Search Results (820)

Polymer-based insulation materials are widely used to enhance the energy efficiency of buildings; however, their growing application raises concerns related to resource use and end-of-life management. Rigid polyurethane (PUR) foams are key core materials in structural insulated panels due to their favorable thermal and mechanical performance, yet their life cycle environmental impacts—particularly at end-of-life—remain insufficiently quantified. In this study, a cradle-to-grave life cycle assessment (LCA) of PUR-based insulation used in structural insulated panel systems is conducted in accordance with ISO 14040/44 and EN 15804 standards. The assessment is performed using Sphera LCA software (version: GaBi 10.5) and the CML 2016 impact assessment method. Formulation-level variations in rigid PUR foams, including changes in methylene diphenyl diisocyanate content and pentane blowing agent ratio, are explicitly incorporated to evaluate their influence on key environmental impact categories. The results indicate that increasing pentane content leads to higher global warming potential, while this effect may be mitigated or intensified by concurrent changes in diisocyanate content and foam density in fully formulated systems. Three end-of-life scenarios—landfilling, incineration with energy recovery, and mechanical recycling—are analyzed. The findings provide material-level, decision-relevant insights that support environmentally informed formulation strategies and contribute to the development of more circular polymer-based insulation solutions for the built environment. Full article

Addressing the technical bottlenecks of excessive surface density in traditional magnetic metal powder absorbers and excessive thickness in conventional foam-based absorbers, this study proposes a novel lightweight, ultra-wideband microwave-absorbing metamaterial. This metamaterial, through multi-layer and multi-dimensional structural design, has constructed a composite structure composed of a resistive film frequency-selective surface, a foam wave-absorbing medium layer and a reflective layer, achieving the controllable regulation of microwave absorption performance and the integration of structure and function. The research results show that the fabricated absorbing metamaterial achieves efficient electromagnetic wave absorption over a wide frequency band of 94 GHz under the ultra-light and ultra-thin conditions with a density as low as 0.078 g/cm³ and a thickness of only 4.9 mm. This study provides an effective design concept and solution for developing new lightweight, thin-layer, wide-band, and highly microwave-absorbing materials. Full article

Head injuries remain one of the major health concerns in contact sports such as boxing. Despite the widespread use of protective gloves and helmets, their biomechanical effectiveness in mitigating head acceleration and reducing brain injury risk remains uncertain. This study aims to biomechanically assess available boxing equipment solutions and identify the brain–skull system’s response to physical forces from a boxing punch. A dedicated experimental setup was developed using mini triaxial accelerometers and a high-speed camera to measure head accelerations in a Primus unbreakable dummy. Tests were performed using gloves of different masses (0 oz, 10 oz, and 16 oz) and three head protection configurations: no helmet, rugby helmet, and boxing helmet. The resultant accelerations were analyzed and compared across test conditions. Peak wrist accelerations ranged from 195.00 to 271.77 m/s², while head accelerations did not exceed biomechanical injury thresholds. The boxing helmet, composed of multilayer polyurethane foam, did not consistently decrease acceleration; in some cases, it produced higher overloads due to increased head mass and moment of inertia. A rugby helmet made of open-cell EVA (ethylene vinyl acetate) foam with lower density exhibited more favorable energy-dissipation characteristics under low-impact conditions. Glove mass also influenced acceleration differently between male and female participants, likely due to variations in punch velocity and force generation. This work is a pilot study using two trained adult volunteers to validate the combined IMU–video measurement framework. The results serve as hypothesis-generating mechanistic observations rather than population-level effect estimates. Protective effectiveness in boxing depends on a complex interaction between material properties, geometry, and user biomechanics. Optimal equipment design should balance energy absorption and mass to minimize both linear and rotational accelerations. Future studies should integrate advanced material modeling and finite element simulations to support the development of adaptive, lightweight protective systems. Full article

