Cellular Foam Research Articles

3D-printed activated carbon for post-combustion CO2 capture

The applicability of 3D-printed activated carbons for their use to CO 2 capture in post-combustion streams and the influence of activation conditions on CO 2 uptake and CO 2 to N 2 selectivity were studied. For two monoliths with the same open cellular foam geometry but low and high burnoff during activation, a series of fixed-bed breakthrough adsorption experiments under typical post-combustion conditions, in a wide range of temperature (313 and 373 K), and partial pressure of CO 2 up to 120 kPa were carried out. It is shown that the higher burnoff during activation of the 3D printed carbon enhances the adsorption capacity of CO 2 and N 2 due to the increased specific surface area with sorption uptakes that can reach 3.17 mol/kg at 313 K and 120 kPa. Nevertheless, the lower burnoff time on monolith 1 leads to higher selectivity of CO 2 over N 2 , up to 18 against 10 on monolith 2, considering a binary interaction to a mixture of CO 2 /N 2 (15/85 vol%) at 313 K. The single and multicomponent adsorption equilibrium is conveniently described through the dual-site Langmuir isotherm model, while the breakthrough curves simulated using a dynamic fixed-bed adsorption linear driving force model. Working capacities for the 3D printed carbon with lower burnoff time lead to the best results, varying of 0.15–1.1 mol/kg for the regeneration temperature 300–390 K. Finally, consecutive adsorption-desorption experiments show excellent stability and regenerability for both 3D printed activated carbon monoliths and the whole study underpins the high potential of these materials for CO 2 capture in post-combustion streams. • Printed activated carbon monoliths were developed as adsorbents for CO 2 capture. • Thermal treatment affects the selectivity of CO 2 over N 2 on the monoliths. • CO 2 working capacity on the monolith M1 is 17% higher than monolith M2. • 3D-printed monoliths show high stability and regenerability over consecutive cycles. • A mathematical model has been developed for process simulation to CO 2 capture.

Design and Synthesis of Vanadium‐Titanium‐Incorporated Mesoporous Silica Catalysts for the Oxidative Dehydrogenation of Propane

AbstractA series of vanadium and titanium‐incorporated mesostructured cellular foams (MCF) silica with different vanadium contents were synthesized by direct hydrothermal method, which applied as catalysts for the oxidative dehydrogenation of propane (ODP). Vanadium doping amount significantly affects the distribution and coordination environment of VOx and TiOx species on the MCF silica. With the increasing of V content, the TiOx species incorporated into silica framework were substituted by some framework V species to form more polymeric or small TiO2 nanoclusters. VOx species were incorporated on both silica surface and TiOx species surface. The interaction between highly dispersed VOx and polymerized TiO2 enhanced the C3H6 formation rate. The 3 V5Ti/MCF catalysts showed the highest propylene productivity (4.2 kgpropylene kgcat−1 h−1, at 500 °C) among the xV5Ti/MCF catalysts because of the highest concentration isolated/oligomeric VOx species incorporated on the appropriate polymerized TiO2 surface.

Application of amine-functionalized mesostructured cellular foam assisted electromembrane extraction for the determination of tramadol and methadone from urine samples

Application of amine-functionalized mesostructured cellular foam assisted electromembrane extraction for the determination of tramadol and methadone from urine samples

Effect of Bipolar Plate Material on Proton Exchange Membrane Fuel Cell Performance

Commercialization of proton exchange membrane fuel cells can only materials provided its performance is closely related to existing technologies useful in commercial application. Other critical parameters like the utilization of cheaper materials should be taken into account during the manufacturing of the cell. A key component in the cell that has direct correlation to the cell performance is the flow plate. The weight coupled with cost of the cell revolves around the flow plate used in the manufacturing of the cell. This study explores materials ideal for the manufacturing of fuel cells in order to improve the overall cell performance. The investigation highlights the critical impact of varying materials used in the manufacturing of flow plates for PEM fuel cells. Stainless steel (SS), aluminium (Al) and copper (Cu) were the materials considered. The flow plate designs considered were serpentine and open pore cellular foam channel. Machine learning using python for the validation of the results with Linear regression, Ridge regression and Polynomial regression algorithm was carried out. The performance of both flow field channels was compared using different bipolar plate materials. The results show that metal foam flow channels overall performance was better than serpentine flow channels with all the various bipolar plate material used and Al material outperformed Cu and SS material. There is a direct correlation in terms of the outcome of the study and literature based on the data generated experimentally. It can however be concluded that molecules of hydrogen are stable on aluminium plates compared to copper and stainless steel.

Foam 3D Printing of Thermoplastics: A Symbiosis of Additive Manufacturing and Foaming Technology.

