Carbon nanotube/graphene oxide‐added CaO‐B2O3‐SiO2 glass/Al2O3 composite as substrate for chip‐type supercapacitor

A CaO‐B₂O₃‐SiO₂ (CBS) glass/40 wt% Al₂O₃ composite sintered at 900°C exhibited a dense microstructure with a low porosity of 0.21%. This composite contained Al₂O₃ and anorthite phases, but pure glass sintered at 900°C has small quantities of wollastonite and diopside phases. This composite was measured to have a high bending strength of 323 MPa and thermal conductivity of 3.75 W/(mK). The thermal conductivity increased when the composite was annealed at 850°C after sintering at 900°C, because of the increase in the amount of the anorthite phase. 0.25 wt% graphene oxide and 0.75 wt% multi‐wall carbon nanotubes were added to the CBS/40 wt% Al₂O₃ composite to further enhance the thermal conductivity and bending strength. The specimen sintered at 900°C and subsequently annealed at 850°C exhibited a large bending strength of 420 MPa and thermal conductivity of 5.51 W/(mK), indicating that it would be a highly effective substrate for a chip‐type supercapacitor.     

Ethanol‐Water‐Derived Sucrose‐Coated‐Al2O3 for Submicrometer AlON Powder Synthesis

Fluffy and homogenous sucrose‐coated‐γ‐Al₂O₃ structured precursor was prepared by drying ethanol‐water sucrose/Al₂O₃ suspension, in which the ethanol content of 85 vol% was optimized. Using the C/Al₂O₃ mixture pyrolyzed from such precursor with 23.2 wt% sucrose, single‐phase AlON powder was synthesized by two‐step carbothermal reduction and nitridation method at 1550°C for 2 h and 1700°C for another 1.5 h. The particle size of the AlON powder was around 0.6–1.0 μm. Compared with those synthesized by the traditional approaches with mechanical C/Al₂O₃, Al/Al₂O₃, or AlN/Al₂O₃ mixtures, the synthesis temperature was reduced about 50°C, and the AlON powder was fine and exhibited good dispersity. Such superiority of this method was attributed to that the pyrolyzed carbon film on Al₂O₃ particle greatly restrained Al₂O₃ coalescence during the thermal treatment.     

Thermal,electrical, and mechanical properties of addition-type liquid silicone rubber co-filled with Al2O3 particles and BN sheets

The addition-type liquid silicone rubber (ALSR) co-filled with spheroidal Al₂O₃ and flaky BN was prepared by the mechanical blending and hot press methods to enhance the thermal, electrical, and mechanical properties for industrial applications. Morphologies of ALSR composites were observed by scanning electron microscopy (SEM). It was found that the interaction and dispersion state of fillers in the ALSR matrix were improved by the introduction of BN sheets. Thermal, electrical, and mechanical performances of the ALSR composites were also investigated in this work. The result indicated that the thermal conductivity of ALSR can reach 0.64 W m⁻¹ K⁻¹ at the loading of 20 wt% Al₂O₃/20 wt% BN, which is 3.76 times higher than that of pure ALSR. The addition of Al₂O₃ particles and BN sheets also improve the thermal stability of ALSR composites. Moreover, pure ALSR and ALSR composites showed relatively lower dielectric permittivity (1.9–3.1) and dielectric loss factor (<0.001) at the frequency of 10³ Hz. The insulation properties including volume resistivity and breakdown strength were improved by the introduction of flaky BN in the ALSR matrix. The volume resistivity and characteristic breakdown strength E₀ are 6.68 × 10¹⁵ Ω m and 93 kV/mm, respectively, at the loading of 20 wt% Al₂O₃/20 wt% BN. In addition, the mechanical characteristics including elongation at break and tensile strength of ALSR composites were also enhanced by co-filled fillers. The combination of these improved performances makes the co-filled ALSR composites attractive in the field of electrical and electronic applications.     

