Alumina Trihydrate Research Articles

Improving insulation performance with woven flax/PP hybrid composite reinforced by synthetic alumina and aluminum trihydrate

Improving insulation performance with woven flax/PP hybrid composite reinforced by synthetic alumina and aluminum trihydrate

Fire-Resistant and Thermal Stability Properties of Fluorosilicone Adhesives by Incorporation of Surface-Modified Aluminum Trihydrate.

Fluorosilicone was combined with aluminum trihydrate (ATH) to induce synergistic flame-retardant and thermal-resistant properties. The surface of ATH was modified with four different silane coupling agents. The flammability and mechanical properties of the fluorosilicone/ATH composites were assessed using an UL94 vertical test and a die shear strength test. The change in shear strength was investigated under aging for 1000 h at -55 °C and 150 °C. Pure fluorosilicone had inherent fire resistance and thus achieved a V-0 rating even at 20 wt.% ATH loading. Upon addition of ATH treated with 3-glycidoxypropyl trimethoxysilane, the composites exhibited the highest shear strength of 3.9 MPa at 23 °C because of the additional crosslinking reaction of fluorosilicone resin with the epoxide functional group of the coupling agent. Regardless of the types of coupling agents, the composites exhibited similar flame retardancy at the same ATH content, with a slight reduction in shear strength at 180 °C and 250 °C. The shear strength of the adhesives gradually decreased with aging time at -55 °C, but increased noticeably from 3.9 MPa to 11.5 MPa when aged at 150 °C due to the occurrence of the additional crosslinking reaction of fluorosilicone.

Aging assessment of silicone rubber materials under corona discharge accompanied by humidity and UV radiation

Abstract High voltage (HV) outdoor insulators are subjected to both electrical and environmental stresses, which may lead to their failure. Among the causes, corona discharge, humidity and UV radiation are considered to be the most damaging factors. Efforts are therefore underway to investigate new materials for improving the performance of insulating systems. In this research work, silicone-based room temperature vulcanized samples filled with alumina trihydrate (ATH), silicon dioxide and magnesium hydroxide (MH) were prepared and exposed to AC corona discharge for a duration of 110 h. The electric discharge was also accompanied by UV radiation and two different humidity levels. Following aging of the test samples, diagnosis was conducted to assess their integrity. Measurements based on determining the static contact angle demonstrated the loss of hydrophobicity of all the materials, while hydrophobicity recovery phenomena revealed that ATH-doped materials demonstrated a comparatively higher increase in the contact angle than in samples filled with silicone dioxide (silica) and MH. Scanning electron microscopy analysis revealed deep cracks and block-like structures on their surfaces. Similarly, energy-dispersive X-ray analysis indicated the signs of surface oxidation of the aged samples. However, the data of elemental composition exhibited the loss of filler contents as well as that of carbon from the base matrix. The overall assessment showed that resistance to suppress aging is influenced by both the filler type and its concentration in the investigated composites. The ATH-filled composites exhibited outstanding performance when exposed to the rigors of corona discharge and other environmental stresses. This research contributes to materials science and HV engineering by addressing the development of composites for enhanced insulator performance, with future aspects lying in the utilization of nano-composites for advanced functionality and durability.

An ab initio molecular dynamics investigation of the behaviour of amorphous substances in anodic aluminium oxide under electric field

In order to elucidate the diffusion behaviour of ions in alumina during the anodic alumina process, the effects of electric field strength, hydration content, and electrolyte on amorphous alumina and hydrated alumina were studied using ab initio molecular dynamics. The results show that the diffusion rate of ions in alumina increases with the increase in electric field strength, but there is an extreme value. The maximum diffusion rate of Al ions in alumina monohydrate is 21.8 μm2/ms/V, while in alumina trihydrate, it is 16.7 μm2/ms/V. The ionic diffusion rate of hydrated alumina is one to two orders of magnitude larger than that of anhydrous amorphous alumina due to the effect of the drag of H ions, which reduces the migration activation energy. Electrolytes also affect the diffusion rate of alumina through the action of H ions. The increase in H ions will not only enhance the diffusion rate of hydrated alumina but also render the hydrous compound more vulnerable to breakdown.

