Fill Insulation Research Articles

Waterborne novolac epoxy‐based thermal resistant and fire‐retardant thermal insulation coatings

AbstractWaterborne novolac epoxy based thermal resistant and fire‐retardant thermal insulation coatings were developed in this work. Novolac (phenolic) epoxy emulsion (PEE) was prepared by the phase inversion method based on formulation optimization by orthogonal array testing. The prepared emulsions have similar particle size, viscosity, and stability to commercial bisphenol a glycidyl ether epoxy emulsion (PZ). DSC results showed that the varnish film based on PEE had a higher glass transition temperature and initial thermal decomposition temperature compared with PZ cured by the same curing agent. Waterborne thermal insulation coating with PEE and PZ as binders and hollow glass microspheres (HGMs) as thermal insulation fillers were studied. The results indicated that the thermal conductivity of the coating decreased with an increase in HGMs content. Specifically, the thermal conductivity of the PEE coating containing 20 wt% HGMs is as low as 0.093 W/(m·K). It reduces the exterior temperature of the hot tank from approximately 200 °C to approximately 106 °C. Furthermore, the HGMs/PEE waterborne thermal insulation coating exhibits good thermal stability and flame retardance.

Reflective and heat insulation coatings enabled by TiO2@polyacrylate hybrid latex and bionic potassium titanate whisker for passive cooling

AbstractReflective and heat insulation coatings are new types of materials coated on constructions. However, their applications are limited by the undesired insulation effect resulting from the poor reflectance in the solar spectrum of the coating film. In this study, a reflective and heat insulation coating is successfully developed by combining titanium dioxide@polyacrylate (TiO2@PA) hybrid latex with a core‐shell structure and an insulation filler of bionic potassium titanate whisker (PTW). The TiO2 nanoparticles are distributed homogeneously in the polymer matrix due to the polymer‐encapsulated TiO2 structure, achieving a total solar reflectance (TSR) of 71.0%. Notably, the as‐prepared reflective and heat insulation coating films exhibit excellent TSR of 86.0% enabled by TiO2@PA latex and PTW, attributed to the synergistic combination of TiO2@PA and PTW with high TSR. The temperature inside the room coated with the reflective and insulation coatings on the roof is 16.6°C lower than that of the uncoated one, while 20 wt% PTW is introduced into the coating formulation. The resulting reflective and heat insulation coatings are attractive for the fields of passive cooling such as building energy conservation, automotive body, and so on, endowing people with a comfortable life, especially in the hot summer.

Preparation of composites with integrated thermal insulation and mechanical properties using mixture design and multi-objective optimization methods

In order to break through the difficulty of balancing the thermal insulation and mechanical properties of composites, a mathematical model of the effects of thermal insulation fillers and reinforcing fibers on the thermal insulation and mechanical properties of composites was proposed using a mixture design approach. The synergistic interaction between fillers was investigated. Multi-objective optimization method was used to optimize the formulation under specific conditions. The optimized composites were prepared with a low thermal conductivity of 0.108 W m−1 K−1, and the compressive and flexural strengths reached 111.098 MPa and 26.985 MPa, respectively. Meanwhile, the tests showed that the composites had excellent thermal insulation effect and thermal stability.

Polyphosphazene with excellent superhydrophobicity, electrical insulation, flame-retardancy, and mechanical durability for composite insulators

