scholarly journals Effect of exfoliated graphite nanoplatelets on the fracture surface morphology and the electrical resistivity of phenylethynyl-terminated polyimide

2012 ◽  
Vol 13 (2) ◽  
pp. 121-125 ◽  
Author(s):  
Dong-Hwan Cho ◽  
Hiroyuki Fukushima ◽  
Lawrence T. Drzal
Keyword(s):  
Electrical Resistivity ◽  
Fracture Surface ◽  
Surface Morphology ◽  
Exfoliated Graphite ◽  
Fracture Surface Morphology ◽  
Graphite Nanoplatelets ◽  
Exfoliated Graphite Nanoplatelets

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.

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.

Kinetic Adsorption of Humic Acids Mixture Obtained from Microalgae on Exfoliated Graphite Nanoplatelets

2018 ◽  
Vol 69 (1) ◽  
pp. 191-195
Author(s):  
Elena Radu ◽  
Elena Emilia Oprescu ◽  
Cristina Emanuela Enascuta ◽  
Catalina Calin ◽  
Rusandica Stoica ◽  
...  
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Alkali Treatment ◽  
Exfoliated Graphite ◽  
Acid Mixture ◽  
Acidic Ph ◽  
Graphite Nanoplatelets ◽  
Mixture Concentration ◽  
Ft Ir ◽  
Exfoliated Graphite Nanoplatelets

The dehydration of polysaccharides fraction in the presence of acid catalysts, is a chemical process in which results as secondary product humic matter. In our work, the humic acid mixture was for the first time based on our knowledge extracted from defatted microalgae biomass rich in polysaccharides by standard alkali treatment, followed by precipitation at acidic pH. The dried humic acid mixture has been characterized using infrared spectroscopic measurements (FT-IR). Exfoliated graphite nanoplatelets (xGnP) were used as new adsorbents for this type of humic acids mixture, their adsorption being investigated. The effect of several parameters such as: contact time, concentration of humic acid mixture, concentration of xGnP, temperature and pH of the solutions were studied. The process of adsorption took place with good results, in the following conditions: at a concentration of humic acid mixture of 18.6 mg L-1, an xGnP amount of 0.01 mg in 25 mL of solution, at a temperature of 25 �� and at acidic pH values, in aqueous solution.

Effect of peanut and walnut shells powders on tensile properties and morphological test by using heat cured PMMA as a matrix for prosthetic Denture

2021 ◽  
Vol 39 (2A) ◽  
pp. 196-205
Author(s):  
Zainab M. Abdul Monem ◽  
Jawad K. Oleiwi ◽  
Qahtan A. Hamad
Keyword(s):  
Fracture Surface ◽  
Surface Morphology ◽  
Matrix Material ◽  
Weight Fraction ◽  
Fracture Surface Morphology ◽  
Ductile Materials ◽  
Walnut Shells ◽  
Peanut Shells ◽  
The Matrix ◽  
Material Powder

In the current Research , the heat cured   matrix material powder of PMMA was reinforced with peanut and walnut shells (natural powders) which are chemically treated with 5% (w/v) (NaOH) to improve the matrix bonding (PMMA) before being used as a reinforcing powder and adding to exactly similar averages particle sizes ≤ (53µm), with different weight fractions of (4, 8, and 12 wt.%). The ASTM D638 is used for composite specimens of the tensile test. The results indicated that the Elastic modulus values reached its maximum value at (8 wt.%.) when reinforced with peanut shells particles (1.053Gpa) , while ,the values of tensile strength, elongation percentage at break, decrease as the weight fraction of peanut and walnut shells powder increase and the lowest values is obtained by reinforcing with peanut shells particles to reach their minimum values at (12 wt.%.) where the lowest values of them are (29 MPa, 2.758% ) respectively. The fracture surface morphology of pure PMMA seemed to be homogenous morphology in (SEM) test, whereas the fracture surface morphology of PMMA composite reinforced by (peanut and walnut shells) powders and shows a roughness fracture surface morphology this refer to semi ductile to ductile materials.

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.

Performance Evaluation of Minimum Quantity Lubrication With Exfoliated Graphite Nanoplatelets in Turning Titanium Alloy

2018 ◽  
Author(s):  
Dinh Nguyen ◽  
Pil-Ho Lee ◽  
Yang Guo ◽  
Patrick Kwon ◽  
Kyung-Hee Park
Keyword(s):  
Minimum Quantity Lubrication ◽  
Exfoliated Graphite ◽  
Experimental Result ◽  
Graphite Nanoplatelets ◽  
Crater Wear ◽  
Minimum Quantity ◽  
Preliminary Experimental Result ◽  
Tribological Surfaces ◽  
Exfoliated Graphite Nanoplatelets ◽  
Carbide Inserts

This paper evaluates the performances of dry, minimum quantity lubrication (MQL) and MQL with nanofluid in turning the most common titanium (Ti) alloy, Ti-6Al-4V, in a solution treated and aged (STA) microstructure. In particular, the nanofluid evaluated here is vegetable oil (rapeseed) mixed with small concentrations of exfoliated graphite nanoplatelets (xGnP). The focus of this paper is on turning process because it poses a challenging condition to apply oil droplets directly onto the tribological surfaces of a cutting tool due to the continuous engagement of tool and work material. A series of turning experiments was conducted with uncoated carbide inserts while measuring the cutting forces with the dynamometer under various conditions to determine its effectiveness and optimal MQL condition in turning. The worn inserts are retrieved to measure flank and crater wear using confocal microscopy. This preliminary experimental result shows that the use of MQL and nanofluid is effective in improving the machinability of Ti alloys in turning processes.

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