Study on detecting main ingredients of silicone rubber based on terahertz spectrum

AbstractThe authors investigated the ingredient detection technique of silicone rubber based on the Terahertz spectrum. For this purpose, 18 diverse high‐temperature vulcanised silicone rubber (HTVSR) formulations were customised, 8 of which are used as calibration set while the rest 10 as prediction set. Based on the Beer‐Lambert Law, the partial‐least‐square (PLS) regression model and the least‐squares support‐vector machines (LS‐SVM) regression model were used to yield the relationships between the absorption spectrums and the content percentages of polydimethylsiloxane (PDMS), alumina trihydrate (ATH), and silica in HTVSR. The results showed that for the formulations tested, the prediction accuracy of all three main ingredients by the PLS regression model could be improved by changing the spectrum range from 0.2–4 to 0.5–2 THz. If the data were pre‐processed by the Savitzky–Golay smoothing method or multiplicative scatter correction method, the prediction accuracy of PDMS could be further enhanced. However, this would lead to a slight decrease in the prediction accuracy of ATH. For the LS‐SVM regression model, the radial basis function (RBF) kernel and the linear kernel were studied. It was found that the prediction accuracy of both kernels was better than that of the PLS regression model. With the LS‐SVM regression model using the RBF kernel, the correlated coefficients of PDMS and ATH in the prediction set could be up to 0.9915 and 0.9742, respectively.

Surface Structural Changes in Silicone Rubber Due to Electrical Tracking.

There is a growing interest in the use of silicone composite insulators for electrical power transmission and distribution applications. However, such materials are susceptible to degradation as they are exposed to electrical and environmental stresses during operating conditions. Therefore, it is crucial to gain a thorough understanding of the degradation mechanism through changes in the material structure that may provide insight into potential failures in the electrical grid. Attenuated total reflection Fourier transform infrared spectroscopy and two-dimensional correlation spectroscopy (2D-COS) were used along with contact angle measurements to characterize changes in silicone rubber samples from actual insulators subjected to tracking wheel testing. The results showed a decrease in absorbance of different infrared bands representing different functional groups, such as Si-O-Si, methyl functional groups, and both Al-O and hydroxyl groups of alumina trihydrate as a function of the number of tracking cycles. The sequence of changes in the functional groups was determined by 2D-COS as Al-O and OH followed by Si-O-Si polymer backbone modes, followed by polymer methyl side chains. An enhancement in the average contact angle with the number of tracking cycles revealed a concomitant increase in surface roughness with electrical tracking.

Improving the tracking and erosion resistance of silicone rubber using Fe2O3 and platinum catalyst

AbstractIn typical HTV silicone rubber for composite insulators subjected to a 4.5 kV inclined plane (IP) test, alumina trihydrate loading exceeds 40 wt%, which limits the rubber content and weakens the antiaging properties. This study compares two methods for enhancing tracking and erosion resistance while reducing ATH content to meet IP test requirements. Increasing Fe2O3 content from 1.5 wt% to 3 wt% promotes the formation of mullite. The formed ceramic layer isolates heat and oxygen and hence facilitates the specimen to pass the IP tests with less content of ATH. By contrast, Pt/NS system cannot suppress the tracking efficiently by forming the SiOC ceramics at high ATH loading. The decomposition of ATH will generate water vapor and lead to holes in the surface. Both moisture and oxygen absorbed have a detrimental effect on the suppression mechanism of the Pt/NS system. Consequently, it is recommended that the content of Fe2O3 can be increased slightly to lower the ATH content in the traditional HTV SiR formula used for the composite insulator. Besides, when the content of ATH is relatively high, the use of the Pt/NS system is not recommended.

