There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Recent advances in graphene based polymer composites

Graphene has emerged as a subject of enormous scientific interest due to its exceptional electron transport, mechanical properties, and high surface area. When incorporated appropriately, these atomically thin carbon sheets can significantly improve physical properties of host polymers at extremely small loading. We first review production routes to exfoliated graphite with an emphasis on top-down strategies starting from graphite oxide, including advantages and disadvantages of each method. Then solvent- and melt-based strategies to disperse chemically or thermally reduced graphene oxide in polymers are discussed. Analytical techniques for characterizing particle dimensions, surface characteristics, and dispersion in matrix polymers are also introduced. We summarize electrical, thermal, mechanical, and gas barrier properties of the graphene/polymer nanocomposites. We conclude this review listing current challenges associated with processing and scalability of graphene composites and future perspectives f...

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Graphene/Polymer Nanocomposites

Composite films of chemically converted graphene (CCG) and polyaniline nanofibers (PANI-NFs) were prepared by vacuum filtration the mixed dispersions of both components. The composite film has a layered structure, and PANI-NFs are sandwiched between CCG layers. Furthermore, it is mechanically stable and has a high flexibility; thus, it can be bent into large angles or be shaped into various desired structures. The conductivity of the composite film containing 44% CCG (5.5 × 102 S m−1) is about 10 times that of a PANI-NF film. Supercapacitor devices based on this conductive flexible composite film showed large electrochemical capacitance (210 F g−1) at a discharge rate of 0.3 A g−1. They also exhibited greatly improved electrochemical stability and rate performances.

Supercapacitors Based on Flexible Graphene/Polyaniline Nanofiber Composite Films

Electromagnetic interference shielding effectiveness of carbon materials

Present work deals with the reinforcement behaviour of graphene nanoplatelets (GNP) in elastomer matrix of acrylonitrile butadiene (NBR) co-polymer. The addition of 20 phr GNP in NBR matrix a significant improvement in tensile strength (∼528%), and elongation at break (∼60%) compared to neat NBR is observed. Hybrid composites of NBR filled with GNP-CB and GNP-MWCNT at judicious proportion exhibit further improvement in the mentioned properties compared to those exhibited by composites containing individual fillers at same loading. This reflects strong synergistic effect on properties by hybrid fillers. Morphological studies reveal the state of dispersion of filler in matrix polymer, and this can be correlated with property improvements. The better synergistic effect of GNP-CB hybrid filler in comparison to GNP-MWCNT for improvement in mechanical and electrical properties as well as thermal stability may be attributed to the better filler dispersion and higher polymer-filler interaction for NBR-GNP-CB hybrid system compared to NBR-GNP-MWCNT system.

Elastomer reinforcement by graphene nanoplatelets and synergistic improvements of electrical and mechanical properties of composites by hybrid nano fillers of graphene-carbon black & graphene-MWCNT

Consideration of interface polarization in the modeling of dielectric property for ethylene vinyl acetate (EVA)/polyaniline conductive composites prepared through in-situ polymerization of aniline in EVA matrix

Carbon nanotubes (CNTs)-reinforced polysulfone (PSU) nanocomposites were prepared through solution mixing of PSU and different weight percent of multi-walled carbon nanotubes (MWCNTs). Thermal properties of nanocomposites were characterized using thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA studies revealed an increase in thermal stability of the PSU/MWCNTs nanocomposites, which is due to the hindrance of the nanodispered carbon nanotubes to the thermal transfer in nanocomposites and also due to higher thermal stability of CNTs. Morphological properties of nanocomposites were characterized by high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscope (FESEM). The influence of CNTs loading on electrical properties of PSU/MWCNTs nanocomposites was studied by the measurement of AC and DC resistivity. Dielectric study of nanocomposites was carried out at different frequencies (10 Hz–1 MHz) by using LCR meter. An increase in dielectric constant and dielectric loss was observed with increase in CNTs content, which is due to the interfacial polarization between conducting CNTs and PSU.

Dipak Khastgir

Papers

Elastomer reinforcement by graphene nanoplatelets and synergistic improvements of electrical and mechanical properties of composites by hybrid nano fillers of graphene-carbon black & graphene-MWCNT

Consideration of interface polarization in the modeling of dielectric property for ethylene vinyl acetate (EVA)/polyaniline conductive composites prepared through in-situ polymerization of aniline in EVA matrix

Thermal and electrical properties of carbon nanotubes based polysulfone nanocomposites

Thermal degradation and ageing of segmented polyamides

Synthesis of conductive adhesives based on epoxy resin and polyaniline.DBSA using the in situ polymerization and physical mixing procedures