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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]

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]

An accurate estimation of the effective thermal conductivity of various insulation materials is essential in the evaluation of heat leak and boil-off rate from liquid hydrogen storage tanks. In this work, we review the existing experimental data and various proposed correlations for predicting the effective conductivity of insulation systems consisting of powders, foams, fibrous materials, and multilayer systems. We also propose a first principles-based correlation that may be used to estimate the dependence of the effective conductivity as a function of temperature, interstitial gas composition, pressure, and structural properties of the material. We validate the proposed correlation using available experimental data for some common insulation materials. Further improvements and testing of the proposed correlation using laboratory scale data obtained using potential LH 2 tank insulation materials are also discussed. [Display omitted] • We develop physics-based insulation property models for cryogenic LH 2 storage tank • Model captures the micro- and macro-features of the insulation system with any gas • We demonstrate the applicability of model to several typical insulation materials • Model performs well against experiment even at extended pressure/temperature range • Model parameters can be evaluated from either physics or experimental measurements [ABSTRACT FROM AUTHOR]

Thermal protection has always been an important issue in the energy, environment and aerospace fields. Porous ceramics produced by the particle-stabilized foaming method have become a competitive material for thermal protection because of their low density and low thermal conductivity. However, the study of porous ceramics for composite systems using particle-stabilized foaming method was relatively rare. Here, silica-alumina composite porous ceramics were prepared by particle-stabilized foaming method, which was achieved by tailoring the surface charges of silica and alumina through adjustment of the pH. Porous ceramics exhibited porosity as high as 97.49% and thermal conductivity (25 °C) as low as 0.063 W m−1 K−1. The compressive strength of porous ceramics sintered at 1500 °C with a solid content of 30 wt% could reach 0.765 MPa. Based on the light weight and excellent thermal insulation properties, the composite porous ceramic could be used as a potential thermal insulation material in the spacecraft industry. [ABSTRACT FROM AUTHOR]

Aerogels are excellent thermal insulation materials with extremely low thermal conductivity. However, the practical applications of traditional oxide aerogels, such as SiO 2 and Al 2 O 3 aerogels, are limited by the disadvantages of easy sintering and intrinsic brittleness. SiC is a good candidate for new aerogel due to its superior stability and good properties from room to high temperatures. However, it is generally supposed that SiC cannot be employed as thermal insulation material because of its high intrinsic thermal conductivity. We herein developed SiC nanowire aerogel with quite low thermal conductivity using freeze-drying method. The fabricated SiC nanowire aerogel exhibits ultra-high porosity (∼99.5%), excellent high-temperature stability (∼1700 °C), extremely low thermal conductivity (0.035 W/(m⋅K)) and good compressive flexibility. The low thermal conductivity is resulted from ultra-high porosity and multi-level nanostructures. Flexible compression behavior is attributed to the capability of moving and buckling of SiC nanowires, originating from both ultra-high porosity and strong connection between nanowires. This exploration highlights the flexible SiC nanowire aerogel as a promising high temperature thermal insulation material. [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]

• 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]

• 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]

• Cyclic loads applied on foam glass aggregates (FGA) at different compaction ratios. • FGA response under deviatoric stresses 25 kPa, 100 kPa, and 200 kPa was investigated. • Resilient modulus (M r) and accumulated plastic strain (ɛ acc) were measured. • Increasing the compaction ratio led to a significant decrease in ɛ acc values. • Revealed that FGA at 40% can be used in infrastructure base layer material. Foam glass aggregate (FGA) is considered as a lightweight and thermal insulation material. It has a wide granular size distribution nature that can influence the material's dynamic response when subjected to moving loads. Therefore, it is crucial to investigate the impact of different compaction ratios on the material's dynamic behavior. This study focused on examining the effects of varying compaction ratios (10%, 20%, 30%, and 40%) on dynamic parameters such as resilient stiffness (M r) and accumulated plastic strains (ɛ acc) of FGA. Uniaxial deviatoric stresses were applied to the material samples in a series to assess their influence on the material's behavior over multiple cycles. The results revealed the significant influence of increasing the compaction ratio to 40% on the material's behavior. At this compaction ratio, the ɛ acc decreased to approximately 71%, 69%, and 86% for deviatoric stresses of 25 kPa, 100 kPa, and 200 kPa, respectively, after subjecting the material to 40,000 cycles. The increase in recoverable strains resulting from the material's fragile property under higher compaction energy led to a decrease in the M r values of FGA samples as the compaction ratios increased. The lower boundary of M r values for FGA ranged from 102 MPa to 189 MPa, while the upper boundary ranged from 150 MPa to 219 MPa under the selected deviatoric stresses. Although the interpretation of the shakedown criterion limitations yielded varying ranges for the colocation of FGA samples, it was found that FGA samples compacted at 40% exhibited robust characteristics suitable for constructing road embankments. This can be beneficial for infrastructure applications due to their excellent lightweight and thermal insulation properties. [ABSTRACT FROM AUTHOR]

