Graphene Nanoplatelets Composites Research Articles

Microstructure and mechanical properties of boron carbide/graphene nanoplatelets composites fabricated by hot pressing

In this study, boron carbide (B4C)-graphene nanoplatelets (GNPs) composites, with enhanced strength and toughness, were fabricated by hot pressing at 1950 °C under a pressure of 30 MPa for 1 h. Microstructure analysis revealed that the GNPs are homogenously dispersed within the B4C matrix. Raman spectroscopy and electron microscopy showed the orientation of the GNPs in the composites. The effects of the amount of GNPs on the microstructure and mechanical properties of the composites were also investigated. The optimal mechanical properties were achieved using 1 wt% GNPs. The relative density, Vickers hardness, flexure strength, and fracture toughness of the B4C-GNPs composite ceramic were found to be 99.12%, 32.8 GPa, 508 MPa, and 4.66 MPa m1/2, respectively. The main toughening mechanisms included crack deflection in three dimensions, GNPs pull-out, and crack bridging. The curled and semi-wrapped GNPs encapsulated individual B4C grains to resist GNPs pull-out and to deflect propagating cracks.

Investigation on Mechanical Properties and Microstructure of B4C/Graphene Binary Particles Reinforced Aluminum Hybrid Composites

In the present study, boron carbide and graphene-reinforced aluminum hybrid composites with various boron carbide (1, 3, 6, 9, 12, 15, 30 wt%) and graphene nanoplatelets (GNPs) content (0.15, 0.30, 0.45 wt%) were produced by the powder metallurgy method. The method consists of mixing, ultrasonic dispersing, mixing, filtering, drying, pressing, and sintering processes. The apparent density, compressive strength, and Vickers hardness of the fabricated composites were determined by density meter, universal test machine, and micro Vickers hardness measurement device, respectively. The phase and microstructural analysis of the fabricated composites were analyzed using an X-ray diffraction device and scanning electron microscope, respectively. The maximum apparent density (2.54 ± 0.005 g/cm3), the highest Vickers hardness (109.8 ± 1.5 HV), the best compressive strength (244 ± 5 MPa), and minimum porosity (4.0%) were obtained at Al-30%B4C-0.15%GNPs composite. The enhancement in Vickers hardness and compressive strength of Al-30%B4C-0.15%GNPs composite was detected as + 293% and + 190% compared with pure aluminum. In conclusion, it was detected that the mechanical strength of Al-30B4C-GNPs composites improved up to 0.15 wt%GNPs content. After 0.15 wt%graphene content, the mechanical strength of Al-30B4C-GNPs composites decreased due to the agglomerated graphene nanoparticles.

Segregated poly(arylene sulfide sulfone)/graphene nanoplatelet composites for electromagnetic interference shielding prepared by the partial dissolution method.

Segregated conductive polymer composites have been proved to be outstanding electromagnetic interference shielding (EMI) materials at low filler loadings. However, due to the poor interfacial adhesion between the pure conductive filler layers and segregated polymer granules, the mechanical properties of the segregated composites are usually poor, which limit their application. Herein, a simple and effective approach, the partial dissolution method, has been proposed to fabricate segregated poly(arylene sulfide sulfone) (PASS)/graphene nanoplatelet (GNP) composites with superior EMI shielding effectiveness (SE) and high tensile strength. Morphology examinations revealed that the GNPs were restricted in the dissolved outer layer by the undissolved cores, and there was a strong interaction between the PASS/GNP layer and the pure PASS core. The resultant PASS/GNP composites showed excellent electrical conductivity (60.3 S m−1) and high EMI SE (41 dB) with only 5 wt% GNPs. More notably, the tensile strength of the PASS/GNPs prepared by partial dissolution reached 36.4 MPa, presenting 136% improvement compared to that of the conventional segregated composites prepared by mechanical mixing. The composites also exhibited high resistance to elevated temperatures and chemicals owing to the use of the special engineering polymer PASS as a matrix.