Due to their light‐weight and cost‐effectiveness, cellular thermoplastic foams are considered as important engineering materials. On the other hand, additive manufacturing or 3D printing is one of the emerging and fastest growing manufacturing technologies due to its advantages such as design freedom and tool‐less production. Nowadays, 3D printing of polymer compounds is mostly limited to manufacturing of solid parts. In this context, a merged foaming and printing technology can introduce a great alternative for the currently used foam manufacturing technologies such as foam injection molding. This perspective review article tackles the attempts taken toward initiating this novel technology to simultaneously foam and print thermoplastics. After explaining the basics of polymer foaming and additive manufacturing, this article classifies different attempts that have been made toward generating foamed printed structures while highlighting their challenges. These attempts are clustered into 1) architected porous structures, 2) syntactic foaming, 3) post‐foaming of printed parts, and eventually 4) printing of blowing agents saturated filaments. Among these, the latest approach is the most practical route although it has not been thoroughly studied yet. A filament free approach that can be introduced as a potential strategy to unlock the difficulties to produce printed foam structures is also proposed.

Microwave foaming of carbon dioxide saturated poly lactic acid

AbstractMicro cellular polymer foams find numerous applications such as in filtration, tissue scaffolds, insulation, and catalyst carriers. This study reports on a solvent free approach to fabricate microcellular poly lactic acid foams through a combination of additive manufacturing and microwave foaming. This approach provides the capability to foam polymers in a repeatable and controllable manner with minimal human intervention. Initially, samples are 3D printed, followed by gas saturation, and microwave foaming. The effect of microwave foaming parameters, namely power, temperature and time on the pore morphology was analyzed using a complete parametric study. The results show that microwave foaming can successfully generate porous structure with power and temperature being the main factors affecting the pore morphology. A combination of midrange power and high temperature results in foams with desired properties of small pore size and high porosity. The resulting foams have pore size as small as 120 μm with porosity of 78%. These foams fabricated using a solvent free approach find applications in biomedical field as three dimensional tissue scaffolds for drug testing and bio‐artificial organ development.

ИЗМЕНЕНИЕ СОСТАВА ПОВЕРХНОСТИ ЯЧЕИСТОГО УГЛЕРОДА ПРИ ФИЗИКО-ХИМИЧЕСКОМ МОДИФИЦИРОВАНИИ

The possibility of using both gas-phase (CO2) and liquid-phase (HNO3, H2O2) modification of cellular carbon foam with the study of changes in the content of oxygen-containing groups on its surface is shown. It has been established that when the cellular carbon foam is activated in a CO2 at a temperature of 350°C, there is no loss of mass of the initial sample, and an increase in the activation time from 1 to 3 hours leads to an increase in the number of functional groups by 11 rel.%. Liquid-phase oxidation allowed us to establish that an increase in the concentration of the oxidant, as well as the temperature and duration of the process leads to an increase in the number of functional groups on the surface.

A study on coconut fatty acid diethanolamide-based polyurethane foams.

The possibility of using coconut fatty acid diethanolamide, a derivate from coconut oil as a bio-based polyol for the synthesis of polyurethane foam was explored. The intrinsic tertiary amine moiety in this polyol (p-CFAD) endowed an auto-catalytic effect in the synthesis process of polyurethane foams, combined with a shorter cream and gelation time compared to the fossil-based polyol 3152. H-nuclear magnetic resonance (1H-NMR) and Fourier transform infrared spectrometry (FTIR) were conducted to characterize the chemical structural features of the p-CFAD, and rheology measurement showed the shear-thinning behavior due to the branched structure. A thermal conductivity comparable to the commercial rigid polyurethane foam was achieved when 40wt% fossil-based polyol 3152 was substituted with the bio-based p-CFAD. With the increased content of the p-CFAD, a transition of the physical properties from rigid PU foam to soft PU foam was observed. Scanning electron microscopy (SEM) revealed the occurrence of the interconnected pores on the cell walls with the increase of the added p-CFAD, implying the possibility of regulating the cellular structure and foam properties via the incorporation of the p-CFAD. Results showed the feasibility of using p-CFAD as a potential polyol in the development of bio-based polyurethane foams with high performance.