The integration of Foamed Concrete (FC) into 3D Concrete Printing (3DCP) processes facilitates the design of energy-efficient building envelopes. However, strategies for optimizing material porosity and printing topology to balance winter and summer performance remain underexplored. This study presents a 2D numerical thermal analysis of an innovative 3D-printed building envelope block characterized by sinusoidal internal partitions. Through a parametric variation in porosity (ranging from 10% to 50%) and internal geometry (amplitude and period of the partitions), 45 distinct configurations were simulated. Performance was evaluated by calculating the steady-state thermal transmittance (U) and the periodic thermal transmittance (Y_ie) under dynamic climatic conditions. The results demonstrate that porosity is the governing parameter; increasing porosity from 10% to 50% reduces U by 31% and, contrary to traditional assumptions for massive structures, also improves Y_ie by 12.3%. These outcomes are physically driven by the drastic reduction in thermal conductivity, which overcompensates for the loss of thermal mass, leading to a net reduction in overall thermal diffusivity. While internal topology plays a secondary role, its optimization allows for fine-tuning dynamic damping without compromising insulation. The study confirms that 3D printing with foamed concrete enables the overcoming of the traditional trade-off between insulation and thermal inertia. High-porosity configurations (50%) with optimized internal topology emerge as the most effective solution, simultaneously guaranteeing beneficial steady-state and dynamic thermal performance for sustainable buildings. Full article

Tight oil reservoirs are widely recognized as a critical successor in global unconventional energy development and are generally characterized by distinct geological features, including fine pore throats, pronounced heterogeneity, and a high concentration of clay minerals (e.g., montmorillonite and mixed-layer illite/smectite). Severe hydration, swelling, and fines migration are readily induced during water injection or conventional water-based fluid operations, thereby resulting in irreversible impairment of reservoir permeability. Despite the excellent injectivity and capacity for viscosity reduction associated with CO₂ flooding, sweep efficiency is severely compromised by viscous fingering and gas channeling, which are induced by the inherent low viscosity of the gas. While CO₂ foam technology is widely acknowledged as a pivotal solution for addressing mobility control challenges, its implementation is hindered by a primary technical bottleneck: the incompatibility between traditional water-based foam systems and strongly water-sensitive reservoirs. A dual challenge comprising water injectivity constraints and gas channeling is presented by strongly water-sensitive tight oil reservoirs. To address these impediments, three emerging low-damage CO₂ foam systems are critically evaluated in this review. First, the synergistic mechanisms of novel quaternary ammonium salts and polymers in inhibiting clay hydration and enhancing foam stability within modified water-based systems are elucidated. Next, the physical isolation strategy of substituting the water phase with a non-aqueous phase (oil/organic solvent) in organic emulsion systems is analyzed, highlighting advantages in wettability alteration and the mitigation of water blocking. Finally, the prospect of waterless operations using CO₂-soluble foam systems—wherein supercritical CO₂ is utilized as a surfactant carrier to generate foam or viscosify fluids via in situ formation water—is discussed. It is revealed by comparative analysis that: (1) Modified water-based systems are identified as the most economically viable option for reservoirs with moderate water sensitivity, wherein cationic stabilizers are utilized to inhibit hydration; (2) Superior wettability alteration and the elimination of aqueous phase damage are provided by organic emulsion systems, rendering them ideal for ultra-sensitive, high-value reservoirs, despite higher solvent costs; (3) CO₂-soluble systems are recognized as the future direction for “waterless” flooding, specifically tailored for ultra-tight formations (<0.1 mD) where injectivity is critical. Current challenges, such as surfactant solubility, high-temperature stability, and cost control, are identified through a comparative analysis of these three systems with respect to structure-activity relationships, rheological properties, damage control capabilities, and economic feasibility. What is more, an outlook is provided on the molecular design of future environmentally sustainable, cost-effective CO₂-philic materials and smart injection strategies. Consequently, theoretical foundations and technical support are established for the efficient exploitation of strongly water-sensitive tight oil reservoirs. By bridging the gap between reservoir damage control and mobility enhancement, this study identifies viable strategies for enhanced oil recovery. Crucially, it supports carbon neutrality and sustainable energy targets via CCUS integration. Full article

