Bridge effect of carbon nanotubes on the electrical properties of expanded graphite/poly(ethylene terephthalate) nanocomposites

In the present study, exfoliated graphite nanoplatelets (xGnP) with different particle sizes were coated onto polyacrylonitrile-based carbon fibers by a direct coating method. The flexural properties, interlaminar shear strength, and the morphology of the xGnP-coated carbon fiber/phenolic matrix composites were investigated in terms of their longitudinal flexural strength and modulus, interlaminar shear strength, and by optical and scanning electron microscopic observations. The results were compared with a phenolic matrix composite counterpart prepared without xGnP. The flexural properties and interlaminar shear strength of the xGnP-coated carbon fiber/phenolic matrix composites were found to be higher than those of the uncoated composite. The flexural and interlaminar shear strengths were affected by the particle size of the xGnP, while the particle size had no significant effect on the flexural modulus. It seems that the interfacial contacts between the xGnP-coated carbon fibers and the phenolic matrix play a role in enhancing the flexural strength as well as the interlaminar shear strength of the composites.

Section: Preparation Of Xgnp-coated Carbon Fibers and Carbon Fiber/phenolic Matrix Compositesmentioning

confidence: 99%

Flexural properties, interlaminar shear strength and morphology of phenolic matrix composites reinforced with xGnP-coated carbon fibers

Park¹,

Lee²,

Drzal³

et al. 2016

“…Thus, the fourth valence electron remains free in each unit, and these free electrons are delocalized over all atoms and contribute to the electrical nature of CNTs. Thus, CNTs can be conducting or semi-conducting types depending on the type of chirality [25][26][27][28][29][30][31][32][33][34][35][36][37] Semiconducting SWNTs are usually in the form of p-type semiconductors [38]. MWNTs are composed of many tubes of SWNTs and therefore are not likely to be strictly one-dimensional conductors.…”

Section: Electronic Nature Of Cntsmentioning

confidence: 99%

Carbon nanotubes-properties and applications: a review

Ibrahim¹

2013

391

122

The carbon nanotube (CNT) represents one of the most unique inventions in the field of nanotechnology. CNTs have been studied closely over the last two decades by many researchers around the world due to their great potential in different fields. CNTs are rolled graphene with SP 2 hybridization. The important aspects of CNTs are their light weight, small size with a high aspect ratio, good tensile strength, and good conducting characteristics, which make them useful as fillers in different materials such as polymers, metallic surfaces and ceramics. CNTs also have potential applications in the field of nanotechnology, nanomedicine, transistors, actuators, sensors, membranes, and capacitors. There are various techniques which can be used for the synthesis of CNTs. These include the arc-discharge method, chemical vaporize deposition (CVD), the laser ablation method, and the sol gel method. CNTs can be single-walled, double-walled and multi-walled. CNTs have unique mechanical, electrical and optical properties, all of which have been extensively studied. The present review is focused on the synthesis, functionalization, properties and applications of CNTs. The toxic effect of CNTs is also presented in a summarized form.

“…According to previous studies of MWCNT/ polymer composites, the percolation thresholds for electrical conductivity were 1-5 wt% MWCNT [11,12] by simple mixing. To reduce the MWCNT content needed in composites, a variety of methods (e.g., processing, modifications, and immiscible blending) have been attempted [4,[13][14][15]. To achieve the required properties, however, several technical issues should be resolved.…”

Section: Melt Extrusionmentioning

confidence: 99%

Characterization and influence of shear flow on the surface resistivity and mixing condition on the dispersion quality of multi-walled carbon nanotube/polycarbonate nanocomposites

Lee¹,

Yoon²

2015

Multi-walled carbon nanotube (MWCNT)/polycarbonate (PC) nanocomposite was prepared by direct melt mixing to investigate the effect of the shear rate on the surface resistivity of the nanocomposites. In this study, an experiment was carried out to observe the shear induced orientation of the MWCNT in the polymer matrix using a very simple melt flow indexer with various loads. The compression-molded, should be eliminated. MWCNT/PC nanocomposite sample exhibited lower percolation thresholds (at 0.8 vol%) and higher electrical conductivity values than those of samples extruded by capillary and injection molding. Shear induced orientation of MWCNT was observed via scanning electron microscopy, in the direction of flow in a PC matrix during the extrusion process. The surface resistivity rose with increasing shear rate, because of the breakdown of the network junctions between MWCNTs. For real applications such as injection molding and the extrusion process, the amount of the MWCNT in the composite should be carefully selected to adjust the electrical conductivity.