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The guarded hot plate method is widely used to measure the thermal conductivity and thermal resistance of materials having low thermal conductivity. An experimental set-up was designed and fabricated in-house to measure these properties. The set-up was built in accordance with ASTM D5470 standards. A novel insulating material waste tire rubber/polypropylene has been developed from the solid blend of waste tire rubber powder (425–300 µm) mixed with virgin polypropylene granules in a 2.5:1 ratio. The thermal conductivity of the newly developed insulating material in cylindrical solid form has been estimated. Further, thermal conductivity of a conducting material i.e., H-13 tool steel has been found out by using the present experimental set-up. In addition, the thermal contact conductance of a well-known thermal paste i.e., silicon grease has also been estimated for a range of temperatures and pressure using the present set-up. In the present study, the procedure for measuring thermal conductivity has been demonstrated along with the strengths and weaknesses of the experimental set-up and the suitability of the method for different materials. The experimental results reveal that the test method is equally suitable for the analysis of thermal interface material, and for measuring the thermal conductivity of solid specimens giving reliable results. [ABSTRACT FROM AUTHOR]

Copyright of Österreichische Wasser- und Abfallwirtschaft is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this research was to develop composites dedicated to thermal insulation, developed on the basis of natural raw materials. The composites consisted of mixture of lime, cement, water, and two biodegradable materials: a local mountain sheep wool treated as troublesome waste and hemp shives obtained by processing decorticated hemp straw of the Białobrzeskie variety. On a laboratory scale, blocks were produced with varying percentages of shives with a fraction of 10 and 30 mm. Sheep wool used was in two ways: (1) mixed in the mass or (2) arranged in a layer between lime. The basic parameter – thermal conductivity of the composites was determined. The research showed that making a composite of lime with hemp shives decreased the thermal conductivity coefficient of the material. The addition of hemp shives reduced the thermal conductivity coefficient by an average of 36% and 45%, when using shives crushed into 10 mm fractions or 30 mm fractions, respectively. The addition of 20% and 40% sheep wool decreased the λ coefficient by approximately 40%. The λ coefficient of the composite formed using hemp shives and wool is 0.0738 W/mK. The proposed composites might be a good alternative to commonly used thermal insulation materials.

Introduction. All insulating macrohomogeneous solid materials change shape under the influence of an electric field. Problem. The presence of minor defects changes the distribution of an electric field and causes a significant concentration of mechanical stresses in a given section of the material, which, under certain circumstances, can cause partial or complete destruction of this material. Goal. The purpose of the work is to determine maximum mechanical stresses according to the von Mises criterion in insulating materials around defects with ionized air and water in an electrostatic field. Also, to analyze the influence of the following parameters on the indicated stresses: the location of the defect, the orientation angle of the semi-major axis of the defect cross-section, the ratio of semi-major and semi-minor axes, elastic and dielectric properties of the insulating material and the defect. Methodology. The study is based on the interrelated equations of electrostatics and structural mechanics for an isotropic piecewise homogeneous medium. The solution of these equations is obtained by the finite element method. Results. Graphs of dependences of maximum mechanical stresses on the ratio of semi-major and semi-minor axes of the ellipsoidal cross-section of the defect have been obtained. The minimum ratio of the greatest stresses in the insulating materials around the surface cracks and pores for ionized air has been 9.3 times for the maximum ratio of major and minor semi-axes of the cross-section of the defect considered in the work, which is 10. For a water defect, the similar ratio has been 2...5.6 times, increasing when the relative dielectric permittivity of the insulating material changes from 7 to 2. When Young’s modulus of the insulating material increases from 1 MPa to 100 GPa, the angles of the inclination of the linearized dependences of maximum mechanical stresses around bounded pores with ionized air (water) to the axis of the ratio of major and minor semi-axes of the defect cross-section have been increased by 35.9° (58.0°) and 18.6° (20.1°) at orientations of major semi-axes at angles of 0° and 45°, respectively. Originality. The numerical-field mathematical two-dimensional model has been developed for the first time, which consists of sequentially solved equations of electrostatics and structural mechanics, for the determination of the distribution of mechanical stresses in an insulating material with a liquid or gaseous defect. It has been established for the first time that the ratio of the elastic properties of the insulating material and the defect determines the angle of the inclination of the linearized dependence of the maximum mechanical stress to the axis of the ratio of major and minor semi-axes of the defect cross-section. Practical value. The types of defects that contribute to the aging of insulation materials under the combined action of an electric field and a stress field to the greatest extent have been established.

