Foam Production Research Articles

Numerical Simulation of Aluminum Foams by Space Holder Infiltration

AbstractThis study explores the simulation and analysis of the infiltration process for manufacturing A356 aluminum alloy foams using vacuum pressure. The infiltration technique, known for its versatility in liquid-state metal processing, is widely employed for metal foam production due to its ease of application. The study investigates the relationship between the geometric parameters of the preform, system pressure, and filling times, revealing a correlation. The simulation using the Flow 3D software determines the pressure and vacuum time required to achieve successful aluminum foam without filling failures. Experimental validation through infiltration casting using NaCl as a removable preform aligns with the simulated results, yielding high-quality aluminum foam samples with diverse pore sizes (0.5 mm, 1.0 mm, and 2.0 mm), uniform and interconnected pore distribution, average porosity percentages of 65%, and a relative density of 0.35. The research contributes insights into optimizing the infiltration process for aluminum foam fabrication, bridging the gap in limited literature on cellular metals.

Factors affecting the rumen fluid foaming performance in goat fed high concentrate diet.

Feeding high concentrate diets is highly prone to rumen bloat in ruminants, which is very common in production. This study explored the factors responsible for the occurrence of foamy rumen bloat. The experiment was conducted using goats as test animals, fed high concentrate diets and scored for rumen distension into high, medium and low bloat score groups. Rumen fluid was collected from 6 goats in each group separately. The foaming production, foam persistence, pH value, viscosity and the content of protein, total saccharide and mineral elements in rumen original fluid (ROL) were measured, and the protein and total saccharide content in rumen foam liquid (RFL) and rumen residual liquid (RRL) were determined. The results showed that the protein content in rumen original fluid and rumen foam liquid was significantly higher than that in rumen residual liquid (p < 0.05), and the protein content in rumen foam liquid was 10.81% higher than that in rumen original fluid. The higher the rumen bloat score, the higher the foam production, foam persistence, viscosity, protein, Ni, Mg, Ca, and K concentrations of the rumen original fluid, and the lower the PH and Na concentrations of the rumen original fluid; correlation analysis showed that the viscosity of the rumen original fluid was significantly and positively correlated with the foam production and foam persistence (p < 0.05). Foaming production and foam persistence of rumen original fluid were significantly and positively correlated with the contents of protein, total saccharide, K, Ca, Mg and Ni (p < 0.05). and negatively correlated with the content of Na (p < 0.05); after controlling other components those were significantly related to the foaming performance of rumen original fluid only protein still was significantly positively correlated with the foam persistence of rumen original fluid (P<0.05). In summary, the contents of protein, total saccharide and mineral elements in the rumen fluid had a significant effect on the foaming performance of rumen in ruminants, with protein playing a decisive role and the other components playing a supporting role. Reducing the content of protein in the diet in production is beneficial to reduce the occurrence of rumen bloat in ruminants.

Genomic and Transcriptomic Insights into the Genetic Basis of Foam Secretion in Rice Spittlebug Callitettix versicolor.

Many animal species produce protective foams, the majority of which exhibit evolutionary adaptability. Although the function and composition of foams have been widely studied, the genetic basis of foam secretion remains unknown. Unlike most species that produce foam under specific situations, spittlebugs continuously secrete foams throughout all nymphal stages. Here, we capitalize on the rice spittlebug (Callitettix versicolor) to explore the genetic basis of foam secretion through genomic and transcriptomic approaches. Our comparative genomic analysis for C. versicolor and eight other insect species reveals 606 species-specific gene families and 66 expanded gene families, associated with carbohydrate and lipid metabolism. These functions are in accordance with the composition of foams secreted by spittlebugs. Transcriptomic analyses of malpighian tubules across developmental stages detected 3192 differentially expressed genes. Enrichment analysis of these genes highlights functions also revealed by our comparative genomic analysis and aligns with previous histochemical and morphological observations of foam secretion. This consistency suggests the important roles of these candidate genes in foam production. Our study not only provides novel insights into the genetic basis of foam secretion in rice spittlebugs but also contributes valuable knowledge for future evolutionary studies of spittlebugs and the development of pest control strategies for C. versicolor.