Investigation of flame retardancy and physical-mechanical properties of mineral-based polyethylene composites

Mineral-based flame retardants are widely used worldwide as they are both effective and inexpensive solutions. Especially alumina trihydrate (ATH) and magnesium hydroxide (MDH) are the first mineral additives that come to mind industrially due to their environmental friendliness and easy availability. In this study, the effectiveness of huntite-hydromagnesite mineral, which is not as widely used as the other two minerals, and its differences from its counterparts were investigated. For this purpose, composites with polyethylene carrier were produced by extruder method using binders at various ratios, and various physical, mechanical, and combustion properties of these samples were investigated. According to the data obtained, the samples containing huntite-hydromagnesite showed UL94 V0 class flame retardant performance with 5% less filler than their counterparts. The same samples showed superior mechanical properties in tensile strength between 23.4% and 70.8% and elongation at break between 60.7% and 73.1%.

Novel organic-inorganic hybrid towards enhancement of flame retardancy, suppression of volatile organic compounds and toxic smokes for asphalt

The enhancement of flame retardancy, the suppression of volatile organic compounds (VOCs) and carcinogenic smokes at elevated temperature are urgent for the widely application of asphalt. In present work, an organic-inorganic hybrid flame retardant (ATH@SA@Fe3+) was designed via simple two-step reactions, including in-situ growth of sodium alginate (SA) on the surface of alumina trihydrate (ATH) and a crosslinking of iron ion (Fe3+) on ATH@SA. The three-dimensional network crosslinking structure of ATH@SA@Fe3+ effectively hindered and retarded the thermal decomposition progress of asphalt, producing fewer hydrocarbon derivatives, reducing VOCs constituents and their release amounts. For the Asphalt/10ATH@SA@Fe3+ composites, the total heat release (THR), the total smoke production (TSP) and the peak smoke production rate (pSPR) was reduced by 28.2%, 35.2% and 28.0% respectively, indicating a high flame-retarding and smoke suppression efficiency via the formation of expanded, impact and continuous carbon layer. Meanwhile, the network crosslinking structure could arrest the molecular motion and lead to the thermal stability, elasticity rutting resistance enhancement of asphalt materials. In perspective, the research results provided a scientific basis for the management of flame-retardant materials for asphalt pavement and the formulation of emission reduction strategies.

Investigation of MQ Resin Enhanced Material Used for On-Site Insulating Bare Conductors

Bare conductors were widely used in the early power distribution system. However, without an insulation layer, it can pose unexpected safety issues. To solve this problem in an effective and economical way, on-site insulating the bare conductors is highly desirable. Unlike the traditional silicone insulating material loaded with high content of inorganic fillers, silicone material reinforced by MQ resin has suitable viscosity to satisfy the requirement of on-site insulating. Benefiting from MQ resin, the formula proposed has excellent mechanical, electrical, and aging properties. It can be observed that the presence of MQ resin is beneficial for mechanical properties because of its core-shell double-layer spherical structure. Furthermore, owing to this special structure, it improves the dispersion of alumina trihydrate (ATH) and enhances the electrical properties of the composites. Although the presence of MQ resin may lead to a slightly negative effect on the thermal property, it can greatly improve flame retardancy by the compounding of a novel Pt catalyst system and ATH. As for the hydrothermal aging performance, the elongation at break of the sample is greatly improved by the addition of MQ resin. Meanwhile, a feasible measure is also proposed to solve the lightning-induced breakage problem of insulated conductors. The results of this paper are helpful for the investigation and application of on-site insulating material for bare conductors.

Effects of Additives on the Mechanical and Fire Resistance Properties of Pultruded Composites.

Under high temperatures, fiber-reinforced polymers are destroyed, releasing heat, smoke, and harmful volatile substances. Therefore, composite structural elements must have sufficient fire resistance to meet the requirements established by building codes and regulations. Fire resistance of composite materials can be improved by using mineral fillers as flame-retardant additives in resin compositions. This article analyzes the effect of fire-retardant additives on mechanical properties and fire behavior of pultruded composite profiles. Five resin mixtures based on vinyl ester epoxy and on brominated vinyl ester epoxy modified with alumina trihydrate and triphenyl phosphate were prepared for pultrusion of strip profiles of 150 mm × 3.5 mm. A series of tests have been conducted to determine mechanical properties (tensile, flexural, compression, and interlaminar shear) and fire behavior (ignitability, flammability, combustibility, toxicity, smoke generation, and flame spread) of composites. It was found that additives impair mechanical properties of materials, as they the take place of reinforcing fibers and reduce the volume fraction of reinforcing fibers. Profiles based on non-brominated vinyl ester epoxy have higher tensile, compressive, and flexural properties than those based on brominated vinyl ester epoxy by 7%, 30%, and 36%, respectively. Profiles based on non-brominated epoxy resin emit less smoke compared to those based on brominated epoxy resin. Brominated epoxy-based profiles have a flue gas temperature which is seven times lower compared to those based on the non-brominated epoxy. Mineral fillers retard the spread of flame over the composite material surface by as much as 4 times and reduce smoke generation by 30%.

