Particulate Nanocomposites Research Articles

Role of grain interface on dielectric and multiferroic properties of 0-3 type (x)CoFe2O4–(1−x)Ba0.8Sr0.2TiO3 nanocomposites

The (x)CoFe2O4–(1−x)Ba0.8Sr0.2TiO3 (0-3 type particulate) nanocomposites with x = 0.00, 0.02, 0.04, 0.06, 0.08, and 1.00 were prepared by the solid-state method. Cobalt ferrite crystallized into cubic crystal symmetry with an Fd3̄m space group. Strontium-substituted barium titanate crystallized into a tetragonal crystal structure with a P4mm space group. Field emission scanning electron microscopy and transmission electron microscopy techniques show the distribution of different sizes of particle. Polarization vs electric field curves show the highest maximum polarization (Pm) of 10.26 μC/cm2, remnant magnetization (Pr) of 11.70 μC/cm2, and coercivity (Ec) of 19.95 kV/cm for x = 0.04 composition at 35 kV/cm. However, it is smaller than the Ba0.8Sr0.2TiO3 phase (Pm = 16.86 μC/cm2, Pr = 13.20 μC/cm2, and EC = 10.80 kV/cm). The highest dielectric constant of around 9800 was found for x = 0.04 composition, with a very small dielectric loss factor of about 0.02, i.e., less than even 2%. This is ∼10 times compared to that of Ba0.8Sr0.2TiO3 (BSTO), which has been explained by considering interaction at the interface of CoFe2O4 (CFO) and BSTO, leakage current, and variation of the lattice parameter of BSTO in (x)CoFe2O4–(1−x)Ba0.8Sr0.2TiO3 nanocomposite. The magnetic hysteresis loops show squeezing near the origin. The magnetic parameters like coercivity, remnant magnetization, and saturation magnetization increased with the increase in the CoFe2O4 weight fraction. Magnetic interaction between surfaces of magnetic CFO and non-magnetic BSTO is evident from the ΔH vs M plots, and it also evidences the magnetism at the surface of BSTO due to uncompensated spins.

In Situ Piezoelectric-Catalytic Anti-Inflammation Promotes the Rehabilitation of Acute Spinal Cord Injury in Synergy.

Relieving inflammation via scavenging toxic reactive oxygen species (ROS) during the acute phase of spinal cord injury (SCI) proves to be an effective strategy to mitigate secondary spinal cord injury and improve recovery of motor function. However, commonly used corticosteroid anti-inflammatory drugs show adverse side effects which may induce increased risk of wound infection. Fortunately, hydrogen (H2), featuring selective antioxidant performance, easy penetrability, and excellent biosafety, is being extensively investigated as a potential anti-inflammatory therapeutic gas for the treatment of SCI. In this work, by a facile in situ growth approach of gold nanoparticles (AuNPs) on the piezoelectric BaTiO3, a particulate nanocomposite with Schottky heterojunction (Au@BT) is synthesized, which can generate H2 continuously by catalyzing H+ reduction through piezoelectric catalysis. Further, theoretical calculations are employed to reveal the piezoelectric catalytic mechanism of Au@BT. Transcriptomics analysis and nontargeted large-scale metabolomic analysis reveal the deeper mechanism of the neuroprotective effect of H2 therapy. The as-prepared Au@BT nanoparticle is first explored as a flexible hydrogen gas generator for efficient SCI therapy. This study highlights a promising prospect of nanocatalytic medicine for disease treatments by catalyzing H2 generation; thus, offering a significant alternative to conventional approaches against refractory spinal cord injury.

Solid waste recycling and organic particulate hybrid nanocomposite technologies for sustainable infrastructure—A comprehensive review

Solid waste has become a major environmental concern globally in recent years due to the tremendous increase in waste generation. However, these wastes (e.g., plastics and agro-residues) can serve as potential raw materials for the production of value-added products such as composites at low cost. The utilization of these waste materials in the composite industry is a good strategy for maintaining the sustainability of resources with economic and environmental benefits. In this report, the environmental impacts and management strategies of solid waste materials are discussed in detail. The study described the benefits of recycling and reusing solid wastes (i.e., plastic and agro-waste). The report also reviewed the emerging fabrication approaches for natural particulate hybrid nanocomposite materials. The results of this survey reveal that the fabrication techniques employed in manufacturing composite materials could significantly influence the performance of the resulting composite products. Furthermore, some key areas have been identified for further investigation. Therefore, this report is a state-of-the-art review and stands out as a guide for academics and industrialists.