Recovery Stress and Storage Modulus of Microwave-Induced Graphene-Reinforced Thermoresponsive Shape Memory Polyurethane Nanocomposites

A special class of smart material was developed using shape memory polyurethane (SMPU) elastomer and graphene nanoplatelets (GNPs) via melt-blending process using micro-compounder. The shape recovery of the developed composites was studied under microwave irradiation. The nanocomposites were developed having 0.2, 0.4, 0.6, and 0.8 phr GNPs in the SMPU matrix. The effects of GNP reinforcement on morphology, shape memory effects, and viscoelastic properties of the composites were investigated. The recovery stress of virgin SMPU increased with reinforcement and maximized on the incorporation of 0.6 phr GNPs. The deformation-induced shape memory creation process influenced significantly the recovery stress of composites as compared to virgin SMPU. The recovery stresses of SMPU at 50, 75, and 100% strain were 1.5, 1.7, and 1.9 MPa, whereas the values of GNP-SMPU composites were 3.2, 3.4, and 4.1 MPa corresponding to 0.6 phr GNP reinforcement. The value of storage modulus above the glass transition temperature of SMPU increased from 9.2 to 15.1 MPa on the addition of 0.6 phr GNPs. The peak of the damping factor, tan δ shifted toward higher temperatures with the increased GNP content. The morphological study confirms the uniform dispersion of GNPs in the SMPU matrix. The microwave-induced heating of 0.8 phr GNP composite shows 80% shape recovery in 60 s, which is faster than convectional heating.

Buckling and Frequency Responses of a Graphene Nanoplatelet Reinforced Composite Microdisk

This is the first research on the vibration and buckling analysis of a graphene nanoplatelet composite (GPLRC) microdisk in the framework of a numerical based generalized differential quadrature method (GDQM). The stresses and strains are obtained using the higher-order shear deformable theory (HOSDT). Rule of the mixture is employed to obtain varying mass density, thermal expansion, and Poisson’s ratio, while the module of elasticity is computed by modified Halpin–Tsai model. Governing equations and boundary conditions of the GPLRC microdisk are obtained by implementing Extended Hamilton’s principle. The results show that outer to inner ratios of the radius ([Formula: see text], ratios of length scale and nonlocal to thickness [Formula: see text] and [Formula: see text], and GPL weight fraction [Formula: see text] have a significant influence on the frequency and buckling characteristics of the GPLRC microdisk. Another necessary consequence is that by increasing the value of the [Formula: see text], the distribution of the displacement field extends from radial to tangent direction, especially in the lower mode numbers, this phenomenon appears much more remarkable. A useful suggestion of this research is that, for designing the GPLRC microdisk at the low value of the [Formula: see text], more attention should be paid to the [Formula: see text] and [Formula: see text], simultaneously.

Green Composites of Poly(3-hydroxybutyrate) Containing Graphene Nanoplatelets with Desirable Electrical Conductivity and Oxygen Barrier Properties.

Poly(3-hydroxybutyrate), a green polymer originating from prokaryotic microbes, has been used to prepare composites with graphene nanoplatelets (GnP) at different concentrations. The films were fabricated by drop-casting and were hot-pressed at a temperature lower than their melting point to provide the molecular chains enough energy to reorientate while avoiding melting and degradation. It was found that hot-pressing increases crystallinity and improves mechanical properties. The Young’s modulus increased from 1.2 to 1.6 GPa for the poly(3-hydroxybutyrate) (P(3HB)) films and from 0.5 to 2.2 GPa for the 15 wt % P(3HB)/GnP composites. Electrical resistivity decreases enormously with GnP concentration and hot-pressing, reaching 6 Ω sq–1 for the hot-pressed 30 wt % P(3HB)/GnP composite. Finally, the hot-pressed P(3HB) samples exhibit remarkable oxygen barrier properties, with oxygen permeability reaching 2800 mL μm m–2 day–1, which becomes 895 mL μm m–2 day–1 when 15% GnP is added to the biopolymer matrix, one of the lowest values known for biopolymers and biocomposites. We propose that these biocomposites are used for elastic packaging and electronics.

Magnesium Phosphate Cements/GNPs Composites by Combustion Synthesis and Acid-Base Reaction

Magnesium phosphate cements (MPC)/graphene nanoplatelets (GNPs) composites were fabricated by combustion synthesis and acid-base reaction. MgO/GNPs mixture powders were obtained by the combustion reaction between Mg powders and CO2 gas. The composites were prepared by mixing MgO/GNPs mixture powders with potassium dihydrogen phosphate (KH2PO4) using borax as retarder. The effect of GNPs content on mechanical and functional properties of the prepared MPC/GNPs composites was investigated. The results show that this MPC/GNPs cements mainly consisted of MgO and KMgPO4•6H2O. Moreover, the crystallinity of KMgPO4•6H2O in lower surface is better than the upper surface due to the difference of temperature. With incorporating small amounts of GNPs into MPC, the spectral absorptivity of the composite was improved to 0.95 in most spectral regions. Nevertheless, the compression strength shows little change with changing the GNPs content, which may be attributed to use coarse MgO powder as reactant. In virtue of short processing time and homogeneous distribution of GNPs, the novel fabrication provides a new route for preparing GNPs-cement based composites.