The Effect of Foaming Agents on the Thermal Behavior of Aluminum Precursors.

Various foaming agents can be used to achieve foaming of the precursors obtained by using the powder metallurgy method. However, the thermal behavior of pure aluminum precursors with different foaming agents has been studied very little in recent times. For the production of aluminum foams with closed cells, 1 wt.% of calcium carbonate (CaCO3), titanium hydride (TiH2), heat-treated TiH2 and zirconium hydride (ZrH2) were used. The foaming capability of the compacted precursors was investigated at temperatures 700, 720 and 750 °C. CaCO3 and TiH2 showed the best foamability at all considered temperatures, while ZrH2 achieved relatively good foaming only at the highest temperature, 750 °C. Due to their low onset temperature of the decomposition compared to the melting point of the unalloyed aluminum, in hydride-based foaming agents the drainage occurred at the bottom part of the foam samples. Among the investigated foaming agents, precursors with heat-treated TiH2 had the worst foaming properties, while CaCO3 showed the best foamability without the occurrence of drainage.

Methodology for the production of Ni-based open-cell metal foam using ultrasound-assisted electroplating

ABSTRACT Metal foam is a new type of metal that has a variety of uses because its properties can be customised to suit a specific need. Since it has the potential to replace traditional metals, it is important to explore the most advanced methods for creating foams with various levels of porosity. However, it is difficult to produce metal foam cost effectively while also achieving the desired properties due to the random structure and complexity of the process. Therefore, this manuscript outlines a step-by-step guide for creating Ni-based foam using electrodeposition, which overcomes these developmental challenges. Also, the manuscript discusses the characterisation of the foam’s integrity parameters at each stage, as well as the problems encountered during production and their solutions to optimise the developmental process. Finally, the manuscript presents mechanical testing results that demonstrate the foam’s compressive strength of 10.21 MPa at 80% length reduction, porosity of 92% and pressure drop through foam of 0.026% was reported. The developed foam can find usability in corrosive and high-temperature filtration systems, substantiated by mechanical testing results, that are also described.

Sustainable production and evaluation of bio-based flame-retardant PU foam via liquefaction of industrial biomass residues

The utilization of low-cost renewable feedstock, such as furfural residue and crude glycerol, presents great potential for advancing the bio-based polymer industry. Firstly, this study explored the feasibility of using furfural residue liquefaction in the presence of crude glycerol to synthesize biopolyols. The optimal conditions for liquefaction were determined to be 220 ℃, 3 h, with a 7% sodium hydroxide loading and 9% biomass loading. The hydroxyl and acid numbers of prepared biopolyols were found to be comparable to those of commercial polyols, which were 460 mg KOH/g and 2.25 mg KOH/g, respectively. Subsequently, newly bio-based flame-retardant polyurethane (PU) foam was produced using obtained biopolyols, isocyanate, and flame retardants. The foam demonstrated a compressive strength of 286 kPa and a density of 0.050 g·cm−3, with its thermal conductivity measured at 0.032 W·m−1·K−1. To enhance the flame retardant and insulation properties of the PU foam, 2% of modified hollow silica (Kh-SiO2) was incorporated. PU foams produced under optimal conditions exhibited a limiting oxygen index of 27.25%, demonstrating exceptional fire-retardant characteristics. Cone calorimetry tests revealed that the PU composites had a 45.7% lower peak heat release rate and a 35.7% lower smoke release rate than neat PU foam. Additionally, the synchronous thermal analyzer (STA) revealed that the PU foam exhibited potential thermal insulation performance. This study provides a technically feasible and sustainable approach to valorize furfural residue and crude glycerol for producing biopolyols and flame-retardant insulation PU foam.

