Characterization of exfoliated graphite nanoplatelets/polycarbonate composites: electrical and thermal conductivity, and tensile, flexural, and rheological properties

2011 ◽  
Vol 46 (9) ◽  
pp. 1029-1039 ◽  
Author(s):  
Julia A King ◽  
Michael D Via ◽  
Faith A Morrison ◽  
Kyle R Wiese ◽  
Edsel A Beach ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Tensile Strength ◽  
Electrical Resistivity ◽  
Ultimate Tensile Strength ◽  
Flexural Strength ◽  
Rheological Properties ◽  
Flexural Modulus ◽  
Exfoliated Graphite ◽  
Graphite Nanoplatelets ◽  
Exfoliated Graphite Nanoplatelets

Exfoliated graphite nanoplatelets (GNP) can be added polymers to produce electrically conductive composites. In this study, varying amounts (2–15 wt%) GNP were added to polycarbonate (PC) and the resulting composites were tested for electrical conductivity (1/electrical resistivity), thermal conductivity, and tensile, flexural, and rheological properties. The percolation threshold was approximately 4.0 vol% (6.5 wt%) GNP. The addition of GNP to polycarbonate increased the composite electrical and thermal conductivity and tensile and flexural modulus. The 8 wt% (5.0 vol%) GNP in polycarbonate composite had a good combination of properties for electrostatic dissipative applications. The electrical resistivity and thermal conductivity were 4.0 × 107 ohm-cm and 0.37 W/m · K, respectively. The tensile modulus, ultimate tensile strength, and strain at ultimate tensile strength were 3.5 GPa, 58 MPa, and 3.5%, respectively. The flexural modulus, ultimate flexural strength, and strain at ultimate flexural strength were 3.6 GPa, 108 MPa, and 5.5%, respectively. Ductile tensile behavior is noted in pure polycarbonate and in samples containing up to 8 wt% GNP. PC and GNP/PC composites show shear-thinning behavior. Viscosity of the composite increased as the amount of GNP increased dueto a volume-filling filler effect. The viscosity of the GNP/PC composites are well described by a Kitano-modified Maron-Pierce model.

Co-milling-assisted exfoliated graphite nanoplatelets filler introduction in polyethylene and alumina composites

2018 ◽  
Vol 53 (13) ◽  
pp. 1815-1826
Author(s):  
Sheng Cai Tan ◽  
Jimmy KW Chan ◽  
Kian Ping Loh
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Composite Materials ◽  
Exfoliated Graphite ◽  
Flexural Properties ◽  
Graphite Nanoplatelets ◽  
Alumina Composites ◽  
Exfoliated Graphite Nanoplatelets ◽  
Polyethylene Composites

This paper aims to investigate the effect of co-milling-assisted exfoliation of graphite into polyethylene and alumina matrices on the mechanical properties of the composites. Tensile mechanical properties of composite materials based on polyethylene reinforced with graphite and graphite-derived fillers at 0–0.75 wt% loading were investigated, while hardness and flexural properties of alumina composites with 0.25 wt% loading of the same additives were assessed. Exfoliated graphite, applied at 0.25–0.75 wt% in pre-exfoliated form or in a co-milling-assisted fashion, has been demonstrated to be effective in enhancing the tensile strength of polyethylene composites. Similar enhancement in hardness and flexural properties was observed in alumina composites with 0.25 wt% loading of the exfoliated graphite. Co-milling-assisted exfoliated graphite nanoplatelets additive introduction has been found to effect a more desirable mechanical properties enhancement in the composites investigated in this study.

scholarly journals Mechanical properties and microstructural investigation of polypropylene/exfoliated graphite nanoplatelets/ nano-magnesium oxide composites

2018 ◽  
Vol 7 (2) ◽  
pp. 897
Author(s):  
A I. Alateyah ◽  
F H. Latief
Keyword(s):  
Mechanical Properties ◽  
Flexural Modulus ◽  
Exfoliated Graphite ◽  
Graphite Nanoplatelets ◽  
Microstructural Investigation ◽  
The Matrix ◽  
Exfoliated Graphite Nanoplatelets ◽  
Polypropylene Matrix ◽  
Xrd Patterns ◽  
Oxide Composites

Polypropylene/exfoliated graphite nanoplatelets composites reinforced with a low concentration of nano-magnesia have been successfully fabricated, using injection molding machine. The mechanical properties and microstructure of the composites were investigated, in the present study. The XRD patterns of the composites showed the peaks of xGnP and n-MgO, where the intensity of the xGnP peaks became stronger with increasing the concentration of xGnP added into polypropylene matrix. In addition, the SEM micrographs revealed a good dispersion of fillers within the matrix. The results showed that increasing the amount of exfoliated graphite nanoplatelets up to 10 wt. % resulted in increasing the composite flexural strength, flexural modulus, and hardness up to 35% and 91%, 6.7%, respectively, compared to the monolithic polypropylene.  