Composite insulator is an important component of the power system which has high requirements for insulating properties, hydrophobicity, long-term reliability, and safety. Aiming to improve the comprehensive performance of composite insulators, we propose a novel composite based on polyphosphazene matrix and inorganic fillers including h-BN, SiO2 and aramid pulp (AF-p). By the synergistic effect of the optimized chemical structure of polyphosphazene and modification by multi-scale hydrophobic electrical insulation fillers, the poly(difluoroalkoxy)phosphazenes (PDFP) composite presents enhanced hydrophobicity with the static water contact angle (WCA) up to 154° and rolling angle (RA) as low as 8°. Benefiting from the multiscale roughness constructed by multi-fillers, the PDFP composite exhibits superior mechanical durability. The contact angle of the sample still exceeds 150° after abrasion by sandpaper (800#) for 1000 cm. Meanwhile, with the addition of hybrid insulation fillers, the Weibull breakdown strength of PDFP/30h-BN/10SiO2-200/6AF-p is improved by 76 % compared to PDFP. Besides, the unique elemental composition of PDFP endows the PDFP composite with excellent flame retardancy with a 55 % limiting oxygen index and V-0 of the UL-94 grade, which guarantees safety for insulator applications. The results confirm the great potential of polyphosphazene for composite insulators.

Continuous Rapid Fabrication of Ceramic Fiber Sponge Aerogels with High Thermomechanical Properties via a Green and Low-Cost Electrospinning Technique.

Ceramic aerogel is an appealing fireproof and heat-insulation material, but synchronously improving its mechanical and thermal properties is a challenge. Moreover, the expensive discontinuous processing techniques inhibit the large-scale fabrication of ceramic aerogels. Here, we propose a water-based electrospinning method, based on the hydrolysis and condensation reactions of ceramic precursor salts themselves, for the continuous and rapid (0.025 m3/min) fabrication of ceramic fiber sponge aerogels with dual micronano fiber networks, which show synchronous enhanced fireproof, thermal insulation, and resilience performance. The elastic ceramic micro/nano fiber sponge aerogels contain robust silica-based microfibers as a firm skeleton and alumina-based nanofibers as elastic thermal insulation filler. The sponges have a high porosity of >99.8%, a low mass density (6.21 mg/cm3), a small thermal conductivity (0.022 W/m·K), and a large compression strength (21.15 kPa at 80% strain). The ceramic fiber sponges can effectively prevent the propagation of thermal runaway when a lithium battery experiences catastrophic thermal shock (>1000 °C) in the power battery packs. The proposed strategy is feasible for low-cost and rapid synthesizing ceramic aerogels toward effective battery thermal management.

Vacuum Pump-Down of the Annular Insulation Space for Large Field-Erected Liquid Hydrogen Storage Tanks

Insulation systems are critical to liquid hydrogen storage tank performance. Tanks in the capacity range of 100 to 1,000 m3 are typically shop built and designed with high-vacuum (HV) multi-layer insulation (MLI), whereas storage vessels larger than 1,000 m3 are typically field-erected and supplied with bulk fill insulation working at moderate vacuum (MV) levels (1-100 millitorr). For large, field-erected vessels, two types of bulk fill insulation typically used: perlite and hollow glass microspheres (glass bubbles). Selection of either material is driven by a tradeoff between CAPEX and OPEX, such as the material and construction cost versus operating thermal performance and maintenance. In either case, the vacuum level needed to achieve optimum performance is likely to drive the field testing and commissioning portion of the construction schedule. A primary goal of this paper is to present practical experience and data for warm vacuum pressure (WVP) and cold vacuum pressure (CVP) levels. Recommended WVP levels needed prior to cooldown consider both perlite powder and glass bubbles. Pumping time expected to achieve target vacuum levels, considering a variety of factors, is also discussed. Recommendations for a standard practice in vacuum-insulated tank commissioning are based on historical NASA data, and those collected during recent projects.

The influence of sodium silicate water glass content on the structure and properties of silicate thermal insulation coating

Thermal insulation slurry was fabricated using sodium silicate water glass (SSWG) as the film-forming material and hollow glass microspheres (HGM) as thermal insulation fillers. The thermal insulation slurry was coated on 316L stainless steel to fabricate a silicate thermal insulation coating. The results show that SiO2 phase is formed by SSWG in the thermal insulation coating after sintering at 680 ℃. Through polymerization and dehydration reactions between Si-OH groups, the Si-O three-dimensional network structure develops at 680 ℃. The optimal value of SSWG to aggregate mass ratios is 2.00. Under this condition, the silicate thermal insulation coating exhibitssmoothsurface, continuous and dense microstructure, high Shore hardness of50.1 HSD,remarkablethermal insulation efficiency of21 %at260 ℃, andexcellentresistance to drop and thermal shock tests without anynoticeablecracks or detachment.