Dynamic mechanical analysis for assessment of carbon fillers in glass fiber epoxy composites

AbstractThe effect of incorporation of micron sized aluminum trihydrate, multi‐walled carbon nanotubes, and graphene nano platelets into glass fiber reinforced epoxy matrix is investigated using dynamic mechanical analysis. The objective of the investigation was to develop polymer central core of high temperature low sag transmission conductor. The effect of individual and hybrid carbon fillers on the viscoelastic properties of the epoxy composites is investigated and discussed. The storage modulus of the glass reinforced epoxy increases by 20% at room temperature due to incorporation of carbon nanofillers. In glass transition region, the increase is higher between 40% and 60% and it varies up to 90% in the rubbery region. Key attributes of carbon filler addition are limited enhancement of storage modulus at room temperature, higher enhancement over glassy, glass transition, and rubbery regions. The carbon fillers extend the temperature range of the glassy region. The cross‐link density, filler efficiency, and degree of entanglement of fibers are estimated to understand the implications of the carbon fillers on the viscoelastic properties. The loss modulus peak of glass epoxy composite increases from 2800 to 3900 MPa with carbon fillers and the increase in glass transition temperature is 47°C. Incorporation of carbon fillers leads to increase of damping factor peak from 0.2 to 0.28. Cole–Cole plots have established the inherent heterogeneity of epoxy systems due to the presence of carbon fillers. Prediction models for storage modulus and damping factor have been proposed to highlight the influence of geometry and size of carbon filler.

Comparative evaluation of flame retardant performance in rigid polyurethane foams: TCPP, TDCP MP, and ATH as promising additives

The high flammability of rigid polyurethane foams has limited emerging applications (sensors, space travel, and others). Enhancing the mechanical, thermal, and flame-retardant properties of RPUF is an important theme in flame retardant science and technology. This study compares the fire performance of polyurethane foams (PUF) containing four different flame retardants: tris (2-chloro-1-methylethyl) phosphate (TCPP), tris (1,3-dichloro-2-propyl) phosphate (TDCP), melamine phosphate (MP), and aluminum trihydrate (ATH). The flame retardants were added at 10% and 20% rates, and the resulting PUFs were characterized for their morphological, mechanical, and thermal properties using various analytical techniques. The fire performance of the PUFs was evaluated using ISO 11925-2 and UL-94 tests. The results demonstrated that all four flame retardants enhanced the fire performance of the PUFs, with TCPP and TDCP exhibiting the most favorable outcomes. The study highlights the importance of using flame retardants in PUFs to improve their fire performance in various applications.

Characteristics stability assessment of silica/alumina trihydrate based silicone elastomer composites subjected to long-term weathering under bipolar direct current for industrial electrical insulation

Room temperature vulcanized silicone rubber (RTV-SiR) coatings co-filled with silica (SiO2) and alumina trihydrate (ATH) fillers were subjected to long-term accelerated weathering under bipolar direct current (DC). Experimentations were conducted on fabricated samples of RTV-SiR with 5% nano-silica and RTV-SiR with 20% ATH in a specially designed weathering chamber. An extended aging (10,000 h) was conducted on samples energized equally under both polarity voltages to evaluate the effect of positive and negative voltages on the performance of RTV coating under bipolar high voltage DC. The electrical stability of specimens was assessed using online leakage current measurement, hydrophobicity, volume, and surface resistivity analysis. For mechanical characteristics of test samples hardness shore-A, tensile strength, weight loss, and elongation-at-break were measured and analyzed. Variations in chemical, morphological, and thermal degradation of the samples with aging were assessed using characterization tools like Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Thermal Gravimetric Analyzer (TGA), respectively. Findings explicated that samples with nano SiO2, offer better hydrophobic recovery and hence better leakage current suppression while ATH-filled composites exhibited enhanced thermal stability and better resistance to mechanical alterations. Furthermore, the comparative analysis of voltage polarity elucidates that the impact of positive DC was more profound in aging.

