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As the research for advanced materials suitable for high-temperature uses continues, the need for oxide ceramic micro-nanofibers with outstanding mechanical and thermal properties becomes increasingly important. By incorporating two types of magnesium sources, specifically Mg(CH 3 COO) 2 ·4H 2 O and MgCl 2 ·6H 2 O, into the precursor, a range of fibers made of magnesium silicate ceramics was produced through electrospinning. X-ray diffraction (XRD) analysis verified that the resulting multiple phases included MgO, MgSiO 3 , Mg 2 SiO 4 , and amorphous SiO 2 , with the phase composition being affected by the diffusion reaction of Mg ions. The fibers produced using the dual-precursor method maintained a stable morphology with a uniform and compact structure after undergoing high-temperature treatments ranging from 1000 to 1200 °C. This study is the first to report the tensile strength of magnesium silicate fibrous membranes, which was found to be 1.54 ± 0.27 MPa and 1.21 ± 0.73 MPa after heat treatment at 800 °C and 1000 °C, respectively. Furthermore, these fibrous membranes demonstrated dependable thermal insulation properties within the testing range of 500–1000 °C, along with a low thermal conductivity at room temperature of 0.0301–0.0306 W m−1·K−1. Characterized by their impressive mechanical strength and high temperature stability, magnesium silicate ceramic micro-nanofibers show significant potential for various applications in the targeted field. [ABSTRACT FROM AUTHOR]

Ceramic aerogels are promising candidates for high-temperature thermal resistance and thermal insulation materials. However, their application can be restricted by their brittleness when exposed to harsh conditions. Herein, this study has developed a novel synthesis process based on a sol-gel method and carbothermal reduction-nitridation to produce a porous TiN composite aerogel from an organic/inorganic hybrid. The resulting TiN displays a polyhedral particle size of around 30–60 nm with nanoscale pores. In addition, the TiN aerogel demonstrates a high BET-specific surface area of 653.42 m2/g and a very low thermal conductivity of 0.046 W/(m·K). Furthermore, the TiN aerogel composite displays a good thermal difference with no shrinkage and cracks of the morphology during the butane blazing torch at 1300 °C for 10 min under air environment, demonstrating its excellent thermal insulation property and anti-oxidation characteristics. The gas-solid reaction mechanism of TiN aerogel based on the Gibbs free energy calculations is also proposed. [ABSTRACT FROM AUTHOR]

This study utilizes modulation of ionic disorder and electronegativity differences for targeted component design of high-entropy ceramic compositions. A series of novel multicomponent ceramics with the general formula (LaGdYSm) x 2 Yb x 1 Zr 2 O 7 (x 1 +4x 2 = 2, x 1 = 0.6,0.4,0.2,0) were prepared by solid-state reaction. The evolution patterns of their microstructures were analyzed using XRD and TEM, and the anti-sintering ability and thermophysical properties were evaluated. The results confirm that the multicomponent ceramics gradually transform from the coexistence of pyrochlore/fluorite dual-phase structure to pyrochlore structure with the tuning of the size disorder degree. After 50h of exposure to air at 1500 °C, the ceramics retained excellent phase stability. Segregation of La and Yb elements with large differences in radius size occurs, forming a mixture of the La-rich pyrochlore and the Yb-rich fluorite phases. The specimen with the maximum size disorder exhibits the lowest grain growth rate and the greatest thermal insulation properties. Large lattice distortions and sluggish diffusion effects are responsible for the mutual inhibition of grain growth in the two-phase coexistence zone. The thermal insulation properties of the ceramics show well correlated with the degree of the size disorder, further validating the effectiveness of the component design. Meanwhile, the thermal expansion coefficients of prepared ceramic can reach 11.49 × ∼11.58 × 10−6 K−1 at 1000–1100 °C. The customization principles used in this work fill a gap in the compositional design methodology for multicomponent lanthanum zirconate-based high-entropy ceramics. It is essential for developing rare-earth zirconates with tunable thermophysical properties in the area of thermal barrier coatings. [ABSTRACT FROM AUTHOR]

The ZrO 2 fiber paper exhibits excellent thermal insulation properties, however, its limited mechanical strength and insufficient thermal stability hinder its widespread applications. The composite fiber papers, using mullite fibers possessing a high aspect ratio and exceptional thermal stability combined with ZrO 2 fibers, were fabricated via a vacuum-assisted filtration method. This method involved the successive stacking of composite fibers with alumina sol, using vacuum-induced directed water flow to create a layered structure reminiscent of nacre. The layered structure of the nacre, which demonstrates remarkable strength and hardness, has also served as a source of inspiration for the architectural design of the fiber paper. The tensile strength of pure ZrO 2 fiber paper was significantly enhanced by the addition of 7 wt% mullite fibers, resulting in a remarkable increase to 0.1805 kN/m. The paper exhibited exceptional resistance to bending, maintaining 96 % of its bending strength even after undergoing 100 cycles. The thermal shrinkage of the composite paper, containing 15 wt% mullite fibers, was reduced from 17.75 % observed in pure ZrO 2 fiber paper to a mere 1.32 % after undergoing heat treatment at a temperature of 1300 °C for 2 h. The composite paper, measuring 5 mm in thickness and consisting of 7 wt% compositions, displayed exceptional thermal insulation properties when exposed to a hot side temperature of 1370 °C. It effectively insulated temperatures up to approximately 1000 °C. [ABSTRACT FROM AUTHOR]

Flexible SiC nanowire aerogel felt has excellent foldability, high-temperature resistance, and thermal insulation properties. However, the large-scale and high-efficiency production of SiC nanofiber aerogel felt remains a challenge. In this work, a three-dimensional network-structured short-chopped carbon fiber felt was used as a template for preparing SiC nanowire aerogel felt. The short-chopped carbon fibers were combed and dispersed using an airflow in a carding machine to obtain the desired felt. This method enables rapid and uniform preparation of carbon fiber felt, enhancing the efficiency of SiC nanowire aerogel felt production. The experimental results showed that the aerogel felt was mainly composed of β-SiC nanowires with a density of 5.29 g/cm3. Additionally, the SiC nanofiber aerogel felt exhibited remarkable superelasticity and low thermal conductivity (0.013 W/m·K). This research contributes to the practical application of flexible SiC nanowire aerogel felt in the field of thermal insulation. • Carding machine dispersed carbon fiber. • Fabrication of large size SiC nanofiber aerogel felt. • SiC nanofiber aerogel felt has flexibility and low thermal conductivity. [ABSTRACT FROM AUTHOR]

Among the family of high-quality fiber materials, mullite fiber membrane is a promising one that possesses abilities of both the thermal resistance and oxidation resistance under high temperature. High-purity mullite nanofibrous membranes were prepared by electrospinning method with low-cost aluminum chloride hexahydrate (AC) as the aluminum source. The effects of sintering temperature and AC content on the phase structure, microstructure, thermal and mechanical properties of the mullite nanofibrous membranes were investigated. The results show that the sintering temperature as low as 1000 °C is the very appropriate temperature for obtaining the high-purity mullite nanofibers with smooth surface. The minimum thermal conductivity of 0.029 W m−1 K−1 and maximum tensile strength of 6.11 MPa are gained from the mullite nanofibrous membranes with AC content of 2 mmol. The mullite nanofibrous membranes with excellent properties can be selected as an ideal candidate for thermal insulation and reinforced applications. [ABSTRACT FROM AUTHOR]