Tribological properties of ethylene–propylene–diene rubber + polypropylene + thermal‐shock‐resistant ceramic composites

This work is part of a program on composites used in thermoelectric devices. Tribological properties of dynamic vulcanizate blends of polypropylene and ethylene‐propylene‐diene rubber filled with 5 wt% of microscale powder have been studied. The microscale thermal‐shock‐resistant ceramic filler contains α‐Al₂O₃, mullite (3Al₂O₃ · 2SiO₂ or 2Al₂O₃SiO₂), β‐spodumene glass‐ceramic and aluminium titanate. We found that our ceramic particles are abrasive; they cause strong abrasion of softer steel ball surfaces during dry sliding friction. To overcome the difficulty of particle dispersion and adhesion, the filler was modified through grafting using three types of organic molecules. Dry sliding friction was measured using four types of counter‐surfaces: tungsten carbide, Si₃N₂, 302 steel and 440 steel. Thermoplastic vulcanizate filled with neat ceramic powder shows the lowest friction compared to composites containing the same but surface‐treated powder. We introduce a ‘bump’ model to explain the tribological responses of our composites. ‘Naked’ or untreated ceramic particles protrude from the polymer surface and cause a decrease of the contact area compared to neat polymer. The ball partner surface has only a small contact area with the bumps. As contact surface area decreases, so does friction and the amount of heat generated during sliding friction testing. Chemical coupling of the ceramic to the matrix smoothens the bumps and increases the contact surface, giving a parallel increase in friction. Copyright © 2012 Society of Chemical Industry     

Investigation of Characterization and Mechanical Performances of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and SiC Reinforced PA6 Hybrid Composites

In this study, the influence of different weight percentages of alumina oxide (Al₂O₃) and silicon carbide (SiC) reinforcement on the mechanical properties of Polyamide (PA6) composite is investigated. Test specimens of pure PA6, 85 wt% PA6 + 10 wt% Al₂O₃ + 5 wt% SiC and 85 wt% PA6 +10 wt% SiC + 5 wt% Al₂O₃ are prepared using an injection molding machine. To investigate the mechanical behaviors tensile test, impact test, flexural test, and hardness test were conducted in accordance with ASTM standards. Experimental results indicated that the mechanical properties, such as tensile, impact, hardness, and flexural strength were considerably higher than the pure PA6. The tensile fracture morphology and the characterization of PA6 hybrid composites were observed by scanning electron microscope and Fourier transform infrared spectroscopic method. Further, thermogravimetric analysis confirms the thermal stability of PA6 hybrid composites. The reinforcing effects of Al₂O₃ and SiC on the mechanical properties of PA6 hybrid composites were compared and interpreted in this paper. Improved mechanical and thermal characteristics were observed by the addition of small amount of Al₂O₃ and SiC simultaneously reinforced with the pure PA6.     

Microwave‐assisted in situ polymerization of polycaprolactone/boron nitride composites with enhanced thermal conductivity and mechanical properties

Polycaprolactone/boron nitride (PCL/BN) composites were prepared by microwave‐assisted ring‐opening polymerization of ε‐caprolactone (ε‐CL). In order to improve the dispersibility and interfacial interaction between BN fillers and PCL matrix, hydroxyl functional BN (mBN) was first prepared to be used as a macroinitiator for ε‐CL. Then BN grafted PCL (BN‐g‐PCL) copolymers were obtained via the in situ method, which acted as in situ compatibilizers in the PCL/BN composites. Various techniques were applied to characterize the mBN and PCL/BN composites. The Fourier transform infrared spectroscopy results confirm the structure of the BN‐g‐PCL copolymer. Field emission SEM graphs exhibit that, for the PCL/mBN composites, the mBN presents a homogeneous dispersion in the matrix and interfacial adhesion between the PCL and mBN is improved. These are beneficial for enhancing the thermal conductivity of the PCL/mBN composites. Notably, the PCL/mBN composite with 5 wt% mBN loading achieves the highest thermal conductivity of 0.55 W m^?1 K^?1, which is 2.75 times higher than that of pure PCL, 0.20 W m^?1 K^?1. This indicates that the excellent dispersion and interfacial adhesion could lead to the construction of continuous thermal conductive paths at a low BN loading and reduce the heat loss caused by phonon scattering in the interface. Furthermore, mBN could help to improve the mechanical properties of the composite. On adding 5 wt% mBN, the tensile strength and tensile modulus of the composite are 1.58 and 2.05 times higher, respectively, than those of PCL. © 2020 Society of Chemical Industry     

Fine Ti‐dispersed Al2O3 composites and their mechanical and electrical properties

