Tuning the electromagnetic interference shielding performance of polypropylene cellular nanocomposites: Role of hybrid nanofillers of MXene and reduced graphene oxide

Electromagnetic interference (EMI) is deemed a disruptive influence on electronically-operated devices and human health, which can cause catastrophic and sometimes irreversible damage. To mitigate such a hindrance, cellular-based polymer nanocomposites, comprising conductive nanofillers, are considered a viable solution and have been shown to exhibit significant potential due to absorption dominancy of EM waves. Herein, we designed both solid and cellular nanocomposite based on polypropylene grafted maleic anhydride (PP-g-MA) comprising various contents of single MXene, as well as hybrid MXene/reduced graphene oxide (MXene/rGO) nanolayers and investigated their EMI shielding performance to systematically assess the influence of hybridization. The influence of including MXene and rGO on microstructure and morphology of PP nanocomposite foams was evaluated, and a correlation between microcellular structure and nanofiller loading was established. Electrical conductivity test showed an increase of conductivity in both types of nanocomposite samples comparing to the pristine PP. A considerable improvement resulted in the EMI shielding effectiveness (EMI SE) of solid hybrid samples at a constant weight percentage of 7 wt% using a 2:1 ratio of MXene to rGO compared to a sample comprising a 1:1 ratio of the nanofillers. When the MXene:rGO content was 10 wt.%, SEA contributed to SET by 83%, while for the cellular nanocomposites, SEA's contribution to SET raised to 92%. Finally, an appropriate improvement occurred in the case of compressive strength of both single- and hybrid-incorporated nanocomposites as a result of robust interactions between the fillers and PP chains. The present study demonstrates that the fabricated hybrid cellular system can act as a successful EMI shielding material, and can stand as a potential candidate for various EMI shielding applications

Real-time 14N NQR-based sodium nitrite analysis in a noisy field

Noise and Radio-frequency interference or RFI causes a significant restriction on the Free induction Decay or FID signal detection of the Nuclear Quadrupole Resonance procedure. Therefore, using this method in non-isolated environments such as industry and ports requires extraordinary measures. For this purpose, noise reduction algorithms and increasing signal-to-noise-and-interference ratio or SNIR have been used. In this research, sodium nitrite has been used as a sample and algorithms have been tested in a non-isolated environment. The resonant frequencies for the 150 g of test sample were measured at 303 K at about 1 MHz and 3.4 MHz. The main novelty in this study was, (1) using two types of antennas in the receiver to improve adaptive noise and interference cancellation, (2) using a separate helical antenna in the transmitter to eliminate the duplexer, (3) estimating the noise before sending the pulse to calculate the weighting factors and reduce the noise by adaptive noise cancellation, (3) reject the interference by blanking algorithm, (4) pulse integration in the frequency domain to increase the SNR, and (5) increasing the detection speed by new pulse integration technique. By interference rejection and noise cancellation, the SNIR is improved to 9.24 dB at 1 MHz and to 7.28 dB at 3.4 MHz, and by pulse integration 44.8 dB FID signal amplification is achieved, and the FID signals are detected at 1.057 MHz and 3.402 MHz at room temperature