Foam Structure Research Articles

Study on the foam properties of peanut oil body (POB)-based oil-in-water-in-oil (O/W/O) foamed emulsion gel: The key role played by the interface between the water phase and the outer oil phase

A novel POB-based O/W/O foamed emulsion gel was constructed. The mechanism by which POB strengthens the foamed emulsion gel was preliminarily explored by studying the microstructure and rheological properties, and the applications of POB in decoration and 3D printing were analyzed. The adsorption of POBs and their fragments might strengthen the interface between the water and internal oil phases, thereby increasing the yield stress of the system, which protected the O/W/O structure from being damaged during whipping, and formed a special foam structure where air-in-oil (A/O) structures and O/W/O structure coexist. Besides, adding POB promoted the overrun of the emulsion gel, and the maximum overrun rate was 68.6 %. Finally, POB-based O/W/O foamed emulsion gel exhibited good decoration and 3D printing performance and is expected to become a healthy and higher-quality foamed food in the future.

Ameliorating the comprehensive performance of rigid polyurethane foam insulating materials by green cork for building energy conservation

Biomass-modified polyurethane (PU) foam materials are vital to promote the sustainable development, but the balance between their mechanical strength and thermal insulating ability remains a challenge compared to the petrochemical-based PU foams. Herein, an appropriate amount of cork is introduced to fabricate PU composite foams with good thermal insulating performance and mechanical strength. The added cork could act as a nucleating agent during the foaming process, further tailor the foam structure and enhance their comprehensive performance. The optimal composite foams containing the peak cork usage of 24% also belong to the high-efficiency insulating materials, with a thermal conductivity of 0.043 W m–1 K–1, a tensile strength of 0.17 MPa, a bending strength of 0.16 MPa, and good impact resistance. This research provides valuable insights for developing the comprehensive PU insulating materials by utilizing eco-friendly cork as substitutes, and offers a reference for highly efficient utilization of biomass resources.

Comparative analysis of the physical and chemical properties of dried products "KalmaKS" from the skin of the Commander and Pacific squid

The modern system of high-quality nutrition for the population includes the use of natural compounds from secondary products of animal origin. In the course of scientific substantiation of using secondary products from the processing of cephalopods, dried products from the skin of Pacific (Todarodes pacificus) and Commander squid (Berryteuthis magister) have been studied, their protein and amino acid composition and functional and technological characteristics have been analyzed. In samples from the skin of the Pacific squid, a high content of glutamic and aspartic acids (8–10 %) is noted; in samples from the skin of the Commander squid – glycine (20 %), proline (10 %) and arginine. High indicators of solubility, water-holding capacity and stability of foam structures are due to the significant content of type I destructured collagen (in a sample from the skin of Commander squid), and hydrophilic amino acids and type III collagen fragments (in a product made from Pacific squid skin). Infrared drying of products promotes denaturation and gelatinization of collagen in the skin of Commander squid, which is confirmed by the brighter color characteristics of the samples and high moisture-binding capacity when the temperature rises to 40 and 60 °C; this fact indicates an increase in the hydrophilic properties of the products of destruction of collagen fractions. Products made from skin, which is a secondary product of squid processing, have high potential for use in the food industry as water-retaining, fat-binding, and fat-emulsifying components.

Shape memory sandwich structure with reprogrammable shape and mechanical properties

Sandwich structures are usually used in aerospace and automotive engineering fields. By selecting different core materials and panels, a large number of design strategies are proposed to obtain various types of sandwich structures for various applications. Here, we developed a kind of shape memory sandwich structure using shape memory foam and laminates. The sandwich structure can not only program its shape utilizing SME but also can adjust its mechanical properties by controlling its temperature or shape. The mechanical and thermal–mechanical properties of shape memory laminates, foam and sandwich structure were characterized, respectively. The energy absorption property and bending resistance of the shape memory sandwich structure after being programmed were studied by compression test and drop weight impact test. Shape programmable and mechanical properties adjustable suggest potential applications of this sandwich structure in an adjustable shock-absorbing interface and space deployable structure.