Copyright of Bolu Abant Izzet Baysal University Journal of Faculty of Education / Bolu Abant İzzet Baysal Üniversitesi Eğitim Fakültesi Dergisi is the property of Bolu Abant Izzet Baysal University Journal of Faculty of Education and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction. All insulating macrohomogeneous solid materials change shape under the influence of an electric field. Problem. The presence of minor defects changes the distribution of an electric field and causes a significant concentration of mechanical stresses in a given section of the material, which, under certain circumstances, can cause partial or complete destruction of this material. Goal. The purpose of the work is to determine maximum mechanical stresses according to the von Mises criterion in insulating materials around defects with ionized air and water in an electrostatic field. Also, to analyze the influence of the following parameters on the indicated stresses: the location of the defect, the orientation angle of the semi-major axis of the defect crosssection, the ratio of semi-major and semi-minor axes, elastic and dielectric properties of the insulating material and the defect. Methodology. The study is based on the interrelated equations of electrostatics and structural mechanics for an isotropic piecewise homogeneous medium. The solution of these equations is obtained by the finite element method. Results. Graphs of dependences of maximum mechanical stresses on the ratio of semi-major and semi-minor axes of the ellipsoidal cross-section of the defect have been obtained. The minimum ratio of the greatest stresses in the insulating materials around the surface cracks and pores for ionized air has been 9.3 times for the maximum ratio of major and minor semi-axes of the cross-section of the defect considered in the work, which is 10. For a water defect, the similar ratio has been 2...5.6 times, increasing when the relative dielectric permittivity of the insulating material changes from 7 to 2. When Young’s modulus of the insulating material increases from 1 MPa to 100 GPa, the angles of the inclination of the linearized dependences of maximum mechanical stresses around bounded pores with ionized air (water) to the axis of the ratio of major and minor semi-axes of the defect cross-section have been increased by 35.9° (58.0°) and 18.6° (20.1°) at orientations of major semi-axes at angles of 0° and 45°, respectively. Originality. The numerical-field mathematical two-dimensional model has been developed for the first time, which consists of sequentially solved equations of electrostatics and structural mechanics, for the determination of the distribution of mechanical stresses in an insulating material with a liquid or gaseous defect. It has been established for the first time that the ratio of the elastic properties of the insulating material and the defect determines the angle of the inclination of the linearized dependence of the maximum mechanical stress to the axis of the ratio of major and minor semi-axes of the defect cross-section. Practical value. The types of defects that contribute to the aging of insulation materials under the combined action of an electric field and a stress field to the greatest extent have been established. References 28, table 1, figures 10. [ABSTRACT FROM AUTHOR]

Abstract The past two decades have witnessed rapid advances in the use of fiber-reinforced polymer (FRP) composites in different engineering fields. Advantages such as high strength-to-weight ratio, corrosion resistance, and tailority have led to immense interest in the use of FRPs in wide spectrum repair and strengthening of structures. Despite their many advantages, FRPs are highly sensitive to high temperatures, which pose a major concern for fire potential structures such as buildings. Applying proper thermal insulation can enhance the fire performance of FRP and reduce the possible fire damage to the FRP strengthened element. This study set out to experimentally investigate the effectiveness of two insulation systems, “FIRECOAT” and “REALROCK” on fire performance of CFRP and GFRP strengthened concrete specimens. Various configurations and exposure durations were considered to evaluate the effectiveness of insulating materials. To perform the experiments, cylindrical concrete specimens were fabricated and strengthened using CFRP or GFRP. After insulating the specimens, they were exposed to a standard fire curve for two different durations of 30 and 60 min. The results indicate that less than 30 min of fire, both insulation systems can provide the required protection. During long exposure duration of 60 min, only REALROCK can provide the required thermal resistance for FRP-strengthened concrete. Within the tested materials, Fire Set 60 outperformed other insulating materials. It was observed that implementing Fire Set 60 in the innermost layer of thermal insulations has crucial importance in preventing the fire induced reductions in strength of FRP-strengthened concrete elements.

Ceramic fiber insulation tiles have the characteristics of low density, high temperature resistance, low thermal conductivity and excellent wave transmission performance. It is suitable to be used as thermal protection material in medium low temperature area of space vehicle. The application of high emissivity coating on the surface of ceramic fiber insulation tiles can effectively solve the problems of easy moisture absorption, low strength and easy performance degradation in the service process of ceramic fiber insulation tile. At the same time, it can block the high temperature erosion airflow and improve the energy reflectivity and thermal shock resistance. This paper mainly introduces the preparation methods of ceramic fiber insulation tiles and the influencing factors of their properties, summarizes the research progress of ceramic fiber insulation tiles and their high emission coatings in aerospace field, and looks forward to their future development. [ABSTRACT FROM AUTHOR]

Recently, the climate and landfill crises have raised concerns in the UK as the country is struggling to meet the sustainability goal it set to achieve. One of the major reasons is due to the inadequate recycling rate of waste paper. Therefore, as an alternative solution to the issue, the aim of our research was to exploit the potential of waste paper as an insulating material to see whether it can be feasible to improve the recycling rate of waste paper in the country. Waste paper has already been in the construction industry for a while, and the use of cellulose insulation is a standard in the Passivhaus construction approach. The study examines cellulose's performance as an insulation material and its potential to combat the climate crisis by creating four separate comparisons and calculations using Life-Cycle Assessment and Standard Assessment Procedures. The study will investigate the benefits and limitations of the material as well as a case study to justify the use of it. A pioneer project in the field is a retrofit and new-built building project—54–58 Akerman Road in London. It utilises cellulose fibre insulation as the main material for the new-built part. The study will use this project as a context to compare whether cellulose fibre insulation is the best solution for the project. Also, the study will compare cellulose insulation with other conventional insulation materials in a more general setting as well as with the traditional paper recycling approach, by providing an indication of the carbon footprint of the insulation, the energy resources involved and the amount of raw material. By conducting the study, we can know whether recycling waste paper into cellulose insulation is the best solution to the crisis we face. This research can guide the UK's recycling and use of waste paper, reduce paper waste and energy consumption and improve the sustainability of building insulation materials. [ABSTRACT FROM AUTHOR]

