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Nano-mechanical properties of silicone polymer-based nanocomposites loaded with multi-walled carbon nanotube (MWCNT) as nanofillers are probed here using the atomic force microscopy (AFM) technique. Further, the effects of MWCNT concentration and X-ray exposure on the nano-mechanical and topographic properties of the polymer nanocomposites are systematically studied. The root mean square surface roughness is found to increase by ∼123% when the neat polymer matrix is loaded with 2.5 wt.% of MWCNT, whereas, for a fixed MWCNT concentration, the surface roughness is found to increase by ∼171% after X-ray irradiation. This is attributed to the X-ray induced polymer degradation, polymer pull-out and poor filler-matrix interaction leading to the aggregation of MWCNT. Adhesion force and adhesion energy are estimated from the AFM-based force-displacement curves. Both quantities are found to increase with MWCNT concentration. After an exposure to diagnostic X-rays (30–70 keV), the adhesion force is found to increase by ∼4 times, which is attributed to the increased tip-surface contact area due to the higher surface roughness of the X-ray exposed samples. Further, the variation of adhesion energy with filler concentration is found to be in agreement with the theoretical values obtained from the Johnson, Kendall and Roberts (JKR) model. The elastic modulus is found to increase with the filler concentration due to an increase in adhesion force. The obtained results are beneficial for the optimal design of nanofiller loaded polymer nanocomposites for various applications, including the fabrication of lead-free radio-opaque nanocomposites. [ABSTRACT FROM AUTHOR]

Silicone polymer‐based nanocomposites containing β‐Bi2O3 nanoparticles with varying concentrations of silica nanoparticles are successfully prepared and characterized for thermal stability, surface topography, and X‐ray attenuation property. Of all the samples studied here, silicone polymer of higher density (S1) containing β‐Bi2O3 (50 wt%) and silica (0.025 wt%) nanoparticles is found to be thermally stable upto 424 and 375°C in argon and oxygen atmosphere, respectively. The atomic force microscopy image of top and cleaved surface of this nanocomposite exhibits an average roughness of 12 and 506 nm, respectively. It also exhibits the highest X‐ray attenuation property, among the samples analyzed here, against X‐rays of energies in the range of 30–66 keV. Therefore, S1 silicone polymer containing β‐Bi2O3 and silica (0.025 wt%) nanoparticles is a potential material for the development of lead‐free and X‐ray opaque aprons, gloves, thyroid collar, gonad shield, and so on. [ABSTRACT FROM AUTHOR]

We report, here, the corrosion inhibition of mild steel specimen in 1 M HCl by tamarind fruit pulp aqueous (TFPA) extract. The inhibition property in the presence of TFPA extract is studied using weight loss, polarization measurement and electrochemical impedance spectroscopy (EIS). The inhibitor efficiency is found to vary from 74% to 88% (weight loss method) with TFPA concentration of 100–600 ppm. The reduction in Tafel slopes shows that TFPA acts as a mixed-type inhibitor. The adsorption of the inhibitor on the metal surface follows Langmuir isotherm. The standard Gibbs free energy of adsorption value of –40 kJ/mol suggests the chemisorption of inhibitor molecules via coordinate bond. AFM results exhibit a decrease in the surface roughness of mild steel, exposed to 1 M HCl from 299 ± 12 to 154 ± 6.6 nm, with increasing concentration of inhibitor from 0 to 600 ppm due to the uniform coverage of inhibitor molecules on the metal surface. X-ray photoelectron spectroscopy de-convoluted high resolution profiles of C 1 s (carbon) for mild steel exposed to 1 M HCl with 600 ppm inhibitor show major peaks corresponding to sp3 C–C/C–H (284.9 eV) and oxygen bondings in C–OH, C=O, COOH with a binding energy of 285.9, 286.9, 288.5 eV, respectively, thereby confirming the adsorption of organic moieties on mild steel surface. Fourier transform infrared spectroscopy further confirms the adsorption of inhibitor molecules on the metal surface. Therefore, tamarind fruit pulp extract is a potential corrosion inhibitor for mild steel, which is cost-effective, green and non-toxic. [ABSTRACT FROM AUTHOR]