Performance Evaluation of a Multifunctional Road Marking Coating for Tunnels Based on Nano SiO2 and TiO2 Modifications

Multifunctional road marking coatings with the functions of high-temperature stability, degradation of exhaust gas, and self-cleaning are of great significance for the safe operation and environmental protection of tunnels. This article uses active acrylic resin and an organosilicon hydrophobic agent as the base material, selects expanded vermiculite and glass microspheres as insulation fillers, and uses ammonium polyphosphate, pentaerythritol, melamine, and aluminum hydroxide as high-thermal-stability systems to prepare a two-component road marking coating base material. Then, nano SiO2 and modified nano TiO2 are added as modifiers to prepare a multifunctional road marking coating for tunnels. The physical and chemical properties of multifunctional road marking coatings are evaluating based on laboratory tests including thermogravimetry and derivative thermogravimetry, differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy, exhaust degradation, and contact angle tests. The results indicate that the developed multifunctional road marking coating effectively reduces the thermal conductivity of the carbon layer through physical changes in the flame retardant system and the heat resistance formed by the high breaking bond energy of nano SiO2 during the combustion process. It forms a ceramic-like structure of titanium pyrophosphate with nano TiO2 that is beneficial for improving flame retardancy without generating harmful volatile gases and has good flame retardant properties. N–V co-doping reduces the bandgap of TiO2, broadens the absorption range of visible light by nano TiO2, improves the catalytic efficiency of visible light, and achieves the degradation efficiency of the four harmful components NOx, HC, CO, and CO2 in automotive exhaust by 23.4%, 8.3%, 2.5%, and 2.9%, respectively. The solid–liquid phase separation in the multifunctional road marking coating in the tunnel causes the formation and accumulation of nano SiO2 and TiO2 particles on the coating surface, resulting in a microstructure similar to the “micro–nano micro-convex” on the lotus leaf surface and making a water droplet contact angle of 134.2° on the coating surface.

Hollow glass microspheres embedded in porous network of chitosan aerogel used for thermal insulation and flame retardant materials

In recent years, biopolymer aerogels as thermal insulation materials have received widespread attention due to natural abundance, cost-efficiency, and environment-friendly. However, the flammability and low strength hinder its practical application. Hollow glass microspheres (HGMs) as an inorganic thermal insulation filler have been filled in biopolymer aerogels to improve flame retardancy. However, the structure formed by HGMs embedded porous network of biopolymer aerogel has rarely been investigated, which not only reduce thermal conductivity through high porosity, but also adjust the filling volume of HGMs and achieve uniform distribution through chemical cross-linking. Herein, a biopolymer aerogel composite was assembled by chitosan aerogel (CSA) and different volume of HGMs by chemical cross-linking, freeze-drying, and silylation modification processes. When the filling volume fraction of HGMs reached 40 %, a skeleton structure was initially formed. The composites with HGMs volume of 40 %–60 % exhibited low density, high porosity, low thermal conductivity, good mechanical property, and excellent flame retardancy. According to GB 8624-2012 standard for classification, the composite with 60 % HGMs achieved class A1 non-combustible.

Investigation of consolidation/thermal insulation property and mechanism of casing cement in the heat-insulating section of geothermal production well

ABSTRACT In the process of geothermal exploitation, heat loss often occurs in the heat-insulating section of the production well, resulting in a decrease in heat extraction efficiency. However, there have been few studies on thermal insulation cement for geothermal well, lacking complete engineering application properties evaluation. In view of this, a new type of thermal insulation composite cement was successfully developed by incorporating thermal insulation filler (Hollow glass beads, HGB), heat stabilizing material (SiO2) and additives. The engineering application properties were evaluated using standardized methods, and the results demonstrated excellent rheology and stability of the cement slurry. The 14d compressive strength of the cement stone reached 21.24 MPa, and the thermal conductivity remained stable at 0.1535 W/(m·K). Finally, the consolidation/thermal insulation mechanism of the material was investigated. Analysis showed that the secondary hydration of SiO2 could generate more C-S-H, and additives could regulate the hydration reaction of slurry. The excellent thermal insulation property of material was derived from interface lattice scattering, the low thermal conductivity of HGB, and the gas heat-conduction recession within HGB. The study results provide a new idea to solve the problem of heat loss of geothermal production well from the perspective of material development.

