Showing papers by "Bharat A. Bhanvase published in 2014"

Ultrasound assisted in situ emulsion polymerization for polymer nanocomposite: A review

Abstract: This review covers an ultrasound assisted synthesis of polymer nanocomposites using in situ emulsion polymerization. First of all, surface modification of core nanoparticles with a coupling agent and surfactant has been employed for the synthesis of core–shell polymer nanocomposites. In addition to application of ultrasound for the synthesis of core–shell polymer nanocomposites, due to its influential efficiency, sonochemistry has been extensively used not only as an aid of dispersion for inorganic nanoparticles and organo-clay, but also acts as an initiator to enhance polymerization rate for synthesis of polymer nanocomposites. In situ emulsion polymerization of hydrophobic monomers, such as methyl methacrylate, butyl acrylate, aniline, vinyl monomers and styrene, using surfactant and water soluble initiator were carried out for a synthesis of core–shell polymer nanocomposite. This technique assists in preparation of stable and finely dispersed polymer nanocomposite with the loading of inorganic particles up to 5 wt.%. Recent developments in the preparation of core–shell polymer nanocomposites using an ultrasound assisted method with their physical characteristics such as morphology, thermal, and rheological properties and their potential engineering applications have been discussed in this review.

Intensification of convective heat transfer in water/ethylene glycol based nanofluids containing TiO2 nanoparticles

Abstract: This paper presents a study of heat transfer performance of water, ethylene glycol (EG) and their mixtures of varying compositions and comparison thereof. The present work demonstrates the enhancement in convective heat transfer in nanofluids. The nanofluids were prepared by adding TiO 2 nanoparticles (having a particle size below 100 nm) in a base fluid. A binary mixture of EG (40%) and water (60%) was used as a base fluid. Nanofluids with varied volume fraction between 0 and 0.5 (volume fraction of TiO 2 nanoparticles) were considered in the present study. The experimental setup used was consisting of a test section that includes 750 mm long copper pipe with 8 mm inner diameter and a heater. The test section was covered with an insulation layer to minimize the heat losses. Temperature measurement was done with thermocouples. The experiments were conducted to study the effects of solid volume fraction, nanofluid flow rate and the inlet temperature on the heat transfer performance of the nanofluids. The results show an enhancement in heat transfer coefficient with increased volume fraction of TiO 2 nanoparticles. The maximum enhancement of 105% in heat transfer coefficient was observed for the nanofluid with solid volume fraction of 0.5.

In situ sonochemical synthesis of Fe3O4–graphene nanocomposite for lithium rechargeable batteries

Abstract: In this paper, we have presented experimental results for preparation of Fe 3 O 4 –graphene nanocomposite that uses an ultrasound assisted method. The graphene oxide (GO) was prepared from graphite powder using modified Hummers–Offeman method. Subsequently, the synthesis of graphene-Fe 3 O 4 nanocomposite was carried out by ultrasound assisted co-precipitation of iron (II) and (III) chlorides in the presence of GO. The formation of GO and graphene-Fe 3 O 4 nanocomposite was confirmed by X-ray diffraction (XRD), Energy dispersive X-ray (EDX) analysis and Fourier transform-infrared (FTIR) analysis. The particle size of Fe 3 O 4 nanoparticles loaded on graphene nanosheets (observed from TEM image) was found to be smaller than 20 nm. The use of ultrasonic irradiations during synthesis of graphene-Fe 3 O 4 nanocomposite resulted in uniform loading of Fe 3 O 4 nanoparticles on graphene nanosheets. The prepared graphene-Fe 3 O 4 nanocomposite material was used for the preparation of anode for lithium ion batteries. The electrochemical performance of the material was tested by cyclic voltammetry (CV) and charge/discharge cycles. It was observed that the capacity of Li-battery when the anode material was made using graphene-Fe 3 O 4 nanocomposite showed stable electrochemical performance for around 120 cycles and the battery could repeat stable charge–discharge reaction.

