Browsing by Author "Nusrath Unnisa, C"

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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
DEVELOPMENT OF POLY(GLYCEROL SUBERATE) POLYESTER (PGS)–PVA BLEND POLYMER ELECTROLYTES WITH NH4SCN AND ITS APPLICATION
(Springer Link, 2018-02-28) Nusrath Unnisa, C; Chitra, S; Selvasekarapandian, S; Monisha, S; Nirmala Devi, G; Moniha, V; Hema, M
Besides commercially available synthetic polymers, the present work has been undertaken to explore the significance of poly(glycerol suberate) (PGS) polyester synthesised under lab scale in energy storage device. In this regard, a blend polymer electrolyte comprising of polyvinyl alcohol (PVA), poly(glycerol suberate) (PGS) polyester along with the various proportions of ammonium thiocyanate (NH4SCN) was prepared adopting solution casting technique. The synthesised polyester PGS was characterised by Fourier transform infrared (FT-IR) spectroscopy, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The prepared electrolyte film was subjected to FT-IR analysis to study the complexation that has occurred within the blend. Its amorphous nature was revealed from X-ray diffraction (XRD) studies. Influence of NH4SCN on the glass transition temperature (Tg) was drawn from differential scanning calorimetry (DSC) technique. The dispersion of dopant within the polymer matrix was supported by scanning electron microscopy (SEM) followed by its elemental composition from energy dispersive spectroscopy (EDS). From the AC impedance technique, maximum conductivity of 3.01 × 10−4 S cm−1 was elicited for the optimised electrolyte (1 g PVA + 0.75 g PGS + 0.6 g NH4SCN). Frequency-dependent dielectric and modulus spectra were analysed to study the mechanism of transportation. Transport parameters evaluated by Wagner’s polarisation method proved that the conductivity was predominantly due to cations. Proton conducting battery was configured with the highest conducting electrolytic film and its cell parameters are presented.
EFFECT OF AZLACTONES ON CORROSION INHIBITION OF MILD STEEL IN ACID MEDIUM
(Journal of Applied Sciences Research, 2010) Parameswari, K; Chitra, S; Nusrath Unnisa, C; Selvaraj, A
The inhibition efficiency of azlactones on corrosion behaviour of mild steel in 1M H2SO4 has been evaluated using weight loss, gasometry and atomic absorption spectroscopy techniques which shows increase in inhibition efficiency with increase in concentration.Effect of temperature strongly ensures stronger physisorption of the compounds, which obeys Langmuir adsorption isotherm. The inhibition efficiency has been synergistically enhanced by the addition of halide ions. The kinetic corrosion parameters analysed in terms of impedance data shows a satisfactory agreement with those obtained by potentiodynamic polarisation method.
EFFECT OF AZLACTONES ON CORROSION INHIBITION OF MILD STEEL IN ACID MEDIUM (Article pdf)
(Journal of Applied Sciences Research, 2010) Parameswari, K; Chitra, S; Nusrath Unnisa, C; Selvaraj, A
The inhibition efficiency of azlactones on corrosion behaviour of mild steel in 1M H2SO4 has been evaluated using weight loss, gasometry and atomic absorption spectroscopy techniques which shows increase in inhibition efficiency with increase in concentration.Effect of temperature strongly ensures stronger physisorption of the compounds, which obeys Langmuir adsorption isotherm. The inhibition efficiency has been synergistically enhanced by the addition of halide ions. The kinetic corrosion parameters analysed in terms of impedance data shows a satisfactory agreement with those obtained by potentiodynamic polarisation method.
POLY(GLYCEROL PIMELATE) POLYESTER AS MODERATE MILD STEEL PROTECTOR IN 0.5 M H2SO4: JUSTIFIED FROM ELECTROCHEMICAL APPROACH AND XPS INVESTIGATION
(Taylor & Francis Online, 2019-08-23) Nusrath Unnisa, C; Hema Priya, V; Subramanian, Chitra
This work reports a facile synthesis of linear long chain aliphatic polyester, namely poly(glycerol pimelate) polyester (PGP) characterised by Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance spectroscopy (1H and 13C NMR). Thermal response of PGP was studied using Thermo gravimetric analysis (TGA) and Differential scanning calorimetry (DSC). Glass transition temperature (Tg) of 117 °C and thermal stability up to 290 °C was noticed from DSC and TGA analysis. As a potential application, the capability and extent of retarding the mild steel dissolution in 0.5 M H2SO4 medium rendered by the synthesised PGP was analysed by electrochemical and non-electrochemical methods. Weight loss measurements carried out at room temperature showed decreased corrosion rate with concentration (10, 50, 100, 500 and 1000 ppm) resulting in a moderate inhibition efficiency of 61.60% at 1000 ppm. Decreased inhibition efficiency was noticed on increasing the temperature from 303 K-333K. Various parameters were derived to understand the mode of adsorption. Increased charge transfer resistance (Rct) from electrochemical impedance method (EIS) and decreased corrosion current density (Icorr) from potentiodynamic polarisation technique on increasing the concentration was in good agreement with weight loss measurements. Suppression of metal dissolution by the formation of film on the metal surface was additionally supported by X-ray diffraction studies (XRD), scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS) followed by Atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) revealed the same with a detailed insight of adsorption of inhibitor on the metal surface.
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.