Preparation Of Foams Research Articles

Preparation and Electrochemical Properties of Phenolic Resin-Based Carbon Foam Doped with Ni/Co-Modified RGO

Preparation and Electrochemical Properties of Phenolic Resin-Based Carbon Foam Doped with Ni/Co-Modified RGO

Enhanced thermal and mechanical properties of flame-retardant expandable graphite modified silk fibroin-based rigid polyurethane foam

At present, in order to reduce the environmental pollution caused by the use of petrochemical products, the preparation of flame-retardant polyurethane foam (PUF) using green raw materials is increasingly attracting widespread attention. A biomass protein-based green flame-retardant rigid PUF (RPUF) with expandable graphite (EG) and silk fibroin (SF) was prepared in a one-step process. Thermal stability, combustion characteristics and compression properties of modified RPUFs were investigated by thermogravimetric analysis, cone test, limiting oxygen index (LOI) test, UL-94 vertical burning test and mechanical compression test. The RPUF with 10 wt% EG (RPUF-SF/EG10) exhibited superior heat resistance, with the highest initial decomposition temperature (Ti), integral programmed decomposition temperatures (IPDT) and activation energy (E). And RPUF-SF/EG10 had the lowest peak heat release rate (PHRR) and total heat release (THR), and it also showed the highest LOI and had a flammability rating of V-0. In Addition, the apparent density and compressive strength of RPUF-SF/EG10 were the largest among the four EG-added materials. The results indicated that RPUF-SF/EG10 had excellent thermal stability, flame retardancy and compression resistance, which was attributed to the synergistic effect of SF and EG in the system. This provided a valuable reference for the development of new, environmentally friendly and high-performance RPUFs.

A novel “reinforcing-foaming-recovering” strategy for achieving thermally insulating green foams with ultrafast degradation

Lightweight porous materials have garnered increasing attention in application domains of intelligent construction and flexible thermal insulation, owing to their customizable 3D porous structures and outstanding performances. Nonetheless, the severe environmental pollution resulting from the accumulation of non-degradable plastic waste in the ecosystem has sparked significant interest in developing bio-degradable thermal insulation foams. The preparation of biodegradable foam, however, typically requires operating specialized equipment for long periods under extreme conditions, which diminishes its environmental friendliness as claimed. Herein, we present a pioneering "Reinforcing-Foaming-Recovering" strategy to achieve ultralight and recyclable green foams with excellent thermal insulation properties. This innovative strategy, involving materials reinforcing and low-pressure foaming complemented by nitrogen-assisted gas recovering enables the preparation of low-density (0.08 g/cm3) biodegradable foams with restricted shrinkage ratio (<5%). Thanks to the easy-to-control foaming method, combined with the improved 3D network cellular structures caused by nitrogen-assisted gas exchange, the achieved green foams exhibit favorable thermal insulation (39.8 mW/m·K) and superior biodegradation efficiency (11.5%/2 months). The approach of energy-efficient nitrogen-assisted low-pressure foaming of degradable polymers offers a promising and practical solution for producing eco-friendly and multifunctional porous materials with economic advantages.

Role of pulse globulins and albumins in air-water interface and foam stabilization

Pulse protein isolates are promising substitutes for animal protein in foam preparation, but they typically are complex mixtures of multiple proteins, and the contribution of the individual proteins to the behavior of the mixture in air-water interface stabilization is largely unknown. The major protein fractions in isolates are the globulins and albumins, and this study systematically investigated the molecular properties, and interfacial and foaming properties of these two fractions for three different pulses: lentils, faba beans and chickpeas. The key parameters of these pulse proteins in air-water interface and foam stabilization were investigated by correlation analysis. Based on this, low denaturation enthalpy tends to result in both high foamability and foam stability, most likely due to a greater conformational flexibility that allows for a faster adsorption to the air-water interface, and higher degree of structural rearrangement at the interface, which increases interfacial network stiffness. For globulin-rich pulse protein fractions, vicilins and convicilins tend to introduce high surface hydrophobicity, which increases the affinity of the proteins for the interface, and increases protein-protein in-plane interactions through hydrophobic interactions, resulting in the enhancement of interfacial network connectivity and the level of network branching. These factors increase the interfacial resistance to large deformations and increase foam stability. Vicilins and convicilins also tend to have a high value of the surface charge and further promote foam stability by increasing electrostatic repulsion between air bubbles. Legumins tend to reduce foamability since they adsorb to the air-water interface slowly and tend to disrupt the interfacial network structure. These findings provide deeper insights in the role of pulse globulins and albumins in air-water interface and foam stabilization. The proposed key parameters will benefit the predictability of the interfacial and foaming behavior of pulse proteins.

