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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]

[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]

This work focuses on the potential of agar from the seaweed Gracilaria fisheri to modify the properties of starch foam. The effects of different ratios of glycerol and agar on the properties of starch foams were investigated. All formulations used in this study produced easy-to-handle, smooth, single-use foam trays with no visible cracks. The addition of agar slightly affected the off-white color of the foam but red and yellow color values significantly decreased with increments of agar content. As the agar content was increased, the foam became less dense. A foam produced at a glycerol:agar ratio of 3:7 exhibited the highest values of flexural stress at maximum load (3.23 MPa), modulus (194.46 MPa) and hardness (97.50), and the highest temperature at maximum weight loss (T max) (337 °C). Therefore, starch foam modified with agar from Gracilaria fisheri showed suitable physical, mechanical and thermal properties for food packaging, and could possibly be used in the place of expanded polystyrene (EPS) foam. [ABSTRACT FROM AUTHOR]

Materials with complex inner structure can be challenging to characterise in an effective way. The effective material parameters significantly depend on the structure, and thus on the interface properties. In the present paper, we focus on metal matrix syntactic foams, and we attempt to determine their effective thermal parameters. We supplement the results with their mechanical properties as well. For thermal characterisation, we use the heat pulse experiment to study their transient thermal response. We observed deviation from Fourier's law in multiple situations, and thus we propose an evaluation procedure for such experimental data using the Guyer–Krumhansl heat equation. We provide an iterative procedure to efficiently find the effective thermal diffusivity values provided by the Guyer–Krumhansl and Fourier equations based on the measured transient response. Furthermore, we studied the effective parameters, the specific heat, mass density, thermal conductivity and thermal diffusivity. We found that the standard estimations significantly overestimate the thermal conductivity. Furthermore, we propose a method for deducing a more reliable thermal diffusivity and thermal conductivity based on the transient temperature history, i.e., we propose to estimate Fourier's thermal diffusivity based on averaging the parameters of the Guyer-Krumhansl equation according to the observed diffusive time scales. We also found that for such metal matrix syntactic foams, even with knowing the constituents, the contact thermal resistance makes more challenging to provide a prior estimate for the effective thermal conductivity, but this difficulty can be resolved using proper effective thermal diffusivity values. • Proposing an iterative evaluation procedure for the Guyer-Krumhansl equation. • Determining the effective thermal parameters of metal matrix synthetic foams. • Correlating the Fourier and Guyer-Krumhansl parameters. • Comparing the effective thermal conductivity estimations to the measured one. [ABSTRACT FROM AUTHOR]

Most of the thermal characterization methods using a uniform heating of a surface (Guarded Hot Plate, Transient Hot Plate, Fluxmeter Method) assume 1D transfer in the measurement area and neglect the in-plane heat transfer in the heating element. This results in limitations regarding the time interval for estimation, the thickness of samples or the possibility of simultaneously measuring thermal conductivity and capacity. To overcome these limits, a new 3D transient analytical model suited to isotropic materials and taking into account the convective lateral heat losses on the periphery of the samples as well as the 3D heat transfers in the heating element has been developed. It is first presented and then validated by comparison with 3D numerical simulations carried out with COMSOL. A study of the reduced sensitivities of the measured temperature to the various parameters and parameters estimations carried out on simulations obtained with the 3D model enable us to define an optimal estimation process. Finally, transient hot plate experiments were carried out on five extruded polystyrene samples with thickness ranging from 9.1 mm to 49.8 mm and on samples of PVC foam, PVC and of the reference anisotropic material IRMM-440. The results validate the theoretical study with a deviation lower than 5% compared to the known values of the thermal conductivity for the isotropic materials when using the 3D model, while the deviation may reach 77% using the1D model for the thickest sample of extruded polystyrene. The deviation reaches 11% for the thermal conductivity of IRMM-440 showing the need for a model taking into account the anisotropy for this type of materials. • 1D heat transfer is most often assumed in thermal characterization methods using plane source. • Experimental devices to ensure a 1D heat transfer are complex. • A 3D analytical model is developed for transient plane source methods. • The accuracy of thermal properties estimation using this 3D model is demonstrated. [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]

This article presents a new application of a well-known theory concerning mixing. The introduction of boundary conditions was proposed, which allowed the determination of a universal formula for the k parameter of the system. A graphical method for solving the problem has been proposed, which is supported by studies of the synthesis of rigid polyurethane foam. Mixing tests were performed using a variable ratio of the diameter of the stirrer to the diameter of the mixing chamber. Block-shaped samples were obtained, which were then characterized in terms of mechanical properties - compressive strength, brittleness, in terms of thermal properties - Thermogravimetric analysis, differential calorimetry, in terms of qualitative and quantitative structure studies using SEM images, and in terms of chemical analysis using FTIR. The proposed method for determining the boundary parameters of blending systems was proved to be applicable to polyurethane blending system. • Analytical considerations regarding the mixing process. • Proposing a new approach to determining important boundary parameters for the polyurethane mixing process. • Proposal to improve polyurethane blending processes to reduce the energy intensity of the process. • Effect of stirrer-to-vessel diameter ratio on the structure and properties of rigid polyurethane foam. [ABSTRACT FROM AUTHOR]

