Insulation Manufacturing Research Articles

Dielectric characteristics of various polymers (pvc, hdpe, eva, pp, ps, pa, and abs) reinforced with out of use tires (gtr)

The massive storage of reused tires constitutes a serious environmental problem. This article focuses on finding a new application for these reused tires (GTR), and for this, the dust from the reused tires has been mixed with different thermoplastic polymers such as Polyvinyl Chloride (PVC), High Density Polyethylene (HDPE), Ethylene Vinyl Acetate (EVA), Polypropylene (PP), Acrylonitrile Butadiene Styrene (ABS), Polystyrene (PS) and Polyamide (PA), checking until the concentration values ​​in GTR allow these new compounds maintaining its dielectric properties within acceptable values, and therefore, its possible industrial applications in the manufacture of insulators for electrical cables. Specifically, the dust from reused tires and with a particle size less than 200 μm, has been mixed with the polymers with four concentrations 5%, 10%, 20% and 50% in GTR, analyzing conductivity, permittivity, dielectric loss factor, dielectric relaxations, etc. in a temperature range of 30ºC to 120ºC, and with frequencies of 1·10-2 Hz, up to 3·106Hz. Finally, the fracture surfaces of the samples have been evaluated by scanning electron microscopy (SEM).

Efficiency of machining polymer, marble and steel materials at abrasive water jet cutting

In recent decades, waterjet cutting technology has become widespread across various industries worldwide, ranging from automotive and insulation manufacturing to aerospace. Concurrently, it’s increasingly important for the applied technological parameters to be efficient and cost-effective. This necessitates the appropriate selection of key technological parameters. In this article, we examined the efficiency of abrasive waterjet cutting in three different material qualities: polymer, ceramic, and steel. The article explores the relationship between cutting depth—considered as one widely accepted indicator of efficiency—and technological parameters, drawing conclusions regarding the machinability of various materials.

Self-Lubrication Mechanism of Surface-Textured Polymer-Matrix Composites under the Induction of Frictional Stress.

Polymer-matrix composites have been widely used in the manufacture of seals, bearings, electrical insulators, and self-lubricating films as engineering applications move toward lighter weight, higher strength, and corrosion resistance. However, the high-speed shear effect of the friction pairs in relative motion leads to localized heating of the polymer surface, resulting in deformation or softening of the device. Herein, acer mono maple and canna leaves were used as templates to construct polymer-matrix sulfonated polyether-etherketone/polytetrafluoro-wax (SPEEK/PFW) composites with a surface-textured structure. As the bionic texture reduces the level of direct contact between the friction pairs, the frictional thermosoftening of SPEEK occurs in the localized areas of the bumps and leads to the release of PFW stored in textures, resulting in the formation of a soft polymer sliding layer in the worn area and greatly enhancing the frictional stability. By investigation of the tribological properties of textured SPEEK/PFW composites under different loads and sliding speeds, the mechanisms from surface wear to matrix softening and spontaneous construction of a slipping layer are summarized. The results of scanning electron microscopy and three-dimensional profilometer characterization of the wear scars show the surface state of SPEEK/PFW after friction, revealing the friction-thermotropic deformation of the surface texture. The results of this study not only improve our understanding of the frictional heat-induced surface self-lubrication mechanism of textured polymer composites but also provide a reference for the development of multiphase hybrid polymer-matrix composites with excellent self-lubrication properties.

Development of a Predictive Model for the Thermal Conductivity of Natural Fiber Insulation: A Novel Approach for Quality Control

ABSTRACT Natural fiber insulation materials can offer a sustainable alternative to mineral and petrochemical-based insulation materials when suitable raw materials and appropriate production processes are considered. Within the scope of our research, natural fibers like cotton, flax, hemp, wool, and coir, as well as regenerated cellulose fiber, were processed into insulation materials and examined concerning their thermal conductivity. We demonstrate that simple test methods for fiber fineness measurement with air-flow methods such as Airflow and Shirley can facilitate incoming inspection and process monitoring for insulation manufacturers. Based on these measurements, a simple model was developed to estimate the thermal conductivity based on the fineness measurements of the raw materials. The model developed on the natural fibers for lower densities was tested on a glass fiber insulation material to check its suitability. The slight deviations achieved between the experiment and the calculation verify the practicability of the concept.