The past two decades have witnessed rapid advances in the use of fiber-reinforced polymer (FRP) composites in different engineering fields. Advantages such as high strength-to-weight ratio, corrosion resistance, and tailority have led to immense interest in the use of FRPs in wide spectrum repair and strengthening of structures. Despite their many advantages, FRPs are highly sensitive to high temperatures, which pose a major concern for fire potential structures such as buildings. Applying proper thermal insulation can enhance the fire performance of FRP and reduce the possible fire damage to the FRP strengthened element. This study set out to experimentally investigate the effectiveness of two insulation systems, "FIRECOAT" and "REALROCK" on fire performance of CFRP and GFRP strengthened concrete specimens. Various configurations and exposure durations were considered to evaluate the effectiveness of insulating materials. To perform the experiments, cylindrical concrete specimens were fabricated and strengthened using CFRP or GFRP. After insulating the specimens, they were exposed to a standard fire curve for two different durations of 30 and 60 min. The results indicate that less than 30 min of fire, both insulation systems can provide the required protection. During long exposure duration of 60 min, only REALROCK can provide the required thermal resistance for FRP-strengthened concrete. Within the tested materials, Fire Set 60 outperformed other insulating materials. It was observed that implementing Fire Set 60 in the innermost layer of thermal insulations has crucial importance in preventing the fire induced reductions in strength of FRP-strengthened concrete elements. [ABSTRACT FROM AUTHOR]

Abstract The purpose of the current study is to explain the thermal performance of a counterflow vortex tube considering air as a working fluid and with different insulating materials such as fiberglass, cotton wool, nitrile rubber sheet and polyurethane for a steady-state, turbulent flow, axisymmetric, 3-D, compressible flow vortex tube with computational fluid dynamics. In the present investigation, the cooling power performance, coefficient of performance, and isentropic efficiency have been analyzed for insulating and non-insulating vortex tubes. The standard k-ɛ model with various intake pressure and mass fractions was used in the ANSYS FLUENT application for the numerical analysis, and outcomes were validated with experimental results. The conclusion drawn with simulation is that by considering insulation with polyurethane along the hot tube and working fluid as air, the performance of the vortex tube has increased by 9.867% when compared with the vortex tube without insulation. [ABSTRACT FROM AUTHOR]

Achieving adequate classroom temperatures is crucial for optimal learning. However, construction decisions are based solely on budgetary considerations, without considering variables such as thermal environment or environmental impact. This research evaluates the impact of using cellulose as thermal insulation in a university classroom located in Bello, Antioquia, Colombia. Measurements, an architectural survey, and other factors affecting the thermal environment were carried out. Subsequently, a computational model was built in Rhino software and thermal simulations were performed with Climate Studio. The results indicate that cellulose can match or improve thermal performance compared to expanded polystyrene, while having a lower environmental impact. This raises a discussion on the choice of materials for future construction at the university. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Insulated gate bipolar transistor (IGBT) is an important power device for the conversion, control, and transmission of semiconductor power, and is used in various industrial fields. The IGBT module currently uses silicone gel as an insulating layer. Since higher power density and more severe temperature applications have become the trend according to the development of electronic device industry, insulating materials with improved heat resistance and insulation performances should be developed. In this study, we intended to synthesize a new insulating material with enhanced thermal stability and reduced thermal conductivity. Poly(imide-siloxane) (PIS) was prepared and crosslinked through a hydrosilylation reaction to obtain a semi-solid Crosslinked PIS. Thermal decomposition temperature, thermal conductivity, optical transparency, dielectric constant, and rheological property of the Crosslinked PIS were investigated and compared to those of a commercial silicone gel. The Crosslinked PIS showed high thermal stability and low thermal conductivity, along with other desirable properties, and so could be useful as an IGBT-insulating material. [ABSTRACT FROM AUTHOR]

Heat gains and losses via building envelopes are impacted by varied characteristics such as geometry, orientation, properties of the building materials, and the type of construction and its interface with the exterior environment. Current studies are investigating the use of phase change materials (PCMs) characterized by high latent heat and low thermal conductivity that may cause temperature time lag and reduce amounts of heat transferred through building envelopes. The prime objectives of this research are evaluating zones' energy consumption by type for an educational facility in a dry arid climate, examining the effects of a PCM (RT28HC) and polyurethane insulating material, comparing these effects to the existing situation with respect to cooling energy savings and CO2 emissions, and studying the effect of varying PCM thicknesses. The working methodology depended on gathering the real status and actual material of the building, constructing models of the building using Design Builder (DB) simulation software, and comparing the insulation effect of incorporating polyurethane and phase change insulating materials. A parametric study evaluated various PCM thicknesses (6, 12, 18, 24, 30, and 36 mm). Validation was performed primarily for a selected year's energy usage; simulation results complied with field measurements. The results revealed that an 18 mm PCM had a high efficiency regarding thermal comfort attributes, which reduced cooling energy by 17.5% and CO2 emissions by 12.4%. Consequently, this study has shown the significant potential of PCM regarding improved energy utilization in buildings. [ABSTRACT FROM AUTHOR]

