, resistance measurements were taken in three zones of the sand pack. The resistance was then converted into resistivity and finally into brine saturation. As foam travels through the sand pack, it is predicted to displace the brine initially in place. This gradually increases each zone's resistivity (decreases the brine saturation) by displacing the brine. Also, an increase in the surfactant concentration results in higher resistivity. Finally, a comparison of three different surfactant concentrations was evaluated in terms of resistivity results, water saturation, and foam propagation monitoring to obtain the optimum surfactant concentration involved in foam flooding.

Fabrication, Processing, Properties, and Applications of Closed-Cell Aluminum Foams: A Review.

Closed-cell aluminum foams have many excellent properties, such as low density, high specific strength, great energy absorption, good sound absorption, electromagnetic shielding, heat and flame insulation, etc. As a new kind of material, closed-cell aluminum foams have been used in lightweight structures, traffic collision protections, sound absorption walls, building decorations, and many other places. In this paper, the recent progress of closed-cell aluminum foams, on fabrication techniques, including the melt foaming method, gas injection foaming method, and powder metallurgy foaming method, and on processing techniques, including powder metallurgy foaming process, two-step foaming process, cast foaming process, gas injection foaming process, mold pressing process, and integral foaming process, are summarized. Properties and applications of closed-cell aluminum foams are discussed based on the mechanical properties and physical properties separately. Special focuses are made on the newly developed cast-forming process for complex 3D parts and the improvement of mechanical properties by the development of small pore size foam fabrication and modification of cell wall microstructures.