Harnessing the Flexibility of Lightweight Cellulose Nanofiber Composite Aerogels for Superior Thermal Insulation and Fire Protection.

Thermally insulating materials from renewable and readily available resources are in high demand for ecologically beneficial applications. Cellulose aerogels made from lignocellulosic waste have various advantages. However, they are fragile and breakable when bent or compressed. In addition, cellulose aerogels are flammable and weather-sensitive. Hence, to overcome these problems, this work included the preparation of polyurethane (PU)-based cellulose nanofiber (CNF) aerogels that had flexibility, flame retardancy, and thermal insulation. Methyl trimethoxysilane (MTMS) and water-soluble ammonium polyphosphate (APP) were added to improve the cross-linking, hydrophobicity, and flame-retardant properties of aerogels. The flexibility of chemically cross-linked CNF aerogels is enhanced through the incorporation of polyurethane via the wet coagulating process. The aerogels obtained during this study have exhibited low weight (density: 35.3-91.96 kg/m3) together with enhanced hydrophobic properties, flame retardancy, and decreased thermal conductivity (26.7-36.7 mW/m K at 25 °C). Additionally, the flame-retardant properties were comprehensively examined and the underlying mechanism was deduced. The aerogels prepared in this study are considered unique in the nanocellulose aerogel category due to their integrated structural and performance benefits. The invention is considered to substantially contribute to the large-scale manufacture and use of insulation in construction, automobiles, and aerospace.

Binders for materials based on glass and mineral fibers (overview)

The article presents an overview of the existing types of binders for heat and sound insulation made of glass and mineral fibers. The interest in the development or modification of binders for the manufacture of thermal insulation used in the transport, construction, and industrial sectors is due to increased requirements for their operational characteristics, as well as fire and environmental safety requirements. Trends in the development of binders for fibrous thermal insulation materials that meet modern requirements are indicated: thermal protection systems must have sufficient strength and flexibility to maintain their integrity during manufacture, transportation and installation in target volumes, sufficient elasticity to restore volume after compression, low specific gravity, low coefficient of thermal conductivity, resistance to flame, low smoke emission and resistance to moisture gain during heating and cooling.

Electrostatic Powder Coating as a Novel Process for High‐Voltage Insulation Applications

A novel strategy for manufacturing of the main insulation of high‐voltage rotating machines is presented. The developed process is based on established electrostatic powder coating equipment. Using complete automation enables the precise and reproducible application of homogeneous powder coating layers. Individual layers can be stacked by process repetitions to achieve a desired layer thickness. This coating strategy alters the particle deposition process by introducing additional capillary bridges that significantly increase powder adhesion. A systematic parameter study is performed to provide process–structure relations connecting various process parameters with the resultant coating thickness and homogeneity. The parameters of the developed coating process are iteratively improved to maximize coating homogeneity and minimize defect density, the most critical parameters in high‐voltage insulation applications. The obtained powder coatings with a target thickness of 1.5 mm are subjected to electrical testing to examine the partial discharge activity as a key criterion for a functional insulating coating. The measurements reveal no significant partial discharge activity up to an electric field strength of 10 kV mm−1, demonstrating that this novel strategy for the production of the main insulation of high‐voltage rotating equipment surpasses the state‐of‐the‐art process in terms of partial discharge activity.

Acoustic properties of commercial thermal insulators

Material manufacturers give very limited or no information of the acoustic properties of thermal insulators in broad perspective. The purpose of our study was to compare the acoustic performance of commercially available thermal insulators. Thirteen insulator types produced by several manufacturers were studied. The acoustic performance was determined holistically by measuring six acoustic quantities: sound reduction index of bare insulator, sound reduction index of encapsulated insulator (insulator between two boards), normal incidence sound absorption coefficient, airflow resistivity, dynamic stiffness per unit area, and reduction of impact sound pressure level in a floating floor. All measurements were conducted according to prevailing ISO standards in an experienced test laboratory. The acoustic performance differed significantly between insulator types for each acoustic quantity. The ranges were 1027 dB, 3352 dB, 0.200.78, 3.02700 kPas/m2, 1.5730 MN/m3, and 1536 dB, when the thickness of the insulator was 100 mm. Closed-pore insulator types usually carried worse acoustic properties than open-pore insulator types. Lower thermal conductivity was associated with worse acoustic performance of two acoustic quantities. Insulator manufacturers should consider to better declare the acoustic properties of insulator products, because this knowledge is needed in the acoustic design of building constructions and other applications.

