Nanocomposite Specimens Research Articles

Understanding surfaces and interfaces in nanocomposites of silicone and barium titanate through experiments and modeling

AbstractBarium titanate (BTO) is a ferroelectric perovskite used in electronics and energy storage systems because of its high dielectric constant. Decreasing the BTO particle size was shown to increase the dielectric constant of the perovskite, which is an intriguing but contested result. We investigated this result by fabricating silicone-matrix nanocomposite specimens containing BTO particles of decreasing diameter. Furthermore, density functional theory modeling was used to understand the interactions at the BTO particle surface. Combining results from experiments and modeling indicated that polymer type, particle surface interactions, and particle surface structure can influence the dielectric properties of polymer-matrix nanocomposites containing BTO. Graphical abstract

Pt-decorated graphitic carbon nitride on carbon paper by x-ray photoelectron spectroscopy

Nanocomposites based on Pt nanoparticles (NPs) and graphitic carbon nitride (gCN) have emerged as promising (photo)electrocatalysts for sustainable energy production, thanks to the synergistical combination of Pt NPs catalytic performances with the favorable gCN chemicophysical properties. In this work, we have focused on electrophoretic deposition of graphitic carbon nitride on carbon paper and subsequent system functionalization with Pt NPs by means of radio frequency sputtering under mild conditions. A final thermal treatment was performed both in air and under inert atmospheres to assess its influence on Pt oxidation states and the related interplay with ultimate functional performances. The present study is focused on x-ray photoelectron spectroscopy characterization of two representative gCN-Pt nanocomposite specimens, annealed in Ar and in air. In particular, we report the survey spectra and the detailed scans for C 1s, N 1s, O 1s, and Pt 4f regions, analyzing the principal spectral features and comparatively discussing the resulting material properties.

An Investigation into the Influence of Graphene Content on Achieving a High-Performance TiO2-Graphene Nanocomposite Supercapacitor.

This study presents the synthesis of TiO2-graphene nanocomposites with varying mass ratios of graphene (2.5, 5, 10, 20 wt. %) using a facile and cost-effective hydrothermal approach. By integrating TiO2 nanoparticles with graphene, a nanomaterial characterized by a two-dimensional structure, unique electrical conductivity and high specific surface area, the resulting hybrid material shows promise for application in supercapacitors. The nanocomposite specimens were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman microscopy, field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Additionally, supercapacitive properties were investigated using a three-electrode setup by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) tests. Notably, the TiO2-20 wt. % rGO nanocomposite exhibited the highest specific capacitance of 624 F/g at 2 A/g, showcasing superior electrochemical performance. This specimen indicated a high rate capability and cyclic stability (93 % retention after 2000 cycles). Its remarkable energy density and power density of this sample designate it as a strong contender for practical supercapacitor applications.

A new investigation on graphene-reinforced 304L nanocomposite made by additive manufacturing process: Microstructure and tribology study

In this study, selective laser melting (SLM), as an additive manufacturing method, was applied to produce graphene/304L nanocomposites with various graphene particle sizes and contents. The effect of the graphene particle size (1 μm and 50 nm) and volume fraction on the microstructure behaviors, constitutional phases, mechanical performance, and wear characteristics of the SLM-processed nanocomposite specimens was studied. It was concluded that the reinforcing particle content and size play a remarkable impact on the densification features and the densification level improvs when the fine starting reinforcing particles are used, due to the development of the reinforcement–matrix wettability. In addition, the microstructure refinement and increased hardness values occurred in the SLM-processed nanocomposite system with the addition of reinforcing particles (both sizes). The wear examination indicated that the coefficient of friction (COF), wear rate, and mass loss decreased due to the reinforcement prominent effect, namely grain refinement and grain-boundary strengthening. According to surface topography analysis, the depth of the groove in the processed sample made by fine graphene reinforcement is lower than the other sample.

