Foam Particles Research Articles

Production of Electrolytic Composite Powder by Nickel Plating of Shredded Polyurethane Foam.

Ni–poly(DPU) composite powder was produced under galvanostatic conditions from a nickel bath with the addition of pulverized polymer obtained during the shredding of polyurethane foam (poly(DPU)). The Ni–poly(DPU) composite powder was characterized by the presence of polymer particles covered with an electrolytical amorphous-nanocrystalline nickel coating. The phase structure, chemical composition, morphology, and the distribution of elements was investigated. The chemical analysis showed that the powder contains 41.7% Ni, 16.4% C, 15.7% O, 8.2% P and 0.10% S. The other components were not determined (nitrogen and hydrogen). The phase analysis showed the presence of NiC phase. Composite powder particles are created as a result of the adsorption of Me ions on the fragmented polymer. The current flowing through the galvanic bath forces the flow of the particles. The foam particles with adsorbed nickel ions are transported to the cathode surface, where the Ni2+ is discharged. The presence of compound phosphorus in galvanic solution generates the formation of amorphous-nanocrystalline nickel, which covers the polymer particles. The formed nickel–polymer composite powder falls to the bottom of the cell.

Investigation on the Controllable Synthesis of Colorized and Magnetic Polystyrene Beads With Millimeter Size via In Situ Suspension Polymerization

A series of colorized and magnetic polystyrene/Fe3O4 (PS/Fe3O4) composite beads with millimeter size are successfully synthesized by introducing hydrophobic Fe3O4 via in situ suspension polymerization of styrene for the first time. Effects of the hydrophobic Fe3O4 content, stirring speed, and surfactant dosage on the macromorphology and particle size of PS/Fe3O4 beads are systematically investigated to realize the controllable synthesis. Moreover, three kinds of hydrophobic pigments are also employed to synthesize colorized polystyrene, which demonstrates the versatility, simplicity, and wide applicability of the proposed method. Scanning electron microscopy (SEM) and element mapping (EM) images demonstrated that the hydrophobic Fe3O4 is well dispersed in the polystyrene matrix. Thermogravimetric analysis (TGA) shows that the resultant PS/Fe3O4 beads possess a better thermal stability than neat PS. PS/Fe3O4 beads have a promising application in the fields of colorized extruded PS board, colorized expanded PS foam particle, and board.

Constructing fibrous-like skeleton by simulated sea mud to improve three-phase foam for stability and fire-extinguishing performance

Combining the three-phase foam and simulated sea mud particle (SM-P: simulated sea mud particle) containing inert substances (SMTP: simulated sea mud three-phase foam) to engineer a new three-phase foam fire extinguishing material was a viable strategy to solve the problem of coal mine spontaneous combustion prevention and insufficient stability of mine fire extinguishing materials. Herein, based on constant temperature heating table and simulated coal spontaneous combustion fire extinguishing device, the experiments were conducted to evaluate the material properties. As expected, the SMTP-20 exhibited excellent stability (73.00 mins at 40 °C), which was 2.19 times that of ordinary three-phase foam (34.33 mins at 40 °C). The introduction of SM-P can also effectively reduce the thermal decomposition of powdered coal, the corresponding temperature of thermal decomposition peak value of raw coal was delayed 17.78 °C. The SMTP-20 could construct a thin fibrous-like foam layer with SM-P to cover the surface of burning coal and effectively seal cracks in the coal from oxygen contact, thereby preventing coal further oxidation. This work not only offers a new three-phase foam with outstanding performance, but also unravels a strategy for preparing three-phase foam with high stability and good fire extinguishing effect.

Multi-angle analysis of the mechanism of polymer materials to improve the sealing quality of boreholes

ABSTRACT The quality of borehole sealing is closely related to the sealing materials. As a kind of sealing material, how polymer materials improve the sealing quality has not been deeply analyzed. This paper based on the analyses of the dynamic contact state between polymer material and borehole wall, taking borehole, polymer material and their contact surface as the research object, this paper analyzes the changes of air leakage channel after sealing, the internal particles of foaming material, and the structure characteristics of contact surface. From multi-angle to obtain the sealing mechanism of polymer material. The results are: (1) the reduction rate D equation of the air leakage channel is derived. It positively relates to the expansion support force of sealing material. (2) Polymer materials could reduce the stress and deformation of coal surrounding borehole by 2.3 ~ 4.5% and 15.2% ~ 19.9% respectively, to narrow the air leakage range outside the hole. (3) The unusual structure of polymer foam particles can be well bonded and fixed with the borehole wall, improve the borehole stability, and reduce the air leakage inside the hole. (4) Polymer sealing material can maintain an average gas concentration of 44.90% within 60 days, not less than 30%, and ensure the extraction effect.

