Application Of Foam Research Articles

Partial discharge characteristics of syntactic foam filled with hollow polymer microspheres

AbstractSyntactic foam materials, due to their advantages of low densities, low water absorption, and high dielectric strengths, have significant application potential in the cores of post insulators. However, because of a large number of microbubble structures within the syntactic foam, it might decrease the partial discharge inception voltage. It is necessary to investigate the partial discharge characteristics of the foam to assess the feasibility of its internal insulation application. In this study, the syntactic foam samples with four different microsphere contents (0%–2%) were prepared, and the physical structures of the materials were characterised by using Fourier transform infrared spectroscopy, scanning electron microscopy, and three‐dimensional computed tomography. Subsequently, finite element simulations of the electric field were performed to analyse the influence of the microsphere content and distribution on the internal electric field of the syntactic foam. The results suggested that both the microsphere content and distribution affected the partial discharge activity. When the microsphere content was low, the doping of microspheres essentially meant that more air gap defects were present, leading to a decrease in the partial discharge performance. However, when the microsphere content was high, the microspheres were distributed in a dense and orderly manner, improving the field concentration phenomenon and hence inhibiting the partial discharge to a certain extent. In conclusion, the findings of this study provide a data reference and theoretical support for the application of syntactic foam in the cores of composite post insulators.

Auxetic Closed Cell Nylon Foams Produced by Vacuum and Mechanical Compression (VMC)

AbstractThis research presents a method to convert a conventional Nylon closed cell foam, with a density of 48 kg m−3, into auxetic metamaterials with densities ranging between 68 and 138 kg m−3. The samples are produced by applying vacuum and mechanical compression techniques. The study reports on the effect of processing parameters such as vacuum time, temperature, and mechanical pressure. Under optimized conditions, the resulting auxetic foams exhibit a tensile Poisson's ratio as low as −0.86, while the minimum compressive Poisson's ratio for the same sample reached −0.16. Based on morphological analyses via scanning electron microscopy (SEM), structural changes induced by the treatment are determined to relate with tensile and compressive properties, including modulus and strength, as well as the analysis of the stress level for different strains. The characterizations also include differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) for the Nylon foam before and after conversion. These findings underscore the potential applications of these auxetic foams in sports and military protective gears, as well as energy dissipation systems.

A Comprehensive Literature Survey of Advanced Foam Applications in Petroleum Engineering for Enhanced Oil Recovery.

A Comprehensive Literature Survey of Advanced Foam Applications in Petroleum Engineering for Enhanced Oil Recovery.

Pottery‐Inspired Flexible Fire‐Shielding Ceramifiable Silicone Foams for Exceptional Long‐Term Thermal Protection

AbstractOwing to their preeminent properties, including mechanical flexibility, thermal insulation, and low cost, silicone foams are widely used in industrial fields. However, flame‐induced structural failure greatly restricts their practical applications. It is challenging for flexible silicone foams to realize reliable thermal protection in thermo–mechanical–oxidative environments. Inspired by traditional pottery, a multiscale‐filler synergistic ceramifiable strategy for creating silicone foam nanocomposites with flexibility and long‐term fireproofing is proposed herein. The foam materials not only maintain mechanical flexibility and elasticity (≈2% residual strain after 1000 cycles) at a temperature range of −60–210 °C but also exhibit exceptional long‐term (>30 min) thermal insulation upon exposure to ≈1300 °C oxidative environments because of their ability to form a gradient robust porous ceramic structure. Moreover, the foam material can provide stable thermal protection for electric cables and lithium‐ion battery packs, making it one of the most reliable thermal insulation materials so far. This work broadens the applications of silicone foams in emerging fields where mechanical buffering and fireproofing are required.

A novel in-situ fibrillation enhancement strategy to achieve super-elastic green foam with enhanced biodegradation