Improvement of electrocaloric properties of P(VDF-HFP)/GNPs composites for refrigerator cooling

Electrocaloric effect originally comes from the cross-coupling between temperature and polarization of dielectric materials. Poly (vinylidene fluoride)/P(VDF) and its copolymers exhibit high displacement and dielectric properties among all ferroelectric polymers with additional advantages like lightweight, flexible and low cost compared with other dielectric materials. Moreover, poly (vinylidene fluoride hexafluoroprophylene)/P(VDF-HFP) copolymers shows highest breakdown strength. P(VDF-HFP) copolymers was used as the main matrix with graphene nanoplatelets (GNPs) conducting materials as nanofillers. The P/GNPs composites thin films were prepared by solution casting method with the final thickness of 30 +/- 5 µm using N, N-dimethylformamide (DMF) as solvents. The GNPs content was varied of 0, 1, 2, 3, 4 and 5% by weight. The dielectric and electrical properties were measured by LCR meter with various frequency of 1 to 100 kHz. The structure and crystallinity were observed by XRD and DSC. The polarization as a function of external electric field was investigated by P-E loop instrument in 40 MV/m with varying temperature from room temperature to 140 °C. Furthermore, electrocaloric effect was measured by indirect method by calculating adiabatic temperature change (ΔT) with help of Maxwell relation. The experimental results show that dielectric constant of P/GNPs composites was increased by increasing the GNPs content but dielectric loss is kept constant with low loading, far away from the percolation threshold. Moreover, the ΔT of the P/GNPs composites is higher than the pure P(VDF-HFP) copolymers that leads to higher electrocaloric effect. The Increasement of the ΔT of P/GNPs composites will be discussed based on their microstructure, phase transition and crystallinity. As conclusion, adding GNPs nanofillers to P(VDF-HFP) matrix can improve dielectric constant as well as electrocaloric properties which has capability for refrigeration cooling system.

A comparative study on microstructural evolution and surface properties of graphene/CNT reinforced Al6061−SiC hybrid surface composite fabricated via friction stir processing

Abstract A comparative study on the surface properties of Al−SiC−multi walled carbon nanotubes (CNT) and Al−SiC−graphene nanoplatelets (GNP) hybrid composites fabricated via friction stir processing (FSP) was documented. Microstructural characterization reveals a more homogeneous dispersion of GNPs in the Al matrix as compared to CNTs. Dislocation blockade by SiC and GNP particles along with the defect-free interface between the matrix and reinforcements is also observed. Nanoindentation study reveals a remarkable ∼207% and ∼27% increment in surface nano-hardness of Al−SiC−GNP and Al−SiC−CNT hybrid composite compared to as-received Al6061 alloy, respectively. On the other hand, the microhardness values of Al−SiC−GNP and Al−SiC−CNT are increased by ∼36% and ∼17% relative to as-received Al6061 alloy, respectively. Tribological assessment reveals ∼56% decrease in the specific wear rate of Al−SiC−GNP hybrid composite, whereas it is increased by ∼122% in Al−SiC−CNT composite. The higher strength of Al−SiC−GNP composite is attributed to the mechanical exfoliation of GNPs to few layered graphene (FLG) in the presence of SiC. Also, various mechanisms such as thermal mismatch, grain refinement, and Orowan looping contribute significantly towards the strengthening of composites. Moreover, the formation of tribolayer by the squeezed-out GNP on the surface is responsible for the improved tribological performance of the composites. Raman spectroscopy and various other characterization methods corroborate the results.