Energy efficient buildings, propulsion components and thermal protection systems require materials with high thermal protective properties. Traditional polymer composites or ceramic materials have limited comprehensive applications because of their poor thermal protective properties or poor processability. Herein, a novel fire resistant and thermally insulating polymer/ceramic hybrid ceramifiable composite was developed based on low temperature sintering principle and foaming on fire strategy. Specifically, the influences of raw materials of low temperature ceramics, such as glass frit, phosphate, etc, on the properties of ceramifiable ethylene-vinyl acetate (EVA) composites were investigated. Its fire resistance and thermal insulation properties were evaluated by simulating different sintering environments. The results show that the ceramifiable composite exhibits the highest improvement in fire resistance because a crystalline phase was formed at high temperatures. Gas evolution from the thermal decomposition of ammonium polyphosphate (APP) and EVA contributes to the formation of the porous structure in ceramic residues. The optimal system can resist above 1000 °C flame for 30 min without disintegration, and the temperature of the unfired side was maintained around 200 °C. The reliability of the strategy was verified by the effective medium theory model. [Display omitted] [ABSTRACT FROM AUTHOR]

Hollow-structured ceramic fibers with multiple components are ideal as lightweight insulation materials. In this study, tetraethyl orthosilicate, boric acid, and zirconia octahydrate were used as raw materials for fabricating SiZrBOC hollow ceramic fibers through coaxial electrospinning. These ceramic fibers exhibit a low thermal conductivity and an excellent temperature resistance. The electrospun SiZrBOC hollow ceramic fibers display a clean and compact morphology with internal folds. Fourier-transform infrared spectroscopy and thermogravimetric analysis (TGA) were used to assess the transformation process and thermal behavior of the hollow ceramic fibers. The results suggest that the incorporation of B promotes the formation of Si–O–B bonds within the system, leading to a maximum yield of 75.49 wt% for the production of the SiZrBOC hollow ceramic fibers. The phase composition and microstructure of the SiZrBOC hollow ceramic fibers were analyzed via X-ray diffraction (XRD) measurements. The pyrolysis at 1000 °C resulted in the appearance of diffraction peaks corresponding to SiO 2 and SiC in the XRD patterns of the SiZrBOC hollow ceramic fibers. Laser thermal conductivity measurements reveal that the SiZrBOC hollow ceramic fibers exhibit a thermal conductivity of only 0.06 W‧m−1K−1 at 25 °C and 0.124 W‧m−1K−1 at 500 °C, indicating a significantly superior thermal insulation performance compared with conventional solid SiZrBOC ceramic fibers. [ABSTRACT FROM AUTHOR]

Mullite fiber-based porous ceramics is one of the most commonly used high-temperature insulation materials. However, how to further reduce the thermal conductivity and improve the strength of such materials has been a challenge in the field of high-temperature insulation. In this paper, mullite micro/nano fiber-based porous ceramic was prepared by introducing mullite nanofibers into mullite microfiber-based porous ceramics and the effect of microfiber/nanofiber weight ratio on the samples properties were characterized and analyzed. Results showed that the compressive strength and high-temperature thermal insulation properties of the porous ceramics increased significantly with an increase in the nanofiber content. For the porous ceramics with similar density (about 0.50 g/cm3), the compressive strength of the sample with a microfibers/nanofibers weight ratio of 1:2 was 1.43 MPa, which was much higher than that of the porous ceramics prepared with only microfibers (0.26 MPa). Meanwhile, the backside thermal equilibrium temperature of the sample with a microfiber/nanofiber weight ratio of 1:2 at 900 °C environment was 355.8 °C, which was much lower than that of the porous ceramic prepared with only microfibers (476.5 °C). In addition, in order to investigate the temperature resistance of mullite micro/nano fiber-based porous ceramics, the sintering temperatures was increased from 1400 °C to 1500 °C. Results shows that the high-temperature thermal insulation performance of mullite micro/nano fiber-based porous ceramics with high mullite nanofiber content decays more seriously. The back-temperature test showed that the thermal equilibrium temperature of the samples with a mullite micron/nanofiber weight ratio of 1:1 in 900 °C environment increased rapidly from 386.3 °C to 454.2 °C when the sintering temperature was increased from 1400 °C to 1500 °C. The preparation of mullite micro/nanofiber-based porous ceramics provides a new strategy to improve the performance of fiber-based porous ceramics. [ABSTRACT FROM AUTHOR]

Titanium dioxide hollow microspheres (HMS-TiO 2) were successfully synthesized through a sol-gel and subsequent high-temperature calcination method using a hard template. These microspheres exhibit an average particle size of about 13.66 μm and a shell layer thickness approximately 1.18 μm. Furthermore, the thermal insulation effect is evident in cementitious materials coated with an HMS-TiO 2 -based composite film. The maximum average near infrared (NIR) reflectance and thermal insulation temperature difference of these coated materials are 46.81 % and 9.3 ℃, respectively. Notably, the modified composite film displays excellent mechanical and impermeable properties when applied to the surface of cement mortar samples. These comprehensive results indicate that introducing HMS-TiO 2 with the synergy of structure and composition significantly enhances the thermal, mechanical, and durability properties of modified waterborne coatings on cement-based materials. This augmentation makes them well-suited for thermal insulation and heat preservation applications in building structures. • Micro-scale hollow TiO 2 was synthesized using a hard template method. • The synergy of structure and composition is crucial for cement coatings. • Hollow TiO 2 -based coatings show excellent thermal insulation properties on buildings. [ABSTRACT FROM AUTHOR]

The extensive mining of natural resources, such as sand, for the construction industry, poses a hazard to the environment. To preserve the environment, the researcher must thus take into account the use of industrial byproducts rather than natural materials. The use of sawdust (SD) produced by the wood industry in foam concretes (FC) has been investigated in this study. This study examined the physical, mechanical, thermal, microstructural and durability characteristics of FC containing SD as a replacement of silica sand (SS) in the rates of 0, 25, 50 and 100 %. Two different SD sizes of 0–4 mm (SD4) and 0–1 mm (SD1) were used in the fabrication of FC mixtures. Protein-based foam agent was used to create FC mixtures. Fourteen mixtures with a 0.6 water/binder (w/b) ratio were produced at two different cement contents of 400 kg/m3 and 500 kg/m3. The fresh, mechanical, physical, and sorptivity characteristics of the FC mixtures were investigated in relation to the impacts of cement dosage, SD size, and SD replacement levels of SS. Durability of FC against high temperature, sulfate attack and freeze-thaw cycles was assessed. Costs and CO 2 emissions from the blends were also assessed. The outcomes revealed that a 25 %SD1 integrated FC mixture with a cement content of 500 kg/m3 generated the highest 28-day compressive strength of 3.56 MPa with a 20 % strength loss as per the Ref.500 mixture. 17 % lower thermal conductivity was gained with the inclusion of 100 %SD4 as per the Ref.400 mixture. The mixture with 50 %SD4 and 400 kg/m3 cement dosage exhibited the best resistance to high temperature. The mixture with 25 %SD1 and 400 kg/m3 cement dosage showed the best frost resistance. SD incorporated mixtures showed better durability performance than the reference mixtures. • This study evaluated the sustainable use of different sizes of SD aggregates in eco-friendly FC. • Fresh, thermal, mechanical and microstructural properties of FC were studied. • Transport properties, cost investigation and environmental impact of FC mixtures were also investigated. • Durability performance for sorptivity, sulfate attack, high temperatures, and freeze-thaw cycles was also carried out. [ABSTRACT FROM AUTHOR]