Measured Impact of Material Settlement in a Timber-Frame Wall with Loose Fill Insulation

Loose-fill thermal insulations in timber-frame structures are designed to provide efficient thermal protection with the ability to fill intricate details. In a previous study, we detected several air cavities formed in timber-framed wall samples filled with loose-fill mineral fiber insulation. This discovery led us to retrofit the walls by adding appropriate insulation, thus enabling us to evaluate the importance of proper amendment. This paper focuses on a wall fragment with an 80 mm high air gap at the top and a 30 mm high cavity in the middle of the wall height. The following paper compares data collected before the discovery and after the replenishment (refill of air gaps with additional insulation), evaluating potential thermal performance improvement. We were able to quantify the impact of these defects on the external wall exposed to realistic conditions. Based on temperature and relative humidity measurements, the results show significant advancement in the middle of wall thickness with an 8 °C and 45% difference. The results show that although this defect did not directly affect the energy balance of the building, it significantly increases the risk of mold growth due to thermal bridging.

Flexible Electrospun strawberry-like structure SiO2 aerogel nanofibers for thermal insulation

Herein, a novel flexible SiO2 aerogel composite nanofiber membrane with strawberry-like structure and excellent thermal insulation properties, in which SiO2 aerogel particles act as thermal insulation filler, was prepared by electrospinning technology. With the addition of nano-pore structure SiO2 aerogel particles, the heat transfer path of the fibers inside the membrane became discontinuous, endowing the as-prepared membrane an ultra-low thermal conductivity of 30.3 mW/(m⋅K) and large surface area of 240 m2/g. Moreover, the nanofibers membrane also possesses the combined merits of excellent fire resistance, high-temperature stability, and temperature-invariant flexibility, rendering it a promising in the application of insulation and gas adsorption. The successful preparation of this flexible nanofiber membrane paves a new way to design materials with excellent thermal insulation and adsorption properties.

Research on Cast-in-situ Pumice Concrete Filler Wall Construction Technology

Since the existing masonry filler wall has the shortages such as: the heavy self-weight, low masonry mortar bond. we invented cast-in-situ insulation filler wall by using pumice concrete which is peculiar in Zhangjiakou region. This paper focused on construction technology for filler wall and problems that should be paid attention to on the construction. Cast-in-situ pumice concrete frame filler wall has the advantages of good entirety, simple construction, fast construction speed, it can reduce labor cost and improve the quality of engineering, thus achieves good technical and economic efficiency.

Research on Interface Modification and Thermal Insulation/Anticorrosive Properties of Vacuum Ceramic Bead Coating

The thermal insulation effect of the coating was closely related to the content of the thermal insulation filler, but too much filler would cause interfacial compatibility problems of various substances in the coating, micro-defects in the coating, and affect the anti–corrosion performance of the coating. Therefore, solving the interface problem was the key to preparing a coating with heat insulation and anticorrosion functions. In this study, organic–inorganic hybrid polymer was used to modify the surface of vacuum ceramic microbeads, and epoxy–silicone resin was used as the film–forming material to prepare a heat-insulating and anticorrosive coating that can withstand 200 °C. The SEM morphology showed that the interface compatibility of the vacuum ceramic beads modified by the organic–inorganic hybrid agent and the film-forming material were improved, the dispersibility was significantly improved, and the beads were tightly arranged; the thermal conductivity of the coating reached 0.1587 W/(m·K), which decreased by 50% after adding 20% ceramic beads, ANSYS finite element simulation showed that the coating has good thermal insulation performance; after the coating underwent a thermal aging test at 200 °C for 600 h, the microstructure was dense, and the low-frequency impedance modulus was still around 109 Ω·cm2. There was no obvious defect in the microstructure after the alternating cold and heat test for 600 h; the low-frequency impedance modulus was still above 108 Ω·cm2, and the low-frequency impedance modulus of the coating was 1010 Ω·cm2 after the 130d immersion test, indicating that the coating had good heat resistance and anti-corrosion performance.