Driven by concerns about the escalating environmental pollution caused by the widespread use of plastic products, there is considerable interest in developing high-performance biodegradable materials. Poly(butylene adipate-co-terephthalate) (PBAT) foams are recognized as a highly sought-after candidate for alleviating plastic pollution, distinguished by their admirable biodegradability and flexibility. However, the extensive applications of PBAT foam are considerably constrained by inadequate melt strength and inherent shrinkage. Herein, a pioneering and scalable strategy, combining the shear-induced in-situ fibrillation process with microcellular foaming, was devised to achieve lightweight and super-resilient PBAT/poly(tetrafluoroethylene) (PTFE) foams. Thanks to the heterogeneous nucleation effect and complex tangled physical networks induced by in-situ nano-fibrillated PTFE, the crystallization and viscoelasticity of PBAT matrix experienced a dramatic enhancement, further bolstering its foaming capabilities and suppressing the shrinkage process. More importantly, the synergy of reduced foam density and reinforcement effect of PTFE nanofibrils played a crucial role in improving the remarkable compression of PBAT/PTFE foams. These foams showed a maximum increase of 40.2 % in strength and 16.3 % in resilience compared to pure PBAT foams. Moreover, the thermal insulation and soil degradation capability of PBAT/PTFE foams were substantially enhanced, achieving 10.3 % biodegradation after just 2 months. This innovative strategy offers a promising avenue for developing high-performance eco-friendly biocomposites.

Performance of the polyurethane foam injection technique for road maintenance applications

Road infrastructure plays an important role in strengthening transportation and driving the economic advancement of countries. However, the increasing traffic volume has accelerated road deterioration, particularly at critical points like bridge-road junctions. Traditional repair methods involving demolition and reconstruction lead to extended closures and high costs. This study explores the polyurethane (PU) foam injection technique as an alternative solution, which can reduce both repair time and costs. The research evaluates the application of PU foam in various road projects across Thailand, highlighting its ability to repair pavement surfaces and structures, even in severely damaged areas. Despite its advantages, the use of PU foam faces challenges due to a lack of standardized quality control. This paper proposes a set of working guidelines for PU foam injection, aimed at key stakeholders such as the Department of Highways, the Department of Rural Roads, and the Department of Local Administration. The findings underline the importance of establishing standardized methods to ensure the long-term effectiveness of PU foam in road maintenance. Future research should focus on refining these guidelines for diverse road conditions to support the sustainable development of national transportation infrastructure.

Effect of the Application of Vibration Foam Rollers Before and After Resistance Exercise on Blood Muscle Injury Markers and Muscle Stiffness

Background: This study aimed to compare the effects of applying a vibrating foam roller before resistance exercise versus after resistance exercise on changes in serum muscle damage markers, muscle stiffness, and range of motion. This study also aimed to provide foundational data for optimizing the timing of vibrating foam roller application to enhance recovery after resistance exercise in practical settings.Methods: Twelve healthy adult males were recruited as participants. Each participant was subjected to three interventions in a random order with a washout period of at least 5 days: vibration foam rolling before resistance exercise, vibration foam rolling after resistance exercise, and resistance exercise without vibration foam rolling. Blood creatine kinase, knee flexion range of motion, and muscle stiffness were measured before, immediately after, 24 hours after, and 48 hours after exercise and foam rolling protocols.Results: Creatine kinase levels in vibration foam rolling after resistance exercise were significantly lower than those in vibration foam rolling before resistance exercise at 24 and 48 hours post-exercise. Muscle stiffness was significantly lower immediately and 24 hours post-exercise in vibration foam rolling after resistance exercise than in vibration foam rolling before resistance exercise and resistance exercise without vibration foam rolling. Knee flexion range of motion was significantly lower in resistance exercise without vibration foam rolling than in vibration foam rolling after resistance exercise at 24 and 48 hours post-exercise.Conclusions: The application of vibration foam rolling after resistance exercise was more effective than that before exercise in decreasing muscle damage markers, reducing muscle stiffness, and improving the range of motion.

A monolithic self-supporting ZnFe2O4/ZnO/ZnNi foam photocatalyst and application in the decomposition of gaseous benzene

Volatile organic compounds (VOCs) are major air pollutants which seriously affect ecological environment and pose threats to human health. In this investigation, a monolithic self-supporting ZnFe2O4/ZnO/ZNF(ZFO/ZnO/ZNF) photocatalyst was developed by in-situ growing ZnFe2O4 and ZnO on ZnNi foam (ZNF). Using benzene as a representative of the target gaseous contaminants, the optimal 5ZFO/ZnO/ZNF achieved a 99.8 % removal efficiency and 99.7 % mineralization efficiency within 20 min at an initial benzene concentration of 600 ppm under simulated sunlight irradiation. Moreover, this catalyst presents the lower ullage during gas–solid reaction, and thus enables durable recycling reuse of the photocatalyst, which still retains a 95.8 % benzene decomposition after 30th consecutive run. The mechanism studies reveal that the metal-mediated Z-type heterostructure of ZFO/ZnO/ZNF enhances rapid transportation of the photo-generated electrons and promotes redox potential, leading to the excellent photocatalytic oxidation activity and mineralization efficiency. This study highlights the potential of self-supporting monolithic metal-mediated catalysts and provides a key strategy for effective VOCs degradation.