Thermo-electrical behaviour of cyclic olefin copolymer/exfoliated graphite nanoplatelets nanocomposites foamed through supercritical carbon dioxide

2019 ◽  
Vol 55 (3) ◽  
pp. 263-282 ◽  
Author(s):  
A Dorigato ◽  
A Biani ◽  
W Bonani ◽  
A Pegoretti
Keyword(s):  
Carbon Dioxide ◽  
Electrical Resistivity ◽  
Supercritical Carbon Dioxide ◽  
Surface Heating ◽  
Exfoliated Graphite ◽  
Cyclic Olefin Copolymer ◽  
Graphite Nanoplatelets ◽  
Cyclic Olefin ◽  
Exfoliated Graphite Nanoplatelets ◽  
Supercritical Carbon

In this work, novel electrically conductive cyclic olefin copolymer/exfoliated graphite nanoplatelets foams were prepared through a supercritical carbon dioxide treatment starting from the corresponding unfoamed materials prepared by melt compounding, in order to investigate their thermo-electrical properties. For both unfoamed and foamed samples, the exfoliated graphite nanoplatelets introduction led to a systematic enhancement of the thermal degradation temperature. Dynamic-mechanical thermal analysis revealed that the nanofiller addition promoted an enhancement of the storage modulus and of the glass transition temperature over the whole range of the applied foaming pressures. While for unfoamed materials exfoliated graphite nanoplatelets introduction determined an important decrease of the electrical resistivity, the foaming process induced the breakage of the conductive path, with a consequent increase of electrical resistivity. Evaluation of the surface heating upon voltage application showed that the surface temperature of unfoamed materials could be noticeably increased at relatively low voltage levels, while a less pronounced surface heating could be obtained with the corresponding nanocomposite foams.

Exfoliated graphite nanoplatelets/poly(arylene ether nitrile) nanocomposites

2016 ◽  
Vol 29 (10) ◽  
pp. 1121-1129 ◽  
Author(s):  
Yingqing Zhan ◽  
Zhihang Long ◽  
Xinyi Wan ◽  
Yi He ◽  
Xiaobo Liu
Keyword(s):  
Electron Microscopy ◽  
Tensile Strength ◽  
In Situ Polymerization ◽  
Decomposition Temperature ◽  
Exfoliated Graphite ◽  
Graphite Nanoplatelets ◽  
Initial Decomposition Temperature ◽  
Arylene Ether ◽  
Exfoliated Graphite Nanoplatelets

In this work, we demonstrate a method for synthesis of exfoliated graphite nanoplatelets (xGnPs)/poly(arylene ether nitrile) (PEN) nanocomposites via an efficient in situ polymerization. The GnPs were treated by the ultrasonic bath to reduce the layers of the GnPs, where the PEN were intercalated subsequently. Therefore, the dispersion of xGnP in the PEN resin was enhanced through in situ polymerization, which was characterized and confirmed by scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. It was found that the tensile strength and modulus were greatly enhanced with the addition of xGnP. For 2.5 wt% of xGnP-reinforced PEN, the tensile strength and modulus were increased to 115 MPa and 3121 MPa, respectively. Owing to the well dispersion of xGnP, the low rheological percolation of 2.5 wt% for PEN nanocomposites was obtained. Besides, with 1 wt% of xGnP, the corresponding initial decomposition temperature ( Tin) increased from 451°C in pure PEN to 470°C. The addition of xGnP showed enhanced thermal stability of PEN nanocomposites, which demonstrated a promising method for preparing advanced polymer-based nanocomposites.

scholarly journals Thermal Conductivity of a Monolayer of Exfoliated Graphite Nanoplatelets Prepared by Liquid-Liquid Interfacial Self-Assembly

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Jinglei Xiang ◽  
Lawrence T. Drzal
Keyword(s):  
Thermal Conductivity ◽  
Self Assembly ◽  
Average Particle Size ◽  
Peak Shift ◽  
Exfoliated Graphite ◽  
Average Particle ◽  
Graphite Nanoplatelets ◽  
Cross Sectional ◽  
Packed Structure ◽  
Exfoliated Graphite Nanoplatelets

A monolayer film composed of exfoliated graphite nanoplatelets (xGnPs) was extracted from a chloroform-water interface and supported on a glass substrate. The nanoplatelets are interconnected at the edges without overlapping forming a very densely packed structure with uniform thickness. Micro-Raman spectroscopy with a 50 mW 532 nm laser generating heat at the center of a xGnP sample was used to probe the thermal conductivity of the xGnP monolayer at different power levels. The Raman G peak shift of graphite was used to record the local temperature rise in the monolayer. The cross-sectional area of heat conduction is determined by the thickness of individual nanoplatelets. A UV-Vis spectrometer was used to measure the absorption of light by the monolayer. Depending on the interface density, the thermal conductivities are around 380 W/m K and 290 W/m K for monolayers with average particle size of 10 μm and 5 μm, respectively.

