The extensive development of electronic systems and telecommunications has lead to major concerns regarding electromagnetic pollution. Motivated by environmental questions and by a wide variety of applications, the quest for materials with high efficiency to mitigate electromagnetic interferences (EMI) pollution has become a mainstream field of research. This paper reviews the state-of-the-art research in the design and characterization of polymer/carbon based composites as EMI shielding materials. After a brief introduction, in Section 1, the electromagnetic theory will be briefly discussed in Section 2 setting the foundations of the strategies to be employed to design efficient EMI shielding materials. These materials will be classified in the next section by the type of carbon fillers, involving carbon black, carbon fiber, carbon nanotubes and graphene. The importance of the dispersion method into the polymer matrix (melt-blending, solution processing, etc.) on the final material properties will be discussed. The combination of carbon fillers with other constituents such as metallic nanoparticles or conductive polymers will be the topic of Section 4. The final section will address advanced complex architectures that are currently studied to improve the performances of EMI materials and, in some cases, to impart additional properties such as thermal management and mechanical resistance. In all these studies, we will discuss the efficiency of the composites/devices to absorb and/or reflect the EMI radiation.

Polymer/carbon based composites as electromagnetic interference (EMI) shielding materials

Besides the excellent high-temperature mechanical properties, Si3N4 and SiC based ceramics containing insulating or electrically conductive phase are attractive for their tunable dielectric propert...

Electromagnetic properties of Si–C–N based ceramics and composites

Novel foam composites comprising functionalized graphene (f-G) and polyvinylidene fluoride (PVDF) were prepared and electrical conductivity and electromagnetic interference (EMI) shielding efficiency of the composites with different mass fractions of f-G have been investigated. The electrical conductivity increases with the increase in concentration of f-G in insulating PVDF matrix. A dramatic change in the conductivity is observed from 10−16 S · m−1 for insulating PVDF to 10−4 S · m−1 for 0.5 wt.% f-G reinforced PVDF composite, which can be attributed to high-aspect-ratio and highly conducting nature of f-G nanofiller, which forms a conductive network in the polymer. An EMI shielding effectiveness of ≈20 dB is obtained in X-band (8–12 GHz) region and 18 dB in broadband (1–8 GHz) region for 5 wt.% of f-G in foam composite. The application of conductive graphene foam composites as lightweight EMI shielding materials for X-band and broadband shielding has been demonstrated and the mechanism of EMI shielding in f-G/PVDF foam composites has been discussed.

Functionalized Graphene–PVDF Foam Composites for EMI Shielding†

We report a facile scale-up process to fabricate a novel type of hybrid paper electrode composed of reduced graphene oxide (RGO), polypyrrole (PPy) and cellulose. Through the optimization of preparation parameters (including the processes of in situ polymerization of pyrrole and chemical reduction of graphene oxide by using NaBH4), the fabricated hybrid paper had an extremely low sheet resistance of 1.7 Ω sq−1. Also, the hybrid paper possessed favorable mechanical flexibility and outstanding conductance stability. When the paper was evaluated as a free-standing and binder-free supercapacitor electrode, the unique construction (i.e., the cellulose fiber frame supporting interpenetrated RGO–PPy nanoacrhitectures) endowed it with high electrochemical activity, such as high areal capacitance of 1.20 F cm−2 at 2 mA cm−2 and good cycling stability with a capacitance retention of 89.5% after cycling 5000 times, which was tested in a three-electrode configuration. In addition, an all-solid-state laminated symmetric supercapacitor was prepared by assembling two pieces of hybrid paper electrodes and using a H3PO4/PVA gel as the electrolyte. The solid-state supercapacitor had a high areal capacitance of 0.51 F cm−2 at 0.1 mA cm−2 and a high energy density of 1.18 mW h cm−3. These results suggest that the hybrid paper is a promising electrode material and may be useful for the development of flexible high-performance and hand-held energy storage devices. More importantly, this work provides a good reference for the fabrication of other types of hybrid paper electrodes.

Flexible, highly conductive, and free-standing reduced graphene oxide/polypyrrole/cellulose hybrid papers for supercapacitor electrodes

Graphene/cellulose nanocomposite paper with high mechanical and electrical performances was reported in this study by combining reduced graphene oxide sheets (RGO) and amine-modified nanofibrillated cellulose (A-NFC) in a well-controlled manner. By adjusting the GO content, various graphene/cellulose nanocomposites with 0.1–10 wt% content of graphene were obtained. The RGO/A-NFC nanocomposite synthesized by the developed method exhibits an electrical percolation threshold of 0.3 wt% with an electrical conductivity of 4.79 × 10−4 S m−1, which is well above the antistatic value. Furthermore, with 10 wt% of graphene, a high conductivity of 71.8 S m−1 was measured for the nanocomposite. Moreover, it was found that on addition of only 0.3 wt% of graphene, the tensile strength increased by 1.2 fold and 2.3 folds compared to that of the neat cellulose and graphene oxide paper, respectively, revealing an excellent reinforcement of graphene sheets. Moreover, the elongation at break of the composite with graphene content was 8.5%, which is similar to that of A-NFC paper and much higher than that of GO paper. It is noteworthy to mention that with 5 wt% of graphene, the RGO/A-NFC composite paper showed a significantly enhanced tensile strength of 273 MPa that is 1.4 fold and 2.8 folds higher than that of the cellulose papers and graphene oxide paper, respectively. Such a high enhancement of electrical and mechanical properties in cellulose paper by graphene has never been reported before for any carbon-based material/cellulose composite paper.

Graphene/cellulose nanocomposite paper with high electrical and mechanical performances

https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/43921/1/CST70-10_1564-1570.pdf

Highly strong and conductive carbon nanotube/cellulose composite paper

We fabricated multiwalled carbon-nanotube/cellulose composite papers and measured their temperature dependences of electrical conductivity. The dependences were described with the Sheng’s fluctuation-induced tunneling (FIT) model. A possible mechanism of the electrical conduction in the composite paper was discussed in the context of the FIT model.

/pdf/electrical-conductivity-of-carbon-nanotube-cellulose-tp3e5ke19f.pdf

Electrical conductivity of carbon-nanotube/cellulose composite paper

Low-frequency noise characteristics for carbon-nanotube (CNT)/cellulose composite paper were experimentally investigated. The measured low-frequency noise exhibited 1/f characteristics and can be explained by Hooge's empirical law. Large noise coefficients suggested that CNT–CNT junctions, not the CNTs themselves, are the dominant source of 1/f noise in the composite paper.

Kousuke Akiyama

Papers

Highly strong and conductive carbon nanotube/cellulose composite paper

Electrical conductivity of carbon-nanotube/cellulose composite paper

Low-Frequency Noise in Carbon-Nanotube/Cellulose Composite Paper