Mechanical, tribological, and electrochemical behavior of hybrid aluminum matrix composite containing boron carbide (B4C) and graphene nanoplatelets

Abstract

Synthesis and characterization of graphene nanoplatelet-La0.7Ca0.3MnO3 composites

ABSTRACTLa0.7Ca0.3MnO3 perovskite and its composites with graphene nanoplatelet (GNP) were prepared using a wet chemical method. The structural, magnetic and magnetocaloric properties of La0.7Ca0.3MnO3: GNP composites were investigated to determine the effect of GNPs. The results of XRD analysis show that the synthesised powders can be almost indexed to pure phase orthorhombic La0.7Ca0.3MnO3. The magnetic measurements demonstrate that 0.7 and 1% GNP amounts cause an increase in the Curie temperature (TC), and for larger amounts of GNP, the TC monotonically decreases, except for the sample with 10% GNP. The results obtained from the Arrott plots show that the magnetic phase transition of the samples transforms from the first to second order with increasing GNP amount. The changes in the magnetocaloric properties are interpreted in terms of perovskite phase formations via structural analysis. The amounts of graphene nanoplatelets in the oxide powders are correlated with the observed magnetocaloric properties. The best magnetocaloric performance with the maximum magnetic entropy change of 3.99 Jkg−1K−1 and refrigeration capacity of 90 Jkg−1 was obtained at a 2 T magnetic field.

Preparation of highly thermally conductive but electrically insulating composites by constructing a segregated double network in polymer composites

Thermally conductive but electrically insulating polymer composites have drawn much attention in various applications including thermal management, electronic packing, etc. Herein, a facile method of preparing polymer composites with both excellent thermal conductivity and electrical insulation is reported. To do this, nylon 6 (PA6)/Graphene nanoplatelets (GNPs) composites were firstly prepared via melt blending, then smashed into micron particles and coated with hexagonal boron nitride (h-BN) powder via VAE resin, finally hot compress molding to form composites. Thus depending on the content of GNPs inside PA6 particles and the content of h-BN coated on the particles, the thermal and electrical conductivity of the composites could be well controlled. For instance, at the total content of fillers is 18.82 vol%, with 1.97 vol% GNPs insides PA particles and 16.85 vol% h-BN coated on the surface, almost ten times improvement of thermal conductivity (from 0.29 to 2.69 W m−1k−1) has been achieved, while still maintain an excellent electrical insulating (as low as 4.13 × 10−9 S/m). It is proposed that this double segregated filler network could provide synergistic enhancement for the thermal conductivity, while the electrical conductivity caused by GNPs could be largely cut off by h-BN filler network. More importantly, this unique structure could be well preserved even after the sample thickness was decreased into a thin film, resulting in a further increase of thermal conductivity (up to 8.96 W m−1k−1) in the flow direction. Since various thermoplastic polymers can be chosen as matrix, and different filler combination can be adopted to construct thermal conductive synergistic and electrical insulating, we believe that this work provides a facial method to fabricate highly thermally conductive composites with a low electrical conductivity.

Tailored sonochemical synthesis of V2O5|graphene nanoplatelets composites and its enhanced Li-ion insertion properties

Ultrasound-assisted surface modification of graphene nanoplatelets (GNPs) has made possible for in situ growth of V2O5 nanoparticles; homogeneously decorating inter-connected two-dimensional GNPs. The as-fabricated One-Step V2O5|GNPs nanocomposite exhibited enhanced electronic conductivity and facilitates higher Li+ ion insertion/ extraction kinetics, attained the high capacity of 297 mA h g−1 (10 mA g−1) corresponding to ∼2 Li+ ion insertion/ extraction. Consequently, the sonochemically tailored One-Step V2O5|GNPs nanocomposite delivered the specific capacity of 248 mA h g−1 at 50 mA g−1 with 83% capacity retention and 98.4% coulombic efficiency for the cycling studies. In addition, the rate capability studies were extended to One-Step V2O5|GNPs cathode at different current density from 10 to 200 mA g-1. On the other hand, the Two-Step (sonochemical synthesis of 200 nm V2O5 particles followed by its deposition on GNPs) V2O5|GNPs composite cathode yielded less specific capacity of 225 mA h g−1 (10 mA g-1) than the One-Step V2O5|GNPs nanocomposite cathode.

Fabrication and electrical properties of regenerated cellulose-loaded exfoliated graphene nanoplatelet composites

Low cost and scalable manufacturing of highly doped cellulose for enhanced multifunctional applications is still an issue. In this work, eco-friendly nanocomposites were fabricated by incorporating regenerated cellulose (RC) of 10, 30, and 50 wt% into an exfoliated graphene nanoplatelets (GNPs), resulting in the intercalation of GnPs. The thermal and electrical properties of hybrid nanocomposites were investigated. The structural property was conducted through scanning electron microscope and X-ray diffraction analyses. Strong frequency-dependent dielectric response was found due to the change of the permittivity and the loss tangent of nanocomposites by different content of RC, which is associated with the polarizations behavior. Non-elastic relaxation at the GNPs–RC chains interfacial areas in an alternating field was identified as the main cause of polarization losses among others. Detailed ferroelectric measurements provided the evidence of the ideal resistive behavior of the nanocomposites, which are confirmed by the resistivity measurements along the out-of-plane direction of the nanocomposite sheets.