Stoichiometry composition of nanofiller SiO2 and ATH to improve properties of silicone elastomer for outdoor high voltage insulators

Silicone elastomer (SE) has several advantages as an insulator material, light weight, dielectric, water repellent (hydrophobic), resistivity, thermal, mechanical and earthquake resistant properties compared to porcelain/ceramic and glass. However, the installation of outdoor insulators with tropical climate temperature exposure above 15 °C, high humidity and uv intensity during the day can degrade its properties which will shorten the life of the insulator. Studies towards improvements to improve the performance of SE insulators under certain conditions can be carried out by using the vulcanization method, formulating the stoichiometry of the filler material. The high-dose filler in SE will increase its mechanical strength and thermal stability, but it can reduce its dielectric properties and the molding process more difficult. Therefore, the purpose of this study was to determine the stoichiometric composition of SiO2 nanofillers and alumina trihydrate (ATH) nanofiller on SE to improve their properties as outdoor high-voltage insulators. Making test-material from silicone rubber resin RTV683 with a mixture of silica powder (20 nm) and ATH powder (20–30 nm). The stoichiometric ratio of resin, filler and hardener compositions varied (80–95: 5–20: 3–7.5). To determine its performance, the specimens were aged by immersing them in 25–50 °C water, artificially polluting and uv radiation the surface to simulate the influence of water diffusion and transfer hydrophobicity to pollution on the surface material. Measurement results before and after treatment indicated that the combination of SiO2 + ATH nanofiller with a composition of 10–15%wt improved the properties of ES such as hydrophobic (average contact angle of water drops > 90°), water absorption < 1.6%, relative permittivity εr < 5, mechanical properties (tensile strength) is 9.57–27.48 N/mm2, surface roughness 0.022–0.153 μm, breakdown voltage 14.8–19.3 kV/cm varies depending on stoichiometric nanofiller, mixing process, curing temperature (50 °C–90 °C) and curing time 2–24 h.

Milling route for the synthesis of nano-aluminium hydroxide for the development of low-density polymer composites

Abstract High loadings of coarse alumina trihydrate (ATH), commercially used in polymers as a fire-retardant filler, cause uneven dispersion and reduce workability and affect physicomechanical properties. Better tensile properties can be achieved by uniform dispersion of nanosize ATH in polymers while maintaining its flame-retardant properties. Consequently, mechanical milling, being a sustainable approach towards the creation of nano-size materials, was carried out to reduce the particle size of coarse ATH in a high-energy planetary ball mill. Investigations were carried out to optimize the milling parameters such as time, rotational speed, milling media size and feed size. During milling, some of the physical properties of ATH change. The energy profile was studied to get the desired product properties. Nano-ATH within the PP matrix reduces the loadings with improvement in tensile and flexural strength. Hence, lightweight PP/nano-ATH composites for suitable use can be developed.

Synergistic Improvement of Flame Retardancy and Mechanical Properties of Epoxy/Benzoxazine/Aluminum Trihydrate Adhesive Composites.

Epoxy resin was mixed with benzoxazine resin and an aluminum trihydrate (ATH) additive to provide flame retardancy and good mechanical properties. The ATH was modified using three different silane coupling agents and then incorporated into a 60/40 epoxy/benzoxazine mixture. The effect of blending compositions and surface modification on the flame-retardant and mechanical properties of the composites was investigated by performing UL94, tensile, and single-lap shear tests. Additional measurements were conducted including thermal stability, storage modulus, and coefficient of thermal expansion (CTE) assessments. The mixtures containing more than 40 wt% benzoxazine revealed a UL94 V-1 rating with high thermal stability and low CTE. Mechanical properties including storage modulus, and tensile and shear strength, also increased in proportion to the benzoxazine content. Upon the addition of ATH to the 60/40 epoxy/benzoxazine mixture, a V-0 rating was achieved at 20 wt% ATH. The pure epoxy passed a V-0 rating by the addition of 50 wt% ATH. The lower mechanical properties at high ATH loading could have been improved by introducing a silane coupling agent to the ATH surface. The composites containing surface-modified ATH with epoxy silane revealed about three times higher tensile strength and one and a half times higher shear strength compared to the untreated ATH. The enhanced compatibility between the surface-modified ATH and the resin was confirmed by observing the fracture surface of the composites.