Application of Foam for Enhanced CO2 Geological Storage: A Mini-Review

Application of Foam for Enhanced CO₂ Geological Storage: A Mini-Review

Visualization Experimental Investigation on Flow Regulation and Oil Displacement Characteristics of Gel Foam in Fractured-Vuggy Carbonate Reservoirs.

Fractured-vuggy reservoirs experience severe channeling during water and gas injection operations, and conventional foam shows weak regeneration capabilities in large-scale fracture spaces, thus failing to effectively seal them. Gel foam combines the advantages of both foam and gel, significantly enhancing the foam's stability and showing good suitability in fractured-vuggy reservoirs. In this article, the plugging and flow regulation properties of gel foam in fractures were studied through fracture displacement experiments. The dynamic plugging capability of gel foam was superior to that of ordinary foam, and its plugging effect was significantly influenced by the fracture opening. Gel foam had strong retention capacity in fractures, and after plugging large-opening fractures, the diversion rate of small-opening fractures was increased by at least 83.3 times during subsequent parallel water flooding, making the flow regulation effect remarkable. Through the oil displacement experiments in typical fractured-vuggy models, the profile control law and enhanced oil recovery performance of gel foam under different fractured-vuggy structures were studied. In the regular fractured-vuggy network, gel foam adhered to occupy the fractured-vuggy space for plugging and controlled the top gas migration direction to synergistically drive the recovery of remaining oil, ultimately achieving a recovery of 95%. In the combination of fractures and irregular vugs, due to the density, gel foam continuously pushed down and right along the fractures to the vugs, pushing the crude oil and formation water in the vugs to migrate to the production well. The recovery of the gel foam flooding stage was as high as 48%, and the final recovery reached 93.5; only a small amount of shielded remaining oil was difficult to drive. The research results are of great significance to the application of gel foam in enhancing oil recovery in fractured-vuggy reservoirs.

Optimization of starch foam extrusion through PVA polymerization, moisture content control, and CMCS incorporation for enhanced antibacterial cushioning packaging

Melt strength and moisture content are critical parameters in starch foam extrusion, as they dictate bubble expansion dynamics, which subsequently determine the foam's properties. Despite continuous advancements in the development and application of starch foams, challenges such as water resistance, mechanical strength, and antibacterial activity remain unresolved. This research investigates the influence of polyvinyl alcohol (PVA) polymerization and moisture content on the properties of extruded foam while also exploring the potential for enhancing antimicrobial functionality by incorporating carboxymethyl chitosan (CMCS) into conventional starch foams. The findings underscore the significance of melt strength and intermolecular entanglements in shaping foam characteristics, confirming that bioactive components effectively improve hydrophobicity, foaming characteristics, and antibacterial capabilities. Moreover, by precisely regulating PVA polymerization and moisture content, it became feasible to optimize foam properties and achieve the desired performance. Specifically, foam with a moisture content of 12 % and a PVA polymerization degree of 1700 exhibited exceptional performance, including the highest foaming ratio of 45.62, the minimal water absorption rate of 6.31 %, and the greatest recovery rate of 88.95 %. Furthermore, increasing CMCS concentrations substantially enhances the antibacterial properties of the foam, demonstrating its potential for application in antibacterial cushioning packaging and emphasizing its versatility and practicality.

Nontarget Analysis Combined with TOP Assay Reveals a Significant Portion of Unknown PFAS Precursors in Firefighting Foams Currently Used in China.

