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In this work, Nafion-based resistivity sensors were investigated for their efficiencies in hydrogen and humidity sensing characteristics. The sensors comprise of Nafion coated on two types of carbon nanomaterials, graphene and carbon nanotubes, respectively, as sensing platform interconnect between pairs of microelectrodes. The study showed that the hydrogen sensing of Nafion/CNT sensor was higher than Nafion/graphene sensor, and its response and recovery times were also faster. In the absence of carbon nanomaterials, Nafion-only sensor was also capable of detecting the presence of hydrogen but its sensing responses were lower with higher signal drift. In humidity sensing, both Nafion/CNT and Nafion/graphene sensors demonstrated lower and inverse humidity responses compared to Nafion-only sensor. Among the fabricated sensors, Nafion/CNT materials were found to offer promising sensing platform for application in real-time hydrogen gas and humidity detection. [ABSTRACT FROM AUTHOR]

• Humidity sensing characteristics of graphite pencil marks drawn on paper as sensing material were demonstrated. • Ethanol-treated sensors have better humidity sensitivities. • Intrinsic resistances of the sensors are directly proportional to their humidity sensitivity. • The humidity sensing characteristics of the pencil graphite were gauged with other forms of carbon materials. [Display omitted] In this study, we have demonstrated the humidity sensitivity of graphite pencil marks sensing material drawn on paper. The fabricated sensing devices (sensors) were characterized for their humidity sensitivity by measuring the resistance changes across the pencil marks. In order to improve the humidity sensitivity of the sensing material, ethanol chemical treatment was applied on the pencil marks to increase their surface hydrophilicity. Sensors with different levels of intrinsic resistances were also prepared and tested. Results showed that the ethanol-treated sensors have better humidity sensitivities and the intrinsic resistances of the sensors were directly proportional to their humidity sensitivity. To evaluate this carbon-based sensing material, the humidity sensing characteristics of the pencil graphite were gauged with other forms of carbon materials that have been reported in previous studies, such as carbon quantum dots film, carbon nanoparticles, carbon nanotubes, graphene oxide and graphene. [ABSTRACT FROM AUTHOR]

The synergistic effects of halloysite nanotubes (HNTs) and carbon nanotubes (CNTs) on the mechanical properties of epoxy nanocomposites were investigated. The addition of hybrid nanofillers (0.5 wt% HNTs–0.5 wt% CNTs) has significantly increased the storage modulus, flexural strength, tensile strength, fracture toughness (K1C), critical strain energy release rate (G1C), and microhardness of the nanocomposites. The tensile strength and Young's modulus increased up to approximately 45% and 49%, respectively. The flexural strength and modulus increased up to approximately 46% and 17%, respectively. K1C, G1C, and microhardness recorded improvements of up to approximately 125%, 134%, and 11%, respectively. The formation of a large number of microcracks (emanated radially) and the increase in fracture surface area (due to crack deflection) were the major toughening mechanisms in the hybrid nanocomposites. SEM images revealed that the hybrid nanofillers were uniformly dispersed in the epoxy matrix and the fracture surface was coarser than that of neat epoxy, suggesting a semi-ductile fracture. This study has shown that the synergistic effects of HNTs–CNTs hybrid nanocomposites at low content (0.5 wt% HNTs–0.5 wt% CNTs) have significantly enhanced the mechanical properties of epoxy nanocomposites. [ABSTRACT FROM AUTHOR]