Fabrication of Uniform and Rounded Closed-Cell Aluminum Foams Using Novel Foamable Precursor Particles (FPPs)

The powder metallurgy (PM) route for the production of closed-cell metallic foams has recently received a significant amount of attention. One of the major issues is the non-uniform and non-spherical nature of the cells produced, which can negatively affect the mechanical behavior. The current paper uses the PM route to process metallic foams for the first time using novel Al-TiH2 foamable precursor “particles” (FPPs). The effect of FPP content (0–10 wt.%) on the developed foam structure of aluminum and its mechanical properties is investigated. An increase in FPP content results in a decline in product density by forming uniform and near-spherical cells. The main advantage of the FPPs is the localization of the blowing agent TiH2 particle content within Al-TiH2 composite particles (i.e., giving rise to a higher local TiH2 content), which has led to the production of pores with relatively high circularities even at very low overall TiH2 contents. The foams produced displayed energy absorption capacities of 10–25 MJ/m3 at 50% strain, and maximum energy absorption efficiencies ranging from 0.6–0.7 (for 40–60% closed cell content)

Variable pressure foaming on functionality and structural properties correlation in flexible polyurethane foam

The production cost of flexible polyurethane foam is significantly dependent on the cost of polyol, which constitutes the largest percentage of materials used in foam production with the characteristics to induce superior mechanical properties. Suitable fillers that are relatively cheap can be introduced in the foam as replacement for polyol. Certain compositions of filler have deleterious effect on some relevant mechanical properties of the foam. This paper investigates the Effects of Variable Pressure Foaming on functionality and structure property correlation in polyurethane foam using different percentage of inorganic fillers at different pressure in flexible polyurethane foam for the dual purposes of achieving sustained mechanical properties of polyurethane foam and reduction in the production cost by using the VPF Technique. Government restricts the use of certain auxiliary blowing agents like chlorofluorocarbon, trichloroethane, carbon dioxide, methylene chloride, acetone, pentane and water. VPF machine, in which we can make different densities of foam without adding auxiliary blowing agents which are banned in the Europe and other countries. These blowing agents are highly carcinogenic and ozone depletors, which are also harmful for human beings’ health and greenhouse effect. Water is a natural blowing agent, producers have tried to raise the water level substantially as an ABA agent, With the high exotherm associated with high water level formulations, there is so much urea formation that it is difficult to make flexible PU foams and inferior foam quality and durability, scorching in the foam and pose a fire hazard during foam manufacturing. For the rapid cooling process, it required excess Toluene Diisocyanate usage and allowed excess TDI vapour to be released into the atmosphere. In VPF, enclosed chamber and the exhaust is vented through carbon beds, it filters the TDI fumes which are very harmful for human beings’ health and for the environment. Foams can be achieved by foaming under vacuum, thus substantially reducing the water level and TDI usage. VPF technique offers a unique combination of environmental friendliness, superior product consistency and unique foam properties. It provides us with a platform for new product technology and a reliable process to meet the increasingly stringent environmental regulations.

Varying precipitation conditions allow directing the composition and physical properties of soy protein concentrates.

Soy protein concentrates (SPCs) are common food ingredients. They typically contain 65% (w/w) protein and ∼30% (w/w) carbohydrate. SPCs can be obtained with various protein precipitation conditions. A systematic study of the impact of these different protein precipitation protocols on the SPC protein composition and physical properties is still lacking. Here, SPCs were prepared via three different protocols, that is, isoelectric (pH 3.5-5.5), aqueous ethanol (50%-70% [v/v]), and Ca2+ ion (5-50mM) based precipitations, and analyzed for (protein) composition, protein thermal properties, dispersibility, and water-holding capacity. SPCs precipitated at pH 5.5 or by adding 15mM Ca2+ ions had a lower 7S/11S globulin ratio (∼0.40) than that (∼0.50) of all other SPC samples. Protein in SPCs obtained by isoelectric precipitation denatured at a significantly higher temperature than those in ethanol- or Ca2+ -precipitated SPCs. Precipitation with 50%-60% (v/v) ethanol resulted in pronounced denaturation of 2S albumin and 7S globulin fractions in SPCs. Additionally, increasing the precipitation pH from 3.5 to 5.5 and increasing the Ca2+ ion concentration from 15 to 50mM caused a strong decrease of both the dispersibility of the protein in SPC and its water-holding capacity at pH 7.0. In conclusion, this study demonstrates that the SPC production process can be directed to obtain ingredients with versatile protein physicochemical properties toward potential food applications. PRACTICAL APPLICATION: This study demonstrates that applying different protein precipitation protocols allows obtaining SPCs that vary widely in (protein) composition and physical properties (such as protein dispersibility and water-holding capacity). These varying traits can greatly influence the suitability of SPCs as functional ingredients for specific applications, such as the production of food foams, emulsions, gels, and plant-based meat alternatives. The generated knowledge may allow targeted production of SPCs for specific applications.