Firefighting foam is a significant source of per- and polyfluoroalkyl substances (PFAS) pollution, yet the PFAS profiles in foam formulations, particularly in China, remain unclear. Here, using target and nontarget analyses, we investigated 50 target PFAS in firefighting foams currently utilized in China, identified novel PFAS, and discovered new end products through a total oxidizable precursor (TOP) assay. We identified a total of 54 PFAS compounds (spanning 34 classes and containing seven novel PFAS) with total PFAS concentrations of 0.03-21.21 mM. Among seven novel PFAS, four PFAS met persistence, bioaccumulation, and toxicity criteria, and another PFAS had the highest ToxPi score among the identified 54 PFAS. Moreover, the predominant PFAS varied significantly in the studied foams and differed markedly from those used in other countries. After the TOP assay, nontarget analysis uncovered 1.1-55.5% more PFAS precursors and 8.25-55.5% more fluorine equivalents compared to traditional target analysis combined with TOP assay. Specifically, three double-bond perfluorinated alcohols were identified for the first time as end products of the TOP assay. This study provides crucial information for pollution control and risk assessment associated with PFAS in firefighting foam applications and emphasizes the importance of combining nontarget analysis with TOP assay in uncovering unknown PFAS precursors.

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.

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.

A new seismic metamaterial design with ultra-wide low-frequency wave suppression band utilizing negative Poisson's ratio material

In this paper, we present a new seismic metamaterial (SM) for the suppression of Lamb waves and surface waves utilizing the negative Poisson's ratio (NPR) foam. The periodic cell of the metamaterial is composed of a square cylinder made of steel in the center and NPR foam connecters at the corners. Utilizing the unique resonance properties of the NPR material, an ultra-low-frequency broadband wave suppression is achieved. First, the characteristics of bandgaps (BGs) of the proposed structure with different materials were analyzed using the finite element (FE) method. It shows that the application of the NPR foam can significantly broaden the BGs compared with the case using traditional rubber. The vibration modes were analyzed to investigate the mechanism of BG generation, and the results show that the broad BG is achieved via the unique local resonance mechanism of the NPR foam. Subsequently, the frequency-domain analysis was carried out to verify the shielding effect of the designed SM on Lamb waves, using a periodic structure consisting of 10 × 6 unit cells. It shows that the designed SM can effectively attenuate Lamb waves in the range of 3–44 Hz with attenuation up to −590 dB at 32 Hz. A parametric analysis shows that the NPR foam with small thickness, high modulus, low mass density, and low Poisson's ratio can broaden the first complete BG. In addition, the acoustic cone method was combined with the frequency-domain analysis to calculate the BGs of the proposed structure against the surface wave, using a periodic structure consisting of 20 unit cells. It shows that the surface wave can be significantly attenuated within the BG. Finally, real seismic excitations were applied for time-domain analyses, and the simulation results show that the proposed structure can effectively shield the low-frequency seismic surface waves in the range of 0.1–20 Hz. The design scheme proposed in this paper is simple in structure and easy to implement, and is believed to possess bright application potentials in seismic protection.

Rheological Characterization of Inorganic Curing Foam for Preventing Spontaneous Combustion of Coal

ABSTRACT This study examines the rheological characteristics of inorganic cured foam (ICF). The apparent viscosity, yield stress, and modulus of elasticity of fresh cement-fly ash composite slurries with varying fly ash blending ratios at water/ash ratios of 0.4, 0.5, 0.6, and 0.7 were determined. The findings indicate that, under identical testing conditions, the apparent viscosity, yield stress, and modulus of elasticity of fresh cement-fly ash composite slurries (FCFS) gradually decrease with increasing water/ash ratio. The apparent viscosity and modulus of elasticity of inorganic curing foam (ICF) decrease as the volume expansion rate increases, while the linear viscoelastic region (LVER) broadens with higher volume expansion rates. Furthermore, the fitted apparent viscosity-shear stress curve for FCFS aligns with the power law model, whereas the apparent viscosity-shear stress curve for ICF slurries is better represented by the Carreau-Yasuda function model. The results of the study will contribute to the industrial application of inorganic curing foams for the prevention of spontaneous coal combustion.

Application of the polyurethane foam recycling product as an asphalt extender for sustainable road construction

Polyurethane foam (PUF) is widely used across industries owing to its excellent properties, but it has caused a solid waste stream in the environment. Alcoholysis has been found to be an effective and eco-friendly approach to address this issue. However, substantial by-products are generated in the alcoholysis process, presenting challenges to waste PUF recycling. The by-products of the PUF recycling process (BPF) exhibit similar physical properties to asphalt binder. Therefore, this study uses BPF as an asphalt extender to prepare BPF-asphalt, focusing on its influence on asphalt binder properties. The results show that BPF can greatly maintain or even improve the performance of asphalt binder with good compatibility and workability through physical mixing. The optimum amount is 10 % of the mass of the base asphalt binder. Differences in chemical composition lead to differences in BPF-asphalt properties. Thermal polymerization of polystyrene with small molecular weight in BPF plays an important role in improving the high-temperature performance and fatigue resistance. The presence of diethylene glycol has a negative effect on the performance of BPF-asphalt. This study demonstrates the feasibility of the solution of BPF as an asphalt extender to alleviate the disposal pressure of waste PUF and the consumption of asphalt resources.

