Faculty Publications

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    Thermal degradation and swelling of thermoplastic vulcanizates from NBR/SAN and NBR/Scrap computer plastics blends
    (Huthig GmbH, 2009) Anandhan, S.; Rajeev, R.S.; De, S.K.; Bhowmick, A.K.
    Thermoplastic elastomeric blends of nitrile rubber (NBR)/poly(styrene- coacrylonitrile) (SAN) and NBR/scrap computer plastics (SCP) based on acrylonitrile-butadiene-styrene terpolymer (ABS) were prepared. Thermoplastic elastomeric blends of NBR/SAN containing various amounts of a model waste nitrile rubber powder (w-NBR) were also prepared. Thermogravimetric analysis of the above blends was performed in a nitrogen atmosphere. Both Friedman and Flynn-Wall-Ozawa methods were used for the evaluation of activation energies of thermal degradation of these blends. The dynamically vulcanised blends exhibit higher amount of activation energies for thermal degradation than the unvulcanised ones. Swelling studies were performed in various solvents having different solubility parameter values and maximum swelling was found to occur in a solvent having a solubility parameter that was closer to that of the blend components, i.e., around 20MPa1/2. Dynamically vulcan-ised blends show excellent resistance to IRM #903 oil as well as four chosen solvents possessing different solubility parameters (E).
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    Machining characteristics of multiwall-CNT reinforced Al/Al-Si composites using recurrence quantification analysis
    (2011) Gangadharan, K.V.; Umashankar, K.S.; Ravish; Desai, V.
    Aluminium (Al)/Aluminium alloy composites are emerging as very promising materials, especially in the fields of aerospace and automotive for their various attractive and technically demanding properties. Discontinuously reinforced aluminium metal matrix composites with reinforcements as nanoparticles of ceramics in general and carbon nanotubes in particular have emerged as the forerunner for a variety of general and special engineering and structural applications. In many of the fields where these materials find applications, machining is invariably required for getting correct geometries, dimensions and surface finish of the components. Hence, establishing the machining characteristics of these materials in terms of the deterministic nature of dynamic signals such as cutting force signals and vibration signals is very important and sought after. Machining process has been understood to be nonlinear and chaotic in nature. In this paper a relatively new technique called Recurrence Plots (RP) and Recurrence Quantification Analysis (RQA), a tool to analyse nonlinear and chaotic systems, is used to study the machining characteristics of cast and powder metallurgy Al and Al-Si alloys (LM6 and LM25), CNT reinforced Al/Al-Si composites produced by powder metallurgy route. Cutting force signals were sensed, acquired and analysed using RQA technique. Determinism (DET), which is one of the variables of RQA, indicates the determinism present in a signal. The values of DET were used to compare the machining characteristics. For all the three materials the deterministic nature of the cutting force signal was highest when reinforced with 0.5 weight percentage CNT, followed by respective base alloys produced by powder metallurgy method and casting route. © 2011 Jordan Journal of Mechanical and Industrial Engineering.
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    LiClO4-doped plasticized chitosan and poly(ethylene glycol) blend as biodegradable polymer electrolyte for supercapacitors
    (Institute for Ionics, 2013) Sudhakar, Y.N.; Muthu, M.; Bhat, D.K.
    Biodegradable polymer electrolyte comprising the blend of chitosan (CS) and poly(ethylene glycol) (PEG) plasticized with ethylene carbonate and propylene carbonate, as host polymer, and lithium perchlorate (LiClO4), as a dopant, was prepared by solution casting technique. The ionic conductivity has been calculated using the bulk impedance obtained through impedance spectroscopy. The variation of conductivity and dielectric properties has been investigated as a function of polymer blend ratio, plasticizer content and LiClO4 concentration at temperature range of 298-343 K. The DSC thermograms show two broad peaks for CS/PEG blend and increased with increase in the LiClO4 content. The maximum conductivity has been found to be 1. 1 × 10-4 S cm-1 at room temperature for 70:30 (CS/PEG) concentration. The electric modulus of the electrolyte film exhibits a long tail feature indicative of good capacitance. The activation energy of all samples was calculated using the Arrhenius plot, and it has been found to be 0. 12 to 0. 38 eV. A carbon-carbon supercapacitor has been fabricated using this electrolyte, and its electrochemical characteristics and performance have been studied. The supercapacitor showed a fairly good specific capacitance of 47 F g-1. © 2012 Springer-Verlag.
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    Thermoplastic vulcanizates from post consumer computer plastics/nitrile rubber blends by dynamic vulcanization
    (Springer Japan, 2013) Anandhan, S.; Bhowmick, A.K.