Impact response of additively manufactured density-graded open-cell foams

Additive manufacturing has made it possible to fabricate materials that were unachievable with traditional methods. This study focuses on understanding the deformation behavior and energy absorption mechanics of additively manufactured cellular materials with gradually varying densities. Foams have unique deformation behavior due to their intricate topology and composition, resulting in excellent energy dissipation capability. Varying the density can significantly influence their deformation response and improve energy absorption and impact resistance. Voronoi tessellation is employed to model the foams, as it effectively captures the cell morphology in foam structures and produces stochastic cellular topologies accurately. Resin-based additive manufacturing techniques are employed to fabricate cellular materials with varying density configurations for low-velocity and high-velocity impact experiments. The study demonstrates that density-graded foams effectively dissipate a broad spectrum of impact energies, surpassing uniform counterparts by transmitting reduced stress, especially at lower energy levels. This characteristic enhances their suitability for advanced energy absorption applications. The results also show that at high impact velocities, the direction of density gradation influences energy dissipation and peak stress transmission.

A time-resolved investigation at multiple-length scales of the structure of liquid foam stabilized by albumins from pea

HypothesisThe structural details of foams made with pea albumins are affected by the pH of the initial solution and followed heat treatment. ExperimentsAn in situ, time-resolved investigation of foams prepared with pea albumins was conducted using small-angle neutron scattering (SANS) in combination with imaging and conductance measurements. Solutions were tested at pH three pH values (3, 4.5, and 8) before and after heating (90 °C for 1 and 5 min). FindingsThe characteristic structures present in the foam from the nano to the meso-scale differed during drainage depending on solution pH. Foams obtained at pH 3, had the largest bubble radius and thinnest plateau border, as well as the highest extent of liquid drainage. At pH 4.5, close to the isoelectric point of the proteins, foams displayed similar bubbles’ behavior to those at pH 8, but with the largest film thickness. In this case, the proteins were extensively aggregated. Heating of the solutions prior to foaming did not significantly affect the foam aging regardless of pH. The quantification of specific surface areas and film thickness over time without sample disruption shows to be a powerful approach to designing foam structures.

In situ preparations of bi-continuous interpenetrating porous composites with high energy absorption

In this paper, porous composites with bi-continuous interpenetrating aluminum foam (AF) and lattice structure were prepared via different sequences. The effect of the preparation sequence on the mechanical properties was analyzed. The results showed that the composites prepared by disordered-ordered and ordered-disordered sequences had higher mechanical properties than the sum of their single components. Porous composite prepared by the disordered-ordered sequence had a discontinuous interface while the one prepared by the ordered-disordered sequence presented a continuous bonding interface and a bubble-free layer. The energy absorption of the porous composite structure prepared by the disordered-ordered sequence was enhanced by the factors of 0.89 and 1.12 over the sum of their single components, while the ordered-disordered was enhanced by the factor of 1.9 and 3.81, which was attributed to the metallurgical bonding, 3D mechanical constraints and the fraction of bubble-free layer that formed between the interfaces. The continuous interface contributed the excellent mechanical properties of the composites due to its higher failure strength before detaching. The presence of the bubble-free layer increased the interfacial contact area, which can effectively absorb energy and exhibit significant deformation resistance. The porous composite exhibited excellent comprehensive performance, which provided a new idea for the structurally and functionally integrated design of porous composites.

Multiscale analysis of interlocking effects for polymer additive manufacturing on aluminum foam

AbstractHybrid structures are increasingly relevant for lightweight design and functional components. Various manufacturing techniques for creating hybrid components exist, often focusing on combining metal and polymer components. The present study examines a novel approach for manufacturing hybrid functional structures by directly printing thermoplastic onto aluminum profiles using closed‐cell aluminum foam, with the mechanical interlocking resulting in a structural bond. The filling of pores in the aluminum foam with the polymer affects the bond strength of this hybrid compound. Within a simulation‐based process design the additive manufacturing process parameters are investigated using a computational fluid dynamics (CFD) model with Fluid‐Structure Interaction for the pore‐filling process and a finite element (FE) model to evaluate the resulting bond strength. The material throughput, the nozzle distance, and the polymer temperature are the key process parameters taken into account. A parameterized, virtual foam model is used within this framework, where a linear movement of the extruder nozzle and the resulting polymer strand is investigated. This method includes the mesh conversion from the CFD results to the FE mesh for structural analysis by exporting the iso‐surface for the polymer geometry embedded in the pores of the aluminum foam structure. This approach made it possible to investigate the phenomena that occur in the process in more detail, particularly to quantify the influence of air inclusions. Thus, a decisive contribution to the hybridization of aluminum foams has been made, which opens up further potential for research and application in the long term.