The Role of Foam in Improving the Workability of Sand: Insights from DEM

Foam as a soil conditioner can transform the mechanical properties of the excavated natural muck and lubricate the interface between the cutting tools and muck, thus reducing the tools’ wear and promoting the efficiency of earth pressure balance (EPB) shield tunneling. This paper aims to explore the meso-mechanism of foam in improving the workability of sand by combining discrete element modeling (DEM) with experimental investigations of slump tests. A “sand-foam” mixture DEM model was generated by simplifying the sand grains and foam as individual particles with different properties. The particle-scale simulated parameters were calibrated based on a series of experimental observations. The effects of foam on the inter-particle contact distribution and the evolution of contact forces during the slumping process were investigated in detail through numerical modeling. It was found that injecting foam into sand specimens could increase the coordination number and the contact number around sand grains. Although the force transmission pattern changes from “sand-sand” into the coexistence of “sand-foam”, “sand-sand” and “foam-foam” contacts, the magnitude of contact forces transferred by foam particles is significantly lower than that by sand particles. The presence of foam reduces contact-scale frictional strength and thus reduces the stability of the microstructures of sand. In addition, the normal direction of inter-particle contact force deflects from the vertical to the horizontal and the magnitude of contact force decreases significantly with the influence of foam.

Visual Simulation of Turbulent Foams by Incorporating the Angular Momentum of Foam Particles into the Projective Framework

In this paper, we propose an angular momentum-based advection technique that can express the turbulent foam effect. The motion of foam particles, which are strongly bound to the motion of the underlying fluid, is viscous, and sometimes clumping problems occur. This problem is a decisive factor that makes it difficult to express realistic foam effects. Since foam particles, which are secondary effects, depend on the motion of the underlying water, in order to exaggerate the foam effects or express more lively foam effects, it is inevitable to tune the motion of the underlying water and then readjust the foam particles. Because of such a cumbersome process, the readjustment of the foam effects requires a change in the motion of the underlying water, and it is not easy to produce such a scene because the water and foam effects must change at the same time. In this paper, we present a method to maintain angular momentum-based force from water particles without tuning the motion of the underlying water. We can restore the lost turbulent flow by additional advection of foam particles based on this force. In addition, our method can be integrated with screen-space projection frameworks, allowing us to fully embrace all the advantages of this approach. In this paper, the turbulence of the foam particles was improved by minimizing the viscous motion of the foam particles without tuning the motion of the underlying water, and as a result, lively foam effects can be expressed.

Simulative study of polymeric core–shell foam particles for the enlargement of the material portfolio in 3‐D high‐frequency welding

AbstractThe steam chest molding process is currently state of the art concerning the generation of three‐dimensional polymeric foam components made from particle foams. An adaption of the high‐frequency welding process shows advantages regarding the required energy and the used water. Due to the low dielectric loss factors of the most common foam materials (PE, PP, and PS), they cannot be heated sufficiently by an electric field. To enable heating of these foams, the particles may be coated with a second material that shows a high dielectric loss. The possible heat development of the modified particles was simulatively investigated. To ensure a realistic simulation, the properties of the used materials are analyzed beforehand. The heating simulation shows clear dependence regarding the particle size and the shell thickness. By a suitable combination, sufficient heating is achievable. For single particles, an irregular temperature distribution is calculated, mainly caused by the difference of permittivity resulting in a local variation of electrical flux density. Bigger particles and thicker shells will result in faster heating ramps and higher overall temperatures. The additional calculation regarding a particle–particle interaction shows a homogenization of the temperature distribution across the particle surface.