The effect of graphene nanoplatelet thickness on the fracture toughness of Si3N4 composites

Si3N4 composites with 3 and 5 wt% of graphene nanoplatelet (GNP) additions were prepared by spark plasma sintering. We used both commercially available GNPs and thinner few-layer graphene nanoplatelets (FL-GNPs) prepared by further exfoliation through ball milling with melamine addition. We found that by employing thinner FL-GNPs as filler material a 100% increase in the fracture toughness of Si3N4/3 wt% FL-GNP composites (10.5 ± 0.2 MPa m1/2) can be achieved as compared to the monolithic Si3N4 samples (5.1 ± 0.3 MPa m1/2), and 60% increase compared to conventional Si3N4/3 wt% GNP composites (6.6 ± 0.4 MPa m1/2). For 5 wt% filler content the increase of the fracture toughness was near 50% for both GNP and FL-GNP fillers. The hardness of the composites decreased with increasing GNP content. However, composites reinforced with 5 wt% of FL-GNPs displayed 30% higher Vickers hardness (12.8 ± 0.2 GPa) than their counterparts comprising conventional GNP fillers (9.8 ± 0.2 GPa). We attribute the enhanced mechanical properties obtained with thinner FL-GNPs to their higher aspect ratio leading to a more homogeneous dispersion, higher interface area, as well as smaller pores in the ceramic matrix.

Highly sensitive detection of bisphenol A in real water samples based on in-situ assembled graphene nanoplatelets and gold nanoparticles composite

The in-situ assembly of well-dispersed gold nanoparticles (AuNPs) and graphene nanoplatelets (GNPs) composite was carried out. The GNPs-AuNPs composite was characterized by Raman spectroscopy, transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). GNPs-AuNPs modified glassy carbon electrode (GNPs-AuNPs/GCE) was fabricated, and its electrochemical behaviors were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The highly sensitive and selective determination of bisphenol A (BPA) at GNPs-AuNPs/GCE in sulfuric acid solution was observed by DPV. Plots of peak currents versus BPA concentrations were fitted successfully to obtain a linear relationship and a nonlinear relationship in the BPA concentration range of 5 × 10−3–100 μM and 0.05–500 nM with good coefficient of determination (R2), respectively. The limit of detection (LOD) was calculated to be 0.027 nM. The recoveries of quantitative analysis of BPA in mountain spring water and tap water at GNPs-AuNPs/GCE were in the range of 96.9%–103.3% and 97.9%–104.2%, with relative standard deviation (RSD) in the range of 0.12–1.10% and 0.48–1.78%, respectively. The GNPs-AuNPs/GCE possessed good anti-interference ability, stability, repeatability, and reproducibility. It could be used as a simple, fast and sensitive electrochemical sensor electrode for determining trace amount of BPA in water samples.

Effect of graphene nanoplatelets content on the microstructural and mechanical properties of AZ80 magnesium alloy

In general, graphene nanoplatelets (GNPs) did not entirely imparted their extraordinary properties to the particulate magnesium matrix composites (PMgMCs) due to the poor wettability between GNPs and Mg matrix alloys as well as presence of agglomerated GNPs. Therefore, in this study, microstructure and mechanical characterizations were used to investigate effect of GNPs content on the microstructural and mechanical properties of AZ80 magnesium alloy. Current study explored the potential and mechanism of GNPs in improvement of mechanical properties of PMgMCs with insight of microstructure. Therefore, AZ80 reinforced by low contents of GNPs (0.1 and 0.6 wt%) were fabricated by rheo casting followed by hot extrusion. Simultaneously enhancement of tensile properties, the strengthening and the fracture strain efficiencies were achieved in AZ80/0.1GNPs composite by cost effectiveness and simple adaptability of manufacture method which results fairly uniform distribution of GNPs. The addition of 0.1 wt% GNPs led to grain refinement (~10%), dynamic recrystallization, stronger basal texture (~750%), more dissolution of β-eutectic phase (~66%) which results more dynamic precipitates (~70%) and reduction of yield asymmetry (~23%). Compared to the AZ80 alloy, the tensile and compressive yield strengths of AZ80/0.1GNPs composite were enhanced by 40% and 15%, respectively. In both tensile and compressive testes, the effective load transfer was the most important strengthening mechanism. Also, the tensile and compressive failure strains of AZ80/0.1GNPs nanocomposite were enhanced by 50% and 37%, respectively. The uniform dispersion of GNPs, increase of non-basal slip, grain refinement, lower eutectic content and smaller discontinuous intergranular precipitates increased failure strain.