Investigating the potential of dihydroxystearic acid as feedstock for rigid polyurethane foam

Rigid polyurethane (PU) foam has been widely used for a multitude of applications, primarily as thermal insulation materials. With the exhortation of “green chemistry” and sustainable development, bio-based polyols are being introduced to replace the conventional petrochemical-based polyols. Hence, the use of 9, 10-dihydroxystearic acid (DHSA), derived from palm oil-based oleic acid, as a feedstock for rigid PU foam production was explored. In this study, the effects of the weight ratio percentage of DHSA on the characteristics of the resulting PU foams were investigated. The DHSA was utilized as a co-polyol to synthesize rigid PU foams by reacting with the diisocyanate compound, blowing agent and additives. In general, the effects of DHSA in the formulations on the quality of the foams were relatively similar to PU formulation without the addition of DHSA, particularly in terms of density, compressive strength, thermal conductivity, cell structure and dimensional stability. The remarkable effect of DHSA addition in the PU formulations was observed through the open PU cell content using a pycnometer and scanning electron microscopy (SEM). The addition of DHSA has the ability to open the cell structure of the resulting rigid PU foams. The open cell content increased notably from 6.83% to 90.99% when the DHSA content was increased from 0% to 50%. The ability of DHSA to produce open-cell rigid PU foam widens up the potential applications of rigid PU foams as sound absorption materials.

The Application of Box-Behnken Design for Investigating the Supercritical CO2 Foaming Process: A Case Study of Thermoplastic Polyurethane 85A.

Thermoplastic polyurethane (TPU) is a versatile polymer with unique characteristics such as flexibility, rigidity, elasticity, and adjustable properties by controlling its soft and hard segments. To properly design and understand the TPU foaming process through supercritical CO2, a design of experiments approach, the Box-Behnken design (BBD) was adopted using commercial TPU 85A as the model compound. The effect of saturation pressure, saturation temperature, and immersion time on the mean pore size and expansion ratio were investigated. The design space for the production of TPU foam was shown, and the significance of process parameters was confirmed using the analysis of variance (ANOVA). In addition, extrapolation foaming experiments were designed and validated the feasibility of the response surface model developed via BBD. It was found that the pore size of TPU 85A foam could be controlled within 13 to 60 μm, and a stable expansion ratio could be designed up to six.

Acid-catalyzed Kraft lignin liquefaction for producing polyols and polyurethane foams

This study investigates the use of acid-catalyzed lignin liquefaction for the production of polyols and polyurethane foams. The liquefaction process was carried out using a kraft lignin powder following a process similar to the Lignoboost® method, based on a previous study, with catalyst (sulfuric acid) weight contents of 0, 3 and 6 wt.% in relation to the lignin. The PU foams were prepared by the free expansion method and analyzed by Fourier transform infrared spectroscopy (FT–IR), thermogravimetry (TG), differential scanning calorimetry (DSC), dynamic-mechanical analysis (DMA), as well as contact angle and apparent density evaluations. The effect of the catalyst concentration on yield, moisture content and molecular weight of the resulting polyols was assessed, and the optimal conditions were obtained for 6 wt.%. FT–IR analysis indicated a suitable foam polymerization. The incorporation of an acid catalyst led to a more hydrophilic foam and a rigid cell structure, with thinner and more uniformly sized cells, as well as higher thermal stability and glass transition temperature.