Construction of foam-templated Antarctic krill oil oleogel based on pea protein fibril and ι-carrageenan

Edible plant-based oleogels with zero trans-fat are promising solid fat substitutes. In this study, Antarctic krill oil (AKO) oleogels prepared from pea protein fibril (PPF) and ι-carrageenan (CG) by foam-templated method were developed for the first time. The modulation of the ratio of PPF and CG concentration on the structure and properties of foam, cryogel and oleogel was investigated and the potential formation mechanism of the foam-templated oleogel was explained. The results demonstrated that the addition of CG significantly decreased the foam size and enhanced the foam stability. The oil absorption and oil holding ability of the dense and reticular porous structure of the cryogel was demonstrated. Fourier infrared spectroscopy confirmed the interaction between PPF and CG involved in the formation of cryogels. With the addition of CG, the network structure and mechanical strength of the cryogel were reinforced, leading to more compact pores and higher capillary suction, which was appropriate for the establishment of good viscoelastic semi-solid oleogels. In addition, the oleogel was effective in masking the fishy odor of AKO. The significance of this study lies in its provision of a novel approach to the preparation of the foam-templated oleogel with PPF and CG as the oleogelators.

On the Potential of Manufacturing Multi-Material Components With Micro/Nanocellular Structures Via the Hybrid Process of Electromagnetic Forming Injection Foaming

Abstract Multimaterial design with a combination of solid and foam structures offers a promising avenue for reducing component weight while enhancing their functionalities. However, the complexity of multistage manufacturing processes poses significant challenges to adopting such approaches. To address these challenges, this paper introduces an innovative concept known as Electromagnetic Forming Injection Foaming (EFIF), which integrates injection molding, forming, and foaming processes into a single hybrid process. This process begins with a simultaneous filling-forming phase, followed by supercritical fluid (SCF) assisted foaming controlled by electromagnetic forming. Through a series of experimental and analytical studies, this work investigates the feasibility and effectiveness of EFIF. First, the impact of pressure drop rate and pressure drop on cell size and density is examined through a specialized experimental setup enabling performing injection, forming, and foaming processes in a single operation. The potential influence of electromagnetic forming on foam injection molding is explored through experiments focusing on the effects of a polymer layer between sheet metal blank and the electromagnetic coils. Additionally, an analytical study evaluates the EFIF process by calculating expected pressure drop rates under different processing conditions and their influence on cell nucleation rates. The results showed the possibility of achieving pressure drop rates up to 1.5 × 105 bar/sec, resulting in nucleation rates up to 1.77 × 109 nuclei/cm3sec. Overall, this paper highlights the potential of EFIF to merge existing technologies into a scalable solution for manufacturing multimaterial components with micro- to nanocellular polymer foams.

Simple Nickel Foam Modification Procedures for Enhanced Ni Foam Supercapacitor Applications

The three-dimensional and porous structure of nickel foam makes it an attractive material for employment in cost-effective electrochemical supercapacitors. This communication presents ac. impedance spectroscopy and cyclic voltammetry electrochemical examinations of potential supercapacitor electrode materials, fabricated by means of simple electrochemical procedures, employed to as-received Ni foam material. This involves the electro-oxidation and Co-catalytic modifications of baseline nickel foam samples. Hence, the supercapacitor-type performance (as evidenced over the examined potential range in 0.1 M NaOH solution) of base nickel foam material could extensively be tailored by means of simple surface and catalytic refinements. The latter was evidenced through the employment of combined electrochemical (cyclic voltammetry, ac. impedance) and SEM/EDX (Scanning Electron Microscopy/Energy Dispersive X-Ray) surface spectroscopy evaluations.