Linking molecular structures of yeast-derived biosurfactants with their foaming, interfacial, and flotation properties

Yeast-derived bola amphiphiles have attracted growing attention in various industrial sectors as green reagents. However, their physico-chemical properties relevant to mineral separation by froth flotation are poorly explored. To bridge this gap, we studied the foaming, interfacial, and flotation properties of acidic sophorolipid (ASL), acidic glucolipid (GL) and alcoholic glucoside (GS) obtained from strain engineering of the yeast Candida bombicola by molecular editing of the headgroups. Bench-scale flotation testing of a copper sulfide ore showed that ASL can effectively separate copper sulfides (85% recovery at 20% grade), GL is less effective (ca. 60% recovery and 13% grade), while GS is a poor collector. To understand this trend, we studied the interfacial and foaming properties of these three biosurfactants. The surface tension study reveals that, contrary to GS, self-assembly of both ASL and GL at the air–water interface is pH-responsive, suggesting that both the biosurfactants acquire a Π-shape. The dependence of the foaming properties of all the three surfactants on pH and concentration does not correlate with the trends in the static surface tension, suggesting the critical roles of dynamic factors, interfacial elasticity and interfacial viscosity. Hydrophobicity of djurleite (a model copper sulphide) in the presence of the three surfactants was assessed using the contact angle and Hallimond flotation methods. ASL and GL only float the pure mineral at alkaline pH, which is consistent with the contact angle data. In contrast, even though GS does not have a significant effect on contact angle, it floats djurleite in a wide pH range, which is explained by the mechanical entrainment of hydrophilic mineral particles in rich GS foams. Overall, these results demonstrate the potential of carboxylic bola biosurfactants for the recovery of copper sulfides from ores. They also bring new insights into the interfacial and foaming properties of bola biosurfactants, which can assist their introduction into other industries.

Graphene Particles Interfere with Pro-Inflammatory Polarization of Human Macrophages: Functional and Electrophysiological Evidence.

The interaction of two types of fragmented graphene particles (30-160nm) with human macrophages is studied. Since macrophages have significant phagocytic activity, the incorporation of graphene particles into cells has an effect on the response to functional polarization stimuli, favoring an anti-inflammatory profile. Incubation of macrophages with graphene foam particles, prepared by chemical vapor deposition, and commercially available graphene nanoplatelet particles does not affect cell viability when added at concentrations up to 100µg mL-1 ; macrophages exhibit differential quantitative responses to each type of graphene particles. Although both materials elicit similar increases in the release of reactive oxygen species, the impact on the transcriptional regulation associated with the polarization profile is different; graphene nanoplatelets significantly modify this transcriptomic profile. Moreover, these graphene particles differentially affect the motility and phagocytosis of macrophages. After the incorporation of both graphene types into the macrophages, they exhibit specific responses in terms of the mitochondrial oxygen consumption and electrophysiological potassium currents at the cell plasma membrane. These data support the view that the physical structure of the graphene particles has an impact on human macrophage responses, paving the way for the development of new mechanisms to modulate the activity of the immune system.

노이즈가 완화된 거품 효과를 표현하기 위한 인공신경망 기반의 투영맵 정제

In this paper, we propose an artificial neural network framework that can represent the foam effects expressed in liquid simulation in detail without noise. The position and advection of foam particles are calculated using the existing screen projection method, and the noise problem that appears in this process is solved through an proposed artificial neural network. The important thing in the screen projection approach is the projection map, but noise occurs in the projection map in the process of projecting momentum into the discretized screen space, and we efficiently solve this problem by using an artificial neural network-based denoising network. When the foam generating area is selected through the projection map, 2D is inversely transformed into 3D space to generate foam particles. We solve the existing denoising network problem in which small-scaled foam particles disappear. In addition, by integrating the proposed algorithm with the screen-space projection framework, all the advantages of this approach can be accommodated. As a result, it shows through various experiments whether it is possible to stably represent not only the clean foam effects but also the foam particles lost due to the denoising process.

