Papers by Rajesh Babu Chunchula
International Journal of Recent Technology and Engineering (IJRTE), 2019
Regular fuel-based vehicles are more reliable because of their rich looks, flexibility, influence... more Regular fuel-based vehicles are more reliable because of their rich looks, flexibility, influence, and preferred effectiveness over non-traditional electrical vehicles. Building a green vehicle is a test given the constraint in power transformation. The energy transfer rate of a sun-oriented power vehicle is less. In this proposition, this paper has endeavored to cover every one of the parameters and components influencing the manufacture of a sun-oriented controlled vehicle. Computer-aided engineering/design has played a significant job to accomplish the execution objectives of the vehicle. The present work visualize utilizing both sunlight based and electric forces to impel the vehicle since sun based power transformation is not enough to meet the complete power necessities. Considering weight, strength, and ergonomics an optimal chassis was designed. Then the chassis frame analyzed for different ride conditions. The suspension system and other vehicle systems were designed by fol...
International Journal of Recent advances in Mechanical Engineering, 2015
The heat transfer enhancement is very important many engineering applications to increase the per... more The heat transfer enhancement is very important many engineering applications to increase the performance of heat exchangers. The active techniques required external power like surface vibrations, electrical fields etc and the passive techniques are those which does not required any external power but the inserts are required to disturb the flow like tape inserts etc moreover literature survey says passive techniques gives more heat transfer rate without external power requirement by keeping different tape inserts. However CFD tool is very important and effective tool to understanding heat transfer applications. Computational heat transfer flow modelling is one of the great challenges in the classical sciences. By incorporating the inserts the heat transfer enhancement is increased due to its importance in different applications. By CFD modelling by taking concentric tube by considering with and without inserts we conclude that heat transfer enhancement by using ANSYS Fluent version 14.5.
Materials Chemistry and Physics, 2014
ABSTRACT Nanocrystalline Nickel Zinc ferrites of composition Ni0.5Zn0.5Fe2-xAlxO 4( where x=0.00-... more ABSTRACT Nanocrystalline Nickel Zinc ferrites of composition Ni0.5Zn0.5Fe2-xAlxO 4( where x=0.00-0.25) have been synthesized by the nitrate citrate auto combustion technique. These samples were sintered at 1000C.All the samples were characterized by XRD, Infrared spectroscopy (IR), Scanning Electron Microscopy(SEM) and Vibrating sample magnetometer (VSM). The XRD patterns confirm the spinel structures. The lattice constant decreases with increasing aluminum concentration which is due to the replacement of Fe3+ with Al3+ ions. Cation distribution proposed from XRD and IR. It is observed that Al 3+ ions are distributed into tetrahedral and octahedral sub-lattices. The saturation magnetization decreases from 70.53 emu/gm to 40.19 emu/gm with the increase of aluminum. This decrease in magnetization is ascribed to the presence of the non-collinear spin (canted spin) structure in octahedral sub-lattice.
Materials & Design, 2010
The present study investigates the influence of 1,2-polybutadiene (1,2-PB) as a coagent for perox... more The present study investigates the influence of 1,2-polybutadiene (1,2-PB) as a coagent for peroxide cured polypropylene (PP) and ethylene octene copolymer (EOC) thermoplastic vulcanizates (TPVs). Addition of peroxide in PP/EOC blend leads to cause crosslinking in EOC phase and b-chain scission in PP phase. As a result, the final properties are determined primarily by the ratio of those two competing reactions. Coagent assisted peroxide system is always an attractive and effective choice in order to avoid the b-chain scission in PP, to increase the crosslink density in EOC phase and to induce the interfacial reactions. In this paper, mechanical, morphological, thermal and rheological characteristics were studied with special reference to the effect of concentration of 1,2-PB. The best overall balance of mechanical properties was observed at 3 phr concentration of 1,2-PB. However, modulus and crosslink density values increase gradually as a function of concentration of coagent. The changes in the melting and crystallizing behavior of the blends were investigated using differential scanning calorimetry (DSC). Scanning electron micrography (SEM) analyses were performed to understand the particle size of the dispersed phase. Fractography was pursued to understand the mode of failure. Rheological properties were studied at different shear modes: oscillatory shear and rate controlled capillary rheometer. A variety of rheological observations such as Payne effect, modulus recovery and comparison of oscillatory and shear mode rheological results were discussed in details.
