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Fire-Retardant Nanocomposite Coatings Based on Nanoclay and POSS
Published in Mangala Joshi, Nanotechnology in Textiles, 2020
P. Santhana Gopala Krishnan, P. Manju, S. K. Nayak
Beyond using MMT, Holder et al. reported enhancement in the fire retardancy of PU foams by coating intumescent CH/VMT clay composites by LbL assembly [13]. The PU foam was coated in such a way that CH/APP layers were stacked over the foam followed by the stacked layers of CH/VMT. The CH/APP layers served as an intumescent coating over the foams. The flammability behaviors were studied using the butane torch test, cone calorimetry, and TGA. The foams coated with both CH/APP layers and CH/VMT layers showed superior properties when compared with the uncoated foams in that the foam that was coated with 4 BLs of clay and 20 BLs of intumescent coating showed a reduction in the HRR peak by 66%, with less smoke emission [34].
Layer-by-Layer Assembly: A Novel Flame-Retardant Solution to Polymeric Materials
Published in Yuan Hu, Xin Wang, Flame Retardant Polymeric Materials, 2019
Referring to the exploitation of the LbL technique, Grunlan and co-workers developed an environmentally friendly coating with renewable composition by combining chitosan with sodium montmorillonite (Laufer et al. 2012a). The thickness of the LbL coating was regulated by adjusting the pH of the chitosan solution: in particular, pH = 6 produced thicker coatings due to the low charge density of chitosan. The deposition of ten bi-layers completely stopped the melt dripping of PU foam exposed to a butane torch flame for 10 s. For the LbL-treated foams, cone calorimeter tests (35 kW/m2 heat flux) showed a decreased peak of heat release rate (−52%).
Environmental Alchemy: Mercury-Gold Amalgamation Mining and the Transformation of the Earth
Published in Ambix, 2023
The nineteenth-century small-scale gold rushes that fuelled the Castellani gold work are most visible today in the activity of artisanal and small-scale gold mining in the Global South, a present-day example of environmental alchemy in action.66 Artisanal and small-scale gold mining uses mercury, quite a lot of it. The consequences of the two metals’ interrelationship play out in real time, and typically fall hardest on subsistence livelihoods in low-income communities. The miner (in Zambia, Perú, Indonesia, or elsewhere) will search for flakes of gold panned from waterways or sifted from crushed rock. Seeing glints of gold, the miner will (for example) unstopper a plastic bottle containing mercury and pour some of the silvery liquid metal onto the dirt and gold specks. The chemical reaction is immediate as the mercury-gold amalgam forms. The miner next fires a butane torch and trains the flame on the amalgam. The mercury rapidly vaporises, leaving behind a spongy gold lump. From this point, the gold will leave the hands of the miner and start to work its way into global supply chains. Gold from artisanal and small-scale gold mining activity fulfils approximately 20% of the global demand for jewellery, central bank reserves, investments, and all sorts of technologies and electronic devices.67
Thermal history analysis on a hot surface using temperature indicating paints
Published in International Journal of Ambient Energy, 2022
P. L. Rupesh, M. Arulprakasajothi
The metal coupons and the double V-notch specimen are prepared with a specified dimension. The CAD model of the specimen is shown in Figure 3. The surface treatment is done by polishing the metal surface using sandpaper so that the uneven surface regions and rust can be removed. The polished metal coupons are cleaned by dipping them in acetone for about 15 min so that chemical contaminants can be removed. After the surface cleaning, the metal coupons are heated in the furnace to 200°C to burn out the oil traces in the specimen. The paint is sprayed on the surface of the specimen, shown in Figure 4. The coupons are again heated for a curing temperature of about 250°C for about 2 h and cooled to room temperature in the oven itself. After the metal coupons and the specimen are baked in the furnace at about 250°C they are heated to elevated temperatures (above 350°C) by using various heating sources. The metal coupons are heated by using the furnace and the double V-notched specimen is heated by using a Butane torch.
Development of thermally stable coarse water-in-oil emulsions as potential DNA bioreactors
Published in Journal of Dispersion Science and Technology, 2021
Maria Romero-Peña, Enders Kaion Ng, Supratim Ghosh
A force tensiometer (K20 by Krüss GmbH, Hamburg, Germany) with a Wilhelmy plate (20 × 10 mm) was used to determine oil/water interfacial tension. A sample of oil (65 mL) with PGPR or AOT was added in a wide-mouth glass beaker (130 mL). The Wilhelmy plate was moved down to be completely immersed in the oil phase, and the position was tared. The plate was then moved up, cleaned with acetone (A18-4, Fisher, US) and flamed with a butane torch (Bernzomatic, OH, USA). A sample of aqueous phase (22 mL) was added in another similar glass beaker and placed over the stage. The plate was moved to reach the Wilhelmy plate, and the system was set at zero position. Then, the previously used oil phase was added with a pipette (VWR, Edmonton, AB, Canada) to fill at the tare. Finally, at zero position, interfacial tension measurements were performed until a standard deviation of 0.1 mN/m could be reached between subsequent measurements. For the determination of critical micelle concentration (CMC), different concentrations of emulsifiers were dissolved in the oil phase, and the interfacial tension measured against an aqueous phase was plotted against emulsifier concentration. The intersection point from the slope of the two distinct portions of the graph was used to find the CMC beyond which no changes in interfacial tension was observed.