Despite the increasing attention on two-dimensional (2D) metal iodides in recent years for their appropriate bandgaps and exceptional optical properties, there is limited understanding of their intriguing thermal transport properties. Here, the strain-tunable mechanic, electronic, and transport properties of the monolayer CaI 2 are calculated in detail by combining first-principles calculations with Boltzmann transport theory. We have checked its thermal, dynamic, and mechanical stability by computing ab -initio molecular dynamics, phonon spectra and elastic constants, respectively. The calculation results from the PBE-GGA and HSE06 methods indicate that the monolayer CaI 2 is an indirect semiconductor, with band gaps of 3.92 eV and 5.12 eV, respectively. Additionally, the effective masses and Fermi velocities for both holes and electrons are also obtained, which indicates that the monolayer CaI 2 owns the excellent electronic transport property. These mechanical constants and electronic parameters are also highly sensitive to the external strain. The calculated real lattice thermal conductivity of the monolayer CaI 2 at 300 K is about 1.01 W/mK, which is rather low among 2D materials, implying its potential application in heat insulation materials or thermal insulation material. With the biaxial tensile strain increasing, its lattice thermal conductivity would further decrease. The difference in lattice thermal conductivities between 0 % and 2 % strain, as well as between 4 % and 6 % strain, is much smaller than that between 2 % and 4 % strains. Subsequently, the group velocities, phonon scattering rates, and cumulative lattice thermal conductivities of the monolayer CaI 2 are discussed under the different strains. [ABSTRACT FROM AUTHOR]

The development of lightweight shape memory materials with exceptional thermal insulation properties is highly important in aerospace applications. Herein, shape memory polyimide (PI) aerogels was fabricated by molecularly designed PI molecular chains through freeze gelation and subsequent thermal imidization. The freezing conditions were controlled to regulate the porous microstructures of the aerogels. The interactions between PI chains formed physically crosslinked netpoints, which could overcome the expansive force and capillary force, thereby creating a stable porous structure. Because shape memory was thermally activated, the shape memory mechanisms associated with the thermal conductivity of the aerogels were comprehensively explored. Upon decreasing the pore size, dense frameworks were formed, contributing to the improved thermo-mechanical and compressive properties. Moreover, the heat transfer efficiency in the aerogel skeleton was enhanced, resulting in a rapid shape recovery response. Benefiting from the physically crosslinked structures, including entangled chains and π-π interactions, the fabricated PI aerogels demonstrated exceptional shape fixation and recovery capabilities. These findings may provide guidelines for designing smart aerogels for aerospace applications. [Display omitted] • Shape memory polyimide aerogels with tunable porous microstructures were fabricated. • The size of the micropores was regulated by controlling the freezing conditions. • The reduction of pore size accelerated the shape recovery process. • The comprehensive exploration of the shape memory mechanisms was conducted. [ABSTRACT FROM AUTHOR]

[Display omitted] • Macro PPBESK beads with hierarchical pores are fabricated via NIPS approach. • PPBESK beads have a good thermal insulation property in a wide temperature window. • The compression modulus of PPBESK beads is more than 50 times higher than PS foam. • The performance can be controlled by the composition of the coagulation bath. Preparation of porous materials from high-performance polymers holds great promise for various advanced engineering applications like thermal insulation. However, it is still a great challenge to fabricate them due to the difficulties in manufacturing them. Herein, a high performance polymer material poly(aryl ether sulfone ketone)s containing phthalazinone and biphenyl moieties (PPBESK) was utilized to fabricate porous materials via a frequently used and simple method named non-solvent induced phase separation (NIPS). Macro porous PPBESK beads have been fabricated in different non-solvent coagulation baths. The kinetics of the phase inversion processes are visualized by the optical microscope. The multi-scale porous structures formed inside the beads endow them an excellent thermal insulation performance in a wide temperature window and a high mechanical performance that the compression modulus is more than 50 times higher than Polystyrene (PS) foam. Therefore, these PPBESK beads provide an optimized combination of functionalities including high mechanical strength and good thermal insulation, which could turn out to be useful in harsh environmental applications. [ABSTRACT FROM AUTHOR]

In the field of building energy conservation, the development of biodegradable biomass aerogels with excellent mechanical performance, flame retardancy and thermal insulation properties is of particular importance. Here, a directional freeze-drying method was used for fabricating composite sodium alginate (SA) aerogels containing functionalized ammonium polyphosphate (APP) flame retardant. In particular, APP was coated with melamine (MEL) and phytic acid (PA) by a supramolecular assembly process. Through optimizing the flame retardant addition, the SA-20 AMP sample exhibited excellent flame retardant and thermal insulation properties, with the limiting oxygen index of 38.2 % and the UL-94 rating of V-0. Such aerogels with anisotropic morphology demonstrated a low thermal conductivity of 0.0288 (W/m·K) in the radial direction (perpendicular to the lamellar structure). In addition, as-obtained aerogels displayed remarkable water stability and mechanical properties, indicating significant potential for practical applications. [Display omitted] • A high-efficiency flame retardant was synthesized. • AMP has a good interface compatibility with sodium alginate. • SA-20 AMP reached V-0 rating and the LOI value was 38.2 %. • Directional freezing endows SA-20 AMP with outstanding thermal insulation properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • A method is developed for the regulation of secondary unstable dendrites during ice crystal growth. • The flexible polyimide (PI) aerogels possesses a micro/nano multi-scale porous skeleton. • The PI aerogels are characterized by ultra-low density and exceptional thermal insulation. The freeze-casting is widely utilized as a tool for regulating micro-scale pore structures in the fabrication of flexible polyimide (PI) aerogels for applications in adsorption, filtration, and fire-retardant. Herein, a confinement-controlled freeze-casting method is developed to fabricate PI aerogels with excellent thermal insulation properties by designing multi-scale structural adaptability. In a confinement-controlled system, the enhanced solid/solid and solid/liquid interface interactions in the solution dispersion system induce dendritic evolution of ice crystals. Under the directional freezing, grown dendritic ice crystals squeeze the loaded particles to form polyamic acid salt (PAAs) cryogels. Followed by template removal and thermal imidization, PI aerogels with a micro/nano-scale slit-like porous structure were obtained. The PI aerogels are characterized by ultra-low density (as low as 9.82 mg/cm3) and exceptional thermal insulation performance (25.0 mW/(m·K) at 25 °C). [ABSTRACT FROM AUTHOR]