Numerical study on the combined application of multiple phase change materials and gradient metal foam in thermal energy storage device

Latent heat thermal energy storage (LHTES) offers significant energy-saving benefits, but its application is limited due to the low thermal conductivity of phase change material (PCM). To address this issue, this article studied the combined application of metal foam structures with different porosity gradients and multiple PCMs with different melting points through numerical simulation to accelerate the melting of PCM and enhance system efficiency. The results showed that the application of multiple PCMs improved the heat transfer performance of the system, reducing the complete melting time by 9.18% compared to using a single PCM with uniform metal foam. Based on the multi-PCM storage system with an average porosity of 0.90, this article designed metal foam structures with one-dimensional and two-dimensional porosity gradients and explored their impacts. The results indicated that in the structure with a one-dimensional porosity gradient along the heat flow direction, the positive gradient decreased thermal resistance, further reducing the complete melting time by 6.18%, while the negative gradient increased it by 19.78%. However, the temperature non-uniformity was lowest with the negative gradient and highest with the positive gradient. The optimal two-dimensional porosity gradient multi-PCM storage model not only reduced thermal resistance but also effectively solved the issue of uneven melting, reducing the complete melting time by 17.96% and increasing the energy storage efficiency by 20.16% compared to the single PCM system with uniform porosity. Furthermore, the article conducted a dimensionless analysis of the optimal structure and different gradient structures, establishing formulas for the liquid fraction concerning modified Fourier number, modified Stefan number, and modified Rayleigh number.

Coupling Liquid Electrochemical TEM and Mass-Spectrometry to Investigate Electrochemical Reactions Occurring in a Na-Ion Battery Anode.

A novel approach for investigating the formation of solid electrolyte interphase (SEI) in Na-ion batteries (NIB) through the coupling of in situ liquid electrochemical transmission electron microscopy (ec-TEM) and gas-chromatography mass-spectrometry (GC/MS) is proposed. To optimize this coupling, experiments are conducted on the sodiation of hard carbon materials (HC) using two setups: in situ ec-TEM holder and ex situ setup. Electrolyte (NP30) is intentionally degraded using cyclic voltammetry (CV), and the recovered liquid product is analyzed using GC/MS. Solid product (µ-chip) is analyzed using TEM techniques in a post-mortem analysis. The ex situ experiments served as a reference to for insertion of Na+ ions in the HC, SEI size (389 nm), SEI composition (P, Na, F, and O), and Na plating. The in situ TEM analysis reveals a cyclability limitation, this issue appears to be caused by the plating of Na in the form of a "foam" structure, resulting from the gas release during the reaction of Na with DMC/EC electrolyte. The foam structure, subsequently transformes into a second SEI, is electrochemically inactive and reduces the cyclability of the battery. Overall, the results demonstrate the powerful synergy achieved by coupling in situ ec-TEM and GC/MS techniques.

Study of three-dimensional spatial diffuse discharge in contact electrode structure applied to air purification

In this work, based on the role of pre-ionization of the non-uniform electric field and its effect of reducing the collisional ionization coefficient, a diffuse dielectric barrier discharge plasma is formed in the open space outside the electrode structure at a lower voltage by constructing a three-dimensional non-uniform spatial electric field using a contact electrode structure. The air purification study is also carried out. Firstly, a contact electrode structure is constructed using a three-dimensional wire electrode. The distribution characteristics of the spatial electric field formed by this electrode structure are analyzed, and the effects of the non-uniform electric field and the different angles of the vertical wire on the generation of three-dimensional spatial diffuse discharge are investigated. Secondly, the copper foam contact electrode structure is constructed using copper foam material, and the effects of different mesh sizes on the electric field distribution are analyzed. The results show that as the mesh size of the copper foam becomes larger, a strong electric field region exists not only on the surface of the insulating layer, but also on the surface of the vertical wires inside the copper foam, i.e., the strong electric field region shows a three-dimensional distribution. Besides, as the mesh size increases, the area of the vertical strong electric field also increases. However, the electric field strength on the surface of the insulating layer gradually decreases. Therefore, the appropriate mesh size can effectively increase the discharge area, which is conducive to improving the air purification efficiency. Finally, a highly permeable stacked electrode structure of multilayer wire-copper foam is designed. In combination with an ozone treatment catalyst, an air purification device is fabricated, and the air purification experiment is carried out.

Photocurable Foam for Three-Dimensional-Printed Porous Structures.