Novel Solvent-Latex Mixing: Thermal Insulation Performance of Silica Aerogel/Natural Rubber Composite.

In this work, the novel natural rubber latex (NRL) mixing was approached. The mixing process was carried out by using n-hexane as the dispersed phase of silica aerogel which acted as thermal insulation filler prior to NRL mixing. The silica aerogel/NR composites were prepared with different silica aerogel contents of 20, 40, 60, 80, and 100 parts per hundred rubber (phr). The morphology of the 40 phr composite showed the NR macropore formation with silica aerogel intercalated layers. The optimal content of silica aerogels and n-hexane were the key to obtaining the NR macropore. The thermal insulation performance of silica aerogel/NR composites was investigated because of their porous structures. The thermal conductivity of the composites were lower than that of the neat NR sheet and decreased from 0.081 to 0.055 W m−1·K−1 with increasing silica aerogel content. The lower densities of the composites than that of the NR sheet were revealed noticeably. In addition, the silica aerogel/NR composites exhibited a higher heat retardant ability than that of the NR sheet, and the comparable glass transition temperatures (Tg) of the composites and the neat NR indicated the maintained flexibility at ambient temperature or higher, which can benefit various temperature applications. The overall results demonstrated that the silica aerogel/NR composites from the novel NRL mixing preparation could be a promising technique to develop the porous materials and be utilised as thermal insulation products and building constructions.

Assessment of Void Insulation Panels for innovative thermal insulation of apartments in heritage buildings

Void Insulation Panels (VIP) or Vacuum Insulation Panels are a technology that allows a sufficient thermal resistance for walls, floor or roof with a small thickness. The solution is more expensive than traditional ones but in historic centres of large cities with high value apartments, it could be an innovative solution for improving thermal comfort and reducing energy consumption. Different configurations of insulation with VIP in historical buildings in Bordeaux and Paris, two of the most expensive cities in France, are studied. The results show a great interest but moisture risk, especially in Bordeaux where the climate is wet due to the Atlantic coast. Special care for the thermal bridges and for the plaster hourdis between the beams of the floor are needed and the vapour barrier has to be continuous on top of the VIP complex plus insulation filler.

Solid-state synthesis and characterization of two-dimensional hexagonal BCN nanosheet using a free template method

The ternary composition of boron carbon nitride (BCN) nanosheet was synthesized through a solid-state reaction in a nitrogen atmosphere for 1 h at 900 °C. The precursors used, which included urea, boric acid and d-glucose, were inexpensive, and the method used for synthesis was simple, low cost, and free template method. The synthesized porous powder was characterized by methods such as X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Fourier transform infrared (FTIR), Field emission scanning electron microscopy (FESEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Graphene-like BxCyNz with BC0.41N1.03 composition had a specific surface area of 353 m2/g. The average diameter of the pores using the Barrett, Joyner, and Halenda (BJH) model was 20.07 nm, which showed that the synthesized powder was mesoporous. XRD test showed the formation of BCN structure without the presence of any impurities, and its crystal size was 9.63 nm. The presence of bonds BN, CN, CN, and BC in the FTIR spectrum showed that the material synthesized by the solid-state process was BCN. According to FESEM results, the sample showed a two-dimensional sheet-like structure with a crumpled morphology. Raman Spectrum showed the thickness of the nanosheets was 88.4 nm. XPS results showed that the final product contained all the CC, BC, BN, and CN bonds. The molar ratio of B:C:N was 1:0.41:1.03, respectively, which indicated that the chemical formula was BC0.41N1.03. As a result, the method used in this research can increase the potential of using this porous powder with a high specific surface area as a lubricant, thermal insulation filler, anti-corrosion filler in paint coatings, adsorption of various gas and hydrocarbon molecules, as well as the application of drug-delivery nanocarriers.