Soft template-based preparation of light-weight and high-strength cross-linked polystyrene foams&amp;mdash;from monoliths to selective permeable membranes

Soft template-based preparation of light-weight and high-strength cross-linked polystyrene foams&amp;mdash;from monoliths to selective permeable membranes

Facile preparation of three-dimensional copper foam incorporated with Au/CuO nanorods as a durable, reusable and efficient SERS substrate

An exceptionally durable and recyclable three-dimensional copper foam (CF) modified CuO nanorods with Au nanostructures on its surface is noticeable for the application in surface-enhanced Raman scattering (SERS). The utilization of CF as a 3D frame substrate allowed for the advancement of its beneficial characteristics, such as an increased surface-active area resulting from its high porosity and superior chemical/physical stability. By thermally oxidizing CF at a temperature of 500 °C, CuO nanorods were fabricated directly onto CF to exploit its advantageous properties, such as its high surface-active area and photodegradation effect. Following that, Au nanostructures were deposited onto the surfaces of CuO nanorods via photoreduction. The purpose of incorporating Au nanostructures was to optimize the SERS phenomenon, since Au exhibits high SERS efficiency and excellent surface stability. The Au/CuO@CF SERS substrate demonstrated the capability to measure MB at a concentration of 0.1 nM. Meanwhile, the recyclability of the Au/CuO@CF was evaluated by subjecting it to UV irradiation three times while utilizing MB samples. Subsequently, the Au/CuO@CF substrate's physical durability was evaluated via sandpaper abrasion test. In addition to confirming the long-term usability, the Au/CuO@CF demonstrated its resilience by maintaining good measurement performance even after being subjected to ambient air for up to 25 days.

Preparation and Effectiveness of a Nano-Modified Composite Gel Foam in Preventing the Spontaneous Combustion of Coal

ABSTRACT In China, coal is considered the cornerstone in the energy mix for ensuring the security of national energy production. With the increasing intensity and depth of coal seam mining in China, spontaneous coal combustion in goaf areas has become a major issue affecting mine safety. The development of a nano-modified composite gel foam to prevent the spontaneous combustion of residual coal was therefore investigated in the current study. Chemical modification through intercalation and grafting was found to significantly enhance the water retention performance of the antioxidant component. In addition, the optimal component ratios were determined using single-factor experiments and response surface methodology. The modified gel foam, consisting of 2.995 wt% gelling agent, 0.25 wt% foaming agent, 0.296 wt% crosslinker, 0.491 wt% foam stabilizer, 3.772 wt% nanoparticles, and 2.964 wt% modified antioxidant, demonstrated environmental friendliness. Thermogravimetric experiments showed that the critical temperature for achieving a significant increase in the dehydration rate rose from 80 to 120°C after modification. Compared with typical inhibitors, the nano-modified gel foam exhibited a superior performance in terms of preventing coal oxidation and spontaneous combustion, particularly at low temperatures. Oxidation during the oxygen absorption and weight gain stages was also effectively inhibited, and the high temperature combustion processes were suppressed.