Analysis of mechanical properties enhancement on composites of AA7175 by multi walled carbon nano tube (MWCNT)

Developed to meet the demands of appealing contemporary materials, nanocomposites are polyphase materials that include a matrix and nano-reinforcement. The major types of nanocomposites are as follows. They are categorized as fiber-reinforced nanocomposites, laminar nanocomposites, and particulate nanocomposites based on the reinforcing component, whereas they are classed as metal matrix, ceramic matrix, and polymer matrix nanocomposites based on the matrix ingredient. Due to its advantages over polymer and ceramic matrix, metal matrix nanocomposites (MMNCs) are the most common type of nanocomposites employed in industrial applications. To improve the physical, mechanical, thermal, and electrical properties of conventional materials, nanocomposites are often formed by reinforcing nanoscale tubes, fibres, particles, or sheets. To keep up with technological advancements, drive market changes, and bridge technological gaps by revolutionizing the product, innovative nanocomposites must be used in advanced engineering applications. The high-strength, light-weight aluminium alloy matrix nanocomposites (AMNCs) are able to replace traditional materials to a greater extent in cutting-edge applications including the automotive, aircraft, marine, defense, leisure, and electronic industries. In this study deals with the property enhancement analysis by means of the assistance of Multi Walled Carbon nano tube (MWCNT) nano particles encouragement in AA7175 aluminium alloy. The main focus of this investigation on the tensile related mechanical properties such as tensile strength, percentage of elongation and yield strength. The composites were created with the mass fractions of 5.0 wt%, 4.0 wt%, 3.0 wt%, 2.0 wt% and 1.0 wt% of MWCNT with 95.0 wt%, 96.0 wt%, 97.0 wt%, 98.0 wt% and 99.0 wt% of AA7175 aluminium alloy. These composite mechanical properties were compared with the pure AA7175 aluminium alloy. Among the comparison of these composites values 3.0 wt% of MWCNT produce the greater results on the considered composites. The composite sample recorded high Ultimate Tensile Strength of 431.12 MPa, low Percentage of elongation of 9.58% and high Yield strength of 396.63 MPa.

Thermal, mechanical, and electrical properties of difunctional and trifunctional epoxy blends with nanoporous materials

In the present study, the aim is to synthesize the particulate nanocomposites with difunctional and trifunctional epoxy blend as matrix and synthesized nanoporous materials as fillers. Organic/inorganic hybrid networks were prepared by the novel solvent free method. Viscoelastic, thermal, and electrical properties of di- and trifunctional epoxy and the effect of different nanoparticles in the particulate nanocomposites have been studied by dynamic mechanical analyzer, thermogravimetry (TGA), and dielectric strength. Epoxy mixed with different compositions of TGPAP and particulate nanocomposites by the addition of different types of nanomaterials shows higher storage modulus than the pure epoxy. The addition of TGPAP and nanofillers decreases the thermal stability of epoxy matrix. The evolved gas analysis (TG-FTIR) was also done in order to study the products formed during degradation. An increase in dielectric strength and impact strength (4%) was also observed in the particulate nanocomposites.

Effective properties of particulate nano-composites including Steigmann\u2013Ogden model of material surface

The objective of this work is inclusion of the Steigmann-Ogden interface in the Method of Conditional Moments to investigate the influence of surface effects on the effective properties of random particulate composites. The particular focus is centered on accounting for the surface bending stiffness. To this end, the notion of the energy-equivalent inhomogeneity developed for Gurtin–Murdoch interface is generalized to include the surface bending contribution. The crucial aspect of that generalization is identification of the formula defining energy associated with the surface bending. With the help of that formula, the real nano-particle and its surface are replaced by equivalent inhomogeneity with properties incorporating the surface effects. Closed-form expressions for the effective moduli of a composite with a matrix and randomly distributed spherical inhomogeneities are derived. The normalized shear moduli of nanoporous material as a function of void volume fraction is analyzed and evaluated in the context of other theoretical predictions.