Pyrochlore ceramics with chemical formula A 2 B 2 O 7 (A= rare earth, B= tetravalent metal) have extremely low thermal conductivities (κ) and are thought to be promising candidates for thermal barrier coatings (TBCs) applications. This study reports κ for nanocrystalline (nc) Gd 2 Ti 2 O 7 pyrochlore fabricated by spark plasma sintering followed by sintering at different temperatures to better understand their thermal properties. The structural analysis confirmed the synthesis of single-phase nc-Gd 2 Ti 2 O 7 pyrochlore. The thermal conductivity investigations displayed a systematic decrease in thermal conductivity from 1.6 Wm−1K−1 to 0.6 Wm−1K−1 for the sample sintered at a lower temperature due to high porosity. The value of the κ is found to decrease sublinearly (κ ∝ T-α, where 0 < α < 1) with temperature for all the nc-Gd 2 Ti 2 O 7 pyrochlore samples. DFT- GGA calculation exhibits that the nc-Gd 2 Ti 2 O 7 is a direct band gap at the Γ point of the Brillouin zone, and its value is increased with the sintering temperature. In addition, the effect of sintering temperature on the specific heat capacity (C p) is insignificant in nc-Gd 2 Ti 2 O 7 structures, as confirmed by the quasi-harmonic approximation. Theoretical and experimentally determined results are in good agreement, and values are compatible with the thermal insulation requirements for various applications. • The thermal conductivity (κ) decreases from 1.6 Wm-1K-1 to 0.6 Wm-1K-1 with lowering sintering temperature. • The thermal conductivity (κ) decreases similarly for the highly dense samples sintered at 1000 ℃ and 1200 ℃. • The κ value decreases sublinearly (κ ∝ T-α, where 0 < α < 1) with temperature for all the nc-Gd 2 Ti 2 O 7 pyrochlore samples. • DFT calculated specific heat capacity (C p) systematically increases with increasing measuring temperature. [ABSTRACT FROM AUTHOR]

The use of bio-based building materials is a sustainable opportunity to reduce the environmental footprint associated with the construction sector. The achievement of this objective is primely achieved through the valorisation of vegetable waste, resulting in a reduction in the use of primary source material and waste generation. Within the scope of this study, the focus is directed towards research concerning the thermal, acoustic, and fire behaviour properties of bio-based building materials. This study conducts a comprehensive bibliometric analysis encompassing all documents meeting these criteria within the Scopus database, spanning two decades, from 2003 to 2023. The comprehensive analysis covered a total of 1081 documents, which were analysed. This analysis furnishes insight into various facets, including the temporal evolution of publications, journals boasting the highest publication counts and impact, influential research areas, countries with substantial contributions and their collaborative patterns, noteworthy affiliations, prolific authors, and seminal documents, alongside recurrent keywords. The objective of this comprehensive study is to provide a detailed analysis of the documents published up to the present day, in order to identify research gaps and potential opportunities in this field, to assist new researchers interested in the subject. The analysis reveals that bio-based building materials have gained substantial attention over the past decade. With each passing year, the published documents have increased their impact and become more specific, underscoring the growing importance of this subject. This evolution has also fostered a broader network of researchers engaged in this field. However, it is noteworthy that the characterization of these materials focuses predominantly on their thermal properties, while research avenues related to acoustic and fire properties remain less explored and present opportunities for future investigation. • This study contributes to identify research gaps and potential opportunities in the field of bio-based building materials. • Studies in bio-based building materials have shown an annual growth of the 25% since 2014, being a topic on the rise. • France and China are the countries with the highest scientific publication on bio-based building materials. • Keywords play a crucial role in making visible the research within bio-based building materials. • "Thermal Conductivity" and "Thermal insulation" are the most repeated keywords in this field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Core-shell mesoporous silica-coated VO 2 (M) nanomaterials (VO 2 @m-SiO 2, VmS) were prepared for the first time. • VmS pore size 3.1769–12.8257 nm, thickness 13–58 nm and structurally controllable. • T c and ΔT c of VmS decrease with increasing mesoporous pore size at suitable thicknesses. • The VmS5/PVB composite film A-T lum up to 62.24%, ΔT sol reach 5.16%. • VmS effectively improves the Mie scattering effect of feedstock VO 2 (M). In this study, a hybrid approach using the Stöber and solvent extraction techniques was employed to synthesize mesoporous silicon-coated VO 2 nanomaterials (VO 2 @m-SiO 2 , VmS) with controllable pore sizes and shell thicknesses. This synthesis was aimed at elucidating the influence of mesoporous silicon coatings on the thermochromic effect and optical properties of VO 2. Experimental findings reveal that the mesoporous silica architecture markedly improve the phase-transition hysteresis of VO 2 while mitigating the Mie effects attributable to particle coarsening, under the appropriate shell thickness. Furthermore, concomitant with the enlargement of the mesoporous aperture, the T lum and ΔT sol of the VmS/PVB films also exhibit upward trends. T lum reaches 73.33% and 62.24% in VmS3/PVB and VmS5/PVB, peak ΔT sol reaches 5.16% in VmS5/PVB. The facile synthesis procedure of VmS, in conjunction with its superior performance across phase transition, optics, and thermal insulation metrics, offers a viable pathway for industrial-scale deployment of VO 2 (M) in smart window applications. [ABSTRACT FROM AUTHOR]

Natural fiber-based foams demonstrate outstanding potential for energy-efficient building and personal protective equipment applications due to their lightweight, high porosity, and sustainability. However, the weak interfacial interaction among fibers, functional additives, and the matrix hampers effective stress dissipation, largely affecting the material performance. Herein, this paper demonstrates a facile strategy for fabricating high-performance collagen fiber-based foams by constructing efficient energy dissipation networks using tannin-modified leather collagen fibers (T-LCF) and waterborne polyurethane (WPU). Tannin acts as a coupling bridge, linking the fiber and polyurethane to create a hydrogen-bonded network, enhancing energy dissipation and imparting excellent mechanical properties. Compared to WPU foam (WPUF), the T-LCF-based foam (WPUF/T-LCF) showed 65%, 34 times, and 35% improvements in tensile strength, compressive strength, and ultimate oxygen index, respectively. This study provides new insights into the cleaner production of high-performance natural fiber-based foam composites and a new way for the high-value utilization of collagen solid waste. [Display omitted] • Innovatively produces high-performance collagen fiber foam with tannin-modified fibers and polyurethane. • Tannin acts as a bridging agent, enhancing mechanical properties and flame resistance. • Foam exhibits significant improvements in mechanical and thermal insulation behaviors. • This innovative approach contributes to the sustainable utilization of collagen solid waste. [ABSTRACT FROM AUTHOR]

Intumescent fireproof coating (IFC) can effectively slow down the temperature rise of base materials by constructing intumescent heat isolation chars. Expandable graphite (EG), combined with a typical intumescent flame-retardant system, shows an excellent expansion effect. However, it is difficult to be evenly dispersed in the coating system due to its low surface energy, thus limiting its application in IFC. In this research, EG encapsulated by polyvinyl alcohol (PVA) film was used in combination with conventional intumescent flame retardants to prepare a fireproof coating. Due to the increased hydrophilicity caused by the hydroxy groups of the PVA, both the dispersion and adhesion of EG can be greatly improved in the coating. Additionally, PVA also plays the role of a charring agent to further upgrade the quality of the produced carbon layer. The prepared IFC displays a satisfying synergistic effect. The experimental results showed that the back-surface temperature of the steel plate coated by PVA@EG was reduced to 232 °C after 20 min, far lower than the 250 °C of the unmodified EG system, and the thermal insulation performance was enhanced significantly. Compared with the untreated EG coating, the HRR, THR, and TSR decreased by 79.5 %, 86.0 % and 24.8 %, respectively, and combustion and smoke suppression performance were improved greatly. All in all, PVA@EG endows the coating with superior flame-retardant and thermal insulation performance and greatly improves the safety of steel structures in buildings. [Display omitted] • The PVA film was encapsulated on the surface of the EG to enhance the dispersion and adhesion of the EG in the coating. • The PVA in PVA@EG can act as a carbon source and increase the residual char. • The PVA @ EG coating exhibits better flame retardant, heat insulation and smoke suppression properties. [ABSTRACT FROM AUTHOR]