Al₂O₃/Ti composites containing 0‐30 vol% dispersed fine Ti particles were fabricated using a hot‐press sintering method at 1500°C from mixtures of Al₂O₃ and TiH₂ powders. During sintering, TiH₂ decomposed to form metallic Ti. The effects of the Ti content on the mechanical and electrical properties of the composites were then investigated. No Ti‐Al intermetallic compounds were detected by X‐ray diffraction, and energy‐dispersive X‐ray spectroscopy indicated the presence of Al‐Ti‐O solid solution and Ti‐O phases. The composites showed enhanced densification; the measured densities were higher than the calculated theoretical values. Microstructural observation revealed homogeneously distributed fine Ti particles dispersed in the Al₂O₃ matrix. The Ti particle size ranged from submicrometer to a few micrometers depending on the Ti content. The fracture mode of the composites was primarily transgranular, in contrast to the intergranular fracture mode of monolithic Al₂O₃. Although the flexural strength was decreased with increase in Ti content, the composite containing 20 vol% Ti displayed the maximum fracture toughness of 4.3 MPa·cm^1/2, which was 37% greater than that of monolithic Al₂O₃. The composites containing more than 15 vol% Ti exhibited drastic decreases in resistivity (~10^?1 Ωcm), which were attributed to the formation of interconnected Ti networks at these Ti contents. The percolation threshold volume for electrical conduction in the present system was calculated to be 13.8 vol%. The results indicate that dispersing fine Ti particles into Al₂O₃ increased the fracture toughness and improved the conductivity of Al₂O₃.     

Novel heat‐conductive composite silicone rubber

The silicone rubber with good thermal conductivity and electrical insulation was obtained by taking vinyl endblocked polymethylsiloxane as basic gum and thermally conductive, but electrically insulating hybrid Al₂O₃ powder as fillers. The effects of the amount of Al₂O₃ on the thermal conductivity, coefficient of thermal expansion (CTE), heat stability, and mechanical properties of the silicone rubber were investigated, and it was found that the thermal conductivity and heat stability increased, but the CTE decreased with increasing Al₂O₃ fillers content. The silicone rubber filled with hybrid Al₂O₃ fillers exhibited higher thermal conductivity compared with that filled with single particle size. Furthermore, a new type of thermally conductive silicone rubber composites, possessing thermal conductivity of 0.92 W/mK, good electrical insulation, and mechanical properties, was developed using electrical glass cloth as reinforcement. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2478–2483, 2007     

Properties of thermally conductive silicone rubbers filled with admicellar polymerized polypyrrole-coated Al2O3 particles

Polypyrrole (PPy) nanolayers were introduced on the surface of alumina (Al₂O₃) particles via admicellar polymerization. The properties of silicone rubbers (SRs) filled with PPy-coated Al₂O₃ and pristine Al₂O₃ as thermally conductive fillers were studied and compared. The results demonstrate that the addition of PPy-coated Al₂O₃ leads to a better interfacial compatibility but lower cross-linking density of the composites than pristine Al₂O₃. The improvement in the compatibility and the decrease in the cross-linking density are paradoxes in affecting mechanical properties. The improvement in the compatibility shows a slight predominance on the strength at low-filler contents. Lower cross-linking density of modified-Al₂O₃/SR composites led to a better processing performance and a higher maximum filler loading amount than the pristine Al₂O₃/SR composites, which is beneficial to increasing the thermal conductivity and maintaining a relatively good strength. The PPy-coated Al₂O₃/SR composite with 83 wt% filler content has a thermal conductivity of 1.98 W/(m K) and a tensile strength of 2.9 MPa, and the elongation at break was 63%. Functionalized fillers by admicellar polymerization used in the fabrication of filler/SR composites not only improve the interfacial compatibility but also optimize and expand the functions of the composites, which has great significance for the production and application of thermally conductive SR in some branches of industry (automotive, electrical engineering, etc.) in the future.     

Effective thermal conductivity and thermal properties of phthalonitrile‐terminated poly(arylene ether nitriles) composites with hybrid functionalized alumina