Efek Sinergis Alumina Trihydrate Dan Melamine Cyanurate Terhadap Ketahanan Api Glass Fiber Reinforced Polymer (GFRP)

&lt;p&gt;&lt;em&gt;Glass Fiber Reinforced Polymer (GFRP) in train interior components must have good fire resistance properties. Therefore, it is necessary to add a flame retardant compound to the GFRP material. In this study, Alumina Trihydrate (ATH) and Melamine Cyanurate (MCA) were mixed into a vinyl ester resin. The method of making GFRP refractory specimens uses the hand lay-up method. GFRP is mixed and tested for fire resistance standard ORE B 106.2. The results obtained after the addition of 25% ATH, a mixture of 25% ATH with 5% MCA, 10% MCA with 25% ATH, and 15% MCA with 25% ATH, 25% ATH in the outer layer, and a mixture of 5% MCA with 25% ATH in the outer layer of the resin weight is able to increase fire resistance. Optimum GFRP fire resistance at the addition of 25% ATH to the weight of the resin in the outer layer. The result of the burned area is 84.84 cm² with a fire extinguishing time of 0.33 seconds after the fire source leaves the specimen. The results show that the mixture of ATH and MCA has a synergistic effect on fire resistance properties, so it becomes a recommendation for interior sidewall panels and ceiling panels on trains according to the ORE B 106.2 standard&lt;/em&gt;&lt;/p&gt;

Thermogravimetric behavior of mesoporous hydrated silica-alumina trihydrate hybrid powder synthesized by sol–gel/doping method

Thermal degradation of mesoporous hydrated silica (MHS), mesoporous silica (MS), and alumina trihydrate (ATH) hybrid systems for flame retardant materials was investigated. The hybrid powders (contains 64 wt% of ATH) were created by doping ATH particles into a silica sol using the typical sol–gel technique with rice husk as a silica precursor. MHS-ATH has 3% more water by weight, three times lower density (0.9 g/cm3), 37 times larger surface area (186.88 m2/g), and enhanced powder flowability as compared to standard ATH. Thermogravimetric analysis (TGA) study reveals that MHS-ATH has higher thermal stability than ATH, with more water released gradually over a wider temperature range, improving the flame retardancy effect. MHS was also compared with its dehydrated form (MS), but TGA studies suggest that MS-ATH has lower thermal stability due to the powder's tendency to absorb moisture.

Thermal stability of polymethacrylic based ELIUM® resin: Effect of comonomers, antioxidants and aluminum trihydrate filler

This paper presents the study of the thermal degradation of methyl methacrylate resin based materials known as ELIUM® resin. Samples under investigation were made from MMA based resin (ELIUM® V1), ELIUM® V1 with a dimethacrylate comonomer (ELIUM® V2), and ELIUM® V2 with a stabilizer package (ELIUM® V3). They were used for trying to discuss the degradation mechanisms. Blocks differing by their thickness made from ELIUM® formulation filled with aluminum TriHydrate used as flame retardant were also investigated in order to better match some industrial materials. Degradation was observed to be mainly driven by unzipping, consistent with the methacrylic nature of ELIUM® resin. Occurrence of oxidation is also discussed depending on materials formulation and temperature. A blend of antioxidants was inefficient for limiting mass loss. At 200 °C, both ATH and ELIUM® degrade, which contributes to overall mass loss. At temperatures below 180 °C, ATH does not seem to induce new degradation mechanisms but would increase oxygen diffusivity. Finally, a first simple kinetic model is proposed to predict mass loss in thick composite blocks aged under air.