Bio-Based Polyurethane Composites from Macauba Kernel Oil: Part 1, Matrix Synthesis from Glycerol-Based Polyol

Polyurethanes are the result of a reaction between an isocyanate and a polyol. The large variety of possible reagents creates many possible polyurethanes to be made, such as soft foams, rigid foams, coatings, and adhesives. This polymer is one of the most produced and consumed polymers in the world with an ever-increasing demand. Despite its usual petrochemical nature, research on bio-based polyurethanes flourishes due to the ease in creating bio-based polyols. This work covers the synthesis of a novel macauba kernel oil polyol by the epoxidation of the oil, followed by a ring-opening reaction of the epoxide with glycerol, used for the preparation of polyurethane foams using different NCO/OH ratios. The FTIR and H1 results confirm the formation of the epoxide and polyol, and the polymers in all NCO/OH ratios were confirmed by FTIR, showing great similarities between the samples, especially PU 1.0 and PU 1.2. Despite the TGs showing close behaviors for the three samples, their DTGs showed great difference between the samples, with PU 1.0 presenting a regular PU DTG profile with three degradation peaks while the other two sample presented five degradation peaks, indicating a higher crosslinking density in them.

Phenolic Foam Preparation Using Hydrofluoroolefin Blowing Agents and the Toughening Effect of Polyethylene Glycol.

In this work, a new class of fourth-generation, zero ozone depletion potential, hydrofluoroolefin-based blowing agents were used to prepare phenolic foam. While hydrofluoroolefin blowing agents have been used previously to prepare polyurethane foams, few studies have been reported on their use in phenolic foams. We introduce an effective method for foam preparation using two low-boiling blowing agents, cis-1,1,1,4,4,4-hexafluoro-2-butene and trans-1,1,1,4,4,4-hexafluoro-2-butene, and their combinations with hexane. Traditionally, phenolic foams have been prepared using chlorofluorocarbons and hydrochlorofluorocarbons, which can have harmful effects on the environment due to their high ozone depletion potential or global warming potential. Conductor-like screening model for real solvents (COSMO-RS) modeling studies were performed to understand the effects of different blowing agent combinations on their boiling points. A series of phenolic foams were prepared by varying the concentration of the hydrofluoroolefin and the hydrofluoroolefin-hexane blowing agent combinations. The concentrations of the surfactant, Agnique CSO 30, and the toughening agent, polyethylene glycol, were also varied to yield a formulation with the optimal properties. The foams formulated with the hydrofluoroolefin-hexane mixture displayed a higher compressive strength and a lower thermal conductivity than those prepared with either hydrofluoroolefin or hexane alone. The cell microstructure of all the foams was examined using scanning electron microscopy. By introducing flexible chains into the resin matrix, PEG facilitates proper distribution of hydrofluoroolefin-hexane blowing agents and other reagents and thereby increases the mechanical strength of the foam.

Preparation and characterization of high-stability gel foam for fracture plugging in reservoirs

A high-stability gel foam is successfully prepared by forming a gel structure in the liquid film using polymer and crosslinker. The foaming properties, gel characteristics, foam stability, and microstructure of the high-stability gel foam are systematically studied. Although increasing the viscosity of the liquid film reduces the foam volume, it significantly enhances the foam stability. Considering the foaming properties, gel characteristics, and economic benefits, the optimal formulation of the gel foam system is determined to be 0.8% surfactant, 0.3% hydroxypropyl guar gum (HPG), and 0.2% organic titanium crosslinker (ATC). Microstructural analysis revealed that, compared to water-based and polymer foams, gel foam has smaller bubble sizes, lower drainage rates, and slower coarsening rates. This improvement is mainly attributed to the increased viscosity and thickness of the liquid film after gel and the formation of a three-dimensional network structure. Water loss rate experiment shows that the foam stability is stronger when the liquid film has certain viscosity and elasticity to resist external disturbances. However, higher viscosity and film strength do not necessarily result in better foam stability. The final water loss rate of the gel foam after being placed at 100 °C for 10 h is 74.45%, much lower than that of other higher-strength gel foams (greater than 99%). Fracture plugging experiments demonstrated that the plugging rate of gel foam is high (80%), whereas water-based foam achieved only 37.5%. The gel foam can effectively plug fractures and expand the swept volume, showing great potential for improving oil reservoir recovery.