Heat consumption is a serious energy waste, especially in an extremely cold environment. In view of their excellent advantages, several kinds of aerogels with different functions were emerged successively and served as critical materials in various areas. In this contribution, a simple strategy was developed to fabricate a high-fidelity and high-performance organic/inorganic composite aerogel by integrating dianhydrid-end capped polyamide acid (PAA) precursor and multi-amino functionalized hydroxyapatite (m-AmHA; used as the inorganic cross-linkers) in different feed ratios. Followed by the freeze-drying and thermal imidization treatments, the chemical cross-linked polyimide (PI) and HA based aerogels (HA x @PI, in which x represents the percentage of HA content) were obtained. The synergistic effect of inorganic filler and microporous structure of aerogel led to a great improvement of mechanical and thermal properties. Most importantly, the resultant HA x @PI aerogels could maintain their excellent physicochemical properties in several extreme environments such as ultra hot (300 °C), extreme cold (-196 °C; liquid nitrogen), water soaking (2 h, 40 °C), acid (pH 2.0; 1 h, 40 °C) and alkali (pH 12.0; 1 h, 40 °C) conditions. Based on these outstanding properties, we believe that such HA x @PI composite aerogels with low cost and high performances endowed them to be an ideal candidate to be employed in several harsh environments in addition to the conventional insulation and flame-retardant materials. • Uniformity dispersed HA contained polyimide-based aerogels were fabricated. • The mechanical properties, flame resistance, and thermal insulation properties were enhanced with the doping of HA. • Such aerogels could withstand several harsh environments, including ultra hot, extreme cold, water soaking, acid and alkali conditions, without influence on their physicochemical properties. [ABSTRACT FROM AUTHOR]

Gas absorption capability of material proposes a dominant role in the energy storage, selective gas absorption/capture. Aerogels with ultra-high porosity, ultra-low thermal conductivity have been widely used in gas absorption. However, a persistent limitation of these materials is their static and unalterable gas absorption capacity. In this work, a wrinkled graphene structure is proposed to adjust the gas capability. A series of molecular dynamics (MD) simulations are carried out to propose an atomic-level understanding of the effects of wrinkled structure, including effects of pressure, surface wettability, number of gas molecules, thermal insulation, and mechanical properties. It is found that the gas capability can be reduced by 20% with wrinkle structure. Notably, the linear response between pressure and gas absorption capability is observed. Moreover, wrinkle structure functions as a thermal resistance to restrict solid heat transfer. The mechanical property of the aerogel composite is improved by a doped graphene sheet with a high wrinkle degree. This work will pave the way for the development of aerogel with high and selective gas absorption capability. • MD model of wrinkled graphene doped silica aerogel is built. • A linear response between pressure and gas absorption capability is found. • Wrinkle graphene damages the gas absorption. • High degree of wrinkle graphene improves the mechanical properties. [ABSTRACT FROM AUTHOR]

High-temperature molten vitreous (HTMV), as the primary means of hazardous waste disposal, was produced in large quantities. Exploring its potential in photothermal applications could extend its high-value. Herein, the HTMV was used to explore the photothermal performance potential. It indicates that the HTMV possesses significant photothermal conversion capability, capable of increasing the tested water temperature by 6.65 °C. The HTMV mass and water volume are critical factors affecting the water temperature outcomes. The HTMV exhibits distinct conversion capabilities when applied at different application scenarios on the test object. Application on the bottom primarily focuses on photothermal conversion with high heat production efficiency, while side application additionally demonstrates excellent thermal insulation properties. Based on heat balance and backpropagation neural network predictions, optimal scheme of HTMV on both inside and outside bottom application scenarios of the heated object can achieve a maximum heat input of 660.6 kJ m−2 and 570.1 kJ m−2, respectively, and reduce carbon emissions by 0.062 kg CO 2 m−2 and 0.054 kg CO 2 m−2. This study not only provides a foundation for the further application of HTMV but also opens a new direction for the development of photothermal conversion materials, which is of great significance in advancing sustainable energy technology. [Display omitted] • HTMV from hazardous waste shows photothermal potential. • HTMV Attached as bottom can additionally increase water temperature by 6.65 °C. • 660.6 kJ m−2 heating and 0.062 kg CO 2 /m2 reduction can be realized. [ABSTRACT FROM AUTHOR]

Thermally conductive, insulating thermal interface materials (TIMs) for solving heat transport problems are facing greater opportunities and challenges than ever before. In this study, a three-dimensional boron nitride (BN)/graphene oxide (GO) skeleton prepared by the ice template method ensures the directional motion of the heat flow. The GO is modified by atom transfer radical polymerisation, so that the GO is connected to the BN through hydrogen bonding and π-π interactions；increases the reaction position of the curing agent with the epoxy group, accelerates the curing reaction of the composite, and synergistically reduce the filler-filler and filler-matrix interfacial thermal resistance. The thermal conductivity of the prepared 3D/BN/GO-EP composites can reach 1.07 W m−1K−1 at a low filler content of 20 wt%, as well as good electrical insulation (volume resistivity 2.59 × 1013 Ω cm) and excellent compression properties (compressible up to 60% of deformation). Meanwhile, Dual Network Co-Transmission Heat Strategy provides a new idea for the research of advanced polymer-based thermal management materials. [ABSTRACT FROM AUTHOR]

• A silicate thermal insulation coating was prepared using water glass, etc. • The properties and structures of the coating were analyzed by various methods. • The coating formed a Si-O three-dimensional network structure at high temperatures. • The optimal preparation parameters and thermal insulation efficiency were determined. Thermal insulation slurry was fabricated using sodium silicate water glass (SSWG) as the film-forming material and hollow glass microspheres (HGM) as thermal insulation fillers. The thermal insulation slurry was coated on 316L stainless steel to fabricate a silicate thermal insulation coating. The results show that SiO 2 phase is formed by SSWG in the thermal insulation coating after sintering at 680 ℃. Through polymerization and dehydration reactions between Si-OH groups, the Si-O three-dimensional network structure develops at 680 ℃. The optimal value of SSWG to aggregate mass ratios is 2.00. Under this condition, the silicate thermal insulation coating exhibits smooth surface, continuous and dense microstructure, high Shore hardness of 50.1 HSD, remarkable thermal insulation efficiency of 21 % at 260 ℃, and excellent resistance to drop and thermal shock tests without any noticeable cracks or detachment. [ABSTRACT FROM AUTHOR]