With the rapid development of infrared detection methods and military surveillance technologies, flexible and wearable infrared stealth materials (ISM) have attracted increasing attention. Inspired by the layered structure of penguins’ fat–feather–oil, this study prepared a three-layer MXene/waterborne polyurethane (WPU)-foam rubber-phase change microcapsule (PCM)/WPU composite material (M-F-P) via the solution blending and doctor-blading method. The outermost layer of the M-F-P composite is an MXene/WPU conductive film, which features a low infrared emissivity and Joule heating performance to adapt to suddenly cold environments. The porous foam rubber in the middle layer provides excellent thermal insulation performance, which effectively inhibits heat conduction and enhances infrared stealth efficiency. Meanwhile, as a four-directional elastic material, it exhibits deformation recovery capability in both the warp and weft directions as well as the 45° direction. The bottom layer of the PCM/WPU film has a phase change enthalpy of 154.3 J/g and possesses efficient thermal management capability. It achieves dynamic thermal regulation through the cycle of heat absorption at high temperatures and heat release at low temperatures. Full article

In this study, we investigated the electrochemical properties and performance characteristics of Co_xS_y and silicon–carbon-based heterostructures synthesized on nickel foam substrates for energy storage applications. Cobalt sulfide films were successfully electrodeposited on nickel foam (NF) using cyclic voltammetry (CV) from the solutions with different Co²⁺ concentrations. The presence of a silicon–carbon sublayer promotes the deposition of cobalt sulfide material. The amorphous phase of α-CoS was observed by the X-ray diffraction technique. Raman spectroscopy confirmed the formation of CoS and CoS₂ phases. A significant increase in electrode areal capacitance is observed with the silicon–carbon film sublayer from 0.5 to 1.3 F·cm⁻² and from 1.6 to 2.3 F·cm⁻² at 3 mA·cm⁻² for samples prepared from solutions with CoCl₂·6H₂O concentrations of 0.005 M and 0.02 M, respectively. In the case of gravimetric capacitance, an increase is observed in the presence of a silicon–carbon sublayer for the SiC@CoS_0.005 sample, rising from 690 F·g⁻¹ to 748 F·g⁻¹ at 4 A·g⁻¹. Conversely, the SiC@CoS_0.02 sample shows a decrease from 1287 F·g⁻¹ to 6590 F·g⁻¹. It was shown that the capacitance of all the electrodes derives from the mix of diffusion-controlled and surface-controlled capacitance processes. The electrochemical impedance spectroscopy (EIS) analysis indicates that the formation of heterostructure materials significantly alters the electrochemical properties by reducing both R_f and R_s. Full article

Large-scale mining of graphite, a crucial strategic mineral, generates substantial amounts of graphite tailings (GT). The stockpiling of this solid waste occupies vast land resources and poses persistent environmental risks due to potential heavy metal leaching. Repurposing GT into construction materials presents a promising solution, with its use as a partial replacement for fine aggregates in cementitious composites being one of the most effective methods. This review systematically consolidates current research on graphite tailings cement mortar (GTCM) and graphite tailings concrete (GTC). Due to its physicochemical properties comparable to natural sand, GT is suitable for producing building materials. Studies consistently demonstrate that a substitution level of 10% to 20% optimizes overall performance. This optimal range enhances particle packing, promotes cement hydration via pozzolanic activity, and refines the microstructure, leading to improved workability, superior mechanical strength, and enhanced durability, including resistance to permeability, freeze–thaw cycles, and chemical attacks. Moreover, the inherent carbon content imparts electrical conductivity to GTC, enabling functional applications like de-icing and structural health monitoring. The successful utilization of GT also extends to lightweight foamed and autoclaved aerated concrete. However, research on the structural behavior of GTC components remains limited. Preliminary findings on beams and columns are encouraging, but comprehensive studies on their seismic performance and design methodologies are urgently needed to facilitate the widespread engineering application of this sustainable material and mitigate the environmental impact of tailings accumulation. Full article