GEL CASTING METHOD FOR THE PRODUCTION OF CERAMIC MATERIALS

Gel casting is one of the new and promising methods for producing ceramics. Modern research on the production of ceramic materials by gel casting covers a wide range of materials, including both dense and porous ceramic materials. The advantages of this method, such as ease of processing, the use of technological equipment of traditional methods, increased productivity, the possibility of obtaining products of large shapes and complex geometry, gave impetus to new research and development. This article provides an overview of publications devoted to research in recent decades on the production by gel casting of both dense ceramics for the manufacture of structural elements and porous ceramics for the manufacture of thermal insulation, porous filters and membranes.

Manufacture of thermal and electrical insulators from epoxy particulate compounds

تضمن البحث تحضير متراكب بوليمري نانوي مكون من خلط الايبوكسي ومطاط اليوريثان وبنسبة %(15) مضاف له دقائق نانو الومينا وبنسب وزنية %(0,2.5,5,7.5,10) ومقارنته مع نفس الخليط وقد اضيفت اليه دقائق نانو تيتانيا وبنفس النسب الوزنية سابقة الذكر. تم دراسة التوصيلية الحرارية واختبار المسح الحراري التفاضلي (DSC) والسعة الحرارية ومتانة العزل الكهربائي للمتراكب النانوي وبينت النتائج زيادة في كل من قيم التوصيلية الحرارية ودرجة الانتقال الزجاجي والسعة الحرارية ومتانة العزل الكهربائي للمتراكب النانوي ازدادت مع زيادة النسب الوزنية للدقائق النانوية وان قيمتها اعلى لنانو الومينا مع توضيح لصور سطح النماذج باستخدام المجهر الالكتروني الماسح .

Reality Check on a Purported Global Sand Shortage: Sensationalism Extrapolated from Isolated Occurrences to Global Phenomena

Since 2013, there has been a proliferation of opinion pieces pertaining to a global shortage of sand.  Because of the current volume of such articles, the situation is taken as fact and industries like fiberglass insulation manufacturers are being criticized for exploiting the earth’s dwindling supply of sand.  Research has shown that these are sensationalized headlines (rather than actual scientific reporting) and they are proliferating because they benefit author of opinion and social media content.  The genesis of the popular sand shortage story can be traced to a 2013 documentary, Sand Wars, and an unintentional foundational basis for the issue derived from a short discussion on international trading and island building in the book, Sand, The Never-Ending Story.  Extensive research conducted for this article confirms that there is no general, worldwide shortage of sand; instead, there are only isolated shortages in some areas outside the US.  Most importantly, the sand that is the subject of the purported global sand shortage stories is not the same sand (industrial sand) that is used by the fiberglass industry.  Finally, that industry’s use of industrial sand has declined over time as it increases the use of recycled glass cullet as a sand substitute.

Resistive High-Voltage Probe with Frequency Compensation by Planar Compensation Electrode Integrated in Printed Circuit Board Design

Resistive voltage dividers tend to have a highly non-linear transfer function as parasitic and stray capacitances exert an increasing influence with increasing frequency. The non-linear transfer function depends on the topology and resistors used and consists of a low-pass filter with an additional high-pass component in the GHz range. Due to the non-linear transfer function the measured signal differs from the original input signal. Here, we present an improved resistive voltage divider with additional compensation capacities to extend the linear bandwidth. With this new concept, the linear bandwidth is improved from 115 kHz to 88 MHz, while maintaining a DC input impedance of 10 MΩ. For high-voltage insulation and easy manufacturing, surface mounted resistors on a printed circuit board with a compensation electrode on the adjacent side are used. The performance of this resistive voltage divider is demonstrated by measuring a series of high-voltage pulses with an amplitude of 2.5 kVpeak-peak. The measured pulse rise time is about 16 ns, corresponding to an average slew-rate of 150 V/ns. Finally, the developed resistive voltage divider is successfully used to measure fast high-voltage transients required for advanced ion mobility spectrometers with integrated collision induced fragmentation.

