S. Prasannakumar

Bio: S. Prasannakumar is an academic researcher. The author has contributed to research in topics: Maleic anhydride & Nanofluid. The author has an hindex of 4, co-authored 7 publications receiving 50 citations.

Synthesis, characterisation and thermal conductivity of CuO - water based nanofluids with different dispersants

Abstract: The aim of the present work is to investigate the change in thermal conductivity and stability of copper oxide (CuO) water-based nanofluids, which are prepared by a two-step process, with different...

Poly(N-vinyl-2-pyrrolidone-maleic anhydride-styrene) grafted terpolymer: Synthesis, characterization, and bactericidal property evaluation against E. coli and S. epidermidis

Abstract: Poly(N-vinyl-2-pyrrolidone-maleic anhydride-styrene) terpolymer was prepared using AIBN initiator with acetone as solvent. The terpolymer was grafted with anti-bacterial agents para-aminobenzoic ac...

Synthesis, characterization, microstructure determination, thermal studies of poly (N-vinyl pyrrolidone-maleic anhydride-methyl methacrylate)

Abstract: Synthesis of Poly (N-vinyl pyrrolidone-maleic anhydride-methyl methacrylate) terpolymer using azobisisobutyronitrile in 1,4-dioxan is described. The polymers with different composition were synthesized and characterized using FTIR, 1HNMR, 13NMR, TGA and DSC techniques. The mono mer-monomer interactions were studied using Finemann-Ross and Kelen-Tudos methods by calculating the reactivity ratio. The reactivity ratio r1 and r2 with respect to methyl methacrylate and N-vinylpyrrolidone-maleic anhydride complexomer are found to be 6.05 and 0.06 respectively. The study showed methyl methacrylate have higher reactivity than N-vinyl-2-pyrrolidone-maleic anhydride complex, i.e., the terpolymer contained methyl methacrylate in higher ratio. The thermal stability of poly (N-vinyl pyrrolidone-maleic anhydride-methyl methacrylate) was 165�C and the glass transition temperature was found to increase from 153�C to 182�C as MMA concentration increase. The studies indicate the activity of the polymer to inhibit bacterial growth is very poor.

Synthesis, characterization, microstructure determination and thermal studies of poly(N-vinyl-2-pyrrolidone–maleic anhydride–styrene) terpolymer

Abstract: A series of poly(N-vinyl-2-pyrrolidone–maleic anhydride–styrene) terpolymers have been synthesized using titanium(III)-dimethylglyoxime redox initiator system. The usage of redox initiators in the terpolymerization was limited; hence it should be considered as a new approach. The reactivity of the monomers has been studied by well-accepted Kelen-Tudos and Fineman-Ross linear methods and compared with the nonlinear RREVM method. The results also suggested that the RREVM method is the most reliable and superior method for the estimation of reactivity ratios. The reactivity ratios for the terpolymer (r1 0.99 and r2 0.05) obtained from the RREVM method showed that the N-vinyl pyrrolidone-maleic anhydride complex was more predominant than styrene in the terpolymer and the complex had more attraction toward itself than styrene. The microstructure determination study depicts that alternating polymer can be prepared by increasing the styrene feed content. The resonance factor and polarity of the complex were calculated as 5.01 and 0.93, respectively, which were different from those of the individual monomers. These calculations would help in predicting the association of monomers during copolymerization. It was observed that the glass transition temperature of the terpolymer increased as the complex ratio in the terpolymer increased. The terpolymer was thermally stable up to 323 °C.

Viscosity and thermal conductivity of ZnO–water-based nanofluids stabilized by grafted SMA-g-MPEG comb-shaped copolymer for heat transfer applications

Abstract: In this work, the effect of poly(styrene-co-maleic anhydride)-grafted methoxy (polyethylene glycol) (SMA-g-MPEG) copolymer as dispersants on the viscosity and thermal conductivity of zinc oxide (ZnO)–water-based nanofluids was studied. Various molecular weight MPEGs were grafted to SMA copolymer by esterification reaction, and ZnO nanoparticles (NPs) were prepared by microwave irradiation method. Prepared ZnO NPs and copolymers were characterized by UV, FESEM, TEM, XRD, FTIR, NMR and TGA techniques. The grafted copolymer was used to enhance the dispersibility of ZnO–water-based nanofluids. The effect of SMA-g-MPEG comb-shaped copolymer on the viscosity and thermal conductivity of the suspensions was investigated at different concentrations (0.1, 0.3 and 0.5 wt%) and solid volume fractions of ZnO NPs (φ = 0.5–3.0%). The suspension with SMA-g-MPEG 2000 dispersant showed improved stabilization at higher particle concentration. The variation of viscosity with shear rate showed the nanofluids behaved as a non-Newtonian fluid at the lower shear rate and Newtonian behaviour with the increase in shear rate. However, thermal conductivities of the ZnO–water-based nanofluids increased with increasing of the particle volume concentration and decreased with increase in the chain length of the grafted molecules. The average chain length of the grafted molecule exhibited enhanced thermal conductivity as compared with that of the base fluids. Finally, experimental values of the thermal conductivity and viscosity were compared with the estimations done by several simple theoretical models.

Effect of Temperature

Abstract: A positive temperature coefficient is the term which has been used to indicate that an increase in solubility occurs as the temperature is raised, whereas a negative coefficient indicates a decrease in solubility with rise in temperature.

Green Synthesis of Zinc Oxide Nanoparticles (ZnO-NPs) Using Arthrospira platensis (Class: Cyanophyceae) and Evaluation of their Biomedical Activities.

Abstract: In this study, zinc oxide nanoparticles (ZnO-NPs) were successfully fabricated through the harnessing of metabolites present in the cell filtrate of a newly isolated and identified microalga Arthrospira platensis (Class: Cyanophyceae). The formed ZnO-NPs were characterized by UV–Vis spectroscopy, Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Data showed the efficacy of cyanobacterial metabolites in fabricating spherical, crystallographic ZnO-NPs with a size ≈30.0 to 55.0 nm at a wavelength of 370 nm. Moreover, FT-IR analysis showed varied absorption peaks related to nanoparticle formation. XPS analysis confirms the presence of Zn(II)O at different varied bending energies. Data analyses exhibit that the activities of biosynthesized ZnO-NPs were dose-dependent. Their application as an antimicrobial agent was examined and formed clear zones, 24.1 ± 0.3, 21.1 ± 0.06, 19.1 ± 0.3, 19.9 ± 0.1, and 21.6 ± 0.6 mm, at 200 ppm against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans, respectively, and these activities were reduced as the NPs concentration decreased. The minimum inhibitory concentration (MIC) values were determined as 50 ppm for S. aureus, 25 ppm for P. aeruginosa, and 12.5 ppm for B. subtilis, E. coli, and C. albicans. More interestingly, ZnO-NPs exhibit high in vitro cytotoxic efficacy against cancerous (Caco-2) (IC50 = 9.95 ppm) as compared with normal (WI38) cell line (IC50 = 53.34 ppm).