In this research, a foam three-dimensional (3D) printing method using digital light processing (DLP) technology was developed to fabricate 3D-printed porous structures. To address the challenges in preparing DLP precursor foam fluid, we designed a specialized foaming device. This device enables the precursor solution to be blended with air, resulting in a stable foam precursor with an adjustable air/liquid fraction and suitable fluidity, crucially enhancing the gas-liquid contact time for the printing process. By manipulation of fluid flow rates, cycle counts, and gas/liquid ratios, one can easily prepare uniform foams with precise control over the pore size and porosity. To avoid significant volume reduction during ultraviolet (UV) curing, nanoparticle fillers were introduced into the network to prevent collapse of the foam structure. Furthermore, the inclusion of an UV absorber enhanced the quality of the printing process by addressing the limitations associated with particle scattering and reflection. The DLP process can readily fabricate intricate structures, featuring a planar resolution below 30 μm and a printing accuracy of less than 1%. Several examples were also demonstrated to highlight the advantages of this technology and its ability to directly print custom foam structures, thereby saving time and material resources.

Elastomer-based soft syntactic foam with broadly tunable mechanical properties and shapability

Fabrication of lightweight composites using thermally responsive expandable microspheres (EM) embedded in an elastomeric matrix to form syntactic foams offers significant opportunities to create functional and structural composites for diverse applications. The morphology of the EM-elastomer composite on the micro- and macro-scales is significantly influenced by the fabrication sequence and parameters (composition, expansion time/temperature, etc.). Herein, we report the morphological evolution of an EM-elastomer composite through the fabrication processes and elucidate the interaction of relevant fabrication parameters. Unlike the majority of published reports on hard EM composites, the in-situ expansion of the closed-cell foam structure within a soft matrix leads to larger void sizes, and the concomitant expansive force of the EM impacts the polymer chain mobility within the soft composite. At the same time, higher EM loading improves the mechanical properties; the evolved microstructure leads to a lightweight but stiff structure. For the first time the report details the thermal expansion of EM under applied pretension, leading to irreversible prestrain-dependent morphological changes toward anisotropic mechanical properties. Additionally, the composites are shaped under constrained expansion. The study provides a comprehensive guide and expands the pathways for the practical application of EM-embedded soft syntactic foams in aerospace, electronics, wearables, robotics, etc.

Impact of Foaming Agent: Water Ratio on Foam Stability of Lightweight Concrete

Foamed concrete, renowned for its lightweight nature and thermal insulating properties, has gained substantial interest in the construction industry. The stability of foamed concrete is directly related to the stability of preformed foam used for making foamed concrete. Foam stability is the prime factor which influences the overall performance and properties of the foamed concrete. Foam stability refers to the ability of the foam to maintain its structure and volume over time. The stability of foamed concrete is greatly impacted by the selection of the foaming agent and the ratio of foaming agent to water (FA/W). Protein based foaming agent (as per ASTM C796/C796M-19) has been used for this study. An excess of water can weaken the foam structure, leading to instability, while inadequate water can lead to issues such as reduced workability and uneven distribution of foam within the mixture. This paper investigates the effect of FA:W ratio on the stability of foam concrete. Three different FA:W ratio i.e. 1:10, 1:20 and 1:30 has been used for this study. Respective slumps to these ratios have also been investigated at different time intervals to check their consistencies. Three mix proportions were used to produce foam concrete of 1000kg/m3 density. Impact of aforementioned FA/W ratios on the properties of foamed concrete (As per; IS 2185 part-4) were discussed in this article.

The impact of chelating agent pH on the stability and viscosity of CO2 foam under harsh reservoir conditions

