Study on the performance of geopolymer insulation materials modified by lightweight aggregate and chopped fiber in synergy

Machine learning assisted quantitative color analysis of aged polymeric electrical insulation materials as a non-destructive method to evaluate embrittlement

Analysis of aging characteristics of transformer insulation materials in substation based on high-frequency laser imaging

Aerogels, as highly efficient thermal insulation materials, exhibit significant potential for applications in building exterior insulation, power battery thermal protection, and aerospace thermal management. However, conventional polymer aerogels possess inherent limitations in thermal insulation performance, mechanical compressive strength, and flame-retardant safety, which impede their widespread engineering adoption. Herein, we propose a synergistic fabrication strategy integrating directional freezing and viscosity modulation. By precisely regulating the temperature gradient and incorporating layered double hydroxides (ZnMgAl-LDH) to tune the viscosity of hydrogel precursors, we enhanced the viscous resistance during ice crystal growth, thereby refining ice crystal dimensions. A honeycomb-like ZnMgAl-LDH/chitosan (CS) inorganic-organic hybrid aerogel with tunable pore size distribution was successfully constructed. The superlattice interface of ZnMgAl-LDH and the organic-inorganic hybrid interface synergistically reinforce phonon scattering (covering both long and short wavelengths), effectively suppressing solid thermal conduction and significantly improving the aerogel's thermal insulation performance. Compared with pure CS aerogel, the hybrid aerogel with optimized pore size displays a lower thermal conductivity (0.03735-0.03936 W/(m·K)) and reduces the surface temperature by 6.9 °C under identical conditions. Moreover, the honeycomb microstructure endows the hybrid aerogel with excellent compressive resilience, retaining 72.4% stress after 50 compression cycles and achieving a compressive modulus 9 times higher than that of pure CS aerogel. Its flame-retardant performance is remarkably enhanced, with the limiting oxygen index (LOI) increasing from 21.5% to 41.4% (meeting high flame-retardant standards) and the peak heat release rate (PHRR) decreasing by 74.9%. Additionally, the hybrid aerogel exhibits superior hydrophobicity and environmental durability, highlighting its great potential for practical engineering applications.

The construction industry needs to transition toward more sustainable materials to reduce environmental impacts. Insulation materials reduce energy demands of buildings, yet traditional options often have high embodied carbon and rely on finite resources. Mycelium-based composites (MBCs) have emerged as promising bio-based alternatives, formed by the colonisation of fungal mycelium on lignocellulosic feedstocks; the mycelium acts as a natural adhesive and upon drying an inert material is produced. MBCs have demonstrated low thermal conductivity (λ) and sustainability benefits, with substrate choice being a key factor in determining both thermal and environmental performance. This study emphasises the need for a functional unit (FU) that accounts for thermal performance rather than mass-based declared units (DUs) in Life Cycle Assessment (LCA). MBCs were produced using Lentinus tigrinus mycelium and five different substrates: ash-wood chips, bark, beech-wood sawdust, hemp shiv, and wheat straw. Thermal conductivity measurements (ASTM C518) were conducted, revealing that ash-wood chip MBCs exhibited the highest thermal conductivity (λ = 0.048 W/m·K), while straw-based MBCs had the lowest (λ = 0.031 W/m·K). Thermal conductivity and density of the material were used to calculate the FU (mass of insulation required to achieve an R-value of 1 m[Formula: see text]K/W). A cradle-to-gate LCA (EN 15804) compared environmental impacts per FU for each MBC produced at lab-scale. Ash-wood chip MBCs demonstrated the lowest total global warming potential (GWP) (-9.77 kg CO[Formula: see text] eq), while straw-based MBCs had the highest (4.04 kg CO[Formula: see text] eq). Further analyses examined whether transport distance, waste designation, and carbon sequestration uncertainty would affect substrate ranking and, consequently, selection. While local sourcing and waste-derived substrates reduced emissions, it did not alter rankings. A Monte Carlo analysis confirmed that even with uncertainty in substrate carbon sequestration, MBCs maintained low GWP values. These findings show that low λ MBCs can be produced from various substrates. Substrate selection should consider thermal and environmental performance, as carbon sequestration, rather than λ, is the dominant factor influencing GWP. This underscores the need to consider broader environmental trade-offs when optimising MBC insulation materials.