Dispersion Strategy improves the mechanical properties of 3D-Printed biopolymer nanocomposite

Homogenous dispersion of nanoparticles in polymer matrices is a technical challenge that if overcome can lead to improved mechanical properties of the resulting nanocomposites. In this work, we successfully refined commercially-available nanoscale, calcium deficient, and poorly crystalline hydroxyapatite (nHA) particles and composited them with acrylate and methacrylate functionalized soybean oil (mAESO) and triethylene glycol dimethacrylate (TEGDMA) producing inks for masked stereolithography (mSLA) -based 3D printing. First, we used shear mixing and ultrasonication on nHA/ethanol mixtures to break down agglomerates and then separated the finest nanoparticles from the remaining agglomerates using centrifugation. The refined nanoparticles (termed fine) were then mixed with the resins and UV-initiator to produce inks for 3D printing. Similarly, we prepared one ink using as-purchased nHA particles (termed raw) and another ink using leftover agglomerates after refinement (termed coarse). We compared the rheological properties of the nHA-resin inks. We used mSLA to fabricate nanocomposite specimens and tested them using flexural, and Mode-I fracture toughness testing following ASTM standards. The dispersion of nanoparticles in the polymer matrix was studied by analyzing backscattered mode scanning electron microscopy images. The nHA particle refinement improved the nanoparticle dispersion in the resin matrix while also increasing the viscosity and shear yield strength of the nanocomposite ink. The flexural fracture strength, flexural modulus, and Mode-I fracture toughness of refined nHA-based nanocomposites were increased by 11 %, 71 %, and 12 %, respectively compared to the raw nHA-based nanocomposites. However, the flexural fracture strain of refined nHA-based nanocomposites was lower by 40 % compared to the raw nHA-based nanocomposites. The nanocomposites became stiffer with the incorporation of refined nanoscale nHA. The separation of nanoscale nHA particles, excellent dispersion of these nanoparticles in polymer matrix, and improved flexural strength and modulus opens a new avenue towards the 3D printing of high-performance nHA-based nanocomposites.

Spherical polystyrene/zinc oxide nanocomposite powder fabricated by continuous process chain of melt mixing and indirect heating

Polymer powders are limited by particle size, shape, and properties in various applications. Preserving the chemical properties of the material throughout the process is a critical part of developing consistently shaped nanocomposite powders across diverse polymer types. The goal of this study is to demonstrate continuous methods to produce spherical Polystyrene (PS) and zinc oxide (ZnO) nanocomposites. A single-screw extruder is used to melt mix PS pellets with ZnO nanoparticles, followed by pelletization, dry grinding, and spheroidization in a Downer Tower to form spherical polymers. To minimize agglomeration, the process incorporates an ethanol treatment and a final sieving step. The resulting nanocomposite powder exhibits exceptional flowability and well-defined spherical morphology. Additionally, incorporating ZnO nanoparticles enhanced the thermal stability and glass transition temperature of the nanocomposite while reducing particle size distribution. Thermogravimetric analysis and X-ray diffraction confirm the preservation of the chemical structure of the spherical nanocomposite specimens throughout processing.

Post-creep residual tensile properties of multi-walled carbon nanotube/epoxy nanocomposites

Epoxy resin as a thermoset polymer is vulnerable to creep loading even at room temperature due to its viscoelastic nature. This study investigated the effect of reinforcing epoxy resin with different functionalized multi-walled carbon nanotubes (MWCNT) contents on the creep response and post-creep residual tensile properties of nanocomposites. The creep tests were performed on the nanocomposite specimens containing different filler contents and the neat epoxy specimen at 40°C under a constant load level of 200 N. It was found that the nanocomposites containing 0.3 wt% MWCNTs experienced 29.6%, 69.1%, and 74.1% decreases in the elastic strain, creep strain, and steady-state creep strain rate, respectively, compared to the neat epoxy. Furthermore, the tensile strength and stiffness of the neat epoxy and nanocomposite specimens were evaluated before and after a partial creep test (at a load level of 200 N for 150 min) by conducting tensile tests. The nanocomposites containing 0.3 wt% MWCNTs demonstrated considerable improvements of 35.9%, 41.2%, 27.9%, and 28.1% in strength, residual strength, stiffness, and residual stiffness, respectively, compared to the neat epoxy. Furthermore, scanning electron microscopy assessment was utilized to investigate the fracture surfaces of the nanocomposite specimens.