Using natural porous and fibrous materials for acoustic and thermal conditioning in the construction sector is a solution to achieve a comfort level in buildings. The novelty of this research work lies in employing agricultural and agro-industry waste to solve noise and thermal insulation problems. This study was conducted to investigate a multilayered panel made of fruit stones and coconut fibre from agro-industry waste. Acoustic absorption, and acoustic and thermal transmission, tests were run on four different fruit stone types, olive, cherry, apricot and peach, plus a coconut fibre layer. Although they are not structural elements, bending tests were run to ensure panels' structural integrity. Acoustic tests complied with the recommendations of Standards ISO 10534–2 and ASTM E 2611–09, based on the standing wave tube to obtain the acoustic absorption coefficient and sound transmission loss, respectively. Standard EN 12667 was considered for the thermal test to determine the thermal conductivity coefficient based on the hot plate method. The results show an average sound absorption coefficient above 0.5 and sound insulation over 25 dB within certain frequency ranges. The cherry panels had absorption values of around 0.7 and apricots had sound insulation values of up to 30 dB. Samples' thermal transmittance coefficient values were between 3.0 and 3.4 (W/m2K), which indicate panels' ability to provide thermal insulation. The cherry and olive panels obtained the lowest thermal conductivity (around 0.14 W/mK). The backing effect of the coconut fibre layer improves all the panels' acoustic absorption and thermal properties. [Display omitted] • These natural materials reduce the environmental impact and support a more sustainable construction industry. • Acoustic and thermal properties of multilayer panels composed of fruit stones and coconut fibres. • The panels made of the studied materials, have inherent strength and stiffness that allows them to be structurally stable. • The results show an average sound absorption above 0.5 and sound insulation above 25 dB in certain frequency ranges. [ABSTRACT FROM AUTHOR]

The incorporation of phase change microcapsule (microPCMs) substantially augmented the temperature regulation capacity of foams, endowing it with outstanding application potential in numerous industrial domains. However, interfacial compatibility issues between the capsule and the substrate always exist and affect foam performance. In this study, a milli-meter macrocapsule (macroPCMs) containing microPCMs was prepared using calcium alginate gel as the second layer wall to physically improve the interfacial compatibility. And poly (N-hydroxymethyl acrylamide) was in situ polymerized in the gel layer and provided active alcohol hydroxyl groups to form chemical grafting with the polyurethane raw materials, which further chemically improved the interfacial compatibility. These measures created a significantly improved foam microstructure and a greatly increased foaming capacity, which thus endow the composite foam with excellent thermal insulation performance and mechanical strength. Compared with conventional microPCMs-based foam, the foaming capacity of the macroPCMs-based foam increased by 40 folds, the temperature regulation duration increased by 7 folds, and the mechanical performance increased by 3 folds. Moreover, the insulated incubator fabricated with the macroPCMs-based foam exhibited two-fold greater thermal insulation efficiency than conventional models containing internal ice incubator, which validated the potential of employing macroPCMs-based polyurethane foam in cold chain logistics applications. [Display omitted] • Double-layered macrocapsules with reactive groups on the shell material was synthesized. • The double-layered microcapsules physically and chemically improved the capsules/foams interfacial compatibility. • The improved interfacial compatibility greatly enhanced the macroscopic performances of the composite foams. [ABSTRACT FROM AUTHOR]

Ultra-lightweight foam concrete (ULFC) is a relatively new construction material that has gained attention recently due to its unique properties. This material is not very heavy and low-density, making it easy to form into different shapes and sizes. Its excellent thermal insulation makes it popular for building walls, roofs, and floors. This review paper provides an in-depth examination of the properties and characteristics of ULFC. Its composition typically consists of cement, water, foam, additives, and the various manufacturing methods used to produce it—the mechanical properties of ULFC, including its compressive strength. The density of ULFC can vary greatly, usually falling between 100 and 600 kg/m3. The diversity of this can be affected by different factors, such as the kind and number of additives applied and the methods of foaming and thickening employed. The paper highlights the various applications of ULFC in the construction industry. Its use is as a TC material, which can help reduce heating and cooling costs; as a structural material, it can help reduce dead loads of structures. The review paper also discusses the challenges associated with ULFC production, including foam stability. Foam insulation concrete emits 302–508 kg CO 2 per cubic meter, primarily due to Portland cement, but enhances building energy efficiency, reducing household CO 2 emissions, while advanced recycled insulation materials offer superior thermal and acoustic properties with lower environmental impact. Additionally, we examine the current research on ULFC and suggest potential avenues for future investigation. This paper aims to introduce and put forward a range of cutting-edge and original recommendations and informative guidelines, with the ultimate objective of directing and shaping future research endeavors that focus on effectively exploiting and utilizing ultra-light foamed concrete. • Utilisation of Ultra-light foamed concrete for sustainable construction. • Mechanical properties and thermal insulation perspective incorporating Ultra-light foamed concrete. • The density of ULFC materials compared with normal concrete. • Microstructures properties of concrete incorporated with ULFC. • Recommendations and observations are advanced for future research in ULFC. [ABSTRACT FROM AUTHOR]

Geopolymer concrete is excellent for thermal insulation because of its low thermal conductivity, it may be utilized as a suitable insulation for building facades. Furthermore, it may lessen the impact of fire on the reinforcement for geopolymer constructions. Precise forecast of temperature increase during fire in buildings is crucial to evaluate efficacy of insulation and the performance of structures when exposed to high temperature. This paper introduced simple equations to predict the thermal properties (density, thermal conductivity, and specific heat) of normal and light weight GC when exposed to increased temperatures. Additionally, numerical investigation using the Ansys workbench software programme was performed to explore the temperature distribution in geopolymer concrete slabs when exposed to increased temperatures according to ISO 834 fire curve. Simple equations were created using multiple regression analysis for estimating the temperature distribution in geopolymer concrete slabs. Additionally, the predicted equations for thermal properties and the temperature rise predicted from the numerical study were experimentally validated. [ABSTRACT FROM AUTHOR]

High-strength thermal insulation mortar, with its excellent mechanical properties and thermal insulation performance, is commonly used in building structure insulation and reinforcement renovations. In this study, vitrified microbeads and expanded perlite (EP) were used as thermal insulation materials to create high-strength thermal insulation mortar. The effects of the replacement percentage of these materials (50%, 65%, 75%, and 80%) on the density, water absorption, porosity, compressive and flexural strength, and thermal conductivity of the mortar were studied. The results show that increased replacement percentages of vitrified microbead (EP) led to a decrease in the density of the mortar and an increase in the water absorption rate and porosity. Furthermore, when the replacement percentages were increased, the compressive and flexural strength and the thermal conductivity of the mortar were reduced. Comparative analysis of the pore structure of high-strength thermal insulation mortar using scanning electron microscopy and digital microscope revealed the influence of vitrified microbead (EP) on the internal pore structure of high-strength thermal insulation mortar. The influence coefficient (η s) of volume replacement percentage of insulation materials was introduced using the Hamilton and Crosser models. Furthermore, the prediction model of thermal conductivity of high-strength thermal insulation mortar was established under different volume replacement percentages of vitrified microbead (EP). The calculated values of the model matched well with the measured values, with the ratios of the calculated values of the model to the experimental ones ranging from 0.85 to 1.15. • The physical, mechanical, and thermal conductive properties of mortar are found to be influenced by the amount of insulation. • The prediction model of thermal conductivity of high-strength thermal insulation mortar is established. [ABSTRACT FROM AUTHOR]