ABSTRACT This study proposes a multi-criteria decision analysis (MCDA) approach to determine appropriate re-roofing material assemblies (MCAs) for retrofitting low-rise residential structures in India's warm-humid climatic zone. The aim was to provide a material selection framework that facilitates informed retrofit decisions, matching energy efficiency objectives with realistic, climate-specific solutions for India's housing sector. Using Bhubaneswar, Odisha, as a representative case, the assessment evaluated 23 MCAs through three major performance criteria: thermal transmittance (Uroof); energy use intensity reductions (EUI); and annual electric cost (EC). The findings revealed that conventional reinforced cement concrete slabs consistently failed to meet performance standards, whereas cases like Madras terrace roofing, high surface reflective indexed paints and a few bio-based and engineered insulation materials offered significant reductions. The re-roofing approach to retrofit offers a potential reduction of 97.5% in Uroof, up to 17.67% in EUI and 43.2% EC. Overall, 14 MCAs of the 23 were identified as suitable to be added in the choice basket for use in the selected case, with 10 MCAs consistently ranked to be ‘Highest preference’ across all criteria. The results demonstrate the framework’s potential to guide climate-responsive, energy-efficient retrofits and provide a scalable approach that can be replicated for other cities and climate zones.

ABSTRACT A large amount of discarded isolation medical gowns and wasted coffee filters end up in landfills, creating an environmental problem . In this study, we introduce a novel approach to repurpose such waste by utilizing it to produce insulation materials with excellent acoustic properties. Loose, bound, and hybrid composite boards were prepared from discarded gowns and filters . The bound and hybrid boards were made using wood adhesive resin binders. All necessary tests , including measurements of thermal conductivity, sound absorption, noise reduction coefficients, thermal stability, mechanical properties, surface morphology, and moisture content of the raw materials, were reported. Results showed that the thermal conductivity ranges from 0.038 to 0.070 W/m·K. The sound absorption coefficient exceeds 0.4 for all composite boards at frequencies above 500 Hz, and the noise reduction coefficient is greater than 0.4. The flexural modulus of the bound boards ranges from 0.28 to 1.6 MPa. The composites are thermally stable between 298°C and 354°C. The moisture content is 0.5% for loose gowns and 4% for coffee filters. These results suggest that the developed composites could be used for thermal insulation and sound absorption in buildings, offering a sustainable alternative to fossil fuel-based materials and contributes to environmental preservation.

Ceramizable Perforated Silicone Foam for Thermal Insulation and Refractory Building Materials

Compositing insulated inorganic nanoparticles in bulk polymers is widely applied to improve electrical insulation and mechanical properties. However, the use of inorganic nanoparticles always faces a trade-off in the coenhancement of both properties, limiting the performance from reaching an ideal state. This study reveals that "molecularization" of inorganic ionic compounds into a polymer network can overcome the trade-off between electrical insulation and mechanical robustness due to the molecular-size effect of inorganics. By using epoxy and calcium phosphate oligomers as examples, chemically functionalized calcium phosphate molecular segments are successfully copolymerized into epoxy to create a hybrid resin. The calcium phosphate molecular segments show increased bandgap and high interfacial fraction in epoxy, directing to a high alternating current (AC) breakdown strength (116.7 kV/mm). Meanwhile, the calcium phosphate molecular segments enhance the strength of the polymer network, increasing the flexural strength and bending toughness to 136.9 MPa and 8.85 MJ/m3, respectively. The overall electrical insulation and mechanical properties are superior to those of all reported and commercial bulk epoxy-based composites we have consulted. This work demonstrates that an inorganic ionic compound with a molecular-size effect is a promising unit for high-performance electrical insulation materials, supporting the development of advanced power equipment in the future.

Waste from the wind power and textile industries poses major environmental challenges. While the textile industry is a significant global contributor to waste, producing around 92 million tons of waste annually, and greenhouse gas emissions, wind power, although one of the cleanest energy sources during operation, still generates waste and associated CO2 emissions, particularly associated with the end-of-life decommissioning of turbine blades. This waste can be reused, combined with bio-based binders, to reduce the construction sector's long-term environmental impact. The present work identifies research trends and gaps in the use of these waste materials, either individually or combined, for the development of thermal and acoustic insulation solutions for the construction sector, by means of a combined bibliometric and content analysis of Scopus and Web of Science documents from 2014 to 2025. The study focuses on bibliometric indicators and reports on physical properties (thermal conductivity, density, mechanical strength, and acoustic performance) of the resulting composites, including those produced with bio-binders. Additionally, a qualitative review of life cycle assessment studies indicates that bio-based and waste-derived insulation materials can significantly reduce environmental impacts compared with conventional mineral or petrochemical insulators. Results reveal growing scientific interest in this subject, highlighting an annual publication growth of 5.09%. They emphasize the performance of natural textile fibers in thermal and acoustic insulation, the mechanical capacity of synthetic fibers, and the semi-structural potential of fiberglass composites. Meanwhile, bio-binders improve the upcycling of textile waste; however, they reveal a significant research gap in the integration of wind turbine blade waste into insulation composites. No indexed studies were found that simultaneously combine textile waste, blade-derived fibers, and bio-based binders in a single insulation system, despite projected cumulative blade waste of 43 million tons by 2050. These findings advocate hybrid innovations and standardized assessments to drive circular economy and low-carbon building solutions.