Advanced Structured Materials, 2013
ABSTRACT Compounding is a unique requirement of the rubber, generally not found in other material... more ABSTRACT Compounding is a unique requirement of the rubber, generally not found in other material. The performance properties can be controlled by properly selecting and adjusting various compounding ingredients. The stages of rubber product manufacturing are broken down into three primary classes: selection of compounding ingredients, mixing or compounding, and vulcanization techniques or final product manufacturing process. The present chapter gives a brief introduction of the all classes with their importance. By proper selection of the variables in each class, the properties can be manipulated from virtually incompressible with a bulk modulus some thousand times greater than shear modulus, to large extent impermeable to gases and liquids and with excellent recovering and abrasion resistance etc.
Journal of Superconductivity and Novel Magnetism, 2014
ABSTRACT Nano crystalline Ni0.5Zn0.5CrxFe2−xO4 particles with x varying from 0.00 to 0.25 in step... more ABSTRACT Nano crystalline Ni0.5Zn0.5CrxFe2−xO4 particles with x varying from 0.00 to 0.25 in steps of 0.05 have been synthesized through citrate gel autocombustion method. When Ni0.5Zn0.5Fe2O4 nano particles were annealed at 1000 °C, the crystallite size increased while the lattice constant decreased slightly. For, the Cr3+ substituted samples annealed at 1000 °C, the variation in lattice constant, bondlengths, Me-Me distances and other structural parameters have been attributed to the dissimilarity in the ionic radius of the displaced (Fe3+) ion and the substituted (Cr3+) ion. Thermal studies indicated the autocombustion process which is an exothermic reaction between the nitrates salt solutions and the citric acid took place at about a temperature of 400 °C for Ni0.5Zn0.5Fe2O4. The M-H loops for all samples indicated a soft ferrite nature for all samples. The non-saturated hysteresis loop and high coercivity for the as prepared Ni0.5Zn0.5Fe2O4 nano particles has been attributed to the core-shell structure of the fine particles. When annealed at 1000 °C the saturation magnetization of Ni0.5Zn0.5Fe2O4 nano particles increased and attained the bulk value (70emu/gm). The specific saturation magnetization has been observed to decrease with increasing Cr3+ substitution and is ascribed to the reduction in the predominant A-B exchange interaction mechanism. By considering the site preferences cations a suitable distribution of the cations among the A & B-sites has been proposed for Ni0.5Zn0.5CrxFe2−xO4 nano particles annealed at 1000 °C and has been verified using the X-ray diffraction line intensity calculations. The FT-IR spectra of the annealed ferrite powders showed two significant absorption bands in the wave numbers around 400 cm−1 & 580 cm−1 and an additional shoulder at 360cm−1. The position and width of the bands have been observed to vary with Cr3+ substitution. The results of IR spectra are in support of the proposed cation distribution.
Advances in Polymer Science, 2010
ABSTRACT
Encyclopedia of Polymeric Nanomaterials, 2014
ABSTRACT SynonymsDynamic vulcanizatesDefinitionThermoplastic vulcanizates (TPVs) are a very speci... more ABSTRACT SynonymsDynamic vulcanizatesDefinitionThermoplastic vulcanizates (TPVs) are a very special class of thermoplastic elastomers prepared by dynamic vulcanization or cross-linking process, which involves the cross-linking of a rubber phase while it is being melt-mixed with a thermoplastic material at elevated temperature.Introduction on Thermoplastic ElastomersThermoplastic elastomers (TPEs) are an interesting class of materials, since they combine the good elastic properties of cross-linked rubbers with the melt (re)processability of thermoplastics. The combination of these properties is obtained by the typical molecular architecture of the material having thermoreversible network structure. Typically, cross-links in thermoset rubbers are chemical in nature: the curing step is irreversible, and once the rubber is molded and cured, the material cannot be (re)processed anymore. They are not only good substitutes for thermoset rubbers but also a new emerging dimension of applications. The th ...