A polymer‐based thermal conductive composite has been developed. It is based on a dispersion of micro‐ and nanosized alumina (Al₂O₃) in the phthalonitrile‐terminated poly (arylene ether nitriles) (PEN‐t‐ph) via solution casting method. The Al₂O₃ with different particle sizes were functionalized with phthalocyanine (Pc) which was used as coupling agent to improve the compatibility of Al₂O₃ and PEN‐t‐ph matrix. The content of microsized functionalized Al₂O₃ (m‐f‐Al₂O₃) maintained at 30 wt % to form the main thermally conductive path in the composites, and the nanosized functionalized Al₂O₃ (n‐f‐Al₂O₃) act as connection role to provide additional channels for the heat flow. The thermal conductivity of the f‐Al₂O₃/PEN‐t‐ph composites were investigated as a function of n‐f‐Al₂O₃ loading. Also, a remarkable improvement of the thermal conductivity from 0.206 to 0.467 W/mK was achieved at 30 wt % n‐f‐Al₂O₃ loading, which is nearly 2.7‐fold higher than that of pure PEN‐t‐ph polymer. Furthermore, the mechanical testing reveals that the tensile strength increased from 99 MPa for pure PEN‐t‐ph to 105 MPa for composites with 30 wt % m‐f‐Al₂O₃ filler loading. In addition, the PEN‐t‐ph composites possess excellent thermal properties with glass transition temperature (T_g) above 184°C, and initial degradation temperature (T_id) over 490°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41595.     

Stability and electrical properties of MoSi2‐ and WSi2‐oxide electroconductive composites

MoSi₂‐ and WSi₂‐based electroconductive ceramic composites were fabricated using 40‐80 vol% fine‐ and coarse‐Al₂O₃, and ZrO₂ particles (refractory oxides) after sintering in argon. Their chemical and thermal stability was tested between 1400°C‐1600°C for up to 48 hours. X‐ray diffraction analysis showed the formation of secondary 5‐3 metal silicide (Mo₅Si₃, W₅Si₃) and silica phases on the grain boundaries and surface. The fraction of the W₅Si₃ (11.4‐38.8 vol%) was significantly higher than that of the Mo₅Si₃ (3.3‐7.3 vol%) in the composites after annealing at 1400°C for 48 hours. The rates of grain growth in the composites (0.013‐0.023 μm/h) were highly decreased by a grain‐boundary pinning effect. This effect was relatively better with the addition of the coarse‐grained oxides due to their more homogeneous distribution throughout the microstructure. The 20–80 vol% MoSi₂‐Al₂O₃ (fine‐grained) composite exhibited an electrical conductivity of 8.8 S/cm at 900°C. At the 60 vol% silicide content, MoSi₂–Al₂O₃ (coarse‐grained) and WSi₂–Al₂O₃ (fine‐grained) showed higher electrical conductivity (126‐128 S/cm) at 900°C. The density, porosity level, particle distribution, intrinsic conductivity of silicide phase, particle size, and fraction of the secondary 5‐3 silicide phase highly influenced their electrical properties.     

Effect of different size complex fillers on thermal conductivity of PA6 thermal composites

ABSTRACT

Nylon 6 (PA6) thermal conductive composites were prepared by melt blending with different sizes of spherical Al₂O₃ and AlN and the filling amount was 60 wt%. This paper explored the effects of different particle sizes and filler kinds on the thermal conductivity and mechanical properties of the composites. The results showed that the composites filled with AlN and spherical Al₂O₃ had higher thermal conductivity than the composites filled with single filler under the same filling amount. When the mass ratio of 48 μm spherical Al₂O₃ and 14 μm AlN was 1:2, the thermal conductivity and thermal diffusivity was 2.44 W/(m·K) and 0.72 mm²/s, respectively. In addition,the tensile strength was 57.50 MPa and the impact strength was 6.13 KJ/m². By comparing actual thermal conductivity value with the theoretical value calculated by Agari model, we found that actual value of alumina filling was close to the theoretical value.     

Surface‐Functionalized White Sapphire α‐Al2O3 Platelets as Nanofillers for Vinylester Composites and Heavy Duty Anchoring Systems

Synthetic α‐Al₂O₃ platelets, also referred to as corundum and white sapphire, represent attractive fillers improving the mechanical properties of vinylester‐based chemical anchoring systems. Even in the absence of coupling agents, as verified by scanning electron microscopic (SEM) analyses of fracture surfaces, α‐Al₂O₃ platelets of 200 nm thickness and 5–10 µm size are uniformly dispersed in vinylester resins which are cured by free radical polymerization at room temperature. With increasing content of ultrahard α‐Al₂O₃ platelets (0–40 wt%) the Young's modulus of α‐Al₂O₃ platelet/vinylester composites increases from 3200 to 9000 MPa. However, 1–5 wt% 3‐methacryloyloxypropyl‐trimethoxysilane (MPS) as coupling agent, added to the vinylester resin or preferably used to functionalize α‐Al₂O₃ surfaces in a filler pretreatment step, improves elongation at break (+50%) without sacrificing high stiffness and strength. The X‐ray photoelectron spectroscopy (XPS) analysis confirms the successful surface‐functionalization of α‐Al₂O₃ platelets by using pretreatments with MPS in toluene, acidified ethanol/water or tetrahydrofuran, respectively. The MPS filler pretreatment simultaneously enhances tensile strength (+22%), elongation at break (+50%), and Young's modulus (+12%) as compared to composites containing unmodified filler. According to SEM analyses of composite fracture surfaces, MPS‐mediated functionalization affords significantly improved interfacial adhesion between α‐Al₂O₃ platelets and the polymer matrix.

