Types Of Foams Research Articles

Study on Flexural Behavior of Glass Fiber Reinforced Plastic Sandwich Composites Using Liquid Thermoplastic Resin.

Experimental and numerical studies of composite sandwich structures are warranted to reap the benefits of these materials when they are well designed. In the current research, new liquid thermoplastic and epoxy resins were used to fabricate four composite sandwich panels with two additional foam types and different densities in the wind turbine industry. A comprehensive comparison of three-point bending test results was made. Finite-element-based simulations using the ABAQUS program with Hashin’s damage criterion were conducted to examine the failure behavior of the GFRP sandwich composites. The flexural behavior of the glass-fiber-reinforced plastic (GFRP) sandwich panels was investigated and compared with the experiments. The results show that the GF/PVC/Elium composite panel gives the highest load absorption, flexural strength, flexural modulus, core shear ultimate strength, and facing stress due to effect of the core foam and resin types. For the PVC foam core sandwich panel, using thermoplastic resin increased the flexural strength by 18% compared to that of the epoxy resin. The simulation results show excellent agreement between the finite-element-predicted failure loads and the experimental results.

Experimental Research on the Effectiveness of Different Types of Foam of Extinguishing Methanol / Diesel Pool Fires

ABSTRACT Storage tank fire can pose great threats to life and environment as it can cause strong radiant heat, fast-spreading flame, and destructive explosion. In this research, a 1.5 m-diameter circular steel pan is used to simulate the full surface fire of a storage tank in an industrial park. A self-built fire-extinguishing system gently releasing foam at the rate of 11.4 L/min was applied for the evaluation of the effectiveness of different types of foam of extinguishing diesel/methanol pool fires. Experiments were conducted to analyze the temperature increases of fires after releasing different types of foam. In this research, the nondimensional average temperature 0.85 and 0.71 regard as the fire extinguishing temperatures of methanol and diesel fuel, respectively. Over the spreading process, the increase in foam spreading length over time still follows the power law. The fastest flow velocity of 6% FP/AR in methanol pool fire and 6% Synthetic foams in diesel pool fire was 0.0136 m s −1and 0.044 m s −1, respectively, with a foam application rate of 11.4 L/min. The results show that, in the methanol pool fire, the cooling effect of the foam is ranked as FP/AR > AFFF > AFFF/AR > S > FP > S/AR. And the cooling effect of foam for diesel is ranked as S > S/AR > AFFF > AFFF/AR > FP > FP/AR. Foam’s cooling impact is especially notable in diesel pool fires. As for methanol pool fires, the foam extinguishing mechanism is mainly based on the “anti-soluble film” effect, which quickly forms a covering layer on the surface of the flammable liquid, seperating the flame from heat feedback and inhibiting the generation of flammable vapors, insulating itself against the air and ultimately asphyxiating the fire.

Animal-Protein-Based and Synthetic-Based Foamed Mixture Lightweight Soil Doped with Bauxite Tailings: Macro and Microscopic Properties.

In order to explore the effect of the foaming agent type on the properties of foamed mixture lightweight soil mixed with bauxite tailings (FMLSB), low-density (437.5 kg/m3 and 670 kg/m3) and high-density (902.5 kg/m3 and 1170 kg/m3) FMLSB were prepared using protein-based and synthetic-based foaming agents (AF and SF, respectively). The foam stability, micro characteristics, compressive strength, fluidity, and volume of water absorption of the FMLSB were investigated. The results showed that the foam made from AF had better strength and stability compared to SF. The internal pore sizes of both AF- and SF-FMLSB at low density were large, but at high density the internal pore sizes and area porosity of AF-FMLSB were smaller than those of SF-FMLSB. In terms of compressive strength, the compressive strength of AF-FMLSB was improved by 17.5% to 43.2% compared to SF-FMLSB. At low density, the fluidity of AF- and SF-FMLSB is similar, while at high density the fluidity of AF-FMLSB is much higher than that of SF-FMLSB. In addition, the stable volume of water absorption of SF-FMLSB is smaller than that of AF-FMLSB at low density, and the corresponding water resistance is better, but the situation is reversed at high density.