Insights into Factors Influencing Thermoplastic Elastomer (TPE) Foam Production and the Role of Induced Crystallization

Insights into Factors Influencing Thermoplastic Elastomer (TPE) Foam Production and the Role of Induced Crystallization

Ion-specific effects on foam films and foam from diluted solution of sodium dodecyl sulfate

The ion-specific effects on extremely diluted solutions of surfactants are poorly studied. The effect of Li+ , Na+ and K+ ions on the properties of foam films and foam stabilized by 0.05 mmol/L sodium dodecyl sulfate (SDS) was studied. Each one of the salts LiCl, NaCl and KCl in the concentration range of 1.1 mmol/L to 50 mmol/L was added to 0.05 mmol/L solution of SDS, for studying the properties of its foam films and foams. It was established that the surface potential of the foam films does not depend on the type of salt added, which means that no ion-specific effects are registered. On the contrary, such effects are evident in the case of foam produced by sparging of gas through porous bottom of column containing the same solutions. Thus, the rates of foaming, foam decay and the foam lifetime vs. the concentration of added salt (LiCl, NaCl and KCl) were studied by means of Dynamic Foam Analyzer (DFA-100, Kruss Ltd, Germany). The foam production number for each one of these cases was calculated as well. It was established that both NaCl and KCl boost the foam, the first one of which being stronger than the second one. On the contrary, LiCl has no effect on the foamability of the system. The present study is an example for manifestation of a salt-specific effect under dynamic conditions, which vanishes under static conditions.

Efficient solar-driven steam generation for clean water production using a low-cost and scalable natural rubber composite sponge

Utilizing well-established foam production technology facilitates the scalability of the methodology described in this study, allowing SSG materials to rapidly transition from the laboratory to commercial and real-world applications.

Adhesive properties of Aphrophoridae spittlebug foam.

Aphrophora alni spittlebug nymphs produce a wet foam from anal excrement fluid, covering and protecting themselves against numerous impacts. Foam fluid contact angles on normal (26°) and silanized glass (37°) suggest that the foam wets various substrates, including plant and arthropod surfaces. The pull-off force depends on the hydration state and is higher the more dry the fluid. Because the foam desiccates as fast as water, predators once captured struggle to free from drying foam, becoming stickier. The present study confirms that adhesion is one of the numerous foam characteristics resulting in multifunctional effects, which promote spittlebugs' survival and render the foam a smart, biocompatible material of biological, biomimetic and biomedical interest. The sustainable 'reuse' of large amounts of excrement for foam production and protection of the thin nymph integument suggests energetic and evolutionary advantages. Probably, that is why foam nests have evolved in different groups of organisms, such as spittlebugs, frogs and fish.

Analysis of Polyurethane Foam Machining Parameter Influence: Current Status and Perspective

Nowadays, polyurethane (PU) foam has successfully replaced various engineering materials in many applications due to its many advantages in mechanical and thermal properties. In various applications, PU foam must be formed into various 3-dimensional models according to user requirements by utilizing CAM software and CNC milling machining to manufacture a product. Thus, the selection of cutting parameters in the milling machining process in terms of the nature and character of the material and cutting tools is essential and significantly influences the geometric structure and surface roughness of the PU foam products produced. Based on the review of this article, several machining parameters must be appropriately considered, including spindle rotation speed, depth of cut, cutting tool selection, and feed rate. Vibration will increase as the spindle rotation speed increases, which brings cutting tools but results in better surface quality. Continuous chip formation can be achieved by selecting the proper cut depth and producing low surface roughness values. Selecting suitable cutting tools and geometries that match the material characteristics can reduce the risk of material damage during the machining process, thereby reducing the surface roughness value. Finally, a low cutting rate will minimize surface roughness but increase the risk of cutting-edge wear.