The injection of CO2 foam into the carbonate reservoir for enhanced oil recovery (EOR) has attracted special interest in the last decades; nevertheless, the understanding of the effect of liquid solution chemistry on foam stability at high temperatures and salinities is limited. Hence, this paper fully investigates the effect of chelating agents L-glutamic acid-N, N-diacetic acid (GLDA) pH, and hydrochloric acid (HCl) on the stability and viscosity of generated CO2 foam for heterogeneous carbonate formation under reservoir conditions. In this paper, Duomeen TTM and Armovis VES surfactants were utilized due to their capabilities to produce viscous CO2 foam under harsh conditions. The foamability, foam stability, and foam structure were studied at 100 °C and 1000 psi using a high-temperature and high-pressure (HPHT) foam analyzer. The measurement of CO2 foam viscosity was determined at 100 °C, 1000 psi, and 70 % foam quality using the HPHT foam rheometer. Rheology experiments and dynamic light scattering investigated the micelle’s size or aggregation behavior of surfactants. The obtained results showed that the Duomeen TTM generated unstable foam; however, foam stability and foamability improved with the decrease in GLDA pH. Armovis VES showed excellent CO2 foam performance, where the foam half-life time of Armovis VES systems was 240 min. The liquid drainage and bubble coarsening were delayed due to the formation of the viscoelastic liquid phase. The foamability of Armovis VES was improved as the GLDA pH decreased. Furthermore, the addition of HCl to Armovis VES solution presented the highest foamability. The outcomes of the HPHT foam analyzer and HPHT viscometer proved that as the pH of Armovis VES solution decreased, higher foamability was produced. The highest foam viscosity was obtained using the synergic effect of 0.5 wt% Duomeen TTM and 0.5 wt% Armovis VES (39 cp at 100/s). In comparison, 1 wt% Armovis VES presented the lowest foam viscosity (30 cp at 100/s). The outcomes of this research can provide insight into the effect of chemistry on CO2 foam and extend its application in oilfield development. This work broadens the design of novel CO2 foam formulation, leading to the improvement of sweep efficiency in CO2-EOR methods and enhance the gas trapping in carbon storage.

Designing a Microstructure of NiCo-LDH@CNTs@Carbon Foam for Efficient Electromagnetic Wave Absorption and Excellent Environmental Tolerance.

The constantly evolving environment imposes increasingly stringent demands on the mechanical qualities of materials employed for absorbing electromagnetic waves (EMWs). Therefore, there is an urgent need for advanced materials capable of efficiently absorbing EMWs and withstanding harsh electromagnetic conditions. In this study, the electrodeposition method was effectively used to synthesize nickel-cobalt layered double hydroxides (NiCo-LDHs) in a controlled manner on a composite structure of carbon nanotubes and carbon foam, creating an exquisite construction. The manipulation of the electrodeposition time facilitated the regulation of the density of the layered structure within the composite material, thereby significantly enhancing its polarization relaxation performance. Increased defect sites and interface polarization enhance impedance matching and the attenuation constant, resulting in greatly improved absorption performance. The optimized sample demonstrated exceptional wave-absorbing performance in comparative experimental analysis, attaining a maximum reflection loss of -58.18 dB. It also has an effective absorption bandwidth of 5.36 GHz at a wavelength of 2.28 mm. The exceptional isolation effect of LDH, coupled with the outstanding insulation ability of the porous carbon skeleton, confers remarkable corrosion resistance and thermal insulation performance on the composite material. Hence, this discovery offers novel insights into designing environmentally tolerant absorbent materials.

Tuning cellular structure in a previously developed microcellular acrylonitrile butadiene styrene/thermoplastic polyurethane blend foams

AbstractThis study investigates the cell structure control in 50% thermoplastic polyurethane (TPU) and 50% acrylonitrile butadiene styrene (ABS) blend foam using CO2 as a physical blowing agent, focusing on the effects of variable foaming parameters on the microstructure. Samples measuring 25 × 25 × 1 mm were produced and analyzed for foam structure. The foaming process involved saturating the samples with CO2 gas at pressures of 4, 5.5, and 7 MPa, followed by rapid pressure release and immersion in a hot glycerol bath. The foaming parameters included varied temperatures (80, 90, and 120°C) and times (5–80 s). Scanning electron microscope (SEM) analysis provided data on cell size and density. Results indicated that increasing the saturation pressure enhanced CO2 uptake in the ABS/TPU blend, with the CO2 uptake rate peaking early in the process. Higher foaming temperatures and extended foaming times led to increased cell size, cell density, and expansion ratio. These findings highlight the significant role of process parameters in controlling the cell structure of ABS/TPU blend foams, offering valuable insights into optimizing foam properties for industrial applications.Highlights Optimization of foam parameters leads to cell structure control in ABS/TPU composite foams for industrial applications. Increasing saturation pressure significantly boosts CO2 uptake in ABS/TPU composite foams. Increasing the foaming temperature and duration leads to larger cell sizes, higher cell density, and greater expansion ratios in ABS/TPU composite foams.