Printed Nanocarbon Heaters for Stretchable Sport and Leisure Garments

The ability to maintain body temperature has been shown to bring about improvements in sporting performance. However, current solutions are limited with regards to flexibility, heating uniformity and robustness. An innovative screen-printed Nanocarbon heater is demonstrated which is robust to bending, folding, tensile extensions of up to 20% and machine washing. This combination of ink and substrate enables the heated garments to safely flex without impeding the wearer. It is capable of producing uniform heating over a 15 × 4 cm area using a conductive ink based on a blend of Graphite Nanoplatelets and Carbon Black. This can be attributed to the low roughness of the conductive carbon coating, the uniform distribution and good interconnection of the carbon particles. The heaters have a low thermal inertia, producing a rapid temperature response at low voltages, reaching equilibrium temperatures within 120 s of being switched on. The heaters reached the 40 °C required for wearable heating applications within 20 s at 12 Volts. Screen printing was demonstrated to be an effective method of controlling the printed layer thickness with good interlayer adhesion and contact for multiple printed layers. This can be used to regulate their electrical properties and hence adjust the heater performance.

The influence of carbon morphologies and concentrations on the rheology and electrical performance of screen-printed carbon pastes

Screen-printing inks containing various morphologies of carbon are used in the production of a variety of printed electronics applications. Particle morphology influences the rheology of the ink which will affect the deposition and therefore the electrical performance of a printed component. To assess the effect of both carbon morphology and concentration on print topography and conductivity, screen printable carbon inks with differing loading concentrations of graphite, carbon black and graphite nanoplatelets (GNPs) were formulated, printed and characterised, with rheological and novel print visualisation techniques used to elucidate the mechanisms responsible. Carbon morphology had significant effects on the packing of particles. The smaller carbon black particles had more interparticle interactions leading to better conductivities, but also higher ink viscosities and elasticities than the other morphologies. Increases in carbon concentration led to increases in film thickness and roughness for all morphologies. However, beyond a critical point further increases in carbon concentration led to agglomerations of particles, mesh marking and increases in surface roughness, preventing further improvements in the print conductivity. The optimal loading concentrations were identifiable using a custom-made screen-printing apparatus used with high speed imaging for all morphologies. Notable increases in filamentation during ink separation were found to occur with further increases in carbon concentration beyond the optimum. As this point could not be identified using shear rheology alone, this method combined with shear rheology could be used to optimise the carbon concentration of screen-printing inks, preventing the use of excess material which has no benefit on print quality and conductivity.

Effect of graphite nanoplatelets on spark plasma sintered and conventionally sintered aluminum-based nanocomposites developed by powder metallurgy

In this work, aluminum (Al)-based nanocomposites reinforced with graphite nanoplatelets (GnPs) have been fabricated by conventional sintering as well as spark plasma sintering (SPS) techniques, and their microstructure and mechanical properties have been studied. The powder metallurgy (PM) route has been adopted to fabricate the various Al–GnP nanocomposites. Characterization of the powder mixtures and the nanocomposites has been carried out through different characterization techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. Compressive strength, Young's modulus, density, and Vickers microhardness of the various nanocomposites have also been determined. The HRTEM results show the formation of nonstoichiometric Al4C3 nanoparticles – during both conventional sintering and SPS – at the interface of the Al grains and GnP, which worsen the mechanical properties of the nanocomposites. SPSed nanocomposites show superior mechanical properties due to higher densification, finer grain size, and homogeneous nanofiller dispersion in the Al matrix, compared to the conventionally sintered Al–GnP nanocomposites.

Characterization of Bacterial Nanocellulose - Graphite Nanoplatelets Composite Films

Bacterial cellulose (BC) was synthesized from pineapple peel extract media with addition of fermentation agent bacteria Acetobacter xylinum. BC was disintegrated from the pellicle into bacterial nanocellulose (BNC) by using a high-pressure homogenizer (hph) machine, which has a three-dimensional woven nanofibrous network. The synthesis of composite films started when BNC, graphite nanoplatelets, and cetyltrimethylammonium bromide (CTAB) were homogenized using an ultrasonic homogenizer then baked on a glass mold at a temperature of 80 degrees Celcius for 14h. A scanning electron microscope (SEM) was used to analyze its morphology. X-Ray diffraction spectra were used to analyze the composite films structure. The functional groups of the composite films were analyzed using the FTIR spectrum. SEM micrograph shows that GNP was evenly distributed into BNC matrix after CTAB addition. GNPs are shown as flat and smooth flakes with sharp corners. Some peak corresponds O-H, C-H, C≡C, and CH3 stretching was identified by using FTIR spectroscopy at wavenumber 3379, 2893, 2135, and 1340 cm-1, respectively. XRD analysis shows that Crystalline Index (C.I) of BNC increases after 2.5 wt% addition of GNP. The presence of CTAB decreases C.I value of composite films. BNC/GNP composite films have the best mechanical properties with Young’s modulus about 77.01 ± 8.564.

Efficient Microwave-Assisted Extraction of Nitrites from Cured Meat and Their Voltammetric Detection at Chemically Modified Electrodes Based on Hexamethyl-p-Terphenyl Poly(methylatedbenzimidazolium) Incorporating Nitrogen-Doped Graphite Nanoplatelets

We describe a fast and reliable procedure for the efficient extraction of nitrites in cured meat using microwave-assisted heat and report their in situ determination via voltammetry using an anion-exchanger ionene, hexamethyl-p-terphenyl poly(benzimidazolium) (HMT-PMBI), and nitrogen-doped graphite nanoplatelets (NGNPs). Cyclic voltammetry and chronoamperometry were utilized to evaluate the concentration of the redox mediator within the film and apparent diffusion coefficient. To investigate the suitability of the composite material for sensing applications, HMT-PMBI/NGNPs were tested for their detection of nitrite in bacon samples without the need of any pretreatments or dilutions. HMT-PMBI/NGNP coated electrodes showed enhanced sensitivity in the detection of nitrite ions in bacon with a limit of detection (LoD) of 0.64 µM, sensitivity 0.52 µA µM−1 cm−2, and operating in a linear range between 1–300 μM. The results highlight that the determination of nitrites in cured meat using microwave extraction is in good agreement with standard procedures such as the ISO 2918 and the AOAC International 973.31 methods.