Multi-scale experimental study on properties of compressed air foam and pressure drop in the long-distance vertical pipe

Compressed air foam has been gradually applied in super high-rise buildings due to its high extinguishing efficiency and great transportation ability. However, the transport characteristics of compressed air foam are unclear because the foam is a complex gas-liquid two-phase fluid. In this study, multi-scale experiments were conducted to investigate the foam properties of compressed air foam and pressure drop in the long-distance vertical pipe. The results show that the foam is compressed as a whole when pressure increases, resulting in a significantly increased foam density. At higher pressures, the bubble coarsening degree decreases, accompanied by a narrower particle size distribution and an increased foam size homogenization. Moreover, a critical pressure phenomenon is observed in foams with different foam expansion ratios. The average foam diameter stabilizes gradually with pressure changes after exceeding the critical pressure. A theoretical model for foam density is developed, considering various pressures, temperatures and foam expansion ratios. When the compressed air foam is transported in the vertical long-distance pipe, the pressure decreases in a slightly downward curve, which is due to the decrease in foam density. Finally, a prediction model for the pressure drop of compressed air foam in the long-distance vertical pipe is proposed, which considers changes in foam density. The accuracy of the prediction model is verified by the multi-scale experimental results. The results deepen the understanding of foam flow in the long-distance vertical pipe and provide useful guidance for applications of compressed air foam in super high-rise buildings.

Characterization of the Aluminium-Based Metal Foam Properties for Automotive Applications

AbstractMetal foams are solids where the gas is filled inside uniformly in the metal matrix. Blowing agent supplies air inside the parent metal, and metal foam has emerged to be a promising material because of its low density, high absorption capacity, low thermal conductivity and high strength which finds its huge applications in automobile components. The present work deals with the application of the aluminium metal foam with different densities 200 and 400 kg/m3 in automobiles. Various tests such as toughness, hardness, bending and compression are carried out for four chosen densities, and the values are compared with the aluminium base metal. The result showed that the hardness value increased significantly by 24.48% with the rise in the density from 200 to 400 kg/m3. Maximum modulus of resilience for the low-density specimen is found to be 2.21 MJ/m3. Surface topography showed irregular pore shapes with discontinuity, resulting in a loss of cell integrity with the neighbouring cell walls. This affected the performance of the foam significantly. Thermal experiments were carried out to determine the thermal conductivity where thermal conductivity increased by 122% with the rise in the density from 200 to 400 kg/m3. Based on the results, it is concluded that aluminium foam with density 400 kg/m3 can be recommended for use in automobile applications due to its lightweight properties, which contribute to improving fuel efficiency, impact absorption capacity and the vehicle’s speed. Additionally, the air trapped within the foam cells serves as a sound barrier and insulator in cars.

Assessing the phytotoxic effects of class A foam application on northern Europe tree species: a short-term study on implications for wildfire management and ecosystem health

Wildfires are an ever-increasing issue due to the driving forces of climate change. Weather events that lead to higher wildfire potential are likely to increase and thus new fire management methods via more sustainable fire suppressant class A foams rather than retardants are being developed. However, despite their adherence to regulations, foam impact on targeted ecosystems, namely forests and forest trees is poorly studied. We aimed to investigate how three tree species (Pinus sylvestris, Alnus glutinosa and Picea abies) will react to a one-time class A foam application. Two separate trials were conducted. During the first the foam was applied to seeds and during the other – to 1-year-old seedlings. Tree growth and physiological status were evaluated. Stress criteria for cellular damage, non-antioxidant and antioxidant stress response and photosynthesis efficacy were measured. Results showed an obvious species effect, as all three reacted differently. The dose effect was also notable, with the higher application rate leading to a proportionally bigger response. Overall, pines were negatively impacted, spruce were positively affected, and alders didn’t experience a notable change. This leads us to conclude that pending the limitation of this experiment the tested foam while phytotoxic in some cases, is unlikely to affect tree survival rates under field conditions and any physiological responses are likely transient in nature.