Naturally-derived aerogels have attracted considerable attention owing to their good biocompatibility, biodegradability and sustainability, but their weak mechanical properties largely limit their applications in various fields. Herein, we proposed the use of a directional freeze-drying method to prepare an anisotropic honeycomb three-dimensional porous aerogel with water-soluble chitosan (CS) as a rigid skeleton and water-soluble biobased epoxy resin as cross-linked hard segments, which had low volume shrinkage and density of 13.9 % and 34.3 mg/cm3, respectively. The resultant aerogel had anisotropic mechanical properties, such as rigidity in the axial direction with a maximum axial modulus of 6.71 MPa, which was 51.6 times larger than that of the pure chitosan aerogel, demonstrating a good compressive elasticity in the radial direction. It also had anisotropic thermal management properties, with a lower thermal conductivity in the radial direction than in the axial direction, down to 0.029 W/mK. The introduction of biobased epoxy resin improved the overall thermal stability, flame retardancy, and increased the biomass content in the aerogel, reducing the carbon footprint of the material. This study paves the way for the construction of a special graded porous, structurally and functionally integrated thermal insulation aerogel, which is of great significance for the development of new thermal insulation materials. [Display omitted] • Anisotropic honeycomb bio-based aerogels have been prepared by directional freeze-drying. • The introducing of bio-based epoxy resin improves the comprehensive properties of aerogel. • The aerogel exhibits low thermal conductivity of 0.029 W/mK in the radical direction. • The aerogel shows low volume shrinkage (13.9 %) and density (34.3 mg/cm3). [ABSTRACT FROM AUTHOR]