Optimal Balance between Heating, Cooling and Environmental Impacts: A Method for Appropriate Assessment of Building Envelope’s U-Value

In Europe, the recent application of regulations oriented to zero-energy buildings and climate neutrality in 2050 has led to a reduction in energy consumption for heating and cooling in the construction sector. The thermal insulation of the building envelope plays a key role in this process and the requirements about the maximum allowable thermal transmittance are defined by country-specific guidelines. Typically, high insulation values provide low energy consumption for heating; however, they may also entail a risk of overheating in summer period and thus negatively affect the overall performance of the building. In addition, the embodied energy and related emissions caused by the manufacturing and transportation processes of thermal insulation cannot be further neglected in the evaluation of the best optimal solution. Therefore, this paper aims to evaluate the influence in terms of embodied and operational energy of various walls’ thermal insulation thicknesses on residential buildings in Europe. To this end, the EnergyPlus engine was used for the energy simulation within the Ladybug and Honeybee tools, by parametrically conducting multiple iterations; 53 variations of external wall U-value, considering high- and low-thermal-mass scenarios, were simulated for 100 representative cities of the European context, using a typical multifamily building as a reference. The results demonstrate that massive walls generally perform better than lightweight structures and the best solution in terms of energy varies according to each climate. Accordingly, the wall’s thermal transmittance for the samples of Oslo, Bordeaux, Rome and Almeria representative of the Continental, oceanic temperate, Mediterranean, and hot, semi-arid climates were, respectively: 0.12, 0.26, 0.42, and 0.64 W/m2K. The optimal solutions are graphically reported on the map of Europe according to specific climatic features, providing a guidance for new constructions and building retrofit.

Influence of thermal aging on the physical characteristics of liquid silicone rubber

Composite insulators with silicone rubber sheds are becoming more and more popular in the past few decades due to their excellent properties, especially hydrophobic transfer ability. Compared to traditional high temperature vulcanized silicone rubber, liquid silicone rubber shows great advantage for good fluidity and simple moulding process, making it perfect for the manufacture of insulators with large diameters. Considering the operation conditions, thermal aging of insulating materials is of great significance for power transmission. In this paper, aging of silicone rubber composites under different temperatures are conducted for 2000 h. Influence of thermal aging on the basic characteristics of sample is investigated, including hardness, hydrophobicity and mechanical strength. The results indicate that the performance of liquid silicone rubber used in this paper meet well the requirements for composite insulators.

Synthesis of silica-cellulose aerogel derived from bagasse through impregnation and ambient pressure drying methods as thermal insulator

The trend of research and development of technological advancement in thermal insulators involves using renewable materials, selecting manufacturing processes that require the lowest possible energy, or using waste materials that may help subdue the reduction of petroleum reserves. This review discusses the potential substitution of petroleum by natural materials in thermal insulation manufacturing. This review presents an overview of the definition, properties, materials, and methods that can be used in the manufacture of thermal insulators based on results reported in the literature. Many materials are currently being investigated to produce thermal insulator such as cellulose. Cellulose fiber has a big potential to be used in the manufacture of thermal insulators because cellulose possesses many advantageous properties over petroleum-based polymers, i.e. biocompatibility, biodegradability, thermal stability, chemical stability, and low cost. Another material that may be used is silica, as it has high temperature resistance and low thermal expansion. Bagasse containing high cellulose and silica with the composition of 32-44% cellulose and 55.5%-70% silica. Therefore, bagasse proves appealing to be processed into thermal insulator. Aerogels are among the best thermal insulating materials known. This review proposes the impregnation method followed by the ambient pressure drying (APD) method to synthesize cellulose-silica aerogel. The impregnation of silica into cellulose aerogel will increase mechanical strength, flexibility, and the resulting silica-cellulose aerogel will be transparent with a very low thermal conductivity.

Analysis and Optimization on Non-uniformity of Temperature Distribution in Hydrophobic Cycloaliphatic Epoxy Resin Insulators during the Curing Process

Hydrophobic cycloaliphatic epoxy resin (HCEP) insulators are a new generation of outdoor transmission line insulators with good application prospects. However, the HCEP has obvious curing internal stress due to the uneven internal temperature distribution. In this paper, the curing reaction of HCEP mixture is analyzed and a three-dimensional transient temperature field model of HCEP insulator is established. The internal temperature field of HCEP insulator during curing is analyzed for the first time. The results show that the curing reaction of HCEP mixture conforms to autocatalytic reaction. The structure of umbrella skirt causes the uneven temperature distribution inside HCEP insulator. Based on a surrogate model, it is found that thermal conductivity has a great influence on axial temperature distribution, while curing temperature plays a leading role in curing degree and temperature overshoot. The optimal curing temperature is found according to Pareto front. This paper is beneficial for the theoretical analysis and engineering guidance for manufacture of HCEP insulators.