DETECTION OF SARS-COV-2 FROM SURFACE OF PATIENTS’ LEFTOVER FOOD PACKAGES AT A COVID-19 QUARANTINE CENTRE

In healthcare facilities, food waste and its packaging are mostly managed as non-infectious general waste. However, waste from SARS-CoV-2 positive patients, are treated as medical waste as they may be contaminated by the virus. We investigated the possibility of SARS-CoV-2 contamination from positive COVID-19 patients to their leftover food packages at a quarantine centre. Food packages surface was swabbed using prewetted cellular foam, placed into viral transport media and analysed using real time reverse transcription polymerase chain reaction. SARS-CoV-2 RNA was detected in two samples (4.5%) from asymptomatic patients who were at day-2 positive SARS-CoV-2 with cycle threshold (Ct) value (RdRp/E), 34.96/35.72 and 37.1/36.48 respectively. Detection of SARS-CoV-2 supports that there is contamination to the waste. These poses risk of exposure as SAR-COV-2 survive on the surfaces, thus, safe handling and disposal of food waste should be maintained. However, further study involving viral culture should be explored to determine the viability of the SARS-CoV-2 from leftover food packages

SYSTEM ANALYSIS OF TECHNOLOGICAL PROCESSES

The article discusses ways to solve engineering problems in the study of technological processes using methods of system analysis. The essence of this method is to study the technology as a cybernetic system with an assessment of the" reactions” of this system to external influences formed during an active experiment. At the same time, optimization problems are solved analytically. Analytical optimization is based on two main principles. The regression equations obtained as a result of processing experimental data and testing statistical hypotheses are models that adequately describe real processes. Each of these equations is an algebraic function of several variables, to which methods of mathematical analysis are applicable, including the study of extremums of functions in partial derivatives. The next step is to develop a process algorithm and develop computer programs that allow you to select the composition and predict the properties of the product. As an engineering interpretation, it is possible to construct optimized nomograms that allow solving both direct and inverse problems; that is, predicting the result or selecting technological factors. The research methods described in the article are implemented in the study of technologies of cellular concrete, foam concrete, cement-polymer concrete and products made of mineral wool and foam glass. As an example, the article considers the optimization of the selection of the composition of fine-grained concrete reinforced with chopped glass fiber. The implementation of the developed method allowed us to determine the optimal value of the determining parameters, including the consumption of fiber and plasticizer, as well as to form a method for studying the properties of products.

Self-healing performance of lightweight and electrically conductive ethylene-vinyl acetate copolymer/carbon nanotubes composite foam

Conductive polymer composite foams (CPCFs) featuring light weight and good electrical conductivity have received much attention in a diverse range of applications; however, mechanical damage can seriously affect its electrical conductivity in practical use. Therefore, CPCFs with self-healing ability has aroused much research interest. In this work, an eco-friendly method for preparing ethylene-vinyl acetate copolymer/carbon nanotubes (EVM/CNTs) composite foam using supercritical N2 as a foaming agent was reported. This strategy could effectively construct the porous cellular foam structure, in which CNTs were evenly distributed on the cell wall and had the effect of heterogeneous nucleation and improving the viscosity of EVM embryo material, which resulted in reduced cell size, increased cell number and thicker cell wall. When 9 phr CNTs were added, the EVM/CNTs foam conductivity was 8.6 × 10−9 S‧m, the density was 0.14 g‧cm−3, and the resilience was 29%. In addition, the conductivity recovery rate of the foam could reach 66.7% with the healing time of 30 h. More intriguingly, the EVM/CNTs foam was able to fully support the circuits of LED lamp and demonstrate excellent self-healing ability. It exhibited that the EVM/CNTs foam with light weight and environmental protection has great practical application value in the field of conductive and self-healing.

Sound Absorption Properties of Porous Metals Under Grazing Flow Conditions

Porous metals could potentially be used for acoustic liners that can operate in adverse conditions such as high temperature and high pressure. Recent developments in synthetic techniques for porous metals have made it possible to produce them for specific applications, which are intended to provide increased sound absorption. However, if a porous metal is employed in the presence of grazing flow, it is difficult to predict its sound absorption properties. In this study, the acoustic properties of two well-known types of stainless-steel porous materials with different porosities, that is, sintered fiber and cellular foam, were investigated using impedance tube and flow duct experiments. The impedance in flow duct experiments in the absence of flow is almost the same as that in impedance tube experiments, except for the cellular foam sample with high porosity, which may not be a locally reacting material. Furthermore, the effects of grazing flow on the impedance of the porous sample can be separated into those due to the average flow velocity and those due to the flow velocity gradient in the wall-normal direction. Both effects depend on the pore structure and porosity of the porous samples.