• Fully bio-sourced building insulation materials from rice straw and natural binders are developed. • A crosslinking method is proposed to prevent the water solubility issue. • The effect of fiber size, binder type and binder ratio on the hygrothermal properties is investigated. • Alginate-based composites shows more serious mold growth than chitosan-based composites. Conversion agricultural straws to building insulation materials has attracted great interest due to their good hygrothermal properties and low carbon footprint. In this study, fully bio-sourced composite materials were designed based on rice straw and natural binders. Sodium alginate and chitosan were used as the binders. A crosslinking method was proposed to prevent the water-soluble issue of the composites using sodium alginate as the binder. The influence of fiber size, binder type and binder ratio on the hygrothermal properties of the composite materials made of rice straw were investigated. It was found that all the materials are insulating with their thermal conductivity values between 0.038 and 0.047 W/(m⋅K). The alginate-based composites had the higher water vapor permeability and moisture sorption capacity than the chitosan-based composites. Larger fiber size and lower binder ratio resulted in lower thermal conductivity and higher water vapor permeability. However, fiber size and binder ratio had a negligible effect on moisture sorption capacity of the composite materials. Additionally, the mold growth was investigated by exposing the composite materials to severe conditions, i.e., 93% RH and 97% RH at 20 °C. Mold proliferation was found to be easier and quicker in the surface of alginate-based composites compared to the chitosan-based composites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Expanded lightweight plates were prepared by combining expanded glass, expanded vermiculite, and expanded perlite particles with an innovative TEOS/MTMS sol-gel binder. • Expanded glass based plate exhibited the greatest compressive strength (7.04 ± 0.44 MPa) and the highest direct tensile strength (0.486 ± 0.04 MPa). • The long term water absorbency values of expanded perlite based plate was found to be 1.76 ± 0.1 v% in the 1st day and increased slightly to 9.96 ± 0.04 v% in the 28th day. • Thermal conductivity coefficient of expanded glass based plate performed the best result which was measured as 0.125 W/m.K at 25 °C. • NIR-reflective property of expanded glass based plate was recorded as 83.2 ± 0.5 %. • All inorganic-based plates exhibited high fire resistance performance (withstand temperatures of up to ∼900 °C for 30 min). Thermal insulation materials are a great solution to minimize energy consumption for construction applications. Especially, expanded inorganic lightweights are excellent candidates in terms of their low thermal conductivity and high fire resistance properties. Sol-gel type inorganic based binders are also useful chemical substances to combine lightweight particles. In current study, inorganic-based plates were developed by using expanded glass, expanded vermiculite, and expanded perlite particles with a novel tetraethoxysilan (TEOS)/methyltrimethoxysilane (MTMS) sol-gel binder. The chemical, physical, mechanical and thermal properties of the plates were examined comparatively to reveal the effect of expanded lightweight particle types in the plates. According to the experimental results, the compressive strength of the developed plates was between 7.04 ± 0.44 MPa and 3.15 ± 0.17 MPa whilst the direct tensile strength ranged from 0.486 ± 0.04 MPa and 0.079 ± 0.04 MPa, respectively. Furthermore, the long term water absorbency values of the plates on the 28th day varied between 9.96 ± 0.04 v% and 49.8 ± 0.8 v%. On the other hand, while the thermal conductivity coefficient of the plates at 25 °C ranged from 0.125 to 0.254 W/m.K, infrared reflectance properties were determined between 83.2 ± 0.5 % and 64.1 1.8 %. Besides, all inorganic-based plates exhibited high fire resistance performance (withstand temperatures of up to ∼900 °C for 30 min). The results demonstrated that utilizing expanded inorganic lightweight particles with TEOS/MTMS sol-gel binder could be a promising combination to construct energy saving insulating plates to overcome poor fire resistance properties of conventional organic materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Millimetric hollow glass microspheres/epoxy(HGMs/EP) hollow spheres were prepared. • HGMs/EP hollow spheres showed low density and excellent mechanical properties. • A lightweight, thermal insulated EP composite with lattice structure was designed. • EP composites showed good thermal insulation properties. • Thermal insulation mechanism of the EP composites was proposed. In this study, a novel, lightweight, thermally insulated epoxy resin (EP) composite was designed and fabricated by arranging hollow glass microspheres/epoxy resin (HGMs/EP) hollow spheres and EP matrices using a combination of templates and a simple casting method. The designed HGMs/EP exhibited low density and excellent thermal insulation properties, and their size was of the order of millimeters. HGMs/EP hollow sphere–reinforced EP composites exhibit considerably lower density (0.73 ± 0.06 g/cm3; 39.16 % lower) and thermal conductivity (0.121 ± 0.016 W/(m·K); 37.31 % lower) than the traditional HGMs/EP composites with the same HGM content. Overall, the designed HGMs/EP hollow sphere–reinforced EP composites are excellent candidates for providing thermal insulation in construction materials. [ABSTRACT FROM AUTHOR]