Destructive quantum interference (DQI) provides a unique approach to controlling the leakage current in the OFF state of molecular devices. However, the DQI in π-conjugated molecular building blocks cannot exhibit ultralow conductance due to the existence of covalently bonded σ-transport channels. Thus, suppressing the σ-contribution via σ-DQI is essential for the fabrication of molecular junctions with high insulation and effective modulation of conductance in single-molecule junctions. Here, we demonstrate the existence of σ-DQI even in a simple series of CmCn ring molecules, with parallel chains of m and n alkyl units (where m, n=6, 8 or 10), by measuring their electrical conductance and Seebeck coefficients. Counterintuitively, the conductance of the symmetric CnCn rings is lower than that of the corresponding single chains (Cn), which is in contrast to the conductance superposition law in multi-channeled systems. Combined theoretical calculations reveal that the gauche conformation in a shorter chain fixed by another chain leads to the decreased conductance in alkyl rings, which originates from the phase-coherent tunneling and DQI in σ-conjugated systems. Our finding suggests that through appropriate conformation locking by cyclization, the covalent alkane system can exhibit DQI, which offers strategies for future designs of molecular electronic devices and materials. [ABSTRACT FROM AUTHOR]

Measurement of the complex permittivity of a substance in a wide frequency range, for example, from 10 mHz to 100 kHz, provides useful information on the dielectric properties of the substance. In this regard, some of such dielectric properties can be analyzed more clearly if we pay attention to the frequency spectra of electric modulus, which is a reciprocal of complex relative permittivity. Especially, the imaginary part of the electric modulus can be a powerful tool for dielectric materials research. In this paper, this fact is demonstrated clearly by showing abundant examples acquired by the author's laboratory. First, the equations of electric modulus that hold for various dielectric relaxation processes, including their derivation, are shown in an easy‐to‐understand manner. After that, for several insulating polymers, actual measurement examples of broadband complex permittivity spectra are shown, up to frequencies of about 100 kHz and a much broader range up to several THz. In the first example of showing permittivity spectra, polyamide exhibits an incredibly high relative permittivity value of 106 at high temperatures such as 200 °C at a frequency as low as 10 mHz. This is a result of the phenomenon often called electrode polarization. In other words, if electric charge carriers accumulate in an insulator facing a nearby electrode and have the polarity opposite to that of the electrode, the permittivity of the insulator goes up. In such a case, the dielectric loss factor usually shows a very high value in the low‐frequency range and decreases in inverse proportion to the frequency. This reflects the fact that the charge carriers are transported, and the conductivity can be derived from this frequency dependence much more easily with apparently higher reliability than measuring the dc leakage current. Furthermore, it is shown that the coefficient of thermal expansion can be estimated from the permittivity spectra relatively accurately for several polymers that satisfy the necessary condition. Next, taking examples in electric modulus spectra measured in important insulating polymers such as engineering ones, it is demonstrated that the processes of dielectric polarization and relaxation, which are difficult to see in permittivity spectra, can be recognized obviously. Moreover, the effects of the addition of nanosized or microsized fillers to epoxy resin on its thermal property and filler‐induced inhomogeneity are analyzed using the electric modulus spectra measured in these samples. The effects of thermal aging treatment and simultaneous aging treatment with heat and radiation on the degradation of cross‐linked polyethylene are also analyzed by paying attention to the frequency spectra of its imaginary electric modulus. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Polonorum seria Zootechnica is the property of West Pomeranian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article reports on the revalorization of hemp waste from the textile industry, focusing on the development of new sustainable materials with high insulating properties. Wet-laid technology was used to manufacture nonwovens with different binding fibers, polylactic acid, and viscose fibers. The characterization of the acoustic insulating capacity was carried out using a Kundt tube, and the thermal insulating performance by measuring the heat transmission resistance (R) and thermal conductivity (λ). The results showed that the developed nonwovens have lower thermal conductivity values of about 0.027–0.034 W/(m K), were even lower than those of traditional thermal insulating materials, being the sample with 100 g/m2 of areal density and with a composition of 80% of hemp, 10% of polylactide and 10% of viscose the one with the lowest thermal conductivity (0.027 W/(mK). Their acoustic absorption capacity was around 0.76 at a frequency of 6 kHz, in samples containing high hemp waste (>80 wt%). However, the heterogeneous, discontinuous, and high void density structure that contributes to excellent insulating properties, lead to a decrease in their mechanical properties. This demonstrated that these materials are suitable for substituting traditional materials in insulating applications. Additionally, antifungal tests were carried out. However, hemp nonwovens proved to be inefficient against fungal proliferation. [ABSTRACT FROM AUTHOR]