Improved Compressive Properties of Lattice Structure Based on an Implicit Surface Hybrid Optimization Design Method via Selective Laser Melting

In recent years, the lattice structure produced by additive manufacturing is a type of metal foam that has been increasingly investigated for its unique mechanical properties. However, the conventional Computer-Aided Design (CAD) is inefficient, the triply periodic minimal surfaces are rarely mixed, and the smooth transitions at the boundaries are not considered. In this study, a hybrid optimization design method based on implicit surfaces is proposed, which combines multiple implicit surfaces to achieve the continuous change in the curvature at the structure junctions and reduce the stress concentration. The hybrid lattice structures designed by this method were additively manufactured using 316L alloy via a selective laser melting. The results of the finite element analysis and mechanical compression test show that the hybrid lattice structures generated by this method exhibit a higher yield strength and energy absorption. These works can be used for other implicit surfaces, improve and enrich the types of implicit surfaces, and provide more good choices for practical applications.

Energy-absorbing mechanism and crashworthiness performance of thin-walled tubes diagonally filled with rib-reinforced foam blocks under axial crushing

Thin-walled structures are widely used as crucial structural components for energy absorbing applications. To design lightweight thin-walled-involved composite structures with better mechanical performance remains an open issue. In this study, the X-shaped rib-reinforced foam-filled tubes were designed and tested under quasi-static axial compression. Two types of foams, i.e., the aluminum foam and the additively manufactured polylactide (PLA) foam were considered as lightweight fillers. The effects of foam block filling ratio (rib angle) and arrangement of different foam fillers on the axial crushing performance of the diagonally rib-reinforced foam block-filled tube were analyzed. Results indicated that tubes that were diagonally filled with PLA foam blocks possessed better energy absorption capacity, whereas the higher mean crushing strength was achieved by diagonally filling with two aluminum blocks. It also revealed that tubes filled with different foam blocks did not always show advantages over those filled with the same foams. Moreover, the diagonally aluminum foam blocks filled tubes with a large rib angle could induce the global buckling, whereas that with the rib angle of 120 degrees exhibited better mechanical properties in load consistency and specific energy absorption capacity. Numerical simulations were conducted to reveal the energy absorption enhancement mechanism of the tubes filled with varying combinations of the reinforced fillers. Results indicated that the interaction between the foam blocks and the reinforced rib contributed most to the increased energy absorption. Further, an analytical model for evaluating the crushing strength of the developed structure was proposed. The theoretical predictions are in good agreement with the experimental results. The idea of tailoring the fillers arrangement and assembling pattern would promote the development of optimal energy-absorbing thin-walled involved composite structures.

Heat transfer analysis using a duct filled with metal foams

Thick-walled pipe experiencing internal flow is widely used in a variety of applications in the industry. Some of the most prominent ones are heat exchangers, heat pipes, furnaces, etc. In this study, conjugate heat transfer has been examined in a pipe filled with a porous medium experiencing a constant external heat flux. Th e an al ysis is ba se d on a tw o- dimensional domain using a quasi-thermal equilibrium model. Effects of porosity, pore density, Reynold’s number and thermal conductivity of solid and fluid on the Nusselt number have been studied. Three types of porous foams based on the pore density have been chosen for the analysis: 10 PPI, 40 PPI and 60 PPI. The results have been generalized for use in a wide range of Newtonian fluids. Additionally, the pressure drops across the pipes fi ll ed wi th po ro us media have been studied as a function of pore density and Reynold’s number. Numerical results indicate augmented performance with porous foams of high pore densities. However, using a porous medium with higher pore density leads to higher pressure drop, thus needing pumping power. The computational model used in this manuscript predicts that Nusselt number is increased by 38.7 % with Reynold’s number < 10000, when the porous medium is changed from 10 PPI to 60 PPI. The numerical data presented in the manuscript supports the application of low porosity foam with low pore density to achieve better thermal transport at the cost of pressure drop.