     

Investigation of Sm2O3 additive on mechanical and electrical properties of Li2O‐ stabilized β″‐alumina electrolyte

Li₂O‐ stabilized β″‐alumina was synthesized by the double zeta process. The effect of Sm₂O₃ additive as the sintering aid, on microstructure, mechanical and electrical properties of Li₂O‐ stabilized β″‐alumina ceramics was studied by means of X‐ray diffraction, field emission scanning electron microscope, biaxial flexure test and ionic conductivity measurement. The results indicated that both the fracture strength and the ionic conductivity of the sample containing 0.2 wt% Sm₂O₃ improved approximately 52% and 54%, respectively, that can be attributed to its higher density, higher amount of β″‐Al₂O₃ phase and more uniform microstructure.     

A computational and experimental study on the effective properties of Al2O3‐Ni composites

It has been demonstrated that effective medium approximation and mean field homogenization technique is a useful computational tool to predict the effective thermal and structural properties of alumina‐nickel (Al₂O₃‐Ni) composites. Nickel particle size and volume fraction, thermal interface resistance and porosity are found significant factors that affect thermal conductivity, elastoplastic behavior, elastic modulus and thermal expansion coefficient of Al₂O₃‐Ni composite. To complement the computational design, Al₂O₃‐Ni composite samples with designed range of volume fractions and nickel particle size are developed using spark plasma sintering process and properties are measured for model verification.     

A multiscale methodology quantifying the sintering temperature‐dependent mechanical properties of oxide matrix composites

A novel methodology combining multiscale mechanical testing and finite element modeling is proposed to quantify the sintering temperature‐dependent mechanical properties of oxide matrix composites, like aluminosilicate (AS) fiber reinforced Al₂O₃ matrix (AS_f/Al₂O₃) composite in this work. The results showed a high‐temperature sensitivity in the modulus/strength of AS fiber and Al₂O₃ matrix due to their phase transitions at 1200°C, as revealed by instrumented nanoindentation technique. The interfacial strength, as measured by a novel fiber push‐in technique, was also temperature‐dependent. Specially at 1200°C, an interfacial phase reaction was observed, which bonded the interface tightly, as a result, the interfacial shear strength was up to ≈450 MPa. Employing the measured micro‐mechanical parameters of the composite constituents enabled the prediction of deformation mechanism of the composite in microscale, which suggested a dominant role of interface on the ductile/brittle behavior of the composite in tension and shear. Accordingly, the AS_f/Al₂O₃ composite exhibited a ductile‐to‐brittle transition as the sintering temperature increased from 800 to 1200°C, due to the prohibition of interfacial debonding at higher temperatures, in good agreement with numerical predictions. The proposed multiscale methodology provides a powerful tool to study the mechanical properties of oxide matrix composites qualitatively and quantitatively.     

Effect of various electrophoretically deposited nano‐silica contents on the properties of poly(vinylidene fluoride‐co‐hexafluoropropylene)‐based electrospun polymer electrolytes

Poly(vinylidene fluoride‐co‐hexafluoropropylene) (P(VDF‐HFP)) based composite polymer electrolyte (CPE) membranes were successfully prepared by electrospinning followed by electrophoretic deposition processes, and desirable polymer electrolytes were obtained after being activated in liquid electrolytes. The physicochemical properties of the CPEs with different electrophoretically deposited nano‐SiO₂ contents were investigated by SEM, XRD, TGA, linear sweep voltammetry and electrochemical impedance spectroscopy measurements. When the ratio of electrophoretically deposited nano‐SiO₂ to P(VDF‐HFP) is up to 4 wt%, the results show that the CPE membrane presents a very uniform surface with abundant interconnected micropores and possesses excellent mechanical tensile strength with high thermal and electrochemical stability; the ionic conductivity at room temperature can reach 3.361 mS cm^?1 and the reciprocal temperature dependence of the ionic conductivity follows a Vogel ? Tamman ? Fulcher relationship. The interfacial resistance of the assembled Li/CPE/Li simulated cell can rapidly increase to a steady value of about 950 Ω from the initial value of about 700 Ω at 30 °C during 15 days' storage. The battery performance test suggests that the CPE also shows excellent compatible properties with commercial LiCoO₂ and graphite materials. © 2015 Society of Chemical Industry     