Preparation of silicon foam supported CoMn catalysts and their catalytic performances in higher alcohol synthesis via syngas

A series of silicon foam supported CoMn catalysts were prepared using impregnation, precipitation, and hydrothermal methods. Combining the characterization techniques such as XRD, H2-TPR, N2 physical adsorption, TEM, and XPS, the effect of different catalyst preparation methods on the catalytic performance in the synthesis of higher alcohols from syngas was investigated. It is shown that there are Co2+(Co2C) and Co0 species on the surface of the catalyst. The active sites of Co2C-Co0 on the surface of the catalyst prepared by hydrothermal method have a good synergistic effect, which is conducive to the generation of alcohols. A higher proportion of Co2C also promotes the associative adsorption and insertion of CO, resulting in the highest alcohol selectivity. Under the reaction conditions of t=260 °C, p=5.0 MPa, GHSV=4500 h–1 and H2/CO(volume ratio)=2:1, the catalyst exhibited the best reaction performances with CO conversion of 11.1%, total alcohol selectivity of 34.7%, and C2+OH selectivity of 34.5%.

Ultrahigh-strength cellulose nanofiber foams via the synergy of freeze-casting and solvent exchange

Ultrahigh-strength and lightweight materials have found wide use. However, it is difficult for artificial materials to maintain high strength while being lightweight, as the mechanical properties of most materials are strongly dependent on density. In this study, we combined the methods of freeze casting and solvent exchange to prepare cellulose nanofiber foams with lightweight and ultrahigh strength. Freeze casting created the continuous 3D network at the microscale while solvent exchange promoted the reconstruction of cellulose nanofibers via the alkali-induced mercerization effect. The foams thus possessed an ordered hierarchical structure that contained lamellar layers at the microscale and a high density of pores at the nanoscale. A quadratic exponential positive correlation between relative modulus and relative density was identified for the foams. The maximum compressive and bending moduli of the foams were 26.09 and 42.10 MPa, respectively, while its density was 210.16 mg/cm3. The study provides a robust method for the preparation of lightweight and high-strength cellulose foams.

Microcellular foaming-derived strong ultra-high molecular weight polyethylene/high-density polyethylene foams for thermally insulating and oil-water separating applications

Ultra-high molecular weight polyethylene (UHMWPE) has excellent weather & chemical corrosion, abrasive resistances, and hydrophobicity, endowing UHMWPE foams promising perspectives in many applications, such as thermal insulation and oil-water separation, especially in harsh environment. However, the preparation of UHMWPE foams presents significant challenges due to its exceedingly high melt strength. In this study, a self-enhancement strategy was developed to tailor the melt viscoelasticity and foaming behavior of UHMWPE by blending with high-density polyethylene (HDPE). Remarkably, the inclusion of 40 wt% HDPE contributes to the achievement of the maximum expansion ratio reported to date for the UHMWPE foam, up to 36.5, and meanwhile, significantly expanded the foaming temperature range. The incorporation of HDPE notably improved the mechanical properties of the UHMWPE foams. With 30 wt% HDPE, the compressive strength and modulus of the foams increased by 50.9 % and 109.9 %, respectively. The foams with 40 wt% HDPE also demonstrated superior thermal insulation, exhibiting a thermal conductivity as low as 39.81 mW·m⁻¹·K⁻¹, marking a 92 % reduction compared to pure UHMWPE. Furthermore, the open-cell structure of the UHMWPE/HDPE composite foams displayed exceptional oil-water separation efficiency. This study introduces an innovative, eco-friendly approach for crafting UHMWPE foams tailored for multifunctional applications in harsh environmental conditions.