Melting/solidification of phase change material in a multi-tube heat exchanger in the presence of metal foam: effect of the geometrical configuration of tubes

One of the likely methods for enhancing heat transfer in a latent thermal energy storage system is the conception of a thermal unit. In this study, the orientation of oval tubes (horizontal, vertical, and oblique) in phase change material (PCM, C19-C20)-based shell-tube heat exchanger was analyzed with respect to the metal foam (MF) type (graphite, copper, and nickel) in comparison to the case of pure PCM. For this purpose, a two-dimensional mathematical model was developed to investigate the thermal efficiency of the PCM-metal foam based composite energy storage unit. It was concluded that the orientation of the oval tubes (oblique, horizontal, and vertical) has a negligible impact on the performance of the thermal unit during the melting/solidification processes. Based on the liquid/solid fraction, total enthalpy and the average temperature in the annular space, the performance of a heat exchanger during fusion/solidification periods is in the order: copper-MF > graphite-MF > nickel-MF > pure PCM. Whatever the adopted MF or the geometry of tubes, the melting process is expedited compared to the solidification mechanism.

Microplastic Contamination in Urban, Farmland and Desert Environments along a Highway in Southern Xinjiang, China.

The different types of microplastics (MPs), including debris, fibers, particles, foams, films and others, have become a global environmental problem. However, there is still a lack of research and understanding of the pollution characteristics and main causes of MPs in the arid region of Xinjiang, China. In this survey, we focused on the occurrence and distribution of MPs in urban, farmland and desert areas along a highway in the survey area. Our results showed that the main types of MPs were polypropylene (PP) flakes, polyethylene (PE) films and both PE and PP fragments and fibers. The abundance levels of MPs in street dust of Korla, Alar and Hotan districts equaled 804, 307 and 1526 particles kg−1, respectively, and were positively correlated with the urban population. In farmland areas, there were only two types of MPs (films and fibers), of which the film particles dominated and accounted for 91% of the total on the average. The highest abundance rate of MPs reached 7292 particles kg−1 in the desert area along the highway. The minimum microplastic particle sizes were 51.8 ± 2.2 μm in urban street dust samples, 54.2 ± 5.3 μm in farmland soil samples and 67.8 ± 8.4 μm in samples from along the desert highway. Particle sizes < 500 μm were most common and accounted for 48–91% of the total in our survey. The abundance and shape distribution of the MPs were closely related to the different types of human activities.

Innovative water-based dynamic liquid bubble membrane generation device for gas/vapour separation

Gas and vapour separation by membrane technology has become a promising method because of its high energy efficiency and low capital investment. Here, we demonstrate a proof of concept of the design of a new type of liquid membrane called the “dynamic liquid bubble membrane” (DLBM) connected by plateau borders. The DLBM is composed of a network of bubbles formed by passing a gaseous mixture through water containing a surfactant. The bubble network serves as a membrane to selectively separate the gases/vapours of mixtures according to the different solubilities of the gases in the bubble liquid. To the best of our knowledge, this type of liquid foam has not been described previously. The effects of key experimental factors, such as the surfactant concentration in the water of the membrane solution and the bubble velocity (controlled by the slope of the device) of the DLBM, on the CO2/CH4 separation performance were investigated. The retentate gas (CH4) remained over 99.9 % for the high CH4 concentration injection mixture (>66.7 % CH4). Then, O2/CO2 was used to simulate the fluid of the alveolar lining during the full in-breath process. We found that carbon dioxide transferred outside the bubble film, while oxygen was retained inside the bubble. This finding supports a further understanding of the CO2 transport mechanism of alveoli. We further demonstrated that the thickness of the bubble film was closely correlated to mass transfer resistance theory, while the gas selectivity was completely unaffected. This innovative DLBM generation device is a highly attractive and promising prototype for designing a green and highly efficient gas/vapour separation membrane technology.

Recovery of Green Polyols from Rigid Polyurethane Waste by Catalytic Depolymerization.