Organic-solvent assisted synthesis of highly dispersed iron based Fischer-Tropsch catalysts with MCF support: The effect of organic-solvent

The development of efficient catalysts for Fischer-Tropsch synthesis has attracted much attention in recent years. Mesoporous cellular silica foams (MCFs) supported iron-based Fischer-Tropsch catalysts are prepared via the organic solvent-assisted impregnation methods. The organic solvents (ethanol, acetic acid, glucose, and citric acid) have a great impact on both the structure and performance of the catalysts. In the case of catalyst Fe/MCF-E, obtained by ethanol-assisted impregnation, forming a highly dispersed ɛ-iron phase supported on the supports during relevant industrial FTS process, exhibited excellent stability and activity for 100 h. The Fe/MCF-E catalyst showed C2-C4 olefin selectivity of 30.9% and FTY (iron-time-yield) of 4.68 mol/(gFe· s)·10−5 at 270 °C, and achieved a total olefin selectivity of 48.6% and FTY of 38.59 mol/(gFe· s)·10−5 at 300 °C. These results highlight a convenient strategy to prepare highly stable and active MCF-supported iron based catalysts for FTS.

Effect of the crystallization of modified polybutylene terephthalate on its foaming using supercritical CO2: Transition from microcellular to nanocellular foam

A method for regulating crystallization was developed to prepare micro- and nano- cellular foams of polybutylene terephthalate (PBT) using supercritical CO2 (scCO2). This method involves the formation of branching and crosslinking structures in PBT. After modification, the crystallization temperature of PBT increased from 191.7 to 195.8 °C, while its enthalpy of crystallization decreased from 46.8 to 41.3 J/g and disordered lamellar crystals were formed, particularly, in the case of PBT with a crosslinking structure. In addition to enhanced viscosity and heterogeneous nucleation owing to lamellar crystals, a transition from microcellular foam to nanocellular foam was achieved after the modification of PBT. Interestingly, the transition was only observed in PBT with a crosslinked structure because of its significantly reduced crystallinity, which prevented the appearance of large unfoamed areas. As a result, microcellular PBT foams transformed to nanocellular PBT foams with a cell size of 0.33 µm and cell density of 6.37 × 1013 cells/cm3 upon optimizing the polymer chain structure and supercritical CO2 foaming conditions such as the saturation temperature and saturation time.

Initial Assessments of a Handheld Indentation Probe's Correlation With Cancellous Bone Density, Stiffness, and Strength: An Objective Alternative to “Thumb Testing”

Abstract Objective: During shoulder arthroplasty, surgeons must select the optimal implant for each patient. The metaphyseal bone properties affect this decision; however, the typical resection “thumb test” lacks objectivity. This investigation's purposes were to determine the correlation strength between the indentation depth of a handheld mechanism and the density, compressive strength, and modulus of a bone surrogate; as well as to assess how changing the indenter tip shape and impact energy may affect the correlation strengths. Methods: A spring-loaded indenter was developed. Four tip shapes (needle, tapered, flat, and radiused cylinders) and four spring energies (0.13 J–0.76J) were assessed by indenting five cellular foam bone surrogates of varying density, every five times. After each indentation, the indentation depth was measured with a separate probe and correlated with manufacturer specifications of the apparent density, compressive strength, and modulus. Results: indentation depth plateaued as the bone surrogate's material properties increased, particularly for indentation tips with larger footprints and the 0.13 J spring. All tip shapes produced strong (R2≥0.7) power-law relationships between the indentation depth metric and the bone surrogate's material properties (density: 0.70 ≤ R2 ≤ 0.95, strength: 0.75 ≤ R2 ≤ 0.97, modulus: 0.70 ≤ R2 ≤ 0.93); though the use of the needle tip yielded the widest indentation depth scale. Interpretation: these strong correlations suggest that a handheld indenter may provide objective intra-operative evidence of cancellous material properties. Further investigations are warranted to study indenter tip shape and spring energy in human tissue; though the needle tip with spring energy between 0.30 J and 0.76 J seems the most promising.

Optimization of structural parameters for the sound absorption performance of a cellular ceramic foam

PurposeThe purpose of this paper is to provide an optimization schedule of structural parameters for the sound absorption performance of a cellular ceramic foam in the sound frequency range of 200–4,000 Hz.Design/methodology/approachThe cellular ceramic foam with porosity of about 60–75% and the pore size of about 1–7 mm was successfully prepared by using natural zeolite powder as the main raw material. For this ceramic foam, the sound absorption performance was measured, and the absorption structure was optimized by some important structural parameters. With orthogonal experiment, optimization of structural parameters was found for absorption performance. By means of the range analysis method, the main factor is known to influence the performance of ceramic foam.FindingsThe present ceramic foam may have good absorption performance although at relatively low frequencies of 400–4,000 Hz while structural parameters of sample are appropriately combined. With orthogonal experiment, optimization of structural parameters for the absorption performance was found to be as follows: sample thickness, 25 mm; porosity, 73.5%; pore size, 4–5 mm and air gap depth, 20 mm. To influence the performance, sample thickness is the main factor, air gap depth is the second and both of pore size and porosity would have a relatively slight effect.Originality/valueThis paper presents a method to optimize the structural parameters of a cellular ceramic foam for sound absorption performance by means of orthogonal experiment.