Development of highly reinforced maleated natural rubber nanocomposites based on sol–gel‐derived nano alumina

In the present study, sol–gel synthesized alumina (Al₂O₃) nanoparticles were characterized by Fourier transform infrared spectra, X‐ray diffraction, field‐emission scanning electron microscopy. Then, Al₂O₃ nanoparticles were employed to improve cure, mechanical, and thermal properties of maleated natural rubber (MNR) nanocomposites. The MNR nanocomposite with 2 phr nano Al₂O₃ exhibited excellent value of cure rate index and exceptionally high value of mechanical properties like modulus and tensile strength in comparison to unfilled MNR compound. Thermogravimetric analysis indicated that nano Al₂O₃ was able to improve the thermal stability of MNR composites to some extent. Additionally, the present study revealed that the interfacial interaction between MNR and nano Al₂O₃ was far better than that between NR and nano Al₂O₃ as confirmed from crosslinking degree measurement and morphological analysis. The present article offers a fresh approach to prepare high performance nano Al₂O₃‐based MNR compounds for future industrial application. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46248.     

Mechanical and thermal conductive properties of fiber‐reinforced silica‐alumina aerogels

We report the formation of Al₂O₃‐SiO₂ fiber‐reinforced Al₂O₃‐SiO₂ aerogels with the content of fibers in the range from 40 wt% to 55 wt% by sol‐gel reaction, followed by supercritical drying. The structure and physical properties of fiber‐reinforced Al₂O₃‐SiO₂ aerogels are studied. We find that the fiber‐reinforced Al₂O₃‐SiO₂ aerogels can be resistant to the temperature of 1200°C. The integration of fibers significantly improves the mechanical properties of Al₂O₃‐SiO₂ aerogels. We find that the bending strength of fiber‐reinforced Al₂O₃‐SiO₂ aerogels increases 0.431 MPa to 0.755 MPa and the elastic modulus increases from 0.679 MPa to 1.153 MPa, when the content of fibers increases from 40 wt% to 50 wt%. The thermal conductivity of the fiber‐reinforced Al₂O₃‐SiO₂ aerogels is in the range from 0.0403 W/mK to 0.0545 W/mK, depending on the content of fibers.     

Al2O3/h-BN/epoxy based electronic packaging material with high thermal conductivity and flame retardancy

The long-term and stable operation of integrated circuits and microelectronics requires packaging epoxy resin (EP) exhibit high thermal conductivity for efficient heat dissipation, and excellent flame retardancy in case of thermal runaway. We achieved such EP composite via filling poly-dopamine (PDA) modified nanoscale Al₂O₃ spheres and microscale h-BN sheets. The PDA modification increases the compatibility between fillers and EP and largely reduces the viscosity, improving the dispersion of fillers in EP thus the thermal conductivity of EP composites. In addition, NH₃, H₂O, and N₂ generated during the combustion of phenolic hydroxyls and aminos in PDA combined with the physical barrier effect of Al₂O₃ and h-BN can improve the flame retardancy of EP composites. As a consequence, the EP composite filled with PDA modified Al₂O₃ (26.67 wt%) and h-BN (13.33 wt%) (i.e., PDA-BNAO/EP) shows a thermal conductivity of 1.192 W/mK (654.9% of EP), a peak heat release rate of 194.9 W/g (33.8% of EP), and total heat release of 15.2 kJ/g (54.5% of EP), respectively. What's more, the viscosity of PDA-BNAO/EP is 20,443 mPa s, which is only 20% of BNAO/EP (whose viscosity is 102,281 mPa s). More importantly, the PDA-BNAO/EP has good dynamic mechanical properties with the storage modulus of 14.69 Gpa, glass transition temperature of 91.9°C and good electrical insulation, which is desired for packaging of microelectronics. PDA-BNAO/EP composite should be a promising candidate for widespread packaging materials of microelectronics.