Microstructural Analysis and Mechanical Properties of Pure Al–GNPs Composites by Stir Casting Method

The present investigation deals with the microstructural and mechanical properties of pure aluminium graphene nano-platelets (GNPs) composites. The contents of GNPs were varied from 0.50 to 2 wt% in pure aluminium matrix. The composites fabrication was done through stir casting technique, and the investigations revealed that pure Al–0.5% GNPs composite displayed better mechanical properties in comparison with pure Al–1% GNPs, 1.5% GNPs and 2% GNPs composites for tensile strength and hardness test. The SEM, fractographic analysis, XRD and TEM analyses were examined to investigate the surface morphology, and phase analysis confirms that there is a uniform distribution of GNPs in the base matrix (pure Al) and results in low porosity. This leads to a considerable improvement in the mechanical properties of pure Al–0.5% GNPs compared to other weight percentages due to high surface area and curled nature of graphene and makes it potential for diverse applications.

Electrospun Poly(ethylene-co-vinyl alcohol)/Graphene Nanoplatelets Composites of Interest in Intelligent Food Packaging Applications.

Graphene nanoplatelets (GNPs) were synthetized from graphite powder and, thereafter, embedded in poly(ethylene-co-vinyl alcohol) (EVOH) fibers by electrospinning in the 0.1–2 wt.-% range. The morphological, chemical, and thermal characterization performed on the electrospun nanocomposite fibers mats revealed that the GNPs were efficiently dispersed and rolled along the EVOH fibrilar matrix up to contents of 0.5 wt.-%. Additionally, the dielectric behavior of the nanocomposite fibers was evaluated as a function of the frequency range and GNPs content. The obtained results indicated that their dielectric constant rapidly decreased with the frequency increase and only increased at low GNPs loadings while the nanocomposite fiber mats became electrically conductive, with the maximum at 0.5 wt.-% GNPs content. Finally, the electrospun mats were subjected to a thermal post-treatment and dark films with a high contact transparency were obtained, suggesting that the nanocomposites can be used either in a nonwoven fibers form or in a continuous film form. This study demonstrates the potential of electrospinning as a promising technology to produce GNPs-containing materials with high electrical conductivity that can be of potential interest in intelligent packaging applications as “smart” labels or tags.

Enhanced Electrical and Electromagnetic Interference Shielding Properties of Polymer-Graphene Nanoplatelet Composites Fabricated via Supercritical-Fluid Treatment and Physical Foaming.

Lightweight high-density polyethylene (HDPE)-graphene nanoplatelet (GnP) composite foams were fabricated via a supercritical-fluid (SCF) treatment and physical foaming in an injection-molding process. We demonstrated that the introduction of a microcellular structure can substantially increase the electrical conductivity and can decrease the percolation threshold of the polymer-GnP composites. The nanocomposite foams had a significantly higher electrical conductivity, a higher dielectric constant, a higher electromagnetic interference (EMI) shielding effectiveness (SE), and a lower percolation threshold compared to their regular injection-molded counterparts. The SCF treatment and foaming exfoliated the GnPs in situ during the fabrication process. This process also changed the GnP's flow-induced arrangement by reducing the melt viscosity and cellular growth. Moreover, the generation of a cellular structure rearranged the GnPs to be mainly perpendicular to the radial direction of the bubble growth. This enhanced the GnP's interconnectivity and produced a unique GnP arrangement around the cells. Therefore, the through-plane conductivity increased up to a maximum of 9 orders of magnitude and the percolation threshold decreased by up to 62%. The lightweight injection-molded nanocomposite foams of 9.8 vol % GnP exhibited a real permittivity of ε' = 106.4, which was superior to that of their regular injection-molded (ε' = 6.2). A maximum K-band EMI SE of 31.6 dB was achieved in HDPE-19 vol % GnP composite foams, which was 45% higher than that of the solid counterpart. In addition, the physical foaming reduced the density of the HDPE-GnP foams by up to 26%. Therefore, the fabricated polymer-GnP nanocomposite foams in this study pointed toward the further development of lightweight and conductive polymer-GnP composites with tailored properties.