Preparation and characterization of micro-cellular melamine foam supported SiO2 aerogel for building thermal insulation

This study aims to complement the advantages of SiO2 aerogel and melamine foam (MF) to produce high-performance building insulation materials. The optimal sol–gel scheme was determined by controlling system temperature, water content, amount of ethanol and amount of acid-base catalyst (orthogonal experiment). The density and porosity of MF/SiO2 aerogel were regulated by adjusting aging time, aging temperature and type of aging agent. Furthermore, the effects of different volume fractions hydrophobic modifier on the surface free energy and wettability of MF/SiO2 aerogel were also investigated. The experiment results showed that the prepared MF/SiO2 aerogel satisfies requirements for low density (0.089 g/cm3), low thermal conductivity at room temperature (0.0256 W m−1·K−1), and excellent hydrophobic performance (the contact angle was 140.1°). Meanwhile, it was found that SiO2 aerogel was stably and uniformly distributed in the pores of the MF and effectively enhanced the mechanical property (a maximum compressive strength of 0.2058 MPa), heat-shielding performance, flame retardant property, and sound absorption capacity(αmax = 0.76, αave = 0.31).Therefore, the MF/SiO2 aerogel composites exhibit exceptional application potential in comparison to conventional building insulation materials (such as EPS, Rock wool board, etc.) due to their significantly low thermal conductivity and remarkable flame retardant properties.

Foam-mat drying of black soldier fly larvae: optimisation of foaming, drying kinetics, and powder characteristics

Abstract Desirable conditions for foaming, drying kinetics, and characteristics of black soldier fly larvae (BSFL) powders were studied. Pre-pupal BSFL was fractionated under wet conditions. A pasty liquid, free of fibrous material, was used and adjusted to a moisture content suitable (88%) for foaming. The influence of emustab (: 1-2 g/100 g), maltodextrin (: 3-5 g/100 g), and whipping time (: 9-15 min) on the BSFL foam properties were analysed according to a central composite design (23) with added axials. Optimal conditions for foam preparation (: 1.5 g/100 g, : 4 g/100 g, and : 15 min) revealed excellent foam properties (density: 409.69 kg/m3, stability: 72.49%, porosity: 60.51%, and overrun: 153.64%). For the drying process, foamed (optimum conditions) and liquid (no additives) samples were compared at different temperatures (40, 60, and 80 °C) to determine the drying kinetics and powder quality. For kinetic modelling, five mathematical expressions were fitted to the experimental data. The Newton, Henderson &amp; Pabis, Page, Logarithmic, and Midilli models were adequate () to represent the drying kinetics of the BSFL foams and liquids. However, the mathematical models that best described the kinetic curves were those proposed by Midilli and Page ( and ). In addition, foam dried at 60 °C exhibited excellent powder quality characteristics. Thus, this study provides new alternatives to process protein-rich food and feed (above 54.82%) in short periods with positive economic, social, and environmental impacts.

Multifunctional ceramifiable silicone foam for smart fire fighting

The development of multifunctional silicone foam with high fire safety is of great significance to realize intelligent fire protection but challenging. Herein, a multifunctional ceramifiable fire-retardant silicone foam (MCSF) was fabricated by Ti3C2Tx nanosheet (MXene), multiwalled carbon nanotube (MWCNT), γ-aminopropyltriethoxysilane (APTES), Karstedt catalyst (Pt) and vinyl dimethylsiloxane via water–oil interface induced self-assembly and dehydrogenation foaming at room temperature. MCSF possessed low density and good mechanical properties. Its improved thermoelectric performance and sensitive fire-warning capability of MCSF were attributed to the skeleton supporting effect and unique electron transport effect between MWCNT and MXene. When being burned, MCSF was able to trigger the fire-warning system within 2.4 s and repeatedly alarm the fire reignition. Furthermore, owing to the synergism between APTES and Pt, MCSF exhibited good ceramization performance. When encountered high temperature, the MCSF surface rapidly ceramized, generating a ceramic-like barrier layer to block the further flame ablation, and it quickly self-extinguished after removing from flame. Besides, MCSF showed impressive thermal insulation and durable piezoresistive sensing. This work provides a new strategy for the preparation and application of multifunctional fireproof polymer foams.