Flame Retardant Additives in Polylactic Acid (PLA) Photopolymer Resin for 3D Printing Digital Light Processing (DLP)

Digital light processing (DLP) technology has been developed based on stereolithography (SLA) 3D-printing principle. The biodegradable and low-cost polylactic-acid (PLA) has so far been used as polymeric material for photopolymer resin in SLA and DLP. To achieve functional SLA-processed product, the properties of such PLA has been improved, with the aim to make it flame retardant, less viscous, and having light transmittance characteristics. In this study, the liquid raw PLA photopolymer was changed by adding different contents of Ammonium Phosphate (APP), melamine cyanurate (MCA), Aluminum Tri-hydroxide (Al2O3) and Nano-silicon dioxide (SiO2) additives. The solid PLA nanocomposite specimens were printed by using DLP device according to the standard geometry for burning test UL-94 to evaluate its flame-retardant property. In addition, the printing product and residue after burning test was analyzed for their morphological characteristic by using SEM. The results showed that the low weight fraction of MCA showed excellent performance. PLA/MCA successfully kept green body form until the sintering temperature of stainless steel was achieved. It can become a reference for application DLP 3D printing products in the casting and sintering process.

One-step preparation of silver nanoparticle containing polymer nanocomposites via stereolithography technique

As a technique that uses ultraviolet light to cure photo-polymers layer by layer with high spatial resolution and surface quality, stereolithography (SLA) allows for precise process control and optimization for various UV-curable polymers and their nanocomposites with various nanoparticles. In this study, UV-curable polymer nanocomposites were prepared with the addition of different contents of silver nitrate via SLA technique for use in antibacterial applications. In-situ synthesis of AgNPs was achieved during the SLA process without any additional treatments. The effect of AgNO3 addition on the curing of the resin and the mechanical properties of the nanocomposite specimens were investigated. To understand the fracture mechanism of the nanocomposite samples, the fractured surfaces of the samples were evaluated by SEM, and the AgNO3 content of the nanocomposite was evaluated by EDX. The nanocomposites containing 0.3 wt. % AgNO3 exhibited improved mechanical properties. Further increasing the AgNO3 content to 3 wt. % led to deterioration in the physical and mechanical properties of the polymer nanocomposites.

Inorganic Fullerene-Like WS2 Reinforced Polyamide Powders for Improved Mechanical Properties in Laser Sintered Nanocomposite Parts

Polyamide (PA) is a widely utilized engineering polymer, and its thermal and mechanical properties can be further improved by adding nanofillers. However, adding inorganic fullerene-like tungsten disulfide (IF-WS2) nanoparticles (NPs) to PA to produce composite precursor powders for additive manufacturing is challenging. Here, we report a novel and cost-effective method for fabricating PA-12 based nanocomposite (NC) powders with fixed/partially encapsulated IF-WS2 nanoparticulate fillers utilizing an advanced mixing technique because simple wet mixing (WM) can only attach fillers weakly to the powder surfaces when compared to the proposed method. The resulting nanocomposite powders maintained nearly the original particle size distribution of PA-12. They also exhibited improved rheological properties, melting, and crystallization behaviors compared with those prepared by the WM method. The laser-sintered PA-12 nanocomposite specimens revealed enhanced powder thermal stability and higher tensile strengths than pristine PA-12, validating the advantages of the novel technique for the fabrication of polyamide nanocomposite powders and their suitability for utilization in laser sintering additive manufacturing. These results demonstrate that high-performance engineered PA-12 nanocomposite components can be directly laser sintered, and this technique can potentially be extended to fabricate other engineered polymeric nanocomposite powders.