Low velocity drop weight impact behaviour of Al2O3-Ni-ZrO2 and Al2O3-Ni-Cr2O3 ceramic composites

Particulate Al2O3 matrix nanocomposites containing 1 vol.%Ni were prepared by the heterogeneous precipitation method and the addition of 5 vol.% ZrO2 (ANZ) or 1 vol.% Cr2O3 (ANC). The prepared samples were subjected to the low energy drop weight impact tests to compare the behaviour of the composites under low energy impact and to investigate the damage mechanisms. The pure Al2O3, Al2O3/Ni, Al2O3/ZrO2 and Al2O3/Cr2O3 compositions with the same additive ratios were also produced to make the comparison systematically. Also, the Vickers hardness measurements were carried out and a significant increase in hardness was attained for both ANZ and ANC composites. The average hardness value around 24.8?1.0GPa was measured for the ANZ and ANC composites which means ~15% improvement compared to the pure Al2O3. Between all the compositions, the maximum force (Fmax) value was obtained for the ANZ (for 12 J impact energy level Fmax = 26617N) according to the low energy drop weight impact test results. Tensile radial crack network formation, cone formation, fracture and crushing of the cone structure were observed as damage mechanisms for all compositions. The volume of conical frustum structure was evaluated for each composition and the effect of microstructure on possible ballistic performance was also discussed.

Particulate nanocomposites based on bismaleimide–graphene oxide: Thermal studies

The structurally different bismaleimides (BMIs) such as 4,4’-bismaleimidodiphenyl ether (BMIE), 4,4’-bismaleimidodiphenyl sulphone (BMIS) and 4,4’-bismaleimidodiphenyl methane (BMIM) were synthesized. The materials graphite (G), graphene oxide (GO) and washed graphene oxide (WGO) particles are separately blended (3% w/w) with BMIs and thermally polymerized under appropriate conditions. The effects of the presence of the nanoparticles in BMIs were investigated using Differential Scanning Calorimetry (DSC). The DSC results show that the blended nanoparticles alter both the cure exotherm and the enthalpy of curing of the BMIs. Thermogravimetric analysis (TGA) was employed to understand the thermal stability of the cured pure BMIs and their blends with nanoparticles. The presence of the nanoparticles in the crosslinked BMIE matrix shifts the onset of the thermal degradation temperature to higher temperature region (around 15 °C). Among all the materials investigated, the nanoparticles incorporated BMIS increases the char residue. This is due to the efficiency of the physical dispersion and the possible chemical interactions shown by nanoparticles in the cured bismaleimides. The SEM results reveal that the debris of GO are removed by the base washing of GO and the incorporated nanoparticles are well dispersed in the cured BMIM.

Effect of boron carbide addition on strengthening mechanisms, cold workability and instantaneous strain hardening behaviour of Cu4Si14Zn nanocomposites

The present work investigates the mechanical alloying (MA) of Cu4Si14Zn (silicon brass) matrix reinforced with B4C particulate nanocomposites (0, 3, 6, 9 and 12 wt%) and consolidated by VHP technique. This research correlates the microstructural modifications and various strengthening mechanisms occurred in sintered specimens on the cold workability and strain hardening behaviour. The sintered nanocomposites were characterized by advanced microscopic techniques such as XRD, SEM, and TEM to identify phase formation, grain refinement, and dislocations respectively. Based on the existing literature, strengthening mechanisms were computed. The deformation behaviour has evaluated and correlated with the strengthening mechanisms. The results explained that the dispersion strengthening (Orowan) has contributed more to the total strength and influenced the plastic deformation behaviour compared to other strengthening mechanisms. The plastic deformation behaviour in terms of true effective stress, true hydrostatic stress, instantaneous Poisson's ratio, and strain hardening index (ni) has investigated. Among the developed nanocomposites, Cu4Si14Zn – 6 wt% B4C reinforced nanocomposite has exhibited superior deformation and strain hardening behaviour with appreciable strength (824 MPa) and strain (44%).

