Synthesis of polyvinyl alcohol (PVA) infiltrated MWCNTs buckypaper for strain sensing application

Buckypaper (BP)/polymer composites are viewed as a viable option to improve the strain transfer across the buckypaper strain sensor by means of providing better interfacial bonding between the polymer and carbon nanotubes (CNTs). Multiwall carbon nanotubes (MWCNTs) BP/polyvinyl alcohol (PVA) composites were fabricated by a sequence of vacuum filtration and polymer intercalation technique. The optimized conditions for achieving a uniform and stable dispersion of MWCNTs were found to be using ethanol as a dispersion medium, 54?µm ultrasonic amplitude and 40?min sonication time. FTIR analysis and SEM spectra further confirmed the introduction of oxygenated groups (-COOH) on the surface of MWCNTs BP and the complete infiltration of PVA into the porous MWCNTs network. At MWCNTs content of 65 wt. %, the tensile strength, Young's modulus and elongation-at-break of PVA-infiltrated MWCNTs BP achieved a maximum value of 156.28?MPa, 4.02?GPa and 5.85%, improved by 189%, 443% and 166% respectively, as compared to the MWCNTs BP. Electrical characterization performed using both two-point probe method and Hall effect measurement showed that BP/PVA composites exhibited reduced electrical conductivity. From the electromechanical characterization, the BP/PVA composites showed improved sensitivity with a gauge factor of about 1.89-2.92. The cyclic uniaxial tensile test validated the high reproducibility and hysteresis-free operation of 65-BP/PVA composite under 3 loading-unloading cycles. Characterization results confirmed that the flexible BP/PVA composite (65 wt. %) with improved mechanical and electromechanical properties is suitable for strain sensing applications in structural health monitoring and wearable technology, as an alternative choice to the fragile nature of conventional metallic strain sensors

Adsorption

Removing of wastewater pollutants by novel adsorption techniques is urgent as they are continuously defiling the limited freshwater resources, seriously affecting the terrestrial, ecosystems, aquatic, and aerial flora and fauna. Emerging carbon nanotube (CNT)-based adsorbent materials are effective for efficient handling of wastewater pollutants. This chapter describes the mechanisms of CNT, and its forces to host the wastewater pollutants. Such details would help to considerably improve the performance of classical adsorbent technologies. Additionally, the functionalization of CNT and adsorption isotherms are considered as they have been significantly used for achieving maximum adsorption capacity and disclosing the adsorption phenomena of CNT, respectively. Some multifunctional CNT-based adsorbent are also discussed with reusability phenomena which need to be addressed before large-scale implementation of CNTs for water purification. Some suggestions and research clues are given to inform investigators of potentially disruptive CNT technologies and/or optimize the CNT sorption performances that have to be investigated in more detail