Frequency of Decompensation in Patients with Hepatocellular Carcinoma in Child Pugh Class A Undergoing Trans Arterial Chemoembolization

Objective: To determine the frequency of decompensation in patients with hepatocellular carcinoma in Child Pugh Class A undergoing trans arterial Chemoembolization. Study Design: Descriptive case series Place &Duration: Study was conducted at gastroenterology department with collaboration of interventional radiologists Gambat Institute of Medical Science's Khairpur for six months during the time period of November 2020 to April 2021. Methodology: 218 patients of either sex with hepatocellular carcinoma presenting to Gastroenterology Department fulfilling the inclusion criteria were enrolled in the study. TACE involved injection of a chemotherapeutic agent (doxorubicin) mixed with lipoidol into selectively or super selectively catheterized branches of the arteries feeding the tumor followed by injection of gel foam particles to reinforce the effect of the treatment. Data was used to calculate incidence of decompensation in patients with hepatocellular carcinoma in Child Pugh Class A undergoing transarterial Chemoembolization. Results: The frequency of decompensation in patients with hepatocellular carcinoma in Child Pugh Class A undergoing transarterial Chemoembolization was 9.2%. Conclusion: We conclude frequency of decompensation in patients with hepatocellular carcinoma in Child Pugh Class A undergoing transarterial Chemoembolization was 9.2%. Keywords: Hepatocellular carcinoma, decompensation, chemoembolization

Laser induced hydrogen emission from ethanol with dispersed graphene particles

Efficient hydrogen emission from ethanol with disperse graphene foam particles by using a continuous wave infrared laser diode is reported. The products of ethanol dissociation - hydrogen, methane and carbon oxide were measured using mass spectrometry. It was found that the most efficient generation of hydrogen was observed when graphene particles were irradiated by a focused laser beam proceeded at the surface of ethanol solution. The process was assisted by intense white light emission resulting from the laser induced multiphoton ionization of graphene combined with the simultaneous emission of hot electrons. The hot electron emission enables the efficient dissociation of ethanol molecules located close to the solution surface with graphene foam particles.

Microplastics pollution in the South American Pantanal

Microplastics represent an emerging global threat to freshwater ecosystems. Studies regarding their presence in floodplains are still incipient. Microplastics in the Pantanal’s affluent and floodplains were sampled close to their potential urban sources and in the Pantanal lowlands. A plankton net (68 ​μm mesh size), with a 150 ​ml collection flask was used for sampling. The flask content was filtered over a 0.45 ​μm Whatman paper, 47 ​mm in diameter, and examined under a stereomicroscope at 45X to identify and count microplastics (expressed as x100 ​L−1). Microplastic sizes were determined by image microscopy. The average microplastic size was 192 ​± ​142 ​μm and it was not significantly different in the urban tributaries (206 ​± ​158 ​μm) than in the Pantanal (181 ​± ​131 ​μm). The average ​± ​std microplastic concentration was 9.6 ​± ​8.3, ranging from 1 to 31 x100 ​L−1. Fibers, fragments, pellets, and XPS (closed-cell extruded polystyrene foam) particles represented respectively 50%, 19%, 22%, and 9% of the total microplastics. Microplastics concentrations were higher in the urban tributaries (19.9 ​± ​5.8 x100 ​L−1) than in the Pantanal lowlands (4.5 ​± ​2.5 x100 ​L−1). Fibers were the most important fraction, followed by fragments. In the lowlands, pellets were scarce and XPS were absent. A comparison between microplastic composition in the floodplain and the urban areas suggest that microfibers and fragments could be either transported from the urban areas or have a local origin. These results indicate that the biota of the Pantanal and its affluents is exposed to microplastics. More research is needed to understand the extent of the microplastic pollution and the risks posed by this contamination in the aquatic and terrestrial ecosystems of the Pantanal.

Lightweight and high-strength GMT/PEFP/GNP composites with absorb-dominated electromagnetic interference shielding property

As the problem of electromagnetic wave pollution is becoming more and more serious in our daily life, it is urgent to develop a kind of electromagnetic interference (EMI) shielding materials with high-strength and high absorptivity to meet the demand of industrial application. In this study, a facile method is developed to prepare EMI shielding composites with both powerful absorbing and robust mechanical properties by impregnating the suspensions of graphite nanoplatelets (GNP) and polyacrylate expandable foam particles (PEFP) into the porous glass fiber mat reinforced thermoplastics (GMT), and then hot forming and pressing, the thickness of GMT/PEFP/GNP composites is 2 mm. GNP not only acted as an efficient conductive pathway in the GMT/PEFP/GNP composites matrix, but also formed a conductive cell structure with the foamed PEFP, which increased the electromagnetic waves absorption. The total shielding efficiency (SET) of the GMT/PEFP/GNP-4.0 wt% composite is up to 33.8 dB at 11 GHz, and the power coefficient of reflectivity is 0.71, which is lower 17% than that of GMT/GNP composites without the cell structure constructed by PEFP in the matrix. Furthermore, the melting of polypropylene (PP) in the mats act as the interface adhesive for glass fiber (GF) and GNP, so the tensile strength is enhanced up to 22.8 MPa for the GMT/PEFP/GNP-4.0 wt% composites with lightweight, due to the formation of cell structure constructed by the PEFP. Therefore, this paper provides a simple method to prepare lightweight and high-strength GMT/PEFP/GNP composites for EMI shielding, which is of great significance for industrial application.