Effects of Al2O3 nanoparticles volume fractions on microstructural and mechanical characteristics of friction stir welded nanocomposites

The objective of the present study is to investigate the effect of Al2O3 nanoparticles volume percentage on tribological, mechanical and microstructural characteristics of 6061-T6 aluminum alloy based particulate-nanocomposite (P-NCs) fabricated using friction stir welding (FSW) process. Optical microscopy (OM) and scanning electron microscopy (SEM) was employed to evaluate the (a) microstructures of the produced nanocomposites to ascertain the distribution of Al2O3 nanoparticles in the nugget zone; (b) nanocomposite depth formed on Al-alloy matrix, and (c) fractured and wear characteristics. Results reveal that the produced P-NCs had a depth of 3286 µm across the perpendicular x-section of the weld nugget zone of P-NCs. With the increase in a volume percentage of Al2O3 nanoparticles there was a tremendous increment in the microhardness up to 125 HV which is higher than as-received AA6061-T6. It was also noticed that the tensile strength and the wear resistance of produced P-NCs were significantly increased at 0.3 vol% of Al2O3 nanoparticles as compared to 0.2 and 0.4 vol%. The corresponding mechanical and wear properties results were correlated to microstructure and fractography results.

Processing parameters optimization to produce nanocomposite using friction stir welding

This paper deals with the fabrication of particulate metal-matrix nanocomposites (PMNCs) reinforced with Al2O3 nanoparticles via friction stir welding (FSW) process. The reinforcement particles (RPs) are incorporated inside the base matrix on abutting edges under different FSW process parameters to achieve maximum joint efficiency. The effect of different parameters namely tool rotational speed, transverse speed, and volume fraction of Al2O3 nanoparticles as input parameters on the ultimate tensile strength (UTS) of the produced nanocomposites has been investigated using the Taguchi methodology. Analysis of variance was employed to obtain the significance of independent variables on overall quality characteristics of friction stir welded nanocomposites. The multi-response optimized variables were found as: tool rotational speed = 2000rpm, transverse speed = 70 mm min−1 and volume fraction of Al2O3 nanoparticles = 0.30%. Based on the optimized parameters, the maximum ultimate tensile strength of the produced PMNCs was 218 MPa. The optimum results obtained using Taguchi method has been validated by conducting confirmation experiments. Macro and microstructural characterization of the produced nanocomposites using scanning electron microscopes revealed that the increase in the amount of heat due to tool stirring action as well as the addition of Al2O3 nanoparticles in the nugget zone leads to improve the interfacial bonding between the reinforcement particles and the base metal matrix and in turn produce the fine PMNCs.

Dynamic behavior of particulate metal matrix nanocomposite plates under low velocity impact

The main purpose of this work is to investigate low velocity impact behavior of metal matrix nanocomposite plates reinforced with silicon carbide nanoscale particles. First, a micromechanical model is proposed to predict the effective mechanical properties of metal matrix nanocomposites. Two features of the nanocomposite microstructure affecting the elastic properties, including agglomerated state of silicon carbide nanoparticles and size factor, are taken into account in the micromechanical simulation. Then, finite element method is used to analyze the time histories of contact force and center deflection of silicon carbide nanoparticle-reinforced metal matrix nanocomposite plates. Several detailed parametric studies are accomplished to explore the influence of volume fraction, diameter and dispersion type of silicon carbide nanoparticles, spherical impactor velocity and diameter, plate dimensions, as well as different boundary conditions on the dynamic response of metal matrix nanocomposite plates. The presented approach accuracy is verified with the available open literature results displaying a clear agreement. The results indicate that adding the silicon carbide nanoparticles into the metal matrix materials leads to a reduction in plate center deflection and an increase in contact force between the plate and projectile. Moreover, it is found that the nanoparticle agglomeration dramatically decreases the contact force and increases the center deflection of metal matrix nanocomposite plates.

Experimental and numerical study of the effect of silica filler on the tensile strength of a 3D-printed particulate nanocomposite