Epoxy (EP) resin insulations are widely used in electronic devices and power systems. They are gradually finding their way as winding insulation material for medium frequency transformers (MFT) due to their attractive insulating and adhesive properties along with low cost and easy processing. However, their dielectric insulation properties are compromised at high frequencies and high temperatures due to poor thermal properties. In this context, the surface-treated hexagonal boron nitride (h-BN) micro fillers and core-shell TiO 2 @SiO 2 nanofillers are doped in epoxy (EP) to enhance their thermal and electrical insulation properties under high frequencies and high temperatures. Results reveal that the thermal conductivity of the EP increases continually, whereas the electrical breakdown strength is reduced above the threshold content of micro/nano fillers. Particularly, the micro h-BN addition is beneficial for thermal conductivity enhancement, whereas the core-shell structure of TiO 2 @SiO 2 improves the electrical insulation properties of the EP. The multi-layer core model is used to explain the dynamics of the fillers. The homogeneous dispersion and optimal content of suitable micro-nano fillers can produce efficient EP composites as the electrical insulation for medium frequency transformers. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel naturally grown mycelium-composite insulation brick was bio-produced by cultivating a biocompatible and fast-growing fungus, Pleurotus ostreatus , in the rye berries feedstocks. The resultant mycelium composites consisted of a core of colonized substrate, encased by a layer of water-repellent fungal skin. The microstructure of mycelium composites shows that fungal fibers grow from feedstocks and bonded adjacent feedstocks. The impact of density and moisture on the mechanical properties of mycelium composites were studied, finding that composites with increased density presented an improvement of flexural strength under both low and middle levels of Relative Humidity (RH). However, under high level of RH, composites have a lower flexural strength but a greater deformation. The mechanical strength of mycelium composites, however, meets the existing transportation and construction requirements. Based on the measured thermal properties of mycelium composites, EnergyPlus analyses were conducted to evaluate their performance in buildings' operational energy in comparison with conventional natural insulation materials, i.e., lightweight expanded clay aggregate (LECA) and expanded vermiculite (EV). Compared with LECA and EV, the use of mycelium-composite for building insulation reduced the indoor temperature fluctuations. Compared with LECA and EV, mycelium-composite insulation reduced the total annual heating and cooling energies as well as the total annual CO 2 emissions for buildings located in US Climate Zone 2–8, with the only exception being in Zone 1 or the very hot climate zone. Therefore, naturally grown mycelium-composite, as demonstrated in this study, is promising to provide sustainable building insulation materials. [ABSTRACT FROM AUTHOR]

The highly thermally conductive yet electrically insulating polymeric materials are exhibiting tremendous potential for thermal management materials. However, the practical application of these materials is restrained by the limited thermal conductivity (TC) and deterioration of mechanical properties. In this work, an ultraflexible polyamide-imide (PAI) film with a sandwich-like structure composed with assembled well-oriented functionalized boron nitride nanosheets (FBN) by facile layer-by-layer solution-coating strategy is constructed. The design of the layered structure and highly oriented arrangement of interconnected FBN (Herman's orientation parameter ƒ up to 0.847) endows the obtained PAI composite film with super-flexibility, ultrahigh in-plane thermal conductivity (λ //), superior thermal transfer capability (ΔT max = 24.4 °C) and excellent electrical insulation performance. The PBP composite film reaches an ultrahigh λ // of 45.7 W m−1 K−1 with only 23 wt% FBN loading and exhibits a remarkable TC enhancement factor over 23 because of the more continuous phonon transfer networks that constructed by interconnected well-oriented FBN which could effectively suppress the phonon scattering. Furthermore, the mechanical properties of the layered composite film (PB4P) exhibit noteworthy enhancement compared with uniform PBN composite film, in which the tensile strength is increased by 110% and toughness enhancement is 329%. Meaningfully, our fabrication strategy has the advantage of simplicity and adaptability for commercial amplification. The composite film developed in this work provides a promising prospect for the thermal management system of modern power electronic devices. [Display omitted] [ABSTRACT FROM AUTHOR]

Thermal insulation materials play an important role in energy conservation and the sustainable development of natural resources. Herein, novel silica composite nanofibers (SiO 2 NFs) with closed cell structure and excellent thermal insulation performance were designed and prepared via electrospinning technique using hollow SiO 2 /TiO 2 spheres (HSTSs) as pore-forming agent and infrared shielding agent. The addition of HSTSs broke the continuity of heat transfer pathways inside the NFs and enhanced the infrared thermal radiation shielding performance of SiO 2 NFs, endowed it with ultra-low thermal conductivity and low infrared transmittance. Meanwhile, the materials exhibited good flexibility, high tensile strength, low density and excellent thermal stability, indicating promising application as insulation materials. This research not only provides a novel strategy to prepare porous nanocomposite fibers for thermal insulation, but also offers a new insight for the development of porous materials with multiple functions. [Display omitted] • A novel strategy for constructing porous thermal insulators is reported. • Hollow SiO 2 /TiO 2 spheres broke the heat transfer pathways of the fiber and enhanced its infrared shielding performance. • The obtained SiO 2 composite nanofibers show great potential as thermal insulators in high-temperature. [ABSTRACT FROM AUTHOR]