Additive manufacturing of channeled acoustic topological insulators.

We propose and fabricate an acoustic topological insulator to channel sound along statically reconfigurable pathways. The proposed topological insulator exploits additive manufacturing to create unit cells with complex geometry designed to introduce topological behavior while reducing attenuation. We break spatial symmetry in a hexagonal honeycomb lattice structure composed of a unit cell with two rounded cylindrical chambers by altering the volume of each chamber, and thus, observe the quantum valley Hall effect when the Dirac cone at the K-point lifts to form a topologically protected bandgap. Moderately protected edge states arise at the boundary between two regions with opposite orientations. The resulting propagation of a topologically protected wave along the interface is predicted computationally and validated experimentally. This represents a first step towards creating reconfigurable, airborne topological insulators that can lead to promising applications, such as four-dimensional sound projection, acoustic filtering devices, or multiplexing in harsh environments.

Adequate Correlation between the Physical and Mechanical Properties of Glass Foam

The paper presents experimental results obtained in the manufacturing process of a glass foam by adequate correlation between its physical and thermal properties (density, porosity, thermal conductivity) and mechanical (compressive strength) by a slight controlled overheating of the foamed material. Using a powder mixture of glass waste (87-91.5 %), coal fly ash (3-9 %) and silicon carbide (4-5.5 %) microwave heated at 935-975 ºC by this unconventional technique, constituting the originality of the work, was obtained a glass-ceramic foam with moderate compressive strength (1.8-2.6 MPa) and very low thermal conductivity (0.058-0.070 W/m·K). The material overheating generated a homogeneous porous structure characterized by closed cells with relatively large dimensions (without the tendency to join neighboring cells) making it difficult to transfer heat across the material. The foamed product is suitable for the manufacture of thermal insulation blocks for the inner or outer walls of the building without excessive mechanical stress, being an advantageous alternative by comparison with known types of polymeric or fiberglass thermal insulation materials.

Adequate Correlation between the Physical and Mechanical Properties of Glass Foam

The paper presents experimental results obtained in the manufacturing process of a glass foam by adequate correlation between its physical and thermal properties (density, porosity, thermal conductivity) and mechanical (compressive strength) by a slight controlled overheating of the foamed material. Using a powder mixture of glass waste (87-91.5 %), coal fly ash (3-9 %) and silicon carbide (4-5.5 %) microwave heated at 935-975 ºC by this unconventional technique, constituting the originality of the work, was obtained a glass-ceramic foam with moderate compressive strength (1.8-2.6 MPa) and very low thermal conductivity (0.058-0.070 W/m·K). The material overheating generated a homogeneous porous structure characterized by closed cells with relatively large dimensions (without the tendency to join neighboring cells) making it difficult to transfer heat across the material. The foamed product is suitable for the manufacture of thermal insulation blocks for the inner or outer walls of the building without excessive mechanical stress, being an advantageous alternative by comparison with known types of polymeric or fiberglass thermal insulation materials.

Study on the ageing effect of alumina/epoxy composites modified by atmospheric plasma jet

AbstractAlumina/epoxy resin (Al2O3/EP) composite material is widely used in the manufacture of insulators. However, the operation environment of long‐term high‐voltage direct current will destroy Al2O3/EP surface insulating performance. In this article, Al2O3/EP was modified by atmospheric pressure Ar and Ar/CF4 plasma jet, and its aging effect was studied by investigating the physicochemical characteristics and the electrical performances of the sample 0 ~ 100 days after modification. The experimental results show that after plasma treatment the surface roughness of the material increases; the O/C ratio on the surface of the material increases after Ar treatment, and the F element is grafted on the surface after Ar/CF4 treatment. These changes lead to the increase of surface energy and hydrophilicity, and the improvement of electrical performance. The surface properties change within 100 days owing to the oxidation reactions and the variability of recombination chemical bonds and molecular chains after high‐energy plasma treatment. The surface O/C ratio of the materials treated by Ar plasma is obviously reduced, the hydrophobicity is restored to some extent, and the electrical properties are also obviously weakened. In comparison, the properties of Ar/CF4 plasma‐modified materials do not change significantly.