Studies on Al-Si based hybrid aluminium metal matrix nanocomposites

A lightweight Hybrid Aluminium Metal Matrix Nanocomposite (HAMNC) is proposed for brake rotor application in this work. Hypereutectic Aluminium-Silicon (Al-Si) grade LM30 alloy is opted as the matrix with Boron Carbide (nB4C) and Rutile (nTiO2) nanoparticles as reinforcements. The brake rotor samples are produced using ultrasonic squeeze-assisted stir-casting, which is cost-effective and feasible for mass production. The hybrid nanocomposite specimens are fabricated by maintaining 1 wt% of nB4C and by varying TiO2 nanoparticles from 0 wt% to 1.00 wt% in steps of 0.25 wt%. The formulations are subjected to microstructure study and dry sliding wear test. The Field Emission Scanning Electron Micrographs (FESEM) reveal that the stir-casting method combining ultrasonic and squeeze effects aids in the uniform distribution of nano reinforcements. The tribological findings show that the hybrid nanocomposite containing 0.75 wt%. of nTiO2 has an 82.76% lower specific wear rate compared to the parent LM30 alloy. Further, the HAMNC brake rotor is 60% lighter than the brake rotors made of Grey Cast Iron making it a potential replacement material.

Mechanical, thermal, and morphological studies of adding POSS reinforcement to the PA6/NBR composites

ABSTRACT In this study, a hybrid nanocomposite made of the polyamide 6 (PA6) and nitrile butadiene rubber (NBR) with polyhedral oligomeric silsesquioxanes (POSS) was prepared and mechanical, thermal, and morphology of nanocomposite were tested. The nanocomposite specimens were prepared through the melt mixing method. Tensile and Charpy impact showed that adding the NBR increases the impact strength while decreasing the tensile strength. However, POSS nanoparticles can improve the weakness of adding NBR rubber to the PA6. Additionally, traditional analytical techniques, including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA), and scanning electron microscopy (SEM) were conducted.

Effect of intercalated and exfoliated graphite particles on the mechanical properties of polymer composite: A micromechanics-computational approach

This study investigated the effects of intercalation and exfoliation of the graphite flake particles on the mechanical properties of elastomeric composites using analytical, computational, and experimental techniques. Relying on the modified Eshelby and incremental Mori–Tanaka approach, a new micromechanics model was proposed to estimate Young’s modulus and develop a constitutive model for expanded graphite (EG)-filled elastomer in finite strain deformation. It was found that when the initial graphite flakes expanded, the actual volume fraction and ultimate aspect ratio of the dispersed particles significantly affected the mechanical properties of the EG-reinforced composites. The present model and subsequent predictions reflect the initial flake diameter, actual volume fraction, ultimate aspect ratio of the particles, and other convenient physical properties of the composite constituents. In addition, molecular dynamics simulations were performed to evaluate the elastic properties of the EG-Matrix interphase region using the COMPASS force field function. The MD results showed that Young’s modulus of the interphase region increased significantly as the quantity of the graphene layer increased. The micromechanics-constitutive model results were validated using the experimentally determined stress–strain relation of the composites. EG- and CB-elastomer nanocomposite specimens were fabricated and tested in the experimental program. Field emission scanning electron microscopy (FESEM) analysis of the cryo-fractured surfaces of the elastomer compounds showed good interactions between the constituents. Numerical computations indicated that the proposed model incorporating the new parameters could accurately predict the experiment at a small particle concentration.

Anisotropy induced in magnetic field in GNPs/epoxy composites used as an effective heat dissipation electronic packaging material

AbstractThis article investigates the effect of different magnetic fields on modulating the alignment of graphene nanoplatelets (GNPs) and their impact on the thermal conductivity of epoxy nanocomposites. Various nanocomposite specimens were fabricated with different GNP contents by using magnetically field‐aligned GNPs in the fabrication process to enhance the thermal conductivity. The results showed that the in‐plane thermal conductivity of the Bmf (Bidirectional magnetic field) sample with 5 wt% GNPs added reached 0.75 W m−1 K−1, which is 276.6% higher than that of pure epoxy resin and the anisotropy coefficient (K∥/K⊥) reached 3.3. In addition, temperature rise tests were performed to simulate the thermal conductivity of nanocomposites used as an electronic packaging material, and the results indicated that the composites achieved a significant increase in in‐plane thermal conductivity with a lower amount of filler. This provides valuable insights into the preparation of thermally conductive composites and demonstrates their potential as a thermal management packaging material for next‐generation electronic devices.