Lightweight and multiscale nanocomposites are considered to be the most promising materials applied in the field of advanced aerospace and modern building industry, owing to their outstanding mechanical, thermal and flame-resistant properties served in high-temperature oxidizing environments. Herein, a novel siliconoxycarbide (SiOC) modified needle quartz fiber felt reinforced phenolic resin nanocomposite (SiQF/PR) with a hierarchical macro-/micro-/nano-scaled structure is reported. The as-prepared highly porous SiQF/PR nanocomposite exhibits a multiscale three-dimensional network and the micro-sized SiOC particles, derived from the hydrolysis of methyltrimethoxysilane (MTMS) and dimethyldiethoxysilane (DDS), are uniformly incorporated into the phenolic aerogel. The resultant nanocomposite has a bulk density of 0.30–0.35 g/cm3, and the maximum compressive strength reaches 4.20 MPa and 3.34 MPa in xy and z directions, respectively. Thermal stability and oxidation resistance experiments show that the SiQF/PR multiscale composite has a good ablation and heat insulation performance under oxyacetylene test condition, and the backside temperature of SiQF/PR is only 55.5 °C under 1.8mw/m2 for 120 s, and line ablation rate of SiQF/PR multiscale nanocomposite decreases by 20.1% at 1.8 MW/m2 and 59.5% at 0.4 MW/m2 compared to non-SiOC modified composite. These results indicate that the lightweight SiQF/PR nanocomposite fabricated by this method is very suitable for architectural or aerospace applications as high-performance insulation material. [Display omitted] [ABSTRACT FROM AUTHOR]

Biomass-derived aerogels have received extensive attention as potential thermal management materials for energy-efficient buildings. However, it remains a huge challenge to fabricate a fully bio-based aerogel with excellent mechanical property, flame retardancy, and low thermal conductivity. Herein, we demonstrate a novel and facile strategy to manufacture a fully biomass-based aerogel from naturally abundant ammonium alginate (AL) and phytic acid (PA), in which PA acting as both flame retardant and cross-linking components constructs a strong network with AL matrix. Consequently, the resultant biomass aerogel with a low density of 0.052 g/cm3 exhibits ultrahigh mechanical modulus (25.1 ± 3.1 MPa) and specific modulus (440.4 ± 54.4 MPa cm3·g−1), much superior to those of biomass aerogels ever reported. Due to the existence of the uniform three-dimensional porous network, the biomass aerogels exhibit low thermal conductivity (34–38 mW/m·K) and excellent thermal insulation performances. Further, the introduction of PA endows the aerogel with high flame retardancy (limiting oxygen index value of 57%, UL-94 V-0 rating, and extremely low heat release), while the biodegradability of the materials keeps at a high level with a biodegradation rate of 91.43%. Combining with the advantages of mechanically strong property, high flame retardancy, excellent thermal insulation, and biodegradation, the aerogel of this work provides a new strategy to fabricate thermal insulation materials with high environmental safety. [Display omitted] [ABSTRACT FROM AUTHOR]

• Lignocellulosic bio-wastes from forest management and agro-industry as building materials are reviewed. • Some bio-wastes produced in Euro-Mediterranean countries are selected. • Studies on eco-efficient boards made of natural fibers and other bio-wastes are analysed. • Further studies on properties of bio-wastes and eco-efficient boards are needed. This study investigates the possibility of using agro-industrial wastes for building products, mainly focusing on their insulation properties. A classification of bio-wastes is provided, namely of the lignocellulosic ones and their features and properties are described. Information about three main topics is collected: world production and consumption of some crops already used as building materials, their chemical composition and their most studied properties. Since the considered materials are lignocellulosic and they have many common features, a comparison is made. The aim is to have comparable information to support future research related to the production of eco-efficient indoor insulation boards. The result of this research is the choice of four different agro-industrial wastes produced in the Euro-Mediterranean Countries. This area was chosen as buildings typically have little or no insulation due to the regional mild climate; however, particularly with climate change, indoor hygrothermal comfort is poor. The collection of information allows some conclusions to be reached about the different bio-wastes already studied and identify gaps in the literature. [ABSTRACT FROM AUTHOR]