Sun is the main source of solar energy, and the energy it releases to the Earth's surface in one hour is more than what the whole planet consumes in a year. This present work is about characterizing novel material that can be used as energy storage and diffuser in constructing flat plate solar collector. Materials used are clay and granite dust obtained from Okelele and Kulende Quarry sites, both in Ilorin, Kwara State, Nigeria. The materials were sun-dried; the clay crushed before the two materials were sieved into different particle sizes. They were thereafter blended into different ratios and then characterized for thermal, physical and mechanical properties. Results showed that the highest thermal conductivity, thermal diffusivity and compressive strength were obtained from sample of particle size 0.075 mm and clay: granite ratio 50:50 (0.268176 W/mK, 3.58514 × 10-4 m²/sec and 3.571 N/m², respectively). This same blend has a density of 0.91 g/cm³ and specific heat capacity of 824 J/kgK. This sample, having the optimal thermal, physical and mechanical properties will be a good replacement for conventional insulating materials currently being used for solar flat-plate collector construction as it will serve as both energy storage and diffuser. [ABSTRACT FROM AUTHOR]

Background: Several methods have been used to detect defects or debonds nondestructively in materials or construction. Each of these nondestructive testing methods has advantages and limitations. Generally, they are suitable for testing a certain range or a specific type of material and structure and some of them require careful analysis to identify the features of the defects. Objective: The present work proposes a nondestructive testing method based on electro-acoustic technique (NDTPEA) to detect internal defects of dielectric materials, which can identify the defects from the original stress wave generated at the internal defect surface. Methods: Electric polarization occurs in the dielectric under the action of a high-voltage electric field. When the intensity of the electric field changes suddenly, the polarization charge generates a stress wave. If there are defects, such as cracks and debonding, in the medium, the position and size of the internal defects of the insulating material can be determined according to the stress wave. Results: The waveform and velocity of stress wave is measured by a PVDF film. According to the velocity and time of the stress wave in the dielectric, the position of the internal defects or debonding of the specimen can be determined. The maximum error for measuring the wave transmission time is 1 ns, and the maximum measurement error in the defect thickness direction was 0.00253 mm. Conclusions: In the NDTPEA, the detected wave originates from the vibration of the polarized charge at the defect, i.e., the defect is the source of the stress wave. The measured stress wave does not undergo any reflection or refraction, and the waveform is truly regular, without coupling factors. The wave shape and time characteristics can all reflect the characteristics of the defects. [ABSTRACT FROM AUTHOR]

Sun is the main source of solar energy and the energy it releases to the earth's surface in one hour is more than what the whole planet consumes in a year. This work is about developing a novel material to use as both energy storage and diffuser in constructing flat plate solar collector. Materials used are clay and granite dust obtained from Okelele and Kulende Quarry site, both in Ilorin, Nigeria. The materials were sundried; the clay crushed before the two materials were sieved into different particle sizes. They were thereafter blended into different ratios and then characterized for thermal, physical and mechanical properties. Results showed that the highest thermal conductivity, thermal diffusivity and compressive strength were obtained from sample of particle size 0.075mm and clay: granite ratio 50:50 (0.268176 W/mK, 3.58514x10-4 m²/sec and 3.571 N/m² respectively). This same blend has a density of 0.91 g/cm³, specific heat capacity of 824 J/kgK. This sample, having the optimal thermal, physical and mechanical properties will be a good replacement for conventional insulating materials currently being used for solar flat-plate collector construction as it will serve as both energy storage and diffuser. [ABSTRACT FROM AUTHOR]

This study investigates the effect of water absorption on the flexural strength of kenaf/glass/unsaturated polyester (UPE) hybrid composite solid round rods used for insulating material applications. Three volume fractions of kenaf/glass fibre 20:80 (KGPE20), 30:70 (KGPE30), and 40:60 (KGPE40) with three different fibre arrangement profiles of kenaf fibres were fabricated by using the pultrusion technique and were aimed at studying the effect of kenaf fibres arrangement profile and its content in hybrid composites. The fibre/resin volume fraction was maintained constant at 60:40. The dispersion morphologies of tested specimens were observed using the scanning electron microscope (SEM). The findings were compared with pure glass fibre-reinforced UPE (control) composite. The water absorption results showed a clear indication of how it influenced the flexural strength of the hybrid and non-hybrid composites. The least affected sample was observed in the 30KGPE composite type, wherein the kenaf fibre was concentrated at the centre of a cross-section of the composite rod. The water absorption reduced the flexural strength by 7%, 40%, 24%, and 38% of glass/UPE (control), 20KGPE, 30KGPE, and 40KGPE composites, respectively. In randomly distributed composite types, the water absorption is directly proportional to the volume fraction of kenaf fibre. At the same time, flexural properties were inversely proportional to the volume fraction of kenaf fibres. Although the influence of water absorption on flexural strength is low, the flexural strength of pultruded hybrid composites was more influenced by the arrangement of kenaf fibre in each composite type than its fibre loading. [ABSTRACT FROM AUTHOR]