Synthesizing Large‐Scale Fluid Simulations with Surface and Wave Foams via Sharp Wave Pattern and Cloudy Foam

AbstractThis paper presents a unified framework to simulate surface and wave foams efficiently and realistically. The framework is designed first to project thee‐dimensional (3D) water particles from an underlying water solver onto two‐dimensional screen space to reduce the computational complexity of determining where foam particles should be generated. Because foam effects are often created primarily in fast and complicated water flows, we analyze the acceleration and curvature values to identify the areas exhibiting such flow patterns. Foam particles are emitted from the identified areas in 3D space, and each foam particle is advected according to its type, which is classified on the basis of velocity, thereby capturing the essential characteristics of foam wave motions. We improve the realism of the resulting foam by classifying it into two types: surface foam and wave foam. Wave foam is characterized by the sharp wave patterns of torrential flows, and surface foam is characterized by a cloudy foam shape, even in water with reduced motion. Based on these features, we propose a technique to correct the velocity and position of a foam particle. In addition, we propose a kernel technique using the screen space density to reduce redundant foam particles efficiently, resulting in improved overall memory efficiency without loss of visual detail in terms of foam effects. Experiments convincingly demonstrate that the proposed approach is efficient and easy to use while delivering high‐quality results.

Microstructures, Aging Behavior and Thermal Expansion of 7075 Al–Silica Particle Waste Composite Foams Produced with Recycled Aluminum Cans

7075 Al–SiO2 composite foams were prepared by direct melt foaming method. The microstructures of the composite foams showed uniformly distributed particles in the composite foams. Aging studies showed that the hardness values of as-quenched composite foams were higher than that of 7075 Al foam and all the foam samples revealed two clear aging peaks. The aging behavior of the 7075 Al foam was different in kinetic and magnitude from of the 7075 Al–SiO2 composites, where the levels of peak hardness attained in the two peaks of 7075 Al foam were higher than those of the composite foams. Also, the aging times to attain the two peaks of the 7075 Al foam were shorter than those of the composite foams. DTA analyses indicated that the precipitation sequences of the composite foams were similar to that of the 7075 Al foam. However, the precipitation peaks of the composite foams were shifted to higher temperatures and the sizes of the hardening precipitate formation peaks in the composite foams were decreased, indicating that the formation of hardening precipitate zones was suppressed by the incorporation of the SiO2 particles or increasing the content of the foaming agent. The CTE of the 7075 Al foam was higher than that of the 7075 Al–15 vol % SiO2 composite foam.

Coastal biomonitoring survey on persistent organic pollutants using oysters (Saccostrea mordax) from Okinawa, Japan: Geographical distribution and polystyrene foam as a potential source of hexabromocyclododecanes

The present study determined contamination levels of POPs, such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordane compounds (CHLs), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs), in oysters (Saccostrea mordax) collected throughout the seacoast of Okinawa, Japan and their geographic distribution. PCBs, DDTs, CHLs, PBDEs and HBCDs were detected in almost all the oyster samples analyzed and higher concentrations of PCBs, DDTs and CHLs were found in oysters from southwestern populated areas. On the other hand, HBCDs in oysters showed similar levels throughout Okinawa and the highest concentration in a northern rural site with less human and industrial activities, although oyster concentrations of PBDEs were relatively lower. When POPs in expanded polystyrene (EPS) buoys and polystyrene foam debris floated and drifted on coastal seawater were analyzed, extremely high concentrations of HBCDs were detected in some of these EPS buoys and polystyrene foam debris but other POPs were below the limit of detection in all the samples. To evaluate the specific exposure route of HBCDs for oysters, we further analyzed HBCD diastereomers, and PCB congeners by way of comparison, in seawater and sediment samples collected at an urban site and a rural site and estimated their biota (oyster)-sediment accumulation factors (BSAF) and bioaccumulation factors (BAF). Interestingly, the highest log BAF values were found for α-HBCD despite its lower log Kow than those of γ-HBCD and PCB congeners, although log BSAF values for HBCDs were lower than those for PCBs. Considering that α-HBCD was detected in a few polystyrene foam samples as the predominant diastereomer, oysters inhabiting the coastal region of Okinawa might be frequently exposed to micronized polystyrene foam particles containing HBCDs.