Low electric field induction in BaTiO3-epoxy nanocomposites

Epoxy is widely used material, but epoxy has limitations in terms of brittleness in failure, and thus researchers explore toughening and strengthening options such as adding a second phase or using electromagnetic fields to tailor toughness and strength, on demand and nearly instantaneously. Such approach falls into the category of active toughening but has not been extensively investigated. In this research, Si-BaTiO3 nanoparticles were used to modify the electro-mechanical properties of a high-performance aerospace-grade epoxy so as to study its response to electric fields, specifically low field strengths. To promote uniform dispersion and distribution, the Si-BaTiO3 nanoparticles were functionalised with silane coupling agents and mixed in the epoxy Araldite LY1564 at different content loads (1, 5, 10 wt%), which was then associated with its curing agent Aradur 3487. Real-time measurements were conducted using Raman spectroscopy while applying electric fields to the nanocomposite specimens. The Raman data showed a consistent trend of increasing intensity and peak broadening under the increasing electric field strength and Si-BaTiO3 contents. This was attributed to the BaTiO3 particles’ dipolar displacement in the high-content nanocomposites (i.e., 5 wt% and 10 wt%). The study offers valuable insights on how electric field stimulation can actively enhance the mechanical properties in epoxy composites, specifically in relatively low fields and thin, high-aspect-ratio composite layers which would require in-situ mechanical testing equipped with electric field application, an ongoing investigation of the current research.

The effect of aligning graphene‐oxide nanoplatelets on moisture absorption and thermal stability of polymeric nanocomposites

AbstractThis article investigates the effect of aligning graphene‐oxide nanoplatelets (GONPs) on the moisture absorption and thermal stability of polymeric nanocomposites. Various nanocomposite specimens were fabricated using different GONP contents to improve water uptake resistance and thermal stability by aligning GONPs using an AC electric field during manufacturing. The results showed that aligning 0.3 wt% GONPs resulted in the most significant improvements, with the reductions of 76% and 54% observed in the water uptake of nanocomposites at the initial and saturation stages, respectively. The thermal stability of the nanocomposite specimens was also investigated using thermogravimetric analysis, in which nanocomposites containing 0.3 wt% randomly dispersed GONPs demonstrated improved performance compared with the neat epoxy specimen. However, aligning GONPs resulted in a marginal effect on the thermal stability parameters of nanocomposites. Moreover, Fourier transform infrared spectroscopy was conducted to investigate the chemical nature and hydrophilicity of the specimens. In addition, the freeze‐fractured surfaces of the neat and nanocomposite specimens were investigated using scanning electron microscopy. The results indicated the role of nanoparticle alignment in enhancing the performance of nanocomposites under hygrothermal conditions in terms of water uptake, which is of high importance in the marine industry.

Mechanical and wear performance of A356/Al2O3 aluminum nanocomposites by considering the mechanical milling time and microstructural properties

PurposeThe paper aims to examine the mechanical and wear performance of A356/Al2O3 (alumina) nanocomposites. The correlation between wear performance and the microstructural properties that result from various mechanical milling periods was investigated.Design/methodology/approachThe production of nano alumina reinforced (1 Wt.%) A356 aluminum nanocomposite specimens was carried out using the traditional powder metallurgy method, incorporating three different mechanical milling times (1, 2 and 4 h). Subsequently, mechanical and wear performance assessments were conducted using hardness, compression and pin-on-disc wear tests.FindingsAlthough the specimens subjected to the most prolonged mechanical milling (4 h) demonstrated superior hardness and compressive strength properties, they exhibited a remarkable weight loss during the wear tests. The traditional evaluation, which supports that the wear performance is generally correlated with hardness, does not consider the microstructural properties. Since the sample milled for 1 h has a moderate microstructure, it showed better wear performance than the sample with higher hardness.Originality/valueThe originality of the paper is demonstrated through its evaluation of wear performance, incorporating not only hardness but also the consideration of microstructural properties resulted from mechanical milling.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2023-0031/

Microstructural and micromechanical modeling of gum-gelatin-based soft tissue engineering scaffolds