The current work examines the impact of isopropanol (IPA) on the electrochemical characteristics of nickel foam and Pd-modified Ni foam electrodes in a 0.1 M NaOH medium, with respect to the kinetics of the hydrogen evolution reaction (HER) over the temperature range of 20–40 °C. Comparative HER/IPA examinations are presented for a highly catalytic polycrystalline Pt electrode. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and cathodic Tafel polarization experiments were carried out in this work, where the IPA concentrations ranged from 1.0 × 10⁻⁵ to 1.0 × 10⁻³ M. The introduction of small amounts of isopropyl alcohol into the working electrolyte noticeably facilitated the catalytic efficiency of the hydrogen evolution reaction on the surface of Ni foam electrodes. This is most likely related to the fact that IPA molecules undergo partial electrooxidation to acetone (qualitatively confirmed by GC-MS analysis) during initial CV cycling, which is believed to significantly diminish the surface tension phenomenon during the HER, thus promoting hydrogen bubble separation from the electrode surface. It should also be noted that acetone will continuously be produced at the Pt anode, making it essential to consider further migration of (CH₃)₂CO molecules to the working cell compartment. Most importantly, isopropanol was found not to undergo significant surface electrosorption on the nickel foam-based catalysts, which could otherwise significantly inhibit the hydrogen evolution reaction On the contrary, the presence of IPA in the electrolyte solution seems to have a detrimental effect on the kinetics of both the HER and the UPDH (underpotential deposition of H) processes on the surface of the polycrystalline Pt electrode, which is a superior electrochemical catalyst for HER, but highly susceptible to surface contamination. Full article

Rigid polyurethane (PUR) and polyisocyanurate (PIR) foams are widely used as thermal insulation materials due to their excellent thermal conductivity and low density. However, fire resistance remains a critical property determining their safe application in construction, transportation, and energy systems. This study provides a comparative overview of the fire behavior of PUR and PIR foams, focusing on structural aspects, decomposition mechanisms, flame retardancy, and performance of emission of toxic gases during the combustion process. Despite extensive studies on PUR and PIR foams, systematic comparative investigations addressing the combined influence of recycled PET-based polyester polyols, isocyanurate content, and fire-related properties—including thermal degradation, heat release, and toxic gas emissions—remain limited. PIR foams, characterized by higher isocyanate indices and the presence of isocyanurate rings, show superior thermal stability, reduced heat release rates, and enhanced char formation compared with PUR foams. Experimental analysis of thermal degradation (TGA/DTG) and heat release (cone calorimetry) confirms that PIR foams demonstrate higher resistance to ignition and slower fire propagation. The results emphasize the critical role of molecular architecture and crosslink density in shaping the fire performance of rigid foams, highlighting PIR systems as advanced insulation solutions for applications requiring stringent fire safety standards. The PIR foam was prepared using a polyester polyol derived from recycled PET, which could help in achieving better fire properties during the combustion process. Compared with PUR foams, PIR foams exhibited an approximately 50% reduction in peak heat release rate, an increase in char yield from about 3 wt.% to over 22 wt.%, and a shift of the main thermal degradation peak by approximately 55 °C toward higher temperatures, indicating substantially enhanced fire resistance. Full article

In the era of growing demand for sustainable solutions in construction, increasing attention is being paid to the potential use of waste materials as components of building composites. This article presents the results of a study on the impact of ground polyurethane foam waste on the mechanical properties and durability of cement mortars. The waste, derived from industrial production processes, was used as a partial replacement for fine aggregates in various proportions. The analysis included bulk density, compressive and flexural strengths, water absorption, and resistance to freeze–thaw cycles. The results indicate that adding waste reduces the density of the mortar, which can be advantageous in applications requiring lightweight materials. The most favourable balance of strength retention, density reduction, and frost resistance was observed with a 1% addition, as the mortar maintained good mechanical performance and freeze–thaw durability while achieving reduced weight. Higher waste content (2–3%) led to significant deterioration of the mechanical properties due to increased porosity. All samples exhibited increased strength after 25 freeze–thaw cycles, possibly due to continued hydration under moist low-temperature conditions. The analysis of the microstructure of cement coatings with the addition of polyurethane foam enabled the explanation of the causes of the observed changes in physico-mechanical properties resulting from ageing factors. This study suggests that small amounts of waste can be effectively used to produce lightweight and environmentally friendly construction materials, supporting circular economy practices. Full article

