Shailaja Pande

Improved Electromagnetic Interference Shielding Properties of MWCNT-PMMA Composites Using Layered Structures.

Electromagnetic interference (EMI) shielding effectiveness (SE) of multi-walled carbon nanotubes–polymethyl methacrylate (MWCNT–PMMA) composites prepared by two different techniques was measured. EMI SE up to 40 dB in the frequency range 8.2–12.4 GHz (X-band) was achieved by stacking seven layers of 0.3-mm thick MWCNT–PMMA composite films compared with 30 dB achieved by stacking two layers of 1.1-mm thick MWCNT–PMMA bulk composite. The characteristic EMI SE graphs of the composites and the mechanism of shielding have been discussed. SE in this frequency range is found to be dominated by absorption. The mechanical properties (tensile, flexural strength and modulus) of the composites were found to be comparable or better than the pure polymer. The studies therefore show that the composite can be used as structurally strong EMI shielding material.

Mechanical and electrical properties of multiwall carbon nanotube/polycarbonate composites for electrostatic discharge and electromagnetic interference shielding applications

Home-made multiwall carbon nanotubes (MWCNTs) were used as a reinforcing conducting filler for a thermoplastic polymer, polycarbonate (PC) and the mechanical and electrical properties of the composites were investigated for electrostatic discharge (ESD) and electromagnetic interference (EMI) shielding applications. A uniformly dispersed MWCNT/PC composite system was fabricated using solvent casting and a combination of solvent casting and compression molding techniques. The effect of MWCNTs on the failure mechanism of the polymer under tensile loading showed a ductile to brittle transition with increasing amount of carbon nanotubes. ESD studies showed that the composite films of 2 and 5 wt% functionalized-MWCNT/PC with respective charge decay times of 1 and 0.6 s show promise as electrostatic dissipative materials. EMI shielding effectiveness of a five-layered system (∼2 mm thickness) of as-synthesized-MWCNT/PC composite films at 20 wt% loading reached 43 dB in the X-band (8.2–12.4 GHz). The primary mechanism of shielding was absorption, suggesting possible use as an EMI absorbing material. By using low pressure (contact pressure) compression molding the EMI shielding properties of bulk composites (∼2 mm thickness) improved by about 14 dB at 10 wt% MWCNT loading.

Graphene Quantum Dots

© D ro pS en s, S .L . | 1 .0 DropSens launches aqueous soluble Graphene Quantum Dots (GQDs) synthetized via a bottom-up method. These fluorescent nanoparticles exhibit extraordinary optical and electronic properties due to their quantum confinement and edge effects. GQDs are characterized by their chemical inertness, low toxicity biocompatibility, high fluorescent activity and excellent photostability. GQDs can be used in a wide range of applications, such as electrochemical sensors, photoluminescence sensors, electrochemiluminescence sensors and electronic sensors.

Single-Walled Carbon Nanotubes

Product Description The dispersibility and bundle defoliation of single-walled carbon nanotubes (SWCNTs), which can be applied to materials produced by the CoMoCAT process, have been extensively investigated by SouthWest NanoTechnologies (SWeNT) and at the University of Oklahoma. The procedure employed to disperse SWCNTs has a significant impact on the final suspension characteristics, including solution concentration, stability, and the fraction of individual nanotubes. Even though it is possible to obtain a stable dispersion of bundles where the majority of bundles are not exfoliated, the specific aim is to create dispersions of exfoliated tubes. A number of technical approaches, including covalent and non-covalent stabilization of SWCNTs, can be adopted to prepare a stable and homogeneous dispersion of SWCNTs. The non-covalent approach has been of particular interest since the surface structure and properties of the nanotubes remain intact when this methodology is used.