Polyurethane (PU) is one of the most versatile polymers available and can be found in an infinite number of formats ranging from rigid or flexible foams to elastomers. Currently, most Rigid PU Foam (RPUF) waste is landfilled, even though a small amount is mechanically recycled, in which the material is conditioned in size to a very fine powder, which is introduced as a filler. In this work, chemical recycling of two types of rigid PU foams is studied, the major difference being the aliphatic or aromatic nature of the isocyanate used in the synthesis. A solvolysis process is developed, a chemical depolymerization that breaks the chains by means of a chemical agent, a solvent, in the presence of a catalyst and under controlled process conditions. The glycolysis products are purified by vacuum distillation, centrifugation, and acid water treatment, depending on the most suitable process for each waste type. Optimal process conditions are established to obtain high-purity green polyols by performing a set of catalytic glycolysis reactions at laboratory scale with the previously conditioned RPUF waste samples. The physicochemical properties of the polyols, such as hydroxyl value, acid value, average molecular weight (Mn), and viscosity, are analyzed. The chemical structure and thermal stability of the polyols are studied by means of FTIR and TGA, respectively. Partial substitution of the commercial polyol (up to 15 wt.%) by the recycled polyols for RPUF synthesis is studied and characterized.

Hierarchical porous N-TiO2/carbon foam composite for enhancement of photodegradation activity under simulated sunlight

Nitrogen doped TiO2 (N-TiO2) photocatalyst was synthesized via sol-gel combined with low temperature reflux method using urea as nitrogen source. Hierarchical porous carbon foam (HPCF) with the characteristics of micro/mesopores and micron-sized macropores was made by steam activation of a new type of thin-walled carbon foam which was produced from the loose medium component of coal. N-TiO2/HPCF was synthesized by loading N-TiO2 onto the HPCF via impregnation method. The synthesized catalysts were characterized by N2 adsorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), diffuse reflection spectrometry (DRS) and photoluminescence spectroscopy (PL). Phenol was used as a simulated pollutant in wastewater to evaluate the photodegradation performances of naked TiO2, N-TiO2 and N-TiO2/HPCF. The N-TiO2/HPCF composite removed 97 % of phenol in 2 h of simulated sunlight irradiation and displayed the highest photocatalytic activity, which was 4.9 times that of N-TiO2 and 10.8 times that of naked TiO2. The enhanced activity of N-TiO2/HPCF can be ascribed to the combination of both extended visible light adsorption of N-TiO2 and the concentrating effect brought by HPCF. This work demonstrates a facile approach to synthesis an inexpensive and efficient N-TiO2 coated coal-based carbon foam for the treatment of wastewater.

Foam based fracking in unconventional shale reservoir

As the energy demand increases globally, oil and gas industry has started to explore the unconventional shale resources. Shale gas production has become feasible by the application of hydraulic fracking technology which involves the process of injecting water, chemicals and sands at high pressure to create small fractures within tight shale formations to stimulate the production. But the major problem using hydraulic fracturing involves excessive water consumption, formation damage etc. but, fracking methods with low water consumption viz., foam based fracking and nanoparticles based foam fracking are novel and much effective techniques for unconventional shale resources are discussed in detail in the present paper. When nanoparticles are added in the foam, it acts as proppants and enhances the quality of fracturing fluid rheology. The present paper discusses the foam characteristics and its proppants carrying capacity, reviews recent studies on different types of foam based fracking, and nanoparticles stabilized foam fracking. Experimental studies, field applications, its major advantages and disadvantages are also discussed.

Crashworthiness of foam filled truncated conical sandwich shells with corrugated cores

Polymeric foam filled truncated metallic conical sandwich shells with corrugated cores were proposed, and their energy absorption characteristics under axial compression were systematically investigated. The types of foam filling include: (i) foam filling inner cavity (FFIC), (ii) foam filling corrugated channel (FFCC), and (iii) foam filling inner cavity and corrugated channel (FFICCC). Test specimens were fabricated by combining the step-by-step molding method with the method of in-situ foam filling. Firstly, the crashworthiness of FFIC, FFCC and FFICCC subjected to axial compression was experimentally characterized. Secondly, numerical simulations with the method of finite elements (FE) were performed, with good agreement achieved between measurements and simulations. Subsequently, based upon the validated FE models, interaction mechanisms between foam filler and metallic shell were explored, and the influences of wall thickness, semi-apical angle and loading speed on energy absorption were quantified. The three different foam filled structures were found to exhibit higher energy absorption than their unfilled counterpart. Particularly, the specific energy absorption (SEA) of the FFCC was higher than that of the unfilled structure, attributed mainly to the participation of all foam fillers in the interaction with metal shells that was rarely found in other types of foam-filled structure.