Polymers are commonly found to have low mechanical properties, e.g., low stiffness and low strength. To improve the mechanical properties of polymers, various types of fillers have been added. These fillers can be either micro- or nano-sized; however; nano-sized fillers are found to be more efficient in improving the mechanical properties than micro-sized fillers. In this research, we have analysed the mechanical behaviour of silica reinforced nanocomposites printed by using a new 5-axis photopolymer extrusion 3D printing technique. The printer has 3 translational axes and 2 rotational axes, which enables it to print free-standing objects. Since this is a new technique and in order to characterise the mechanical properties of the nanocomposites manufactured using this new technique, we carried out experimental and numerical analyses. We added a nano-sized silica filler to enhance the properties of a 3D printed photopolymer. Different concentrations of the filler were added and their effects on mechanical properties were studied by conducting uniaxial tensile tests. We observed an improvement in mechanical properties following the addition of the nano-sized filler. In order to observe the tensile strength, dog-bone samples using a new photopolymer extrusion printing technique were prepared. A viscoelastic model was developed and stress relaxation tests were conducted on the photopolymer in order to calibrate the viscoelastic parameters. The developed computational model of nano reinforced polymer composite takes into account the nanostructure and the dispersion of the nanoparticles. Hyper and viscoelastic phenomena was considered to validate and analyse the stress–strain relationship in the cases of filler concentrations of 8%, 9%, and 10%. In order to represent the nanostructure, a 3D representative volume element (RVE) was utilized and subsequent simulations were run in the commercial finite element package ABAQUS. The results acquired in this study could lead to a better understanding of the mechanical characteristics of the nanoparticle reinforced composite, manufactured using a new photopolymer extrusion 5-axis 3D printing technique.

Microstructural and basic mechanical characteristics of ZA27 alloy-based nanocomposites synthesized by mechanical milling and compocasting

Particulate nanocomposites with the base of ZA27 alloy were synthesized using an innovative route, which includes mechanical milling and compocasting. Scrap from the matrix alloy and ceramic nanoreinforcements were mechanically milled using the ball-milling technique, which led to the formation of composite microparticles. The use of these particles in the compocasting process provided better wettability of ceramic nanoreinforcements in the semi-solid metal matrix, which resulted in a relatively good dispersion of the nanoreinforcements in nanocomposite castings. The presence of nanoreinforcements led to the grain refinement in the matrix of nanocomposites. The mechanical properties of the synthesized nanocomposites are improved and compared with the properties of the metal matrix. The observed increase in the hardness of nanocomposites with Al2O3 nanoreinforcements (20–30 nm) was 6.5% to 10.8%, while the yield strength of these nanocomposites has increased by 12.2% to 23.2%. The hardness and compressive yield strength of the nanocomposites with Al2O3 nanoparticles (100 nm) increased by 1.7% to 8.0% and 2.3% to 8.3%, respectively. The increase in hardness of the nanocomposites with SiC nanoparticles (50 nm) was 11.5% to 20.6%, while the increase in the yield strength was 15.6% to 24.5%. The greatest contribution to the overall strengthening in the synthesized nanocomposites is the result of increased dislocation density due to the difference in coefficients of thermal expansion for the matrix alloy and nanoreinforcements.

A comprehensive predicting model for thermomechanical properties of particulate metal matrix nanocomposites

A reliable and optimal design of metal matrix nanocomposites (MMNCs) reinforced by nanoscale particles critically requires establishing the accurate material-characterizing relations of such new systems. So, this paper presents an inclusive model to predict the elastic modulus, thermal expansion coefficient, yield strength and ultimate tensile strength of MMNCs containing nanoparticles. Size factor and the agglomerated state for the nanoparticles into the metal matrix, generation of dislocations by thermal mismatch and Orowan strengthening mechanism are considered in the analysis. The influence of volume fraction and diameter of nanoparticles, material properties of matrix and temperature difference on the MMNCs effective thermoelastic and strength properties are studied in detail. Generally, the predicted values match well with experimental data. The results prove that for accurate estimations of the elastic modulus and thermal expansion properties of the MMNCs reinforced with uniformly dispersed nanoparticles, the size factor must be considered. The more realistic characterizations of the yield strength and ultimate tensile strength of the MMNCs containing uniformly distributed nanoparticles could only be achieved with considering both thermal mismatch and Orowan strengthening mechanism. Additionally, when the nanoparticles are not well dispersed into the metal matrix, speculating the nanoparticles agglomerated state to acquire a more realistic prediction is critically essential. The MMNCs thermomechanical characteristics can be significantly improved by (i) increasing volume fraction, (iii) decreasing the nanoparticle diameter and (iii) uniform dispersion into the metal matrix.