Europe calls for a transition to the circular economy model based on recycling, reuse, the proper design of products, and repair. Recycling requires energy and chemical products for waste processing; on the contrary, reusing reduces the impact of transportation and expands the life of materials that cannot be recycled. This article highlights the characteristics of selected end-of-life materials; it aims to raise awareness among manufacturers to consider products’ conscious design to facilitate their reuse in different sectors. Panels 7 cm thick, realized by assembling cardboard packaging, egg boxes, bulk polyester, and felt, have been experimentally tested to understand whether they can be installed indoors to improve thermal and acoustic comfort. The panels’ equivalent thermal conductivity λeq measured through the guarded hot plate method is 0.071 W/mK. Acoustic tests have been performed in a sound transmission room and a reverberation room. The weighted sound reduction index Rw is 19 dB, the weighted sound absorption coefficient αw is 0.30, and the noise reduction coefficient NRC is 0.64. The measured properties have been compared to those of commercial materials, and the results show that the panels have interesting properties from the thermal and acoustic points of view. They could be employed in the building sector and in disadvantaged contexts where low-income people cannot afford commercial insulating materials. Although other factors, such as fire resistance, need to be evaluated, these results show that the proposed approach is feasible.

The dielectric properties of low-density polyethylene natural rubber (LDPENR) biopolymeric insulating materials can be improved by adding the silica nanoparticles in a certain percentage of weight (w%). In the present study, four types of bio-nano polymeric samples were prepared. To each sample, the nanosilica particles with wt% 1.5%, 3%, 4.5% and 6%. As one characteristic of dielectric, the partial discharge (PD) characteristics, each sample has been tested for 1 hour under AC high voltage field, and the pulses were counted for each sample and grouped into positive and negative pulses. The PD pattern was also plotted based on X-Y axes, namely Φ-q-n pattern. It was found that the number of positive and negative partial discharge (PD) pulses for each silica sample after 60 minutes of testing varied for all samples. It is also found that samples with a higher percentage of nanosilica had fewer PD pulses. The PD pattern in lower w% of silica was identified in the 90 degrees mostly in containing This indicates that w% of nanosilica particles can improve the PD resistance or the insulation quality of LDPE-NR insulation materials. [ABSTRACT FROM AUTHOR]

The production of PURM (rigid polyurethane foam from castor oil source) composites with glass powder (GP) waste is economical and renewable actions of fabrication of thermal insulating materials. Based on these aspects, the study aimed to characterize composites PURM with 5, 10, 20, 30, 40 and 50% of GP waste contents, by mass. It was observed the influence of the GP percentages in PURM matrix of the composites. The results of the characterizations of density, thermal conductivity, morphology by SEM and chemical microanalysis by EDS were introduced and discussed. In general, the structure of pure PURM showed the elongated, regular and large pores; while composites of PURM + GP presented the irregular, small and rounded pores with presence of deformed cells. By density analysis it was percept the proportional relationship between the thermal conductivity and the GP contents. However, thermal conductivities of the PURM-GP5 and PURM-GP10 composites indicated similarities with pure PURM. Therefore, the PURM composites can be used as thermal insulating material, including their environmental advantages, like reduction of raw material content, use of renewable source and of waste material. [ABSTRACT FROM AUTHOR]

The paper presents a microwave based-nonconventional technique of manufacturing a cellular glass obtained by a heat treatment at 803 C of a powder mixture composed of glass waste from cathode ray tube (93 wt.%), MnO2 (7 wt.%) as a foaming agent and water addition (10 wt.%). The cellular glass has excellent characteristics as an insulating material: apparent density of 0.19 g/cm3, porosity of 91.4%, thermal conductivity of 0.043 W/m·K and an acceptable compressive strength of 1.17 MPa. An economical specific energy consumption (1.16 kWh/kg) was obtained.

Epoxy aluminium nitride (AlN) nanocomposites were prepared to understand the influence of thermal ageing on dielectric and space charge performance of the material. It is observed that the real relative permittivity values of epoxy AlN nanocomposites are higher than epoxy resin when wt% of AlN is >1 wt%. Also, the epoxy AlN nanocomposites depicted an increase in dielectric loss compared to the neat epoxy specimen. The space charge variations in the test specimens are analysed by adopting a pulse electro‐acoustic technique. It is observed that the nanocomposites have lesser space charge in the bulk volume of insulating material compared with pure epoxy resin. Also, it is realised that the local electric field is less with nanocomposite material in both virgin and thermally aged specimens. The threshold electric field is observed to be lesser with epoxy resin compared to nanocomposites. Laser‐induced breakdown spectroscopy (LIBS) analysis clearly indicates the reduction in plasma temperature with epoxy AlN nanocomposites compared to pure epoxy resin. Principle component analysis (PCA) has classified the nanocomposite materials having different filler concentrations from the pure epoxy resin, qualitatively based on their LIBS spectra. Thermally aged epoxy AlN nanocomposites are successfully classified from unaged nanocomposite specimens, using PCA. [ABSTRACT FROM AUTHOR]

The paper presents a microwave based-nonconventional technique of manufacturing a cellular glass obtained by a heat treatment at 803 C of a powder mixture composed of glass waste from cathode ray tube (93 wt.%), MnO2 (7 wt.%) as a foaming agent and water addition (10 wt.%). The cellular glass has excellent characteristics as an insulating material: apparent density of 0.19 g/cm3, porosity of 91.4%, thermal conductivity of 0.043 W/m·K and an acceptable compressive strength of 1.17 MPa. An economical specific energy consumption (1.16 kWh/kg) was obtained. [ABSTRACT FROM AUTHOR]