Modern Physics Letters B, 2014
Polycrystalline Nickel Zinc ferrites of chemical formula Ni 0.65-x Mg x Zn 0.35 Fe 2 O 4 (x = 0.0... more Polycrystalline Nickel Zinc ferrites of chemical formula Ni 0.65-x Mg x Zn 0.35 Fe 2 O 4 (x = 0.00 to 0.2 in steps of 0.04) have been prepared by conventional ceramic technique. Calcination and sintering of all samples have been carried out in air atmosphere at 950 o C and 1250 o C respectively, followed by natural cooling to room temperature. All the samples were characterized by the X-ray diffraction (XRD) for structure determination. These samples are then investigated for their magnetic and electric properties, including saturation magnetization, Curie temperature, initial permeability measurements and DC electrical resistivity. Porosity was decreased drastically from 15% to 5% showed better-quality of the sintered samples. There were increments in initial permeability and DC electrical resistivity throughout the series of samples. The variations in the observed properties as a function of magnesium concentration have been discussed in the light of existing understanding.
A design object library (DOL) refers to a digital product information system capable of storing, ... more A design object library (DOL) refers to a digital product information system capable of storing, managing and sharing design objects with rich product information to support multidisciplinary information needs for product life-cycle applications in building design, analysis, ...
Polymer Engineering & Science, 2010
The dynamic viscoelastic properties of uncrosslinked and dynamically crosslinked blends of polypr... more The dynamic viscoelastic properties of uncrosslinked and dynamically crosslinked blends of polypropylene (PP) and ethylene octene copolymer (EOC) were investigated in the melt state to study the mechanism of reinforcement, influence of particle size, and kinetics of modulus recovery. Dynamic vulcanization was performed by coagent assisted peroxide crosslinking system. Addition of peroxide in PP/EOC blend involves two major competing reactions: crosslinking in EOC and degradation of PP by b chain-scission. In this article, morphological and melt rheological properties of the TPVs were studied with special reference to the effect of mixing protocol. Three different mixing techniques were investigated. They are: (i) conventional or preblending method-melt mixing of PP and EOC followed by dynamic vulcanization (ii) phase mixing method-curative master batch of EOC added on the molten PP (iii) split addition of PPpreblending method followed by addition of half part of PP (dilution procedure). The type of mixing protocol has a significant influence on the rheological behavior. Rheological properties have been evaluated at the processing temperature (1808C) in a Rubber Process Analyzer (RPA 2000). A variety of rheological observations such as Payne effect, modulus recovery and shear rate sensitivity were studied by carrying out frequency and strain amplitude sweeps. POLYM. ENG. SCI.,
Polymer Bulletin, 2011
Thermoplastic vulcanizates (TPVs) based on polypropylene (PP) with ethylene–octene copolymer (EOC... more Thermoplastic vulcanizates (TPVs) based on polypropylene (PP) with ethylene–octene copolymer (EOC) and ethylene propylene diene rubber (EPDM) have been prepared by co-agent-assisted peroxide crosslinking system. The study was pursued to explore the influence of two dissimilar polyolefin polymers having different molecular architecture on the state and mode of dispersion of the blend components and their influence on melt rheological properties.
Ophthalmology, 2008
Purpose: To report ocular manifestations associated with chikungunya. Design: Retrospective, nonr... more Purpose: To report ocular manifestations associated with chikungunya. Design: Retrospective, nonrandomized, observational case series. Participants: Nine chikungunya patients with ocular involvement. Methods: All patients with chikungunya infection presenting with ocular complaints from September 2006 to October 2006 were included in the study. The infection was confirmed by demonstration of chikungunya immunoglobulin M antibody in sera of all patients. All patients underwent an ophthalmic examination including fundus photography, fundus fluorescein angiography, confocal microscopy of keratic precipitates, and optical coherence tomography. Positive ocular changes were recorded and tabulated.
Materials Science and Engineering: C, 2012
ABSTRACT Surface modification of polypropylene by nitrogen containing plasma was performed in thi... more ABSTRACT Surface modification of polypropylene by nitrogen containing plasma was performed in this work in order to improve the wettability which resulted in enhanced biocompatibility and blood compatibility. Various nitrogen containing functional groups as well as oxygen containing functional groups were found to be incorporated to the polymer surface during plasma treatment and post plasma reaction respectively. Wettability of the polymers was evaluated by static contact angle measurement to show the improvement in hydrophilicity of plasma treated polypropylene. Cross linking and surface modification were reported to be dominating in the case of nitrogen plasma treatment compared to degradation. The effect of various process variables namely power, pressure, flow rate and treatment time on surface energy and weight loss was studied at various levels according to the central composite design of response surface methodology (RSM). Except pressure the other variables resulted in increased weight loss due to etching whereas with increasing pressure weight loss was found to increase and then decrease. The effect of process variables on surface morphology of polymers was evaluated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Well spread fibroblast cells on nitrogen plasma treated polypropylene due to the presence of CO, NH2+ and NH+ was observed. Reduced platelet adhesion and increased partial thromboplastin time evidenced the increased blood compatibility.