Graphene and coltan

The clean and renewable energy scenario has gone through a transformation process with the discovery of new generation sources and devices for their storage. Sustainable and efficient solutions are sought to satisfy the growing energy demand of today's population. The environmental problems related to fossil fuels are recognized throughout the world, but to abandon them and for renewable energies to cover current demand, they must not only deliver enough energy but must also be accumulated and transported. In this perspective, batteries play an important role in different areas, from energy storage to powering electronic devices, electric vehicles, etc. Electronic devices use relatively little power, so even small improvements in batteries have driven big changes in their performance and daily use. The functionalities of graphene and coltan make them ideal for a variety of applications, which are at the same time development opportunities for Colombia, such as water purification and desalination, catalyzing systems for the production of hydrogen and foams for lighting purposes, and a rapid heating element; graphene used as a photocatalytic coating material in smart buildings can purify the air in cities; It is also a promising material in the fields of printed electronics, sensors, graphene-based field-effect transistor (GFET) biosensors, optical biosensors, and photovoltaic cells. The possibility of incorporating graphene microchips implanted in teeth for bacterial detection and monitoring of oral hygiene is currently being studied, which could facilitate the study and prevention of periodontal diseases in the future; At the University of Manchester, new graphene condoms were obtained thanks to graphene composite polymers, which provide a higher heat transfer rate, improving sensitivity and the ability to disperse active drugs to prevent sexually transmitted diseases uniformly, pregnancy or even increase sexual pleasure. Graphene sheets have also recently been used to measure blood glucose levels through sweat and deliver pharmacological doses through the skin. This research focuses on a case study: the sizing of a Lithium battery with graphite in both electrodes as an alternative solution for greater energy storage. In this process, the participation of graphite in both electrodes is expanded, specifically in the coating of the cathode through layers to reduce losses and thereby improve battery storage. With this proposal, both the anode and the cathode will be made up of intercalator materials (graphite), different from the metallic lithium anode, which is dangerous, and the Li+1 ion can travel reversibly between them. As a result of the work, the structure of the new battery that will be built and tested in the following stages of the research was designed in SolidWorks software.

A novel semi-continuous preparation mode of ultra-low density thermoplastic polyurethane foam

The production of elastomer foam commonly faces challenges like low production efficiency, limited controllability, uneven foaming, and inherent shrinkage characteristics, especially in manufacturing thick foam sheets. Addressing these, this study introduces innovative “semi-continuous foaming with ultra-low-pressure” (SFU) strategy that integrates low-temperature gas-locking, conduction-microwave heating, and N2-assisted gas-exchange, aimed at optimizing the entire process of TPU foam production, from manufacturing and storage to post-processing. The low-temperature gas-locking scheme realizes semi-continuous preparation of elastomer foam; the conduction-microwave heating scheme significantly improves the heating speed and uniformity; and the N2-assisted gas exchange scheme prevents elastomer foam shrinkage, facilitating the creation of high expansion ratio foam. This process offers the flexibility to adjust initial cell sizes (5–30 μm after shrinkage) and expansion ratios (1–24 times) by manipulating parameters such as microwave radiation time, power, and saturation time. Furthermore, the foam was prepared under ultra-low pressure (<7 MPa), resulting in a final expansion exceeding 14.2 times TPU thick sheet (5 mm thickness before foaming) foam with excellent resilience (energy loss coefficient ∼ 10 % and ball resilience ∼ 68.8 %). This study explores the mechanism by which TPU can self-absorb during microwave heating and extends this process to TPU materials with varying thicknesses (16.5 mm thickness before foaming) and chain compositions, as well as different types of elastomeric materials or materials with elastomer-like properties (e.g., PBAT, etc.). The SFU strategy not only significantly reduces energy and gas consumption but also steers the technological advancement of foam production towards a greener and more sustainable future.

Effect of Mg Content Change on the Production of Closed-Cell Aluminum Alloy Foam by Selective Laser Melting

Effect of Mg Content Change on the Production of Closed-Cell Aluminum Alloy Foam by Selective Laser Melting