This article presents a simple thermal characterization method, noted CFM, for the measurement of the apparent thermal conductivity of insulating materials at high temperature (i.e., up to 600 °C). The CFM method is a steady-state relative measurement method which requires a calibration. The calibration of the experimental apparatus was done with a calcium silicate board of known thermal conductivity. Thermal conductivity measurements were carried out on a low-density compressible fibrous felt and a high-density calcium silicate board between 100 and 600 °C. A good agreement was observed with the values obtained with the guarded hot-plate (GHP) method for the low-density fibrous felt and the parallel hot-wire (PHW) method for the high-density calcium silicate board. The measurement of the apparent thermal conductivities of low-density fibrous felts of different apparent densities, combined with a simple conducto-radiative model, allowed to estimate a mean specific extinction coefficient in good agreement with a value derived from transmittance/reflectance measurements. [ABSTRACT FROM AUTHOR]

This work is focused on the upgrading olive oil pomace to obtain high environmentally friendly insulation materials for the construction and building industry. Upgrading of these wastes has been carried out by using the wet-laid technology in combination with different thermoplastic binder fibers both from natural and synthetic origin. After the wetlaid process, the obtained veils or non-wovens were subjected to different processes: a hot-press moulding process or a continuous lamination process. The acoustic insulation properties were obtained by the Kundt's tube while the thermal insulating properties were obtained through determining heat transmission resistance (R) and heat absorption parameter (?). These tests have revealed the excellent insulation properties of the olive pomace-derived materials, specifically, those based on high surface density non-wovens. The complementary process that follows wet-laid, i.e. hot-press moulding or continuous lamination process has a remarkable effect on insulation behaviour. In particular, the hot-pressed materials from olive pomace show better acoustic insulation while the continuously laminated materials offer the best thermal insulation properties. [ABSTRACT FROM AUTHOR]

Optimised quantity of nano‐aluminium (Al) filler mixed with epoxy resin using percolation threshold criteria was adapted to fabricate nanocomposite with desired space‐charge and charge‐trap properties. Surface potential variation due to charge deposition on to the insulating material under transient voltages was investigated, and it showed the improved decay rate with reduced trap depth for the nanocomposites with nanofillers addition in the range between 0.5 and 5 wt%. Threshold electric field calculated based on space‐charge density variation by pulsed electroacoustic measurement was found to be between 7–9 kV/mm and maximum electric field calculated through polarity reversal test is about 9 kV/mm, for 5 wt% (for the optimised value of nanofiller) epoxy nano‐Al composites. [ABSTRACT FROM AUTHOR]

Temperature measurements using thermocouples are an essential input for many industrial processes. It allows the control of their heat balance, the calibration of numerical simulations, and the optimization of process operation and control. Even though it is a very common and straightforward practice, significant errors may occur when the temperature measurements are performed inside an insulating material such as sand, alumina, or other powder materials. For instance, contact resistance, fin effect, and macro-constriction are factors that affect the temperature measured by the thermocouple. Experimental work along with numerical studies were performed to find ways to identify and correct these inaccuracies. The result is a set of recommendations and the development of a new strategy for "a posteriori" error correction which depends on two parameters β = E p /H ACM and θ = T imp /T amb. E p , H ACM , T imp and T amb are respectively the probe penetration depth, the total insulating material thickness, the temperature at the bottom boundary and the ambient air temperature. The new correction strategy has been validated with an experimental laboratory setup and tested using industrial measurements. Results of temperature measurements performed inside insulating material at high temperature show that the error in temperature measurements range from 40 °C up to 100 °C and can be reduced by up to 80% with this new strategy. • Temperature measurements using thermocouples are an essential input for many industrial processes. • Significant errors may occur when the temperature measurements are performed inside an insulating material. • This error can be reduced with a good methodology. • When it is not possible to apply the best practice, a new a posteriori correction method has been developed based on experimental and numerical work. • Error as high as 100 °C can be reduced by up to 80% with this new strategy. [ABSTRACT FROM AUTHOR]

The paper examines conditions for the ignition of high fire point combustible liquids on extended surface materials (e.g. textiles or insulating materials) prone to the so-called «wick effect». It is demonstrated that such liquids may ignite at lower temperatures than their standard fire points. The «wick effect» has to be taken into account when determining the nature of the liquid used to set fire to a person and/or property. The implications of this effect for the spontaneous combustion of liquids and meltable solid organic substances on porous materials is also discussed.ERRATUMAn error was discovered in the article. The reference to GOST R 51355-99 on page 47 was incorrect and should have read as follows: Alekseyev S.G., Barbin N.M., Avdeyev A.S., Pishchal’nikov A.V. Explosion and Fire Hazards of Vodka. Fire and Explosion Safety. 2009, vol. 18, No 2, pp. 20–23. The error was corrected on April 6, 2018.