A study of the liquid pyrolysis products of a propane-butane mixture as a precursor in the synthesis of cellular carbon foam

The chemical composition of the pyrolytic liquid products (PLP) of the propane-butane mixture, which serve as a precursor in the synthesis of carbon foam with the cellular structure (a cellular carbon material), was studied. PLP were shown to be a mixture of hydrocarbons containing 95 wt.% carbon and 4 wt.% hydrogen, which testify to the presence of polycyclic aromatic compounds.A study by means of sequential extraction, structural-group analysis and chromato-mass spectrometry revealed the heterogeneous nature of PLP components and detected both the lighter fractions (14 wt.%) soluble in alkanes and the polynuclear aromatic compounds (72 wt.%) soluble in chloroform. The averaged PLP molecule with the molecular weight 240 аmu contains approximately twenty carbon atoms that form polynuclear structures including five aromatic rings. The following main components were identified: naphthalene, 1,1′-biphenyl, acenaphthylene, 9H-fluorene, anthracene, phenanthrene, fluoranthene, pyrene, acepyrene, triphenylene, benz[e]acefenantrylene, benzopyrene, and benzo[ghi]perylene.

Correlation Modeling between Morphology and Compression Behavior of Closed-Cell Al Foams Based on X-ray Computed Tomography Observations

In the last decades, great attention has been focused on the characterization of cellular foams, because of their morphological peculiarities that allow for obtaining effective combinations of structural properties. A predictive analytical model for the compressive behavior of closed-cell Al foams, based on the correlation between the morphology of the cellular structure and its mechanical response, was developed. The cells’ morphology of cylindrical specimens was investigated at different steps of compression by X-ray computed tomography, in order to detect the collapse evolution. The structure, typically inhomogeneous at local level, was represented by developing a global virtual model consisting of homogeneous cells ordered in space, that was fitted on the experimentally detected structure at each deformation step. As a result, the main parameters characterizing the two-dimensional cells morphology (equivalent diameter, circularity), processed by the model, allowed to simulate the whole compression stress–strain curve by enveloping those obtained for each step. The model, fitted on the previous foam, was validated by comparing the simulated stress–strain curve and the corresponding experimental one, detected for similar foams obtained by different powder compositions. The effectiveness in terms of an accurate prediction of the compression response up to the final densification regime has been confirmed.

Effects of Waste Glass Powder Filler on Intumescent Coating for Steel Structures Application

Intumescent coating is a passive fire protection system used to prevent and resist the spreading of fire. The coating swells several times of its thickness on exposure to the fire, forming cellular foam and acts as an insulative barrier, thus delaying the heat transfer to the protected substrate. The study aims to analyse waste glass powder filler’s effect into intumescent coating formulation limited to one size of waste glass powder. Waste glass is a broken form of leftover by-product from industrial and domestic. Millions of tons of waste glass generated every year, adding with their non-biodegradable nature causing additional environmental pollution. Waste glass powder contains high silica composition known for its high thermal stability, weather resistance, hydrophobicity, low surface tension, and high oxidation resistance. The coating showed improved thermal stability, weather resistance, and adhesion when added into intumescent coating formulation. The lowest recorded backside substrate temperature 154.6 °C compare to coating without the waste glass filler, 333.7 C. The coating also showed less than 0.1% total weight loss for samples with 4% wt. filler after immersion in seawater for 15 days compared to the control formulation, 0.19%. The char morphology analysis showed the emergence of silica and calcium elements occupying the expandable char’s gaps, thus strengthening the char structure.

Reticulated ceramic foams from alumina‐chromia solid solutions: A feasibility study

AbstractOpen cellular ceramic foams were manufactured from plain and chromia‐doped alumina, with a chromium concentration ranging between 1.25 mol% and 5.0 mol%. The (AlCr)2O3 starting powders were prepared by precipitation of a chromia precursor onto the surface of an alumina powder and subsequent calcination. Characterization of the starting powders as well as the foam samples made therefrom were carried out with respect to the chromium concentration in the alumina phase and the influence of the dopant on the cellular structure and sintering behavior of the doped material. While no positive effect on the compressive strength of the ceramic foams was found, the dopant influences the sintering behavior resulting in an increased shrinkage and in a reduction of total porosity.