A super-hydrophobic multifunctional coating (SMC) was designed and fabricated by combining commercial TiO 2 with polydimethylsiloxane and perfluorodecyltrichlorosilane. The main objective of this research is to enhance the feasibility and effectiveness of SMC coating for building protection. After optimization, the comprehensive performance was significantly improved. The SMC not only significantly improves the water repellency of concrete (decreasing the capillary water absorption by 92.91 %), but also endows concrete with great self-cleaning and photodegradation properties. Additionally, ultraviolet–simulated (90 d) and practical environment (150 d) irradiation tests demonstrate the superior radiative cooling properties of SMC. COMSOL finite element simulation indicates about 20 % of ultraviolet light absorbance and 80 % of visible and near-infrared light reflectance on the SMC. The multifunctional SMC coating not only enhances the water repellency and self-cleaning properties of concrete, but also demonstrates excellent radiative cooling capabilities. These findings highlight the potential of the SMC coating as a promising material for sustainable and energy-efficient building applications. [Display omitted] • A novel multifunctional coating was designed to protect buildings. • The water absorption of concrete can be reduced by 92.91 % with protection (8 days). • The coating possesses great self-cleaning and photodegradation properties. • The coating can protect building against solar radiation and high temperatures. [ABSTRACT FROM AUTHOR]

Aluminosilicate aerogels are promising thermal insulation materials for high temperature applications. In this study, aluminosilicate aerogels were effectively synthesised using affordable precursors: dispersible boehmite powder and waterglass solutions, with subsequent drying achieved by supercritical CO 2 processing. According to the evaluation of their properties, the Al–Si aerogels exhibited low densities (0.11 g/cm3), low thermal conductivities (<0.021 W/m·K) and high specific surface areas (SSA) (516 m2/g for an Al:Si molar ratio of 3:1). When waterglass-based aerogel and aluminosilicate samples were treated at high temperature (1200 °C), the formation of mullite was demonstrated for the aluminosilicate aerogel with a molar ratio of Al:Si 3:1, which showed a higher value for SSA compared to the waterglass-based aerogel. [Display omitted] • Low-cost waterglass and boehmite precursors were employed in aerogel's preparation. • Aluminosilicate aerogels present low densities and low thermal conductivity values. • Aluminosilicate aerogel materials exhibit uniform structure and high specific surface area. • Porosity is retained after heat treatment at 1200 °C for the aerogel with an aluminium: SiO2 molar ratio equal to 3. [ABSTRACT FROM AUTHOR]

• The fabrication process of Ni-P-Al 2 O 3 hollow microlattice is proposed. • The high-temperature antioxidant property of hollow microlattice is improved. • The heat insulation performance can be enhanced up to 13.9%. Hollow microlattice material is a kind of excellent heat insulation material due to its special microstructural characteristics and ultra-low relative density. However, the possibility of oxidation at the temperature higher than 500℃ limits its application in the high-temperature insulation fields, such as rockets and aircraft engines. In order to overcome this obstacle, this study successfully prepared nano-Al 2 O 3 reinforced metallic hollow microlattice materials with an equivalent density of 26.5 mg/cm3. Heat insulation tests and thermogravimetric (TG) experiments were also carried out to investigate the thermal performances of the Al 2 O 3 reinforced metallic hollow microlattice materials, while the effect of the concentration of the Al 2 O 3 was also investigated in accordance with the comparative tests. The results indicate that the Al 2 O 3 plays a significant role in hindering the high-temperature oxidation of hollow microlattice material, especially with Al 2 O 3 concentration in the range of 2 g/L to 4 g/L, and the heat insulation performance can be improved by 13.9%. [ABSTRACT FROM AUTHOR]

Recycled concrete powder (RCP) is a promising supplementary cementitious material, its application in thermal insulation materials is however very limited. In this study, the influence of RCP substitution on the properties of insulation mortars was investigated. The results showed that as the RCP content increased, the compressive strength and thermal conductivity of insulation mortars decreased by 39.8% and 16.8%, owing to the increasing volumes of porous paste and internal air voids. Note that the mortar containing a high content (50 wt%) of RCP struggled to meet the strength requirements of the specification. Therefore, CO 2 curing was further employed here to alleviate the strength loss and successfully increased the compressive strength by 11%∼38%. It was found that since the CaCO 3 particles formed and densified the microstructure (confirmed by the porosity test), the strength reduction derived from the RCP substitution was compensated for. Consequently, insulation mortars incorporating 50% RCP after CO 2 curing for 7 days exhibited satisfactory compressive strength (∼ 0.22 MPa) and relatively low thermal conductivity (∼ 0.048 W/(m∙K)). The mortars showed improved aesthetic appearance and excellent thermal insulation capacity in both hot and cold environments. This study proposed a successful approach to combining reutilization of RCP and CO 2 curing in insulation mortar generation, which effectively improved the sustainability of materials. • A novel and sustainable EPS insulation mortar is developed for energy-efficient buildings. • The synergistic influence of the RCP substitution and CO 2 curing duration is studied. • Remarkably low thermal conductivity is attained through the incorporation of RCP. • Excellent aesthetic appearance and thermal performance are achieved simultaneously. [ABSTRACT FROM AUTHOR]

A novel lightweight foamed cement-based electromagnetic wave (EMW) absorbing material (Density<0.5 g/cm3) is prepared using secondary aluminum ash (SAA) as a foaming agent and carbon black (CB) as an efficient EMW absorbent, providing a new way to recycle SAA. The pore structure parameters, reflection loss (RL), mechanical strength and thermal conductivity are systematically investigated. The experimental test results indicate that the pore structure of cement matrix prepared by SAA exhibits better EMW loss performance than those prepared by traditional foaming agent. The analysis of the pore structure images indicates that the average pore size is reduced, and pore size distribution shifts towards smaller sizes due to the addition of CB. Furthermore, the roundness of pores is increased due to the formation of more irregular pores. Increasing CB content and thickness can reduce RL, enhance absorbing performance at low frequencies, and broaden effective absorbing bandwidth (EAB). The absorbing performance was tested using the arch reflection method in the frequency range of 1.1–18 GHz, the excellent absorbing performance and the widest EAB (RL<−10 dB) reach −36.34 dB and 14.46 GHz, respectively, at a thickness of 4 cm. Benefiting from excellent pore structure, the foamed cement-based material also exhibits better mechanical strength, and good thermal insulation properties are maintained after adding CB. The compressive and flexural strength can reach 2.18 MPa and 1.02 MPa, respectively, while the thermal conductivity remains below 0.122 W/(m·K). • Lightweight cement-based absorber was firstly prepared using SAA as foaming agent. • The effect of CB on pore structure and EMW absorbing property is investigated. • EAB and minimum RL of the developed absorber reach 14.46 GHz and − 36.34 dB. • A new way to recycle SAA is provided. [ABSTRACT FROM AUTHOR]