Enhanced Thermal Insulation of the Hollow Glass Microsphere/Glass Fiber Fabric Textile Composite Material.

Glass fiber fabrics/hollow glass microspheres (HGM)–waterborne polyurethane (WPU) textile composites were prepared using glass fiber, WPU, and HGM as skeleton material, binder, and insulation filler, respectively, to study the effect of HGM on the thermal insulation performance of glass fiber fabrics. Scanning electron microscopy, Instron 3367 tensile test instrument, thermal constant analysis, and infrared thermal imaging were used to determine the cross-sectional morphology, mechanical property, thermal conductivity, and thermal insulation property, respectively, of the developed materials. The results show that the addition of HGM mixed in WPU significantly enhanced thermal insulation performance of the textile composite with the reduction of thermal conductivity of 45.2% when the volume ratio of HGM to WPU is 0.8 compared with that of material without HGM. The composite can achieve the thermal insulation effect with a temperature difference of 17.74 °C at the temperature field of 70 °C. Meanwhile, the tensile strength of the composite is improved from 14.16 to 22.14 MPa. With these results, it is confirmed that designing hollow glass microspheres (HGM) is an effective way to develop and enhance the high performance of insulation materials with an obvious lightweight of the bulk density reaching about 50%.

A simple, low cost, and template-free method for synthesis of boron nitride using different precursors

In this research, hexagonal boron nitride (h-BN) was synthesized using a simple, low cost, and template-free method with urea-boric acid (UB), melamine-boric acid (MB), and melamine-urea and boric acid (MUB) precursors, followed by the pyrolysis and heat treatment in a nitrogen atmosphere at 1050 °C. Samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Raman Spectroscopy, Fourier transform IR (FT-IR), and Brunauer–Emmett–Teller (BET) techniques. The specific surface areas obtained for h-BN synthesized by UB, MB, and MUB precursors were 87.43, 573.07, and 1005.7 m2/g, respectively. The average diameters of the pores using the Barrett, Joyner, and Halenda (BJH) model were 37.78, 3.68, and 2.13 nm, respectively. A thermogravimetric analysis showed a wider range of decomposition temperatures after using three precursors for synthesizing h-BN. Crumpled, whisker, and flower-like morphologies for UB, MB, and MUB precursors were respectively found using FESEM investigations. The formation of h-BN within the MUB sample was confirmed using the XPS analysis with measured peaks of 398.5 and 190.6 eV belonging to N 1s and B 1s, respectively. Raman spectroscopy revealed a high-intensity peak in 1366 cm−1 related to the E2g mode for h-BN synthesized with MUB. Therefore, the results demonstrate that the employed method can increase the potential of using the h-BN porous powder with a high specific surface area as a lubricant, thermal insulation filler, anti-corrosion filler in paint coatings, adsorption of various gas and hydrocarbon molecules as well as its application in drug-delivery nanocarriers.

DC inline plane test of silicone rubber samples with different filler for high-voltage insulation

<span>This paper is about preparation of silicone rubber (SiR) samples with different filler for high-voltage insulation purpose. The fillers used were silica from waste glass, calcium carbonate from cockle shell, silica/calcium carbonate and wollastonite. All the fillers were crushed into powder and undergo internal mixer and hot press as a material preparation. It was expected that the combination of filler with silicone rubber would give better result when experiencing ageing process. The direct current (DC) inclined plane test was used to investigate the tracking and erosion on silicone rubber composites. The tracking length was observed between the top and bottom electrode. Comparison would then be made between the silicone rubbers with different fillers based on the result obtained from the experiment.</span>