Effects of Soil Conditioning on Characteristics of a Clay-Sand-Gravel Mixed Soil Based on Laboratory Test

Soil conditioning is of great significance for tunneling in soft ground with earth pressure balance shield (EPBS) machines, which leads to safe, highly efficient, and high-quality tunneling. To study the effects of soil conditioning on properties of a clay-sand-gravel mixed soil encountered in an EPBS tunneling project in Beijing, a series of geotechnical test methods was carried out based on laboratory test in this paper. The decay behaviors of foam particles generated by the Waring-Blender method were studied first using the image particle analysis system, and then the feasibility of soil conditioning on the mixed soil was qualitatively and quantitatively assessed through the mixing test, slump test, and friction coefficient test. The preliminary test results indicate that drainage of water in liquid film plays an important role in the decay of foam microstructure. The viscosity and flowability of the conditioned soil were modified dramatically by using various amount of water and foam, and a suitable state meeting the requirement of EPBS machines was obtained. The net power and mixing time, which reflects the interaction between the blending rods and tested soils, as well as the slump value, providing the overall indication for liquidity of the conditioned soils, and friction coefficient, reflecting the friction between steel and tested soils, were used to provide insight into the variation in viscosity and flowability of the tested soils.

3D Printed Thermoplastic Polyurethane Filled with Polyurethane Foams Residues

This work intends to provide a preliminary approach concerning the preparation of 3D printed products derived from recycled raw-materials. In that sense, recycled polyurethane foam (PUF) particles were added (up to 10% wt/wt) to thermoplastic polyurethane (TPU) to prepare 3D printed products. From the results, it was observed that the presence of PUF particles reduces the density of filaments. Moreover, even though filler and matrix are polyurethane (PU) polymers, the fact that PUF scraps consists of crosslinked PU, it affects inter-layer adhesion, reducing the mechanical performance of the 3D printed specimens, especially when high PUF particles contents were used. Nonetheless, despite of the limitations identified, the addition of PUF particles did not affect the thermal stability of the composites, meaning that these composites can be processed at high temperatures. Therefore, PUF scraps were successfully reused which proved to be a low cost additive for the production 3D printed composites (when using low content), with the advantage of being an alternative to the disposal of PUF.

A Convenient and Versatile Strategy for the Functionalization of Silica Foams Using High Internal Phase Emulsion Templates as Microreactors.

Functional porous materials show extensive applications in the environment, biology, aerospace, and so on. In this work, the generation of silica foams and functionalization of pore surface were simultaneously realized through an interfacial sol-gel reaction within high internal phase emulsion (HIPE) microreactors, where a hyperbranched polyethoxysiloxane (PEOS) was used as the sole stabilizer for the HIPEs. With various functional substances containing amino, epoxy, and carboxyl groups initially dissolved in the aqueous phase of HIPEs, these functional groups could be grafted onto the pore surface in the process of forming silica foams. Amino-functionalized silica foam showed fast adsorption of sunset yellow, and the adsorption capacity could reach as high as 1213.13 mg/g. Sodium polyacrylate-modified silica foam exhibited good adsorption capacity of cationic dyes and metal ions, e.g., 280.11 mg/g to methylene and 226.24 mg/g to Cu(II). Epoxy-functionalized silica foam particles were confirmed with a pronounced activity at the oil/water interface due to their Janus-like surface, which could be used as Pickering stabilizer. This HIPE-based synthesis strategy for silica foams shows promising future in adsorption, emulsion stabilization, and compatibilization.