Carbon fiber matrix composites have garnered significant attention due to their exceptional properties, finding wide-ranging applications in industries such as aerospace, transportation, and military. In this study, a novel approach involving the addition of nickel was explored to fabricate carbon fiber-reinforced thermoplastic polymer composites and composite materials filled with nylon 12, utilizing nickel foam as matrix. Subsequently, electromagnetic-thermal multiphysics coupling models were established to analyze the induction heating process. The study investigated the effects of nickel content, spatial location of the main heat source, coil current, and coil frequency on the temperature rise and heat generation. Additionally, a linear fit was applied to determine the material surface temperature and related factors during induction heating. Furthermore, a theoretical formula was derived for induction heating under ideal conditions, elucidating the heat transfer mechanism and the influence of various factors on heat generation. The findings of this research serve as a reference for optimizing the utilization of Joule heat in composites, thereby expanding the application of carbon fiber-reinforced polymer composites in temperature regulation and operational control. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Calcination to generate spider web-like distribution of SiC whiskers to control electrical and thermal conductivity. • SiC/C foam with maximum EAB of 6.9 GHz, perfect C-band coverage. • SiC/C foam combines thermal conductivity, Joule heating, mid-temperature microwave absorption and compression to support repeated mid-temperature heating. • SiC/C closed cell foam has potential for large-scale industrial application. Microwave-absorbing materials (MAMs) for applications such as aircraft protective layers and ship side panels often need to take into account the actual working conditions. Conventional MAMs are often difficult to take into account special functional requirements such as mechanics, high temperature, de-icing, etc. Therefore, there is an urgent need to develop MAMs with harsh environmental adaptability and multifunctional requirements. Here, we utilize SiO 2 microspheres and phenolic resin to prepare precursor foams, and through calcination, we have prepared closed-cell SiC/C foam composites with both microwave absorption properties, mechanical properties and thermal properties. The effective absorption bandwidth (EAB) of the samples is up to 6.9 GHz at a thickness of 7.3 mm, which can satisfy the perfect coverage of the C-band, and can be further broadened by structural design. The samples can satisfy the full coverage of the X-band at 200 °C. The samples have loaded properties, and the maximum compressive strength of the samples is up to 10.5 mm. The samples are loaded with a maximum compression strength of 8 MPa, support repeated medium-temperature heating, and maintain a compression performance of 5.7 MPa after heating. The samples have good thermal conductivity and Joule thermal properties, and the surface temperature can be rapidly increased under the condition of applying a heat source or applying a low pressure to cope with the cold and humid working conditions. The composites in this paper are simple to prepare and have the potential for mass production. [ABSTRACT FROM AUTHOR]

For polymer foams, a high expansion rate is often required to obtain a low thermal conductivity. However, polymer foams with high expansion ratio faces a difficulty of shape recovery. In this work, polystyrene (PS)/polymethyl methacrylate (PMMA)/carbon nanotubes (CNTs) composite foams were prepared by the synergy of ultrasound and H 2 O in supercritical carbon dioxide (scCO 2) foaming. The introduction of ultrasound and H 2 O is beneficial to improving expansion ratio. CNTs can enhance the melt strength of PS/PMMA, which also absorb part of the thermal radiation. Therefore, the PS/PMMA/CNTs foams with 0.5 wt% CNTs exhibits the high expansion ratio (80.7 times), low thermal conductivity (25.98 mW/mK) and 100% compression recovery in water at 85 °C after one compression. In addition, with the increasing of filler contents, the reusability of the foam is further improved. After ten compressions, the PS/PMMA/CNTs foams with 2 wt% CNTs still achieve the 99% recovery. This work provides a new way to prepare polymer foams with super-insulation and reusability. [Display omitted] [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]

Polymeric syntactic foams (PSF) are a kind of composite material, which consists of a polymer matrix reinforced by hollow thin wall glass micro-spheres. Because of their low density, low moisture absorption, relatively high specific strength and stiffness, PSF are often employed in aerospace and submarine applications in which they are subjected to a wide range of temperature conditions. Due to the temperature sensitivity of the polymer matrix, the physical and mechanical behaviour of PSFs is highly sensitive to temperature variations. Besides, their dynamic response is significantly affected by the strain rate. This research investigates the temperature and strain rate dependence of the mechanical behaviour of polyurethane, epoxy and nylon syntactic foams under compressive and tensile loads. The selected materials have in common that their mechanical characteristics, thermal properties, and dimensional stability make them suitable for both impact engineering and thermoforming applications. The experimental results, acquired over a temperature range from −25 °C to 100 °C at low and high strain rates, reveal a clear interplay between temperature and strain rate effects on the mechanical behaviour of the materials under investigation. This synergy is observed to vary based on both the matrix material and the loading mode. Notably, the rate dependency of polyurethane and nylon syntactic foams is significantly influenced by the testing temperature during compression, while in tension the influence of the temperature on the rate dependency is moderate or negligible. In contrast, the rate dependency of the epoxy syntactic foam remains largely unaffected by the testing temperature. Deformation and failure mechanisms were analysed by examining the failure surface of the tested samples using SEM micrographs. • A method to measure the dynamic response of polymeric syntactic foams is presented. • The interaction between the effects of temperature and strain rate is investigated. • The examined foams are characterised by a noticeable strength asymmetry. • The variation of strength and energy absorption in diverse conditions is examined. • The failure mechanisms of the materials is analysed via SEM micrographs. [ABSTRACT FROM AUTHOR]