Xanthan gum short-chain modified TiO2 nanoparticles for the preparation of high-stability foam to effectively improve the efficiency of foam oil repulsion

Nanoparticles excel in foam stability enhancement. In this experiment, xanthan gum (XG) short links were branched on the surface of TiO2 nanoparticles, and the synthesis of novel nanomaterials was verified by analyzing the structure of the nanoparticles by FT-IR, XRD, and XPS, and investigating the dispersion of the nanoparticles by using SEM as well as capturing the cross-sectional images of XG-TiO2 by using TEM and performing elemental analyses. The foams prepared by using cationic surfactant Cetyltrimethylammonium bromide (CTAB) and XG-TiO2 synergistically had excellent performance, and XG-TiO2 was able to effectively prevent the disproportionation reaction of the foams. By adding hydroxide and changing the air pressure, the half-life and foaming volume of the prepared foams were compared and analyzed, and the half-life of the foams was more than twice as much as that of the traditional materials, and the foam morphology of the foams with XG-TiO2 was smaller and more homogeneous. When XG-TiO2 foam was tested for core drive, the total crude oil recovery reached 81.2 %, which was 45.4 % higher than the water drive recovery. This experiment demonstrated the potential of XG-TiO2 nanoparticles in enhancing foam stability and foam drive application.

Facile preparation of conductive silicone rubber composite foams with tunable cell morphologies and absorption-dominant characteristics

Flexible silicone rubber (SR) foams with tunable cellular morphologies were fabricated via supercritical CO2 foaming. Conductive carbon black (CB) modified at a low cost and with high complex viscosity was preferentially selected. The effects of the pore size and void fraction on the electrical conductivity and dielectric permittivity of the SR/CB composite foams were carefully investigated. The pore size of the foams affected the specific shielding effectiveness (SSE) and absorption coefficient (A), whereas the variation in the void fraction did not generate evident changes. In comparison with its solid counterpart, a foam with a pore diameter of 59.9 μm showed a 50 % decrease in density, 31.6 % increase in absorptivity, and 95.7 % increase in SSE, demonstrating a considerable electromagnetic interference shielding effectiveness (EMI SE). Decreases in the pore size and void fraction of the foams improved compression modulus and strength. In addition, sample preparation process was simplified, making industrial production easier.

Preparation of Melamine Urea Formaldehyde Organo Clay Nanocomposite Foams Using Thermal Processing and Microwave Irradiation Techniques and Investigation of Their Thermal Insulation and Compressive Strength

Preparation of Melamine Urea Formaldehyde Organo Clay Nanocomposite Foams Using Thermal Processing and Microwave Irradiation Techniques and Investigation of Their Thermal Insulation and Compressive Strength

Preparation and Properties of a Composite Carbon Foam, as Energy Storage and EMI Shield Additive, for Advanced Cement or Gypsum Boards

This article explores the cutting-edge advancement of gypsum or cement building boards infused with shape-stabilized n-octadecane, an organic phase change material (PCM). The primary focus is on improving energy efficiency and providing electromagnetic interference (EMI) shielding capabilities for contemporary buildings. This research investigates the integration of these materials into construction materials, using red-mud carbon foam (CCF) as a stabilizer for n-octadecane (OD@CCF). Various analyses, including microstructural examination, porosity, and additive dispersion assessment, were conducted using X-ray microtomography and density measurements. Thermal conductivity measurements demonstrated the enhancement of composite boards as the OD@CCF content increased, while mechanical tests indicated an optimal additive content of up to 20%. The thermally regulated capabilities of these advanced panels were evaluated in a custom-designed room model, equipped with a homemade environmental chamber, ensuring a consistent temperature environment during heating and cooling cycles. The incorporation of OD@CCF into cement boards exhibited improved thermal energy storage properties. Moreover, the examined composite boards displayed efficient electromagnetic shielding performance within the frequency range of 3.2–7.0 GHz, achieving EMI values of approximately 18 and 19.5 dB for gypsum and cement boards, respectively, meeting the minimum value necessary for industrial applications.