A strain sensor has been fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers. The piezoresistivity
of this nanocomposite strain sensor has been investigated based on an improved three-dimensional (3D) statistical resistor network
model incorporating the tunneling effect between the neighboring carbon nanotubes (CNTs), and a fiber reorientation model. The
numerical results agree very well with the experimental measurements. As compared with traditional strain gauges, much higher sensitivity
can be obtained in the nanocomposite sensors when the volume fraction of CNT is close to the percolation threshold. For a small
CNT volume fraction, weak nonlinear piezoresistivity is observed both experimentally and from numerical simulation. The tunneling
effect is considered to be the principal mechanism of the sensor under small strains.

Tunneling effect in a polymer/carbon nanotube nanocompositestrain sensor

Lightweight, ultrathin, and flexible electromagnetic interference (EMI) shielding materials are needed to protect electronic circuits and portable telecommunication devices and to eliminate cross-talk between devices and device components. Here, we show that a two-dimensional (2D) transition metal carbonitride, Ti3CNTx MXene, with a moderate electrical conductivity, provides a higher shielding effectiveness compared with more conductive Ti3C2Tx or metal foils of the same thickness. This exceptional shielding performance of Ti3CNTx was achieved by thermal annealing and is attributed to an anomalously high absorption of electromagnetic waves in its layered, metamaterial-like structure. These results provide guidance for designing advanced EMI shielding materials but also highlight the need for exploring fundamental mechanisms behind interaction of electromagnetic waves with 2D materials.

https://science.sciencemag.org/content/sci/369/6502/446.full.pdf

Anomalous absorption of electromagnetic waves by 2D transition metal carbonitride Ti3CNTx (MXene)

Overview of carbon nanostructures and nanocomposites for electromagnetic wave shielding

In order to ensure the operational reliability and information security of sophisticated electronic components and to protect human health, efficient electromagnetic interference (EMI) shielding materials are required to attenuate electromagnetic wave energy. In this work, the cellulose solution is obtained by dissolving cotton through hydrogen bond driving self-assembly using sodium hydroxide (NaOH)/urea solution, and cellulose aerogels (CA) are prepared by gelation and freeze-drying. Then, the cellulose carbon aerogel@reduced graphene oxide aerogels (CCA@rGO) are prepared by vacuum impregnation, freeze-drying followed by thermal annealing, and finally, the CCA@rGO/polydimethylsiloxane (PDMS) EMI shielding composites are prepared by backfilling with PDMS. Owing to skin-core structure of CCA@rGO, the complete three-dimensional (3D) double-layer conductive network can be successfully constructed. When the loading of CCA@rGO is 3.05 wt%, CCA@rGO/PDMS EMI shielding composites have an excellent EMI shielding effectiveness (EMI SE) of 51 dB, which is 3.9 times higher than that of the co-blended CCA/rGO/PDMS EMI shielding composites (13 dB) with the same loading of fillers. At this time, the CCA@rGO/PDMS EMI shielding composites have excellent thermal stability (THRI of 178.3 °C) and good thermal conductivity coefficient (λ of 0.65 W m-1 K-1). Excellent comprehensive performance makes CCA@rGO/PDMS EMI shielding composites great prospect for applications in lightweight, flexible EMI shielding composites.

/pdf/lightweight-flexible-cellulose-derived-carbon-aerogel-3ulu34sed9.pdf

Lightweight, Flexible Cellulose-Derived Carbon Aerogel@Reduced Graphene Oxide/PDMS Composites with Outstanding EMI Shielding Performances and Excellent Thermal Conductivities.

Microwave absorption enhancement of porous C@CoFe2O4 nanocomposites derived from eggshell membrane

Flexible, mechanically resilient carbon nanotube composite films for high-efficiency electromagnetic interference shielding

Real-time cure behaviour monitoring of polymer composites using a highly flexible and sensitive CNT buckypaper sensor

Monitoring the glass transition temperature of polymeric composites with carbon nanotube buckypaper sensor

The graphene platelets (GnPs)/epoxy flexible sensor with high sensitivity and linear can be used to monitor the deformation and damage in structural composites. The dispersion of GnPs in an epoxy matrix was better improved by optimizing ultrasonic time and using the ball mill mixing process. The GnPs/epoxy mixture exhibited relatively low percolation threshold of 0.76 vol.% and its analysis model was analyzed. In this paper, GnPs/epoxy mixture with GnPs loading of 1.00 vol.% was selected as damage detecting and strain sensor, and the characteristics of sensor was demonstrated via various mechanical tests. The monotonic tensile results suggested that there are two different linear change sensing stages, (0–5000μe) and (5000–16700μe), and it exhibits relatively high gauge factor (GF) of 6.5 and 11.6 in different sensing stages. The linear relationship and sensitivity were recoverable and stable upon loading and unloading tensile test. And the gauge factors upon loading and unloading test agree with the GF in monotonic tensile test. The GnPs/epoxy flexible sensor show promising applications for the damage monitoring of structural composite in the field of aerospace.

Duo Chen

Papers

Flexible, mechanically resilient carbon nanotube composite films for high-efficiency electromagnetic interference shielding

Real-time cure behaviour monitoring of polymer composites using a highly flexible and sensitive CNT buckypaper sensor

Monitoring the glass transition temperature of polymeric composites with carbon nanotube buckypaper sensor

Health monitoring for composite materials with high linear and sensitivity GnPs/epoxy flexible strain sensors

Monitoring the manufacturing process of glass fiber reinforced composites with carbon nanotube buckypaper sensor