h) 2018 - 49 Documents

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Author: search.filters.author.Subramanian, Chitra

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    ASSESSMENT OF LOW CARBON STEEL CORROSION INHIBITION BY ECO-FRIENDLY GREEN CHAENOMELES SINENSIS EXTRACT IN ACID MEDIUM
    (The Korean Electrochemical Society, 2018-07-16) Ill-Min, Chung; Venkatesan, Hemapriya; Kanchana, Ponnusamy; Natarajan, Arunadevi; Subramanian, Chitra; Chi-Hee, Youn; Seung-Hyun, Kim; Mayakrishnan, Prabakaran
    The impact of methanol extract of Chaenomeles sinensis (C. sinensis) leaves on acid corrosion of low carbon steel was assessed by gravimetric and electrochemical methods. Phytochemical characterization by total phenolic content (TPC), and total flavonoids content (TFC) of the extract was performed. The TPC and TFC concentrations were identified as 193.50 and 40.55 mg/g. Efficiency increased remarkably in the presence of inhibitor and found as concentration dependent. A maximum inhibition efficiency of 93.19% was achieved using 2000 ppm of the C. sinensis inhibitor. Impedance and surface morphology analysis by SEM and AFM revealed that the anticorrosive activity results from the protective film of phytochemical components of C. sinensis extract adsorbed on the metal surface.
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    LINEAR POLYESTERS AS EFFECTIVE CORROSION INHIBITORS FOR STEEL REBARS IN CHLORIDE INDUCED ALKALINE MEDIUM – AN ELECTROCHEMICAL APPROACH
    (Elsevier, 2018-03-20) Chan Basha, Nusrath Unnisa; Gowraraju, Nirmala Devi; Venkatesan, Hemapriya; Subramanian, Chitra; Ill-Min, Chung; Seung-Hyun, Kim; Mayakrishnan, Prabakaran
    As a motto of framing the strategies to minimise the deterioration in steel reinforced concrete structures as well as the fact that the work carried out with polymers are rare and scanty, polyesters namely Poly (Glycerol azealate) (PGAZ) and 4-(1-(4-methoxy phenyl) cyclo hexyl)phenyl 9-oxodecanoate (MPOD) were synthesised and evaluated for rebar corrosion in simulated concrete pore solution (SCP) for the first time at selected concentrations of 10, 100, 1000 ppm levels with an aid of electrochemical impedance and potentiodynamic polarisation techniques. Nyquist plots favoured increased Rct values suggesting the formation of barrier. Tafel plots represented cathodic inhibition. The experimental datas were best fitted with Langmuir adsorption isotherm facilitating monolayer adsorption. Both the methods employed were in good agreement with each other favouring maximum inhibition efficiency of 71.81% for MPOD and minimum of 57.64% for PGAZ primarily due the difference in aromatic sites as revealed in mechanism.
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    COMPARATIVE STUDY OF ADSORPTION OF LINEAR ALIPHATIC/AROMATIC POLYESTERS AT METAL/0.5 M H2SO4 INTERFACE
    (Elsevier, 2018-10) Nusrath Unnisa, C; Subramanian, Chitra
    Two polyesters namely poly (glycerol adipate) (PGA) and 4-(1-(4-methoxyphenyl) cyclohexyl) phenyl 6-oxoheptanoate (MPOHP) were synthesised in a facile manner and characterised using Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic spectroscopy (NMR). The synthesised polyesters were subjected to evaluate the mild steel protecting ability at various concentrations of 10, 50, 100, 500, 1000 ppm in 0.5 M H2SO4 medium. A precise comparison of metal protecting ability rendered by both aliphatic and aromatic moiety was analysed. As an initiation, gravimetric measurements carried out at room temperature resulted with increased inhibition efficiency with increased concentration. Higher temperature studies suggested physisorption mechanism resulting with decreased inhibition efficiency. Experimental results were best fitted with Langmuir adsorption isotherm model. Electrochemical impedance measurements carried out for the selected concentrations of the inhibitors (10, 100, 1000 ppm) revealed increased charge transfer resistance (Rct) with a maximum inhibition efficiency of 54.07% (PGA) and 69.92% (MPOHP) at 1000 ppm indicating the formation of protective barrier. Potentiodynamic polarisation method suggested mixed type of inhibition of both PGA and MPOHP on the metal surface resulting in decreased metal dissolution that could be evidenced from lowered corrosion current density
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    STUDY OF BIO-SYNTHESISED TRANSITION NANO METAL OXIDES DISPERSED POLYESTER COMPOSITES AS ENHANCED PROTECTORS FOR MILD STEEL IN 0.5 M H2SO4 MEDIUM-A GREEN APPROACH
    (Taylor & Francis Online, 2018-06-12) Nusrath Unnisa, C; Nirmala Devi, G; Selvaraj, Mohana Roopan; Subramanian, Chitra
    A facile, efficient and eco-friendly synthesis of transition nano metal oxides like zinc oxide (ZnO), copper oxide (CuO), tin oxide (SnO) from Persea americana. Mill was executed followed by ex-situ polymerization favoring poly (glycerol succinate) (PGS)/nano metal oxide composite for the first time. The incorporation of nanofillers was confirmed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectrometer (XRD), Scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS). As a comparative approach, the extent of metal dissolution was evaluated in presence of precursor as well as nano dispersed forms for various concentrations (10, 50, 100, 500, 1000 ppm) under the cluster of electrochemical and non-electrochemical techniques. Enhanced inhibition efficiency of 97% was observed in the case of CuO dispersion which was additionally supported by XRD particle size determination. The increase in charge transfer resistance (Rct) and a decrease in corrosion current (Icorr) elicited from electrochemical measurements strictly proved the role of metal – oxide nanoparticles. Further, the mode of inhibitor was found to be predominantly cathodic.