Kinetic studies of semibatch emulsion copolymerization of methyl methacrylate and styrene in the presence of high intensity ultrasound and initiator

Abstract: The present work deals with kinetic studies of copolymerization of methyl methacrylate and styrene using ultrasound assisted semibatch emulsion copolymerization in the presence of sodium dodecyl sulfate (emulsifier) and potassium persulfate (external initiator). The effect of temperature, acoustic intensity, initiator loading, surfactant concentration and monomer concentration on the extent of conversion has been investigated. The extent of polymerization was observed to increase with an increase in the temperature, and concentrations of initiator, monomer and surfactant. Further, the initial polymerization rate increased with an increase in the acoustic intensity from 11.2 to 23.1 W cm−2 and then it was found to decrease with a further increase to 33.80 W cm−2. The novelty of this work lies in the fact that there have been only limited kinetic studies for the approach of ultrasound assisted emulsion copolymerization. It has been also established in the present work that the formation of fine and stable monomer droplets, due to the cavitational activity at/near the interface of immiscible monomer phase and subsequent disruption by micro jets, leads to the smaller final polymer particle size and under optimized conditions, it was found to be about 40 nm.

Computational Studies on Release of Corrosion Inhibitor from Layer-by-Layer Assembled Silica Nanocontainer

Abstract: The present study focuses on ultrasound assisted preparation of silica nanoparticle using Stober’s method and silica nanocontainers with an adsorption of polyelectrolytes (i.e., poly(diallyl dimethylammonium chloride) (PDADMAC) and poly(styrene sulfonate) (PSS)) and a corrosion inhibitor (benzotriazole) by the layer-by-layer approach. The benzotriazole was entrapped between the oppositely charged polyelectrolyte layers (i.e., PDADMAC and PSS). Field emission gun scanning electron microscopy and transmission electron microscopy analysis confirms the successful formation of spherical silica nanoparticles and layer by layer assembled silica nanocontainers. The effect of pH on responsive release of benzotriazole form silica nanocontainers was studied. Various semiempirical models were studied to predict the release mechanism of the benzotriazole. Root-mean-square errors of the predictions of these models were compared in order to select the best fitted model. An artificial neural network model was developed a...

Intensification of corrosion resistance of 2 K epoxy coating by encapsulation of liquid inhibitor in nanocontainer core of sodium zinc molybdate and iron oxide

Abstract: A unique approach for the synthesis of an iron oxide-blended sodium zinc molybdate nanocontainer using an ultrasound-assisted method and its application for 2 K epoxy polyamide nanocomposite coatings has been presented. Sodium zinc molybdate blended with iron oxide was used as the core of the nanocontainer and layer-by-layer assembly of oppositely charged species of polyelectrolyte and inhibitor was made over this core of nanoparticles. The release of imidazole from iron oxide-blended sodium zinc molybdate nanocontainer has been quantitatively evaluated in water at different pH. It has been observed that imidazole plays a major role in the release profile of polyelectrolyte-modified nanocontainer and deciding the corrosion inhibition characteristics. Addition of 4 wt% nanocontainer in coatings results in shifting of corrosion potential (Ecorr) value towards positive direction. The maximum concentration of imidazole released at the end of 1 h was found to be 0.545 mg L−1/g of nanocontainer at pH of 10. The...

Investigation of corrosion inhibition performance of ultrasonically prepared sodium zinc molybdate nanopigment in two-pack epoxy-polyamide coating

Abstract: In the present work, an innovative approach has been used to synthesize sodium zinc molybdate nanopigment using ultrasound-assisted co-precipitation of sodium molybdate and zinc oxide. X-ray diffraction, Fourier transform infrared and elemental analysis of sodium zinc molybdate nanopigment have been performed which confirmed the formation of sodium zinc molybdate particles. Ultrasound-assisted synthesis gave lower particle size of sodium zinc molybdate nanoparticles (467 nm) which can be explained on the basis of improved solute transfer rate, rapid nucleation, and formation of a large number of nuclei in the presence of ultrasound. The corrosion inhibition effect of sodium zinc molybdate nanopigment in 2K (two-pack) epoxy-polyamide clear coat on low carbon steel has also been studied. The results of the corrosion rate analysis, Tafel plots, and electrochemical impedance spectroscopy of the prepared coatings show better corrosion inhibition performance when sodium zinc molybdate particles were incorporate...