Journal of Polymer Research, 2010
Abstract The effects of mixing sequence on the mechani-cal, morphological and thermal properties ... more Abstract The effects of mixing sequence on the mechani-cal, morphological and thermal properties of polypropylene (PP)/ethylene octene copolymer (EOC) TPVs were studied. Three different mixing sequences were employed. They are as follows: (a) preblending methodmelt ...
Journal of Neuro-Ophthalmology, 2007
Two patients presented with retinitis as the initial clinical manifestation of subacute sclerosin... more Two patients presented with retinitis as the initial clinical manifestation of subacute sclerosing panencephalitis (SSPE), a delayed neurologic complication of measles. In one patient, the ocular involvement preceded the neurologic symptoms by 4 weeks and in the other patient by 4 years. The diagnosis of SSPE was suspected when neuropsychiatric manifestations appeared and was confirmed by the typical panencephalitic electroencephalography changes, neuroimaging features of panencephalitis, and high titers of measles antibodies in serum and cerebrospinal fluid. Although SSPE is an untreatable illness, recognition of this unusual presentation is valuable to allow earlier diagnosis and institution of palliative measures.
Journal of Materials Science, 2011
In recent times, polymer-layered silicate nanocomposites have drawn a great deal of attention bec... more In recent times, polymer-layered silicate nanocomposites have drawn a great deal of attention because they often exhibit tremendous improvements in material properties compared with virgin polymers or conventional microor macro-composites. In the present study, nanocomposites were developed from organically modified clay and poly(ethylene-co-vinyl acetate-co-carbon monoxide) by melt mixing. FTIR spectroscopy reveals that the interaction between the organoclay and EVACO is thermodynamically favored. High resolution wide angle X-ray diffraction and transmission electron microscopy were used to study the morphology of the nanocomposites. Elemental mapping by scanning electron microscopy indicates good dispersion and distribution of the nanoclay in EVACO matrix. The mechanical properties of the nanocomposites are optimum at a clay loading of 3%.
Journal of Cataract & Refractive Surgery, 2007
We present 2 cases that came to our institute for refractive surgery and were discovered to have ... more We present 2 cases that came to our institute for refractive surgery and were discovered to have serious systemic conditions requiring immediate intervention. On examination, prolactinoma of the pituitary gland was seen in one patient and multiple sclerosis was diagnosed in the other patient. Prompt treatment of the conditions led to improvement in the neuro-ophthalmic disorders. We recommend a thorough physical evaluation of patients having an ophthalmic examination.
Journal of Applied Polymer Science, 2009
Dynamically cured blends of polypropylene (PP) and ethylene octene copolymer (EOC) with coagentas... more Dynamically cured blends of polypropylene (PP) and ethylene octene copolymer (EOC) with coagentassisted peroxide curative system were prepared by meltmixing method. It was well established that PP exhibits b-chain scission in the presence of peroxide. Principally, incorporation of a coagent increases the crosslinking efficiency in the EOC phase and decreases the extent of degradation in the PP phase. The present study mainly focused on the influence of three structurally different coagents, namely, triallyl cyanurate (TAC), trimethylol propane triacrylate (TMPTA), and N,N 0 -m-phenylene dimaleimide (MPDM), on the mechanical properties of the PP/EOC thermoplastic vulcanizates (TPVs). The reactivity and efficiency of different coagents were characterized by cure study on EOC gum vulcanizate. TAC showed the highest torque values followed by MPDM and TMPTA. Significant improvements in the physical properties of the TPVs were inferred with the addition of coagents. Among the three coagents used, MPDM showed the best balance of mechanical properties in these TPVs. The results indicated that torque values obtained during mixing and the final mechanical properties can be correlated. Different aspects were explained for the selection of a coagent that forms a product with desired properties. The phase morphologies of the TPVs prepared were studied by scanning electron microscopy. Tensile fracture patterns were also analyzed to study the failure mechanism of the samples.
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Papers by Rajesh Babu Chunchula