Mechanical coffee drying is an energy-intensive stage of postharvest processing that directly affects product quality and production costs. This study evaluated the technical and economic feasibility of using expanded polystyrene (EPS) as a thermal insulation material to improve the performance of a mechanical coffee dryer and to demonstrate its potential for sustainable reuse. Experiments were conducted using a total of 210 kg of wet parchment coffee (Coffea arabica L. var. Cenicafé 1) per treatment, corresponding to three experimental replicates of 70 kg each, dried at 50 ± 2 °C, comparing an EPS-insulated dryer (0.02 m thickness) with a non-insulated control. A theoretical model based on steady-state heat transfer through series resistances estimated energy losses and system efficiency for different insulating materials. Theoretical results indicated that EPS, polyethylene foam, and cork reduced heat losses by 58.1%, 54.3%, and 50.9%, respectively. Experimentally, EPS reduced drying time by 7.82%, fuel consumption by 13.9%, and energy demand by 9.5%, while increasing overall efficiency by 6.7% and reducing wall heat losses by 37.7%. Improved temperature stability enhanced heat retention and moisture migration behavior. Economically, EPS reduced operating costs, yielding annual savings of USD 81.5, a 0.45-year payback period, and an annual return on investment (ROI) of 10.86, confirming its viability as a cost-effective and sustainable solution for improving energy efficiency in mechanical coffee drying. Full article

Falls are a leading cause of bone fractures among the elderly, particularly hip fractures resulting from side falls. This research deals with the feasibility of application of shear-thickening fluids (STFs) to design self-protective wearable devices to rapidly respond to sudden impact due to falls. The device consists of a lightweight, flexible foam structure embedded with STF-filled compartments, which remain soft during normal movements but stiffen upon sudden impact, effectively dissipating energy and reducing force trans-mission to the bones. First, a foam-based sandwich panel filled with STF is fabricated and subjected to several falling scenarios through a ball drop test. The induced strain of the device with and without STF is measured using Fiber Bragg Grating (FBG) sensors. Then, the effect of localized STF is explored by fabricating a soft 3D-printed (TPU) sandwich panel filled with STF at selected cavities. It was observed that the application of STF reduces the induced strain by approximately 50% for the TPU skin device and 30% for the foam-based device. This adaptive response mechanism offers a balance between comfort and protection, ensuring wearability for daily use while significantly lowering fracture risks. The proposed solution aims to enhance fall-related injury prevention for the elderly, improving their quality of life and reducing healthcare burdens associated with fall-related fractures. Full article

To evaluate the stability of fiber-reinforced cemented foamed backfill (FCFB) in complex underground mining environments, this study investigates the synergistic effects of fiber content and modified coal gangue (MCG) under acidic and high-temperature conditions. Through a systematic analysis of hydration processes, compressive strength, and deformation characteristics, the research identifies critical mechanisms for optimizing backfill performance. Calcination of MCG at 700 °C enhances gelling activity via amorphous phase formation, while modified aluminum dross (MAD) treated at 950 °C develops dense α-Al₂O₃ and spinel phases, significantly improving chemical stability. In acidic environments, the suppression of calcium silicate hydrate (C-S-H) is offset by the development of Al³⁺-driven C-A-S-H gels. These gels adopt a tobermorite-like structure, substantially increasing acid resistance. Mechanical testing reveals that while 1% fiber reinforcement promotes nucleation and densification, a 2% concentration hinders hydration. Compressive strength at 28 days shows constrained growth due to pore inhibition, and failure modes transition from multi-crack parallel failure (3-day) to single-crack tensile-shear failure. Under acidic conditions, strain concentration in the upper sample highlights a competitive mechanism between Al³⁺ migration and fiber anchorage. Ultimately, the coordinated regulation of MCG/MAD and fiber content provides a robust solution for roof support in challenging thermo-chemical mining environments. Full article

Phycobiliproteins are recognized as potential bioactive compounds and described as highly valued natural products for industrial and biotechnological applications. Moreover, they have been observed to possess antioxidant, anticancer/antineoplastic, and anti-inflammatory activities. Therefore, the search for new methods of their extraction and isolation is still ongoing. Foam fractionation, a bubble separation technique that allows amphiphilic molecules to be separated from their aqueous solutions, is a promising but understudied method. The process may be carried out both under mild conditions that are suitable for proteins and also for diluted solutions. This paper presents the results of applying the foam fractionation process to concentrate and separate phycobiliproteins. Allo- and C-phycocyanin from a thermophilic Synechococcus PCC 6715 strain were used in extract form after biomass cultivation and disintegration. Two ways of running the process were investigated: batch mode and continuous mode, the latter of which has not been reported in the literature previously. The results indicate that the method can be applied on a larger scale, as the outcomes of the continuous mode processes were comparable to those of the batch mode. Moreover, the results indicate that the process provides, to a certain extent, the opportunity of separating phycobiliproteins from each other. Full article