Flame retardancy and smoke suppression of reused flexible polyurethane foam: Synergistic effect of hydrophobic silica aerogel and organophosphorus flame retardant by Kabachnik-Fields reaction

Bi₂Sr₂CaCu₂O8-x (Bi-2212) multi-filament round wire is a high-temperature superconductor (HTS) capable of carrying high transport currents, which makes it suitable for high-field magnet applications. However, its weak Ag-Mg sheath leaves it vulnerable to mechanical stress, posing challenges for high-field magnet design. To better understand and improve mechanical stress management in Bi-2212 winding packs, we conducted an experimental study evaluating the axial stress-strain behavior of five winding pack configurations with varying insulation materials, reinforcement strategies, and construction quality. Using uniaxial tensile testing at 77 K, we measured Young's modulus and Poisson's ratio for each composition. Our results show that pure alumina braid insulation and co-wind reinforcements significantly enhance stiffness compared to aluminosilicate braids, with more than 2.5 times increased winding pack Young's modulus. Rule of mixtures analysis further quantified the contribution of non-wire composite components to overall stiffness. These findings highlight the critical role of insulation material selection and reinforcement design in optimizing Bi-2212 coil performance under stress, providing a foundation for improved mechanical models and more reliable high-field HTS magnet designs.

Glass waste as a host material for microwave absorption and thermal insulation

Environmentally friendly and multifunctional biomass carbon materials for thermal insulation and electromagnetic wave absorption

Abstract On-orbit servicing of high-value spacecraft has consistently been a focal point in space technology research. Space robots capable of adhering to and traversing spacecraft surfaces have garnered increasing attention from researchers. A significant portion of spacecraft surfaces consists of multi-layer insulation (MLI) materials, which, under microgravity conditions, exhibit a non-taut, flexible, and slightly undulating state. This poses substantial challenges for space robots attempting to adhere and crawl on these surfaces, often resulting in instability of the robot’s posture or unintended detachment during movement, leading to mission failure. This paper proposes a strategy for space robots to adhere and climb on the MLI surface of spacecraft. A microgravity simulation system was established on the ground, and experiments on robot adhesion and climbing were conducted. The effectiveness of the proposed method was verified by comparing it with traditional climbing control strategies.

Energy-driven damage constitutive model of thermal insulation materials for deep rock in-situ temperature-preserved coring

Optimizing porous geopolymer insulation materials using response surface methodology and machine learning

Synergistic method of immersion cooling and insulation materials to inhibit thermal runaway propagation in lithium-ion battery modules

This research investigates novel polymeric composite materials made from recycled polyolefin and waste plant biomass (poplar seeds and vegetable peels), which have potential applications in the relatively unexplored field of electrical insulation. For composites made from poplar seeds with low density polyethylene matrix, the structure appears more uniform, even with increased biomass content, in contrast to those utilizing high density polyethylene matrix, which displays notable heterogeneous areas where the polymer appears separated from the fibrous network at higher biomass levels. Concerning the composites of vegetable peels with high density polyethylene matrix, the fragments of vegetable peels are clearly recognizable, and their bond to the polymer matrix appears weaker. When incorporating vegetable peels into the polypropylene matrix, it results in a better distribution of the vegetable peel fragments within the polymer matrix, as well as enhanced structural homogeneity. Overall, the incorporation of biomass reduces the Shore hardness measurement for every polymer matrix. Regarding tear resistance, the inclusion of biomass reduces the values only for low density polyethylene with poplar seeds. For both high density polyethylene and polypropylene, regardless of the biomass type, the property seems to enhance marginally with the addition of biomass. The primary advantage of utilizing these composites is that their water absorption rate is at least twice as low as that of transformer board, while still offering a similar capacity for absorbing transformer oil. All composite types exceeded the minimum required threshold of 70 °C for service exposure, and adhered to insulation class A, similar to cellulose-based insulations. The addition of cellulose to polyolefin composites appears to slightly improve their breakdown strength. The conductivity for this type of composite is at least three times lower than that of cellulose insulation materials, rendering them beneficial for applications in electrical engineering as potential substitutes for cellulose-based materials in multiple electrical insulation uses, e.g., for insulating low voltage electrical machines, as well as serving as a substitute for pressboard in transformers. Additionally, their thermoplastic properties offer enhanced processing versatility, opening up new opportunities for electrical engineering technology, especially with regard to electrical insulation recyclability in the context of a circular economy.

Biomass-based thermal insulation materials: Design strategies, multifunctional integration, and prospects