The prolonged exposure of high-energy ionizing radiations during treatment of cancer/tumour and radiological examinations is hazardous to occupational workers and patients. Lead-incorporated composite materials are traditionally used as radiopaque fabrics, but are heavy, bulky and hence often cause inconvenience to users. Therefore, superior radiopaque protective wears that are preferably lead-free, light weight and flexible are being explored. Towards this goal, we study here the synergistic effect of graphene nanoplatelets and multi-walled carbon nanotube (MWCNT) on the X-ray attenuation property of polymer nanocomposites containing β-Bi2O3 nanofillers. The effect of graphene and MWCNT at different concentrations on Bi2O3-based polymer nanocomposites is studied to attain optimal compositions with respect to its X-ray attenuation property and thermal stability. Surface topography and surface roughness of the nanocomposite blocks are studied using an atomic force microscope (AFM). The effect of the density of polymer on the curing, thermal stability and X-ray attenuation property is also studied by using silicone polymers of density 1.7 (G1) and 1.04 g/cm3 (G2). The X-ray attenuation property of nanocomposites with G1 polymer matrix is found to be better than that of G2. The G1-based nanocomposite containing β-Bi2O3 and graphene is found to be better than the one with G1 polymer containing β-Bi2O3 and MWCNT. Thermal stability of multifiller nanocomposites is found to be better than the one without nanofillers. AFM topography images show a variation in surface roughness of nanocomposites with different fillers, which contributes to the different micro- and nano-structural architectures due to polymer–nanofiller interaction, thereby, affecting the X-ray attenuation of the nanocomposites. Our study shows that the multifiller nanocomposite containing β-Bi2O3 and graphene nanoplatelets offer greater potential for the development of efficient radiopaque fabric materials. [ABSTRACT FROM AUTHOR]

We report here a new approach to remove rhodamine B dye, a toxic contaminant in industrial effluents, from aqueous solution using colloidal casein protein and its complexes with surfactants. The dye removal efficiency of casein is studied in the absence and in the presence of anionic, cationic, and nonionic surfactants. The anionic, cationic, and nonionic surfactants used in this study are sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and Triton X-100, respectively. The presence of Triton X-100 is found to improve the dye removal efficiency of casein from 21 to 84% with a contact time of 5 minutes. The effect of contact time, pH, and temperature on the dye removal efficiency of casein is also studied here. The adsorption of rhodamine B on casein micelles is found to follow the Freundlich adsorption isotherm and a pseudo second order kinetics model. The variation in hydrodynamic diameter of casein in whole and skimmed milk exhibited similar trend for a given surfactant at different concentrations, which suggests that the presence of fat globules, does not interfere with the interaction of casein for a given surfactant. The hydrodynamic diameter of casein micelles in reconstituted aqueous casein solution is found to increase with an increase in the concentration of SDS, which is attributed to the interaction of SDS with micelles at calcium phosphate sequestration centers, which results in micelle swelling. In the presence of CTAB at varying concentration, the diameter of casein micelles in reconstituted aqueous casein is found to decrease. This is attributed to the interaction of cationic group of CTAB with negatively charged κ-casein which makes the micelles more compact as a result of reduced electrostatic repulsion between the micelles. Similarly, the hydrodynamic diameter of casein micelles in reconstituted casein containing varying concentrations of Triton X-100 is found to decrease which suggests that large micelles break down into smaller micelles. Thus, this work gives new insights to the interaction of casein with anionic, cationic, and nonionic surfactants when present in whole milk, skimmed milk, and reconstituted aqueous solution. Further, casein-Triton X-100 complexes are found to effectively remove rhodamine B dye rapidly due to the synergistic interaction between casein, rhodamine B, and Triton X-100. [ABSTRACT FROM AUTHOR]