Guided bubbles and wet foam for realistic whitewater simulation

We present a method for enhancing fluid simulations with realistic bubble and foam detail. We treat bubbles as discrete air particles, two-way coupled with a sparse volumetric Euler flow, as first suggested in [Stomakhin et al. 2020]. We elaborate further on their scheme and introduce a bubble inertia correction term for improved convergence. We also show how one can add bubbles to an already existing fluid simulation using our novel guiding technique, which performs local re-simulation of fluid to achieve more interesting bubble dynamics through coupling. As bubbles reach the surface, they are converted into foam and simulated separately. Our foam is discretized with smoothed particle hydrodynamics (SPH), and we replace forces normal to the fluid surface with a fluid surface manifold advection constraint to achieve more robust and stable results. The SPH forces are derived through proper constitutive modeling of an incompressible viscous liquid, and we explain why this choice is appropriate for "wet" types of foam. This allows us to produce believable dynamics from close-up scenarios to large oceans, with just a few parameters that work intuitively across a variety of scales. Additionally, we present relevant research on air entrainment metrics and bubble distributions that have been used in this work.

Pengaruh Styrofoam Sebagai Bahan Tambah Campuran AC-BC Batu Sungai Tetean Kabupaten Mamasa

Tetean River is a river located in Mamasa Regency, West Sulawesi. In this study, one of the efforts to improve the quality of the AC-BC mixture so that the service life remains stable is by utilizing styrofoam as an additive in the asphalt mixture. Styrofoam is white cork or a type of foam that is often found around in the form of cork that supports electronic goods which has a high economic value because it can be recycled, cheap and practical. Styrofoam is flexible, difficult to decompose, resistant to acids and bases and salts. Styrofoam content used is 0%, 2%, 4%, 6%, and 8%, of the asphalt weight. With the aim of understanding the characteristics of the AC-BC mixture using Styrofoam waste added material, to obtain the marshall stability value of the remaining AC-BC mixture and to determine the effect of Styrofoam on the AC-BC mixture. The test carried out was the AC-BC mixture test using the Marshall method (SNI 06-2489-1991).&#x0D; From testing the characteristics of the AC-BC mixture with Styrofoam added 0% - 8%, using the Conventional Marshall test it has met the general specification standards of Bina Marga 2018 and the value of the remaining Marshall stability obtained using the Marshall Immersion test is 96.48%.

Effect of combined gradation in cross-sectional area and density on the dynamic compressive behavior of foams for moderate impact velocities

The effect of combined gradation in area and density on the dynamic response of foams is studied in this work. The cross-sectional area and density are graded such that the product of these quantities results in a tri-linear variation along the foam’s length, and hence, the foam type is designated as Type-TL. A theoretical model based on the R-PP-L idealization is developed to study the response of the Type-TL foam struck by a rigid projectile. The Type-TL foam offers force distribution over a considerably larger area than a homogeneous foam, which may benefit structural protection.

Статистический подход к описанию напряженного состояния микроструктуры сферопластика

Object and purpose of research. The object of research is a composite material of the syntactic foam type (SF), which forms a heterogeneous medium consisting of a polymer matrix filled with spherical inclusions- micro spheres. The paper suggests that distribution of micro spheres in SF should be used as a qualitative measure for estimation procedures. Comparison of such distribution for various models can be used for explaining the SF efficiency estimations. Materials and methods. The initial data inputs for the study were the composition and structure of syntactic foam and characteristics of its components: polymer matrix and glass micro spheres. Numerical studies were carried out using the earlier developed structural model of SF deformation and damage. The structural model assesses the stressed-strained state of large micro sphere assemblies (models with a number of spheres about 105 are used in the study). Results obtained by the model let us use statistical methods of processing the stress raisers and identify patterns of distributions for predicting the SF strength. The results are verified by comparison with estimations by finite element models. Main results. The structural model of deformation and damage is highly effective in calculation of the stressed-strained state of micro structures with a number of micro spheres of about 105 and more. Conclusion. The structural model developed for SF makes it possible to accurately assess the stresses of its components under external hydrostatic pressure considering a large number of micro spheres. The results show excellent convergence of the stressed-strained state estimates with detailed estimations by FE models. With accurate data on the stressed-strained state of micro structure one can predict how the damage would develop and calculate the process to failure and full loss of buoyance.