Oral and dental diseases, including periodontal disease, are among the most common conditions in the field of dentistry. The best treatment for this complication is the use of different polymers and multi-component biological tissue prepared through the freeze-drying technique. In this study, biocompatible and biodegradable polymers, namely polyvinyl alcohol (PVA) and gelatin (GN), were used for this purpose, along with Arabian gum-hydroxyapatite (HA) for its antibacterial properties. Arabian gum, with weight percentages of 0, 2, 4, and 6 wt%, was added to the polyvinyl alcohol-gelatin composition at −55 °C for 28 h in the freezer and 48 h at −45 °C under a pressure of 0.01 mbar. The resulting porous biological tissue, with four different ratios, was tested for mechanical and biological analysis in a physiological solution. Then, the samples were analyzed using a scanning electron microscope (SEM) and X-ray diffraction (XRD) technique to study the morphology and structure of the compounds before and after placement in biological solutions. Additionally, a wettability and antibacterial test were performed on the nanocomposite specimen. The SEM observations reveal that this method can create a porous structure with a porosity of about 30–50 μm with a spherical and circular architecture, which was further improved by the addition of gum, reducing the percentage of porosity and improving the tissue's tensile strength and elastic modulus. The porosity changes showed a decrease from 72 % to 60 %, and the tensile strength increased from 53.5 kPa to 76 kPa, resulting in an elastic modulus of 510 kPa to 800 kPa. The addition of gum also reduced the rate of destruction of the biological tissue, making it more suitable for soft tissue applications. The obtained results of the pH test showed that the concentration changes were neutral. The contact angle of water droplets was measured to determine hydrophilicity, indicating an improvement in hydrophilicity after the addition of gum. The results showed that the use of PVA and gelatin, due to their ductility and suitable mechanical properties, along with Arabian gum-HA, could accelerate the healing process of dental periodontal problems.

Atomistic insight of torsional behavior of CNT-nanocrystalline Al nanocomposites

In this study, the deformation behavior of nanocrystalline (NC) Al and carbon nanotube (CNT) reinforced NC Al nanocomposite specimens (CNT-NC Al NCs) have been inspected under torsional loading using molecular dynamics (MD) simulations. Torsional loading on the specimens has been applied using a constant twist rate (2°/ps) relative to either end of the specimen. The evolution of grain structure at the nanoscale, the changes in crystal structure at the atomic scale, and their correlation with potential energy are investigated at different stages of torsional deformation. The fracture path for NC Al and CNT-NC Al NCs is seen along the grain boundary, and the CNT fracture process in torsion is similar to tension. The (30) CNT-NC Al NC specimen has unveiled higher torsional failure strength of 69.6 % than NC Al without the CNT specimen. The interaction of the activated slip planes, stacking faults, and dislocation motion with the Burger vector have been discussed in detail during torsion deformation. The correlation between defect evolution with strain contour has also been discussed in this paper.

Mechanical and Electrical Properties and Electromagnetic-Wave-Shielding Effectiveness of Graphene-Nanoplatelet-Reinforced Acrylonitrile Butadiene Styrene Nanocomposites

Polymer nanocomposites have attracted global attention as a metal replacement for electrical and electronic applications. Graphene nanoplatelets (GNPs) are widely used as a nanoreinforcement to enhance the functional and structural properties of thermoset and thermoplastic polymers. In the present study, ABS nanocomposites were prepared by reinforcing 3–15 wt.% GNPs in steps of 3 wt.%. The neat ABS and ABS+GNP nanocomposite specimens for the mechanical test were prepared using injection molding, followed by extrusion, as per American Society for Testing and Materials (ASTM) standards. It was found that the modulus of ABS improved due to the reinforcement of GNPs. Additionally, we noticed higher thermal stability of nanocomposites due to the faster heat-conducting path developed in the nanocomposites by the presence of GNPs. However, observed agglomeration of GNPs at higher concentrations and poor wetting with ABS led to the deterioration of the mechanical properties of the nanocomposites. Moreover, 350 µm thick nanocomposite films were manufactured by compression molding, followed by the extrusion method, and we investigated their electrical conductivity, magnetic permeability, permittivity, and electromagnetic-wave-shielding effectiveness. The developed nanocomposites showed improved conductivity and effective electromagnetic wave shielding by absorption. The 15 wt.% GNP-reinforced ABS composite film showed a maximum shielding effectiveness of 30 dB in the X-band.