Cross-property interaction between stiffness, damage and thermal conductivity in particulate nanocomposite

A nanocomposite made from epoxy and nano silica particles was subjected to compressive fatigue loading and the resulting interaction between stiffness, damage and thermal conductivity investigated. First, the thermal conductivity (K) and the elastic modulus (E) of the as-fabricated materials were measured prior to any fatigue loading. Then, the samples were subjected to cyclic loading, and the thermal conductivity and the modulus of elasticity of the specimens were measured after every 5 to 10 thousand cycle intervals until a significant change in the response of the material was observed. In addition, a semi-analytical model is proposed to quantify damage in the material by taking the modulus of elasticity and thermal conductivity data obtained from the experiment. Finally, the cross-property relation between the modulus of elasticity, the thermal conductivity and the damage density in the material at any state of the fatigue cycle is investigated.

Expansion of Kolarik model for tensile strength of polymer particulate nanocomposites as a function of matrix, nanoparticles and interphase properties

Kolarik proposed a model for tensile strength of polymer particulate composites based on the cubic orthogonal skeleton or three perpendicular plates (3PP) system. In this paper, Kolarik model is expanded for tensile strength of polymer nanocomposites containing spherical nanoparticles assuming the interphase properties. This model expresses the strength as a function of interphase properties. This development is performed using some models such as Pukanszky and Nicolais-Narkis. The expanded model is applied to calculate the thickness and strength of interphase by the experimental results. Furthermore, the strength of polymer nanocomposites is evaluated at different levels of material and interphase properties. The experimental data show good agreement with the predictions of the developed model.

Constitutive modeling of elastoplasticity in spark-plasma sintered metal-matrix nanocomposites

A methodology to model the elastoplastic constitutive response of spark plasma sintered metal matrix particulate nanocomposites is presented. The formulated methodology incorporates the effect of Hall-Petch strengthening, Orowan strengthening, dislocation density strengthening, load transfer strengthening and porosity on the elastoplastic response of metal matrix nanocomposite using a mean-field homogenization approach used in conjunction with a plasticity hardening function for metal matrix that is dependent on the metal matrix crystallite size, inclusion particle size and inclusion volume fraction. The effect of sintering process parameters is incorporated into the model using a grain growth model that can estimate the average matrix crystallite size as a function of sintering time, sintering temperature, inclusion size and inclusion volume fraction. The formulated methodology has been validated against experimentally measured crystallite sizes and stress-strain responses of ball-milled and spark plasma sintered Al-Al2O3 nanocomposite samples synthesized during the current work. Additional validation of the methodology against the experimental stress-strain response of nanostructured aluminum reported in the literature has also been carried out.

Modeling of tensile strength in polymer particulate nanocomposites based on material and interphase properties

ABSTRACTIn this work, a simple model is presented to determine tensile/yield strength in polymer nanocomposites containing spherical nanofillers based on material and interphase properties. The accuracy of the proposed model is estimated by comparing with the experimental strength of several samples from the literature. In addition, the effects of thickness (t) and tensile strength (σi) of the interphase as well as the radius (R) and volume fraction ( ) of the nanoparticles on the tensile strength are explained according to the proposed model. The high level of nanoparticle strength (more than 100 GPa) commonly leads to overestimates of the tensile strength of nanocomposites, whereas the assumption of correct interphase properties produces accurate calculations. The tensile strength of nanocomposites does not change at σi < 38 MPa, while it increases by 140% at t = 20 nm and σi = 90 MPa. However, a maximum 14% growth in tensile strength is obtained with the optimum values of = 0.04 and R = 10 nm. Therefore, the concentration and size of the nanoparticles have minor effects on the tensile strength of nanocomposites, but the major influences of interphase thickness and strength are pronounced. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44869.

Influence of nanoparticle size distribution on the thermal conductivity of particulate nanocomposites

Conventional models for the thermal conductivity of nanocomposites neglect the particle size distribution by assuming all nanoparticles to be uniform in size, although in reality most particles in a nanocomposite are not uniform and the size distribution of the nanoparticles might strongly affect the thermal conductivity of nanocomposites as demonstrated in this letter. By including the lognormal distribution of the nanoparticle size into the thermal conductivity model of nanocomposites embedded with spherical particles, we show that the mean value and the standard deviation (SD) of the nanoparticle radius significantly affect the thermal conductivity of particulate nanocomposites. At the same mean radius of embedded particles, the thermal conductivity of the nanocomposite with lognormal size distribution at can be twice that with a uniform particle size. Our improved model on effective thermal conductivity of nanocomposites with nonuniform particles can provide a more accurate prediction on the thermal conductivity of realistic particulate nanocomposites.