Shear Exfoliation Of Graphite Research Articles

From shear exfoliation of graphite in Coca-Cola® to few-layer graphene for smart ink

Liquid-phase exfoliation of few-layer graphene in Coca-Cola ® was performed by a kitchen blender for rapid preparation of strain/light/humidity sensitive ink. The advantages of Coca-Cola as an exfoliating medium have been identified from the low structural defect (ID/IG = 0.39) and, moderate carbon to oxygen ratio (C/O = 2.6) obtained by the resulting graphene. It is discovered that a deposition of graphene on photo paper allowed a facile fabrication of smart paper that is able to detect minor strain (0 – 2.0%) with GF of 18.7. Meanwhile, the multi-responsiveness of ink towards light/humidity had been validated from the 10 s response time after the exposure to stimulants with the maximum resulting curvature degree of 16° and 14° under light and humidity changes, respectively. Finally, it is shown that our actuator is able to vertically lift a load (545 mg) from its initial flat position upon irradiation of light (200 mW/cm2).

Combination of few-layer graphene and commercial cosmetic film for tetrahydrofuran-sensitive smart film

A shear exfoliation of graphite in Arabic gum solution is one of the interesting non-toxic methods for production of few-layer graphene. While the utilization of Arabic-based graphene is mainly as conductive ink for inkjet or screen printing of circuit for sensing or electronic device, it is noted that there is lack of works reporting on the role of this polysaccharide class-based graphene for smart vapour-driven sensing film. In this brief report, the effect of Arabic gum/graphene presence on the cosmetic oil control film (Clean and Clear®) for bending-unbending performance of vapour-driven film was investigated. It is discovered that the film was able to complete a bending cycle within 13 s while the maximum recorded bending radius was measured at 0.48 cm after exposure to tetrahydrofuran (THF) in controlled environment condition (50%rh and 25 °C). By controlling the distance between THF source and the smart film, we further show the crawling motion of this film that resembling leech with a speed of 0.5 cm/48 s.

Low Operating Voltage Carbon-Graphene Hybrid E-textile for Temperature Sensing.

Graphene-coated polypropylene (PP) textile fibers are presented for their use as temperature sensors. These temperature sensors show a negative thermal coefficient of resistance (TCR) in a range between 30 and 45 °C with good sensitivity and reliability and can operate at voltages as low as 1 V. The analysis of the transient response of the temperature on resistance of different types of graphene produced by chemical vapor deposition (CVD) and shear exfoliation of graphite (SEG) shows that trilayer graphene (TLG) grown on copper by CVD displays better sensitivity due to the better thickness uniformity of the film and that carbon paste provides good contact for the measurements. Along with high sensitivity, TLG on PP shows not only the best response but also better transparency, mechanical stability, and washability compared to SEG. Temperature-dependent Raman analysis reveals that the temperature has no significant effect on the peak frequency of PP and expected effect on graphene in the demonstrated temperature range. The presented results demonstrate that these flexible, lightweight temperature sensors based on TLG with a negative TCR can be easily integrated in fabrics.

Shear exfoliation of graphite into graphene nanoflakes directly within polyetheretherketone and a spectroscopic study of this high modulus, lightweight nanocomposite

This research demonstrates a general approach to produce graphene enhanced polymer matrix composites (G-PMCs) using in situ shear exfoliation of mined graphite directly within molten thermoplastic polymer. It is found that shear exfoliation of 35 wt % graphite within polyetheretherketone (PEEK) after multipass processing creates graphene nanoflakes (GNFs) that are uniformly distributed and bonded to PEEK, resulting in a nearly 400% increase in tensile modulus. Morphology images show surface crystallization of PEEK on GNF surfaces, very good planar adhesion, and size reduction of GNFs in both the c-axis direction and in diameter due to fracture across the basal plane. Spectroscopic analysis from Raman and XPS spectra indicate in-situ formation of chemical bonding between created GNFs and PEEK. This shear exfoliation melt-mixing method allows high GNF concentration, intimate particle-matrix interaction, in situ functionalization, and provides a platform changing technology for lightweight, stiff PMCs with low raw materials costs, tunable properties, and simple part fabrication methods.

Kinetics of liquid-phase shear exfoliation of graphite in synthetic oils

Lubricants modified with nanosized particles are of great interest to science and industry, since they have much better tribological characteristics compared to traditional lubricants. One of the most promising nanoparticles is graphene, which has an extremely low coefficient of friction, is very wear-resistant and environmentally friendly. Today, the main problem for the development of a new nano-lubricant is the creation of an environmentally friendly and cheap technology for the industrial production of graphene suspensions or graphene concentrates for the modification of traditional lubricants. The article describes the process of liquid-phase shear exfoliation of graphite in a rotary apparatus with moving blades, in synthetic oils. The kinetic dependences of the exfoliation process, i.e. the dependence of the concentration of graphene nanostructures in suspension over time at different values of the process parameters. It has been experimentally proved that using a stator-rotor mixer with moving blades, it is possible to obtain graphene nanostructure concentrations of at least 2 mg / ml.

Preparation and Effects of Shear Exfoliated Multilayer graphene on the Viscosity of Sodium Carboxymethyl Cellulose (NaCMC) polymer

Sodium Carboxymethyl Cellulose (NaCMC) is a water-soluble polymer which is widely used as a thickener, stabilizer and viscosity modifier in different industries. As temperature increases, the length of the polymer chain of NaCMC decreases and viscosity of its solution drops sharply. In this paper, multilayer graphene sheets were produced by shear exfoliation of graphite in water/surfactant (Triton X-100) solution and NaCMC was dissolved in the obtained dispersion. The results show that shear exfoliated graphene (SEG) sheets do not affect the initial viscosity of NaCMC polymer solution, while they can dramatically prevent thermal degradation and reduction of after heat aging viscosity. This improved thermal stability not only occurs in low salinity solutions but also in saturated salt solutions. Also, results indicate that by increasing the duration of shear exfoliation process, after heat aging viscosity of NaCMC solutions increases. Finally, Alfalfa extract and Alkyl polyglycoside (APG0810), two eco-frie...

High shear-induced exfoliation of graphite into high quality graphene by Taylor–Couette flow

A scalable method to produce high-quality graphene by shear-exfoliation of graphite is presented. High shear mixing of graphite in the Taylor vortex flow regime allows for the bulk production of few-layer graphene with low content of defects.