Synthesis and properties of foams from a blend of vegetable oil based polyhydroxyurethane and epoxy resin

This article aims to highlight the synthesis of foams from a blend of hydroxyurethane of castor oil and epoxy resin. An epoxidized castor oil of 4% oxirane oxygen was first converted to cyclic carbonate of castor oil at 120°C, 1 atm CO2 pressure and then it was reacted with three different aliphatic diamines to yield amine terminated Polyhydroxyurethane (PHU). Foams were prepared in a metal mould from the blend of PHU, epoxy resin, epoxy hardener and polymethylhydrogensiloxane blowing agent which releases hydrogen gas upon reaction with amine. FTIR and 1H NMR of cyclic carbonate of castor oil and PHU of castor oil were done to confirm their chemical structures. Optical microscopy and scanning electron microscopy of foams was done to assess their cellular morphology along with DSC and TGA to evaluate their thermal properties. Both flexible and rigid type of foams were synthesised in this study. Resilience of flexible foams was inspected using a ball rebound test and compression-recovery test while thermal insulation property was checked by measuring thermal conductivity, thermal diffusivity and R-values of rigid foams from heat transfer study using a heat transfer apparatus.

Numerical investigations of the coupled conductive-radiative heat transfer in alumina ceramics

To further understand the heat transfer behavior of open-cell alumina ceramics, the FVM combined with an improved mesh-agglomeration Monte Carlo ray-tracing method is developed to solve the coupled conductive-radiative heat transfer in open-cell alumina ceramics, where the spectral radiative properties are dealt with gray-band model. The radiative behavior of tomography-based foams and cinema4d-based foams are analyzed and compared, which indicates that the radiative characteristics of the two types of foams are very similar. On the basis of this, cinema4d-based foams with various porosities are used for the evaluation of effective/radiative thermal conductivity, where the porosity and temperature ranges from 0.5 to 0.8 and 1400 to 2000 K, respectively. The results show that for different temperature/porosities, the variation range of the effective thermal conductivity is limited (2.7–5.0 W/m·K), however, the variation range of the share of thermal radiation /conduction is very large. It can be also found that when the porosity is low, the thermal conduction dominates; when the porosity is high and the temperature is high, the effect of thermal radiation becomes important and accounts for >75% of the coupled conductive-radiative heat transfer. These findings can provide a deeper understanding of the conductive-radiative heat transfer in alumina ceramics.

Determination of factors effecting the properties of water-air microdispersion

The article presents the results of laboratory studies on the effect of the liquid-gas ratio and the foaming agent type on the average water-air micro dispersion size obtained from the foaming agent solution. The size of microbubbles significantly effects the efficiency of flotation and depends on the type and concentration of foaming agent used for their production. A generator was used to obtain water-air micro dispersion. The works were performed to work out the water-air micro dispersion parameters of at different liquid-gas ratio and different performance of the generator. The following foaming agents were used as objects of research: sodium butyl aero flot (BTF), flotanol C-7, butyl triethylenetetramine (B-TETA) at a concentration of 0.5 g/dm3. It has been established, that the optimal phase liquid-gas ratio was 1:1, the optimal capacity of the generator was 6-7.2 dm3/h with an average particle size of air-water micro dispersion- 33-41 mm for BTF solution, 103-107 mm for C-7 solution, 90-93 mm for B-TETA solution. The type of foaming agent used in flotation effects the size and stability of microbubbles. It is established that the flotation agents can be arranged in the following line with respect to their ability to create micro dispersion: IIBK→Senfroth 580→B-TETA→OPSB→Flotanol C-7→T-92→BTF. The best results are shown by BTF that creates micro dispersion of 43-58 μm (t 20-40 °С) and stability of 80 sec with concentration of 0.5 g/dm3.