In this study, a multi-functional guar gum aerogel with the oriented lamellar structure, which introduced sodium silicate (Na 2 O·nSiO 2) and phytic acid (PA) as thermal insulation additives and flame-retardant agents, respectively, was fabricated via freeze drying. Our aerogel's chemical structure, morphology, and thermal and mechanical properties were analyzed. The oriented lamellar structure was attributed to the orientated growth of ice crystals, which was induced by the "silicate-guar, guar-phytate, and phytate-silicate" multiple hydrogen bonds formed between Na 2 O·nSiO 2 , PA, and guar gum. The density of the sample with 2 wt% PA could reach 0.0335 g·cm−3, and the porosity was 5 %, along with a specific pore volume of 0.8144 cm3·g−1. The mechanical properties and thermal insulation performed significant differences in the radial and axial direction of the oriented lamella (nearly 100 % resilience while 50 % deformation quantity and 0.0235 W/(m*K) of thermal conductivity in the radial direction, up to 0.079 MPa of compressive strength in the axial direction). The presence of PA attached a good flame-retardant ability to our aerogel (The Limiting Oxygen Index (LOI) was 30.77 %). This work provides a novel and promising method for developing anisotropic aerogel with excellent potential in building energy efficiency and flame-retardant. [ABSTRACT FROM AUTHOR]

Needle-punched fabric reinforced nanoporous phenolic composite (NPC) is a kind of promising ablative thermal protection material for spaceflight. However, in practical applications, typically anisotropic microstructure of NPC may lead to different performances and damage mechanisms under various directional mechanical or thermal loads. Herein, NPC is prepared and cut into specimens along three typical plane directions including XY -plane (0°), Z -plane (90°), and transitional-plane (45°), and their mechanical, thermal insulation, and ablation behaviors are systematically investigated. Benefiting from the woven fabric in XY -plane, NPC in 0°-plane direction exhibits highest tensile strength (169.2 ± 12.6 MPa), and CT image-based simulation further verifies that woven fabrics are primary load-bearing structure. Meanwhile, NPC in 45°-plane direction shows highest compressive strength (443.1 ± 18.2 MPa) but low compressive stress at low strain, demonstrating a weak bonding between two layers of woven fabrics. Moreover, the heat transfer simulation indicates that horizontally stacked woven fabrics effectively protect the internal material from thermal erosion, thus NPC in 0°-plane direction exhibits optimal thermal insulation. The ablation testing and micro-CT observations further demonstrate that the angle between woven fabric and thermal load significantly influences the ablation mechanism. The present work will further promote the structural reliability and optimization of needle-punched composites. [Display omitted] [ABSTRACT FROM AUTHOR]

The anisotropic cellulose nanofiber (CNF)/carbon nanotube (CNT) aerogels hold a great promise in directional applications due to their distinct xylem-like aligned penetrating pore structures. The aspect ratio of CNF plays a crucial role in the pore structures of aerogels, directly dominating the final macroscopic properties of materials. Herein, three types of CNF with different aspect ratios were extracted through the 2,2,6,6-tetrmethylpiperidine-1-oxyl radical (TEMPO) oxidation process by changing the doses of oxidant. The corresponding anisotropic CNF/CNT aerogels were prepared by the unidirectional freeze-drying method and then their pore morphologies and properties were investigated in detail. The resulting aerogel with the shortest aspect ratio of CNF exhibited the densest porous structure, thereby obtaining the highest compressive strength of 110 kPa and elastic modulus of 383 kPa, while that containing the longest CNF possessed the highest thermal conductivity coefficient of 0.17 W m−1 K−1 and the worst thermal insulation. This research explored the relationship between the properties of the CNF/CNT aerogels and devisable pore structures caused by various aspect ratios of CNF, thus providing a new insight into the development of CNF/CNT aerogels with tunable performances. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) possesses excellent thermal properties, making it an ideal material for thermal insulation. Incorporating Phase Change Materials (PCMs) capsules into Polyurethane has proven to be an effective strategy for enhancing building envelopes. This innovative design substantially enhances indoor thermal stability and minimizes fluctuations in indoor air temperature. To investigate the thermal conductivity of the Polyurethane-Phase Change Materials foam composite, we propose a hierarchical multi-scale model utilizing Physics-Informed Neural Networks (PINNs). This model allows accurate prediction and analysis of the material's thermal conductivity at both the meso-scale and macro-scale. By leveraging the integration of physics-based knowledge and data-driven learning offered by Physics-Informed Neural Networks, we effectively tackle inverse problems and address complex multi-scale phenomena. Furthermore, the obtained thermal conductivity data facilitates the optimization of material design. To fully consider the occupants' thermal comfort within a building envelope, we conduct a case study evaluating the performance of this optimized material in a detached house. Simultaneously, we predict the energy consumption associated with this scenario. All outcomes demonstrate the promising nature of this design, enabling passive building energy design and significantly improving occupants' comfort. The successful development of this Physics-Informed Neural Networks-based multi-scale model holds immense potential for advancing our understanding of Polyurethane-Phase Change Material's thermal properties. It can contribute to the design and optimization of materials for various practical applications, including thermal energy storage systems and insulation design in advanced building envelopes. [ABSTRACT FROM AUTHOR]

• Rigid polyurethane foam as the preferred thermal insulation. • Analysis of the influence of fly ash on material thermal conductivity. • Calculation of the heat balance for a wall with polyurethane insulation. • Study of the temperature field in the cross-section of the wall. Limitations in natural resource availability have a significant impact on prices of thermal energy. As a result, a growth of interest in the technology of insulation materials is observed. The paper presents a comparative analysis of rigid polyurethane foams, which are widely used as insulation materials. Rigid polyurethane foam with 10 wt.% addition of coal fly ash is compared to a reference foam, without any addition. The thermal conductivity coefficient of polyurethane materials was determined by the Hot Disk device. Heat transfer for both types of foams was modelled. As a result of the numerical modelling, the temperature field for the wall was obtained. The results of the computations have shown differences in energy losses. Conducted analyses demonstrate that the modified polyurethane foam (with the addition of coal fly ash) performs better as an insulation material. The reduction of heat requirement is 2.9 %. An environmental analysis of the insulation materials was also carried out. Using the SUBRAW index method it was calculated that embodied energy and the carbon footprint are lower in the case of the modified polyurethane compared to the unmodified foam. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel type of PI/SIO 2 composite aerogel was prepared by a confined filling strategy. • The PI/SiO 2 composite aerogels exhibit ultra-low density and super thermal insulation. • The sound insulation and mechanical properties are significantly enhanced owing to the "honeycomb-like" structure. Aerogels have enormous potential in integrated thermal insulation and noise reduction applications. According to the knowledge of the favorable mechanical and acoustic properties of honeycomb structures. We employed anisotropic "honeycomb-like" polyimide (PI) aerogels as the matrix and utilized a confined filling strategy to directionally filled continuous SiO 2 aerogels into the PI aerogel matrix. This resulted in the creation of an exceptional organic–inorganic composite aerogel (PISis) with outstanding thermal and acoustic insulation performance. The radial thermal conductivity of PISis ranged from 22.37 to 27.65 mW·m−1·K−1, and the initial decomposition temperature was approximately 524–557 °C. In the frequency range of 500–6300 Hz, the average sound transmission loss (STL) of the 18 mm thick composite material reached 30.67 ∼ 31.89 dB, and the compressive strength at 10 % strain is 0.416 MPa. The PISis exhibits a density ranging from 0.1012 to 0.1302 g/cm3. These make it an ideal lightweight, high-strength, and efficient material for thermal and acoustic insulation. [ABSTRACT FROM AUTHOR]