An aerogel thermal insulation plate has been successfully prepared by using a polystyrene plastic plate with honeycomb structure as a supporting framework. The thermal conductivity of aerogel honeycomb panel was measured by steady state method and its thermal performance was tested by thermal insulation experiment. Based on the steady-state heat transfer process, a simplified model of series-parallel thermal resistance was established, and the thermal conductivity of the aerogel honeycomb plate varying with the filling rate was calculated, the comparison error with the measured value is within 5%. The results show that the thermal conductivity of the aerogel honeycomb plate can be reduced by 19.6% to 27.6% compared with the XPS plate, and its thermal performance is better than the traditional XPS plate. In the future, the aerogel honeycomb plate can be applied to the thermal insulation of light and fast barracks and other buildings. [ABSTRACT FROM AUTHOR]

Backgrounds for demonstrating the glowing behaviour of certain building materials. One of the key points of the ECJ ruling of October 2014 was the national general building approval required for certain mineral wool insulating materials to prove that the insulating material shows "no glowing combustion". In the meantime, a European test method for smouldering and glowing combustion behaviour has been developed. According to DIBt's list of priorities, this can be used to prove that a building product does not smoulder. The article explains the background of the glow detection, the European test method, the expected future development and the consequences for planners and users of construction products. [ABSTRACT FROM AUTHOR]

The paper presents experimental results of producing glass foam from borosilicate glass waste (laboratory ware) using the microwave energy. More variants of foaming agents (silicon carbide, calcium carbonate and activated carbon) and additives (coal ash and disodium phosphate) were tested in the Romanian company Daily Sourcing & Research. The glass foams have characteristics specific to those made of borosilicate glass waste by conventional heating, i. e. relatively low apparent density (0.34 - 0.47 g/cm³), but higher than those resulting from soda-lime glass waste and compressive strength (1.5 - 2.5 MPa) higher than theirs. As glass foams mainly made of soda-lime glass waste, and those made of borosilicate glass waste are suitable for use as insulating material in construction. [ABSTRACT FROM AUTHOR]

Highlights • The biofouling regularity of algae growth on the surface of outdoor RTV-coated insulators was presented. • The suitable conditions for algae growth on insulator surface were studied in detail. • The presence of algae could decrease flashover performance of the RTV-coated insulators. • The effect of algae on the aging of RTV silicone rubber was insignificant. • To inhibit and prevent biological contamination, some measures presented may be possible. However, their effectiveness needs further investigation. Abstract Recently, to improve the anti-fouling flashover performance of porcelain and glass insulators, room temperature vulcanized (RTV) silicone rubber coatings have been widely applied to their surface. However, it was found that, in warm and humid areas in China, the presence of RTV silicone coating could facilitate the growth of biological contamination such as algae. This study firstly analyzed the biofouling regularity of algae growth on the surface of outdoor RTV-coated insulators, considering growth direction, distribution on sheds, substation equipment, insulating material and effect of corona discharge. The effects of algae on the surface micro morphology, functional groups and flashover voltage of field insulator were then studied. The effects of environmental factors on algae growth were studied in detail. Finally, the influence of algae on the hydrophobicity and flashover characteristics of the RTV coating was examined. Through research, the growth regularity of algae on insulator surface is presented and put forward some measures to prevent and control algae growth. The results also showed that the presence of algae could decrease flashover performance of the RTV-coated insulators. However, the effect of algae on the aging of materials was insignificant. [ABSTRACT FROM AUTHOR]

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Abstract This paper presents an investigation on the current and breakdown voltage measurements in thermoset-thermoplastic blends based on an epoxy-amine/poly-etherimide phase separated material. Thermoset-thermoplastic separated blends could be a novel material for insulation applications and can be compared to epoxy/inorganic composites systems. Pure epoxy network as well as the blends with 10 wt% of PEI were studied in terms of conduction and transient currents. An ohmic behavior below the threshold field (E th) and space-charge-limited conduction (SCLC) above E th are pointed out. Contact emission phenomenon was investigated by means of Schottky model and seems to be valid for both materials. The addition of 5 and 10 wt% of PEI into the epoxy system showed an increase in the values of breakdown voltage with the increase of the PEI amount. Highlights • Electrical characterization of an epoxy/thermoplastic blend is examined • Current is controlled by volume phenomena through SCLC approach • Epoxy and blends showed contact emission at the electrode/sample interface • Breakdown voltage increased with the increase of the percentage of thermoplastic [ABSTRACT FROM AUTHOR]

This paper presents investigation on the properties of value-added lightweight sandwich panels, blockboard and battenboard, made by date palm waste trunks as core layer combined with thin MDF as face layers. Some important physical, mechanical and thermo- acoustic properties of the panels were measured according to standard test methods and apparatus. Completely randomized design of experiments was planned and SPSS package was used for statistical analysis. Based on the experimental results, date palm wood-MDF sandwich panels with good thermal conductivity about 0.14 W/m K and favorable sound absorption up to 0.64 and noise reduction coefficients up to 0.15 can be used as heat and sound insulating materials. In addition, adequate physical and mechanical properties can be introduced date palm wood–MDF sandwich panels as a lightweight, cost-effective and environmental friendly alternative for wood- based panels for interior applications. [ABSTRACT FROM AUTHOR]