    Due to depletion of natural resources and increasing greenhouse emissions, new technologies for the transformation of waste polymers into valuable materials represent one of our greatest current needs. Acrylonitrile-butadiene-styrene terpolymer (ABS) is one of the most widely used engineering plastics and is used as outer casing for electronic equipment. Nitrile rubber (NBR) is used in many applications that demand oil resistance. In an attempt to explore whether these materials can be successfully recycled, we prepared blends of scrap computer plastics (SCP) based on ABS with NBR and waste NBR powder (w-NBR), and investigated their mechanical properties and recyclability. Specifically, we assessed the effect of dynamic vulcanization and replacement of virgin NBR with w-NBR on the properties of 60/40, 70/30, and 80/20 NBR/SCP blends. These blends exhibited thermoplastic elastomeric behavior. The thermoplastic elastomeric blends showed excellent swelling resistance to standard lubricant oil (namely, IRM 903 oil). © 2013 Springer Japan.
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    Simple viscosity criterion for injection moulding thermoplastics
    (Society of Plastics and Rubber Engineers, 2015) Lakkanna, M.; Kumar, G.C.M.; Kadoli, R.
    Thermoplastics are available in abundance with immense properties variations, but only few are processed by injection moulding. So this manuscript deals with this issue by proposing a design criteria contingent to a particular combination of material properties, machine specifications and moulding features. Pertinently embracing their behavioural relationships a unique analytical design criterion was deduced directly from first principles. Comprehending injection conduit to an analogous capillary tube; as well as cognising generalized Newtonian concept for thermoplastic melts with power-law description of in-situ rheological behaviour. The proposed criterion being simple and generic easily adapts in early mould design itself and comprehends entire range of thermoplastic in-situates. Hereafter any thermoplastics could be injection moulded by contingently designing an exclusive mould feed system for it. This percipience was elucidated by continuously sensitising a hypothetical intervene across all thermoplastics while explicitly appraising, why melt kinesis lacunae can never be fully rectified, despite manipulating process parameters many times? Finally, the manuscript extends hereto-believed linear relationship between runner-conduit size and in-situ melt state to direct exponential proportionality with discrete slope and altitude for each thermoplastic behaviour..
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    Sound radiation and transmission loss characteristics of a honeycomb sandwich panel with composite facings: Effect of inherent material damping
    (Academic Press, 2016) Arunkumar, M.P.; Jagadeesh, M.; Jeyaraj, J.; Gangadharan, K.V.; Mailan Chinnapandi, M.C.L.
    This paper presents the results of numerical studies carried out on vibro-acoustic and sound transmission loss behaviour of aluminium honeycomb core sandwich panel with fibre reinforced plastic (FRP) facings. Layered structural shell element with equivalent orthotropic elastic properties of core and orthotropic properties of FRP facing layer is used to predict the free and forced vibration characteristics. Followed by this, acoustic response and transmission loss characteristics are obtained using Rayleigh integral. Vibration and acoustic characteristics of FRP sandwich panels are compared with aluminium sandwich panels. The result reveals that FRP panel has better vibro-acoustic and transmission loss characteristics due to high stiffness and inherent material damping associated with them. Resonant amplitudes of the response are fully controlled by modal damping factors calculated based on modal strain energy. It is also demonstrated that FRP panel can be used to replace the aluminium panel without losing acoustic comfort with nearly 40 percent weight reduction. © 2016 Elsevier Ltd
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    Computational design of mould sprue for injection moulding thermoplastics
    (Society for Computational Design and Engineering info@idsociety.org, 2016) Lakkanna, M.; Mohan Kumar, G.C.; Kadoli, R.
    To injection mould polymers, designing mould is a key task involving several critical decisions with direct implications to yield quality, productivity and frugality. One prominent decision among them is specifying sprue-bush conduit expansion as it significantly influences overall injection moulding; abstruseness anguish in its design criteria deceives direct determination. Intuitively designers decide it wisely and then exasperate by optimising or manipulating processing parameters. To overwhelm that anomaly this research aims at proposing an ideal design criteria holistically for all polymeric materials also tend as a functional assessment metric towards perfection i.e., criteria to specify sprue conduit size before mould development. Accordingly, a priori analytical criterion was deduced quantitatively as expansion ratio from ubiquitous empirical relationships specifically a.k.a an exclusive expansion angle imperatively configured for injectant properties. Its computational intelligence advantage was leveraged to augment functionality of perfectly injecting into an impression gap, while synchronising both injector capacity and desired moulding features. For comprehensiveness, it was continuously sensitised over infinite scale as an explicit factor dependent on in-situ spatio-temporal injectant state perplexity with discrete slope and altitude for each polymeric character. In which congregant ranges of apparent viscosity and shear thinning index were conceived to characteristically assort most thermoplastics. Thereon results accorded aggressive conduit expansion widening for viscous incrust, while a very aggressive narrowing for shear thinning encrust; among them apparent viscosity had relative dominance. This important rationale would certainly form a priori design basis as well diagnose filling issues causing several defects. Like this the proposed generic design criteria, being simple would immensely benefit mould designers besides serve as an inexpensive preventive cliché to moulders. Its adaption ease to practice manifests a hope of injection moulding extremely alluring polymers. Therefore, we concluded that appreciating injectant?s polymeric character to design exclusive sprue bush offers a definite a priori advantage. © 2015 Society of CAD/CAM Engineers
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    Fabrication of hair and copper fiber reinforced polymethyl methacrylate (pmma) composites and evaluation of their mechanical properties, thermal conductivity and color stability for dental applications
    (Society for Biomaterials and Artificial Organs - India sharmacp@sbaoi.org, 2016) Jayaprakash, K.; Nandish, B.T.; Rijesh, M.; Nayak, J.; Bhat, S.M.; Shetty, K.H.K.; Nityananda Shetty, A.; Prabhu, S.