Enhanced Thermal Conductivity of Phase Change Materials Modified by Exfoliated Graphite Nanoplatelets

2009 ◽  
Vol 1218 ◽  
Author(s):  
Jinglei Xiang ◽  
Lawrence Drzal
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Phase Change Materials ◽  
Particle Orientation ◽  
Exfoliated Graphite ◽  
Critical Parameters ◽  
Gravimetric Analysis ◽  
Graphite Nanoplatelets ◽  
Scanning Calorimetry ◽  
Exfoliated Graphite Nanoplatelets

AbstractComposite phase change materials (PCM) were prepared by mixing exfoliated graphite nanoplatelets (xGnP) into paraffin wax. The two types of graphite nanoplatelets that were investigated were xGnP-1 having thickness of 10 nm and a diameter of 1 um and xGnP-15 having the same thickness with a platelet diameter of 15 um. Direct casting and two roll milling were used to prepare samples. Scanning electron microscopy images show that the nanofillers disperse very well in paraffin matrix without noticeable agglomeration. Paraffin/xGnP-15 PCM consistently exhibited higher thermal conductivity than xGnP-1 PCM. The improvement in thermal conductivity was as high as 5 fold for xGnP-15 composites and 2 fold for xGnP-1 composites at 4 vol%. The aspect ratio, particle orientation, and interface density between the conductive particles and the polymer matrix were found to be the critical parameters in determining the conductivities of the resulting nanocomposites. The thermal physical properties of the nanocomposites were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). It was found that the latent heat of nanocomposites was not negatively affected in the presence of xGnP particles and the thermal stability improved.

Characteristics of Exfoliated Graphite Nanoplatelets-Polyamide12 Nanocomposites Processed by Extrusion Injection Molding

2012 ◽  
Author(s):  
Mehdi Karevan ◽  
Kyriaki Kalaitzidou
Keyword(s):  
Injection Molding ◽  
Flexural Modulus ◽  
Low Frequency ◽  
Interfacial Interaction ◽  
Exfoliated Graphite ◽  
Structure Property ◽  
Graphite Nanoplatelets ◽  
Melt Mixing ◽  
Mixing Processes ◽  
Exfoliated Graphite Nanoplatelets

Melt-mixing processes such as extrusion-injection molding induce shear mechanical forces to enhance the melt blend of nanofiller-polymer and have been considered as time and cost efficient in commercial processing of polymer nanocomposites (PNCs). Extensive research has been conducted so far to investigate the overall performance of melt-processed PNCs. However there is lack of systematic studies on the nanomaterial induced phenomena that dominate the properties of the end-use melt mixing processed parts leading to engineered high quality PNCs. Furthermore, studies for exploration of the structure-property relationships in the melt processed PNCs are also limited. In this work, nanocomposites of Polyamide-12 (PA12) reinforced with exfoliated graphite nanoplatelets (xGnP™) up to 15wt% were fabricated using two different compounding techniques: coating followed by melt mixing and direct melt mixing. Effects of the compounding methods on the reinforcing efficiency of xGnP within the PA12 matrix were investigated. To understand the reinforcing mechanisms contributing to alteration of the mechanical properties, rheological behavior of the PNCs were investigated in the linear viscoelastic region and correlated with the state of nanofiller-matrix interfacial interaction and the nanofiller dispersion. The results suggest that xGnP coating of the PA12 powder resulted in improved flexural strength of the PNCs with respect to that of the pure PA12 and of PNCs made by direct melt mixing. The rheological low-frequency measurements demonstrate that addition of xGnP resulted in a larger increase in the melt dynamic viscosity of the coated-melt mixed PNCs than the direct melt-mixed ones. This suggest stronger xGnP-PA12 interfacial interaction and better dispersion state of the nanofiller in the coated-melt mixed PNCs than the latter PNCs. Addition of xGnP content resulted in improved storage modulus for PNCs made by either compounding method. However, the results support the evidence of post-processing induced re-agglomeration or suppressed dispersing efficiency of the coating process at extreme xGnP content as was elucidated through the shear thinning behavior of the melt and the flexural modulus of the highly reinforced parts.

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