Papers by Author: A.K. Banthia

Abstract: Red mud was organophilized by aniline formaldehyde and to know the effect of various filler loading on the properties of PVA-Organophilized red mud composite prepared by a conventional solvent casting technique and comparison of the same with that of the virgin polymer, various characterizations was done. The as-synthesized composite films were typically characterized by FTIR spectroscopy and X-Ray Diffraction.The exfoliation of galleries of organo- red mud was more evident in the composite film containing 2% of filler loading.The morphological image of the composite materials was studied by scanning electron microscopy (SEM) and optical microscope (OM). The thermal properties measured by thermogravimetric analysis (TGA) showed that organored mud enhanced the thermal stability of a series of composite materials freestanding films.The differential scanning calorimetry (DSC) showed increase in glass transition temperature and crystallization of the composite films.

Abstract: The electrical conductivity studies of chemically crosslinked nano composite membranes consisting of poly (vinyl alcohol) (PVA) and phosphomolybdic acid (PMA) with different blending composition and crosslinking density has been conducted over a wide frequency regime. The conductivity of the systems has been studied within the temperature range 25 oC ø T oe 100 oC for the hydrated membranes. The proton conductivity of the membranes was generally of the order of 10-3 S/cm. The conductivity of these membranes shows a temperature dependence of Arrhenius type. The activation energies for the membranes were calculated from the conductivity measurements. Both the pristine and hydrated membranes were also characterized by X-Ray diffraction studies to observe the effects of blending and hydration on the crystallinity of the composite membranes. The membranes showed comparable proton conductivity and better resistance to methanol permeability than that of Nafion 112 under the same measurement conditions. These properties make them good candidates as polymer electrolyte membranes for direct methanol fuel cell application.

Abstract: Vinyl ester BisGMA [Bisphenol-A-glycidyldimethacrylate] resin has been modified by incorporating Titanium dioxide(TiO2)nanoparticles (0.5%-2% by weight). An ultrasonic mixing process was employed to disperse the particles into the resin system prior to casting and curing test specimens. From TEM investigation, it is found that the particles are nano size (5-60nm) and dispersed throughout the entire volume of the resin. Dynamic mechanical analysis was conducted for both the neat resin and nanocomposite. In dynamic mechanical analysis, nanocomposite shows increase in storage modulus (6%), and glass transition temperature (5.8%) from neat resin system. Thermogravimetric analysis shows 7.5% better thermal stability. In addition, the nanocomposite shows enhance in the stiffness by 5% in flexural loading. The Tg and flexural modulus of the nanocomposites were enhanced as the particle volume fraction was enhanced and than decreased.

Abstract: Polycondensations (condensation polymerization) are stepwise reactions between bifunctional or polyfunctional compoents, with elimination of simple molecules such as water or alcohol and the formation of macromolecular substances. Polyborate ester , formed by this process, gives ceramic materials during pyrolysis. Polymer pyrolysis offers an attractive alternative to the typical high temperature powder processing approach in the fabrication of high-performance ceramics. This approach might also prove to be useful in the fabrication of fibers, coatings, and composites. It is within this framework that the present study was undertaken; its aim is the preparation of boron-containing oligomeric precursors which gives boron nitride after pyrolysis. The precursor was synthesized by the condensation reaction between boric acid and urea (or other N-containing reactive multifunctional compounds). The oligomeric precursor and its pyrolysed products were thoroughly characterized by elemental analysis, IR, NMR, XRD, Thermal Analysis and Transmission Electron Microscopy(TEM). The elemental analysis results of the oligomer are---- C-13.40%, H-5.97%, N-32.44% and B-17.09%. X-ray diffraction and TEM studies showed that boron nitride obtained from this system possess tetragonal structure.

Abstract: Nitrides remain a relatively unexplored class of materials primarily due to the difficulties associated with their synthesis and characterization. Several synthetic routes, including high temperature reactions, microwave assisted synthesis, and the use of plasmas, to prepare binary and ternary nitrides have been explored. Transition metal nitrides form a class of materials with unique physical properties, which give them varied applications, as high temperature ceramics, magnetic materials, superconductors or catalysts. They are commonly prepared by high temperature conventional processes, but alternative synthetic approaches have also been explored, more recently, which utilize moderate temperature condition. Transition metal nitrides particularly, molybdenum nitride, niobium nitride, and tungsten nitride have important applications as catalyst in hydrodenitridation reactions. These nitrides have been traditionally synthesized using high temperature nitridation treatments of the oxides. The nitridation temperatures are very high (> 800- 1000 oC). The aim of our work is to synthesize molybdenum nitride by a simple, low-temperature route. The method involves pyrolysis of a polymeric precursor, which was prepared from the condensation reaction between triethanolamine and molybdic acid. The melting point of the product is 180oC. The polymeric precursor and its pyrolyzed products are characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). X-ray diffraction shows that molybdenum nitride (MoN) obtained from this method has hexagonal crystal structure. MoN is obtained by this method at very low temperature (~ 400 oC).