    The objective of the work was to fabricate and evaluate the impact strength, flexural strength, thermal conductivity and color stability of heat cure Polymethyl methacrylate denture base resin, reinforced with human hair fibers and copper fibers. Specimens were prepared by reinforcing human hair fibers of 2mm length and diameter in the range of 64 -78 ?m, in different quantities with respect to two different age groups and genders, to polymer-monomer mix before dough stage. Same procedure was followed to fabricate specimens with copper fibers (2mm length and 200 ?m diameter) too. The impact strength, transverse strength, thermal conductivity, and color stabilities were measured by using standard equipment's. Scanning electron microscope (SEM) was used to study the fractured surface of the fiber reinforced composites. The impact strength increased three times in hair reinforced and about twice in copper reinforced composites. The transverse strength was slightly decreased and the cause for it was investigated. Copper fiber reinforced composite significantly increased the thermal conduction. The human hair and copper reinforced Polymethyl methacrylate showed significant improvements in its mechanical properties and retained color stability similar to control specimens during storage in various beverages.
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    Soft computing techniques during drilling of bi-directional carbon fiber reinforced composite
    (Elsevier Ltd, 2016) Shetty, N.; Herbert, M.A.; Shetty, R.; Shetty, D.S.; Vijay, G.S.
    Due to the intricacy of machining processes and inconsistency in material properties, analytical models are often unable to describe the mechanics of machining of carbon fiber reinforced polymer (CFRP) composites. Recently, soft computing techniques are used as alternate modeling and analyzing methods, which are usually robust and capable of yielding comprehensive, precise, and unswerving solutions. In this paper, drilling experiments as per the Taguchi L27 experimental layout are carried out on bi-directional carbon fiber reinforced polymer (BD CFRP) composite laminates using three types of drilling tools: high speed steel (HSS), uncoated solid carbide (USC) and titanium nitride coated SC (TiN-SC). The focus of this work is to determine the best drilling tool that produces good quality drilled holes in BD CFRP composite laminates. This paper proposes a novel prediction model 'genetic algorithm optimised multi-layer perceptron neural network' (GA-MLPNN) in which genetic algorithm (GA) is integrated with Multi-Layer Perceptron Neural Network. The performance capability of response surface methodology (RSM) and GA-MLPNN in prediction of thrust force is investigated. RSM is also used to evaluate the influence of process parameters (spindle speed, feed rate, point angle and drill diameter) on thrust force. GA is used to optimize the thrust force and its optimization performance is compared with that of RSM. It is observed that the GA-MLPNN is better predicting tool than the RSM model. The investigation in this paper demonstrates that TiN-SC is the best tool for drilling BD CFRP composite laminates as minimum thrust force is developed during its use. © 2016 Elsevier B.V. All rights reserved.
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    Effect of cenosphere surface treatment and blending method on the tensile properties of thermoplastic matrix syntactic foams
    (John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2016) Bharath Kumar, B.R.; Zeltmann, S.E.; Doddamani, M.R.; Gupta, N.; Uzma; Gurupadu, S.; Sailaja, R.R.N.
    The influence of cenosphere surface treatment and blending method on the properties of injection molded high-density polyethylene (HDPE) matrix syntactic foams is investigated. Cenospheres are treated with silane and HDPE is functionalized with dibutyl maleate. Tensile test specimens are cast with 20, 40, and 60 wt % of cenospheres using injection molding. Modulus and strength are found to increase with increasing cenosphere content for composites with treated constituents. Highest modulus and strength were observed for 40 and 60 wt % untreated mechanically mixed and treated brabender mixed cenospheres/HDPE blends, respectively. These values are 37 and 17% higher than those for virgin and functionalized HDPE. Theoretical models are used to assess the effect of particle properties and interfacial bonding on modulus and strength of syntactic foams. Brabender mixing method provided highest ultimate tensile and fracture strengths, which is attributed to the effectiveness of Brabender in breaking particle clusters and generating the higher particle–matrix surface area compared to that by mechanical mixing method. Theoretical trends show clear benefits of improved particle–matrix interfacial bonding in the strength results. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43881. © 2016 Wiley Periodicals, Inc.