K.R. Vishnu Mahesh

Banyan latex: a facile fuel for the multifunctional properties of MgO nanoparticles prepared via auto ignited combustion route

MgO nanoparticles (MNPs) were prepared by a solution combustion route using banyan tree (BT) latex and glycine as fuels. The powder x-ray diffraction results indicate the formation of a single cubic phase and the crystallite size obtained from transmission electron microscopy was found to be ~10–15 nm. Scanning electron microscopy result reveals spherical-shaped particles obtained with BT latex. However, in a chemical route, porous and agglomerated particles were obtained. The energy band gap of MNPs obtained using BT latex and a chemical route were found to be in the range 4.85–5.0 eV. Photoluminescence peaks observed at 473, 514, and 588 nm when excited at 433 nm, which were attributed to surface defects. The enhanced photocatalytic activities of spherical MgO were due to smaller crystallite size, higher surface defects, dye sensitization, and capability to reduce the electron–hole pair recombination. Further, green-synthesized MNPs exhibit superior antifungal activity against various plant pathogens. The present studies demonstrated a green engineering route for the synthesis of multifunctional MNPs using BT latex.

The influence of montmorillonite on mechanical, thermal and fire retardation properties of vinylester/glass composites

This paper presents the influence of dispersing montmorillonite in 2 to 8 wt% in vinylester on the mechanical, thermal and fire retardation behaviour of vinylester/glass composites. X-ray diffraction and transmission electron microscopy results of montmorillonite/vinylester showed exfoliation of montmorillonite up to 4 wt% loading. Glass transition temperature (Tg) and microhardness of montmorillonite/vinylester increased with increase in montmorillonite loading. Tensile strength, interlaminar shear strength, flexural strength, impact strength and fatigue life of vinylester/glass increased by the addition of 4 wt% montmorillonite. Thermogravimetric analysis showed decrease in thermal degradation in 4 wt%/montmorillonite/vinylester compared to 2 wt%/montmorillonite/vinylester. Horizontal and vertical burning rates of vinylester/glass decreased with the addition of montmorillonite. Limiting oxygen index increased by 18% and 25% with the addition of 8 wt% montmorillonite to vinylester and vinylester/glass respectively. Scanning electron microscopy was used to study montmorillonite, vinylester and glass fibre interfacial strengths and the fatigue damage mechanism.

Mechanical behavior of organo-modified Indian bentonite nanoclay fiber-reinforced plastic nanocomposites

The aim of the research was to examine the influence of organo-modified Indian bentonite (IB) nanoclay dispersed in vinylester on the mechanical properties of nanoclay/vinylester/glass nanocomposites. Nanoclay was organically modified using cationic surfactant hexadecyltrimethylammonium bromide (HDTMA-Br) by cation exchange method and dispersed in vinylester using ultrasonication and twin screw extrusion. XRD of nanoclay/vinylester revealed exfoliation at 4 wt.% nanoclay indicating uniform dispersion in the polymer. DSC results showed improvement in glass transition temperature by 22.3% in 4 wt.% nanoclay/vinylester/glass when compared with that of vinylester/glass. Nanoclay/vinylester/glass with 4 wt.% nanoclay showed 29.23%, 23.84% and 60.87% improvement in ultimate tensile strength (UTS), flexural strength (FS) and interlaminar shear strength (ILSS) respectively when compared with those of vinylester/glass. The mode of tensile failure examined by SEM showed no agglomeration of nanoclay in 4 wt.% nanoclay/vinylester/glass specimens.

Effect of laminate thickness on moisture diffusion of polymer matrix composites in artificial seawater ageing

The influence of laminate thickness of polymer matrix composites on moisture diffusion in seawater immersion, as well as the resulting mechanical property degradation for composites of glass/isopolyester (G/IPE), carbon/isopolyester (C/IPE), glass/vinylester (G/VE) and carbon/vinylester (C/VE), was investigated in this paper. Laminates 3 and 10mm in thickness, fabricated using the wet hand lay-up technique, were characterized for moisture absorption in artificial seawater medium, and their flexural strength and interlaminar shear strength (ILSS) degradations were studied. Moisture diffusion was observed to be anamolous to the Fick’s law for both 3 and 10mm thick samples in the later stage of diffusion. Moisture permeability of 10mmthick samples was two to three order greater than that of 3mm thick ones, while the time to moisture saturation remained unchanged. With the increase of laminate thickness, moisture saturation increased by 1.4% for C/VE and 7% for G/IPE. The residual flexural strength and ILSS were greater in case of 10mm thick specimens after 200 days of exposure. SEM examination of the fractured specimens showed greater levels of fibre/matrix debonding in 10mm thick specimens.

Combined influence of organo-modified Indian bentonite nanoclay and fire retardants on thermal and fire behavior of vinylester

This article reports synergetic effect of naturally available Indian bentonite nanoclay and fire retardants on the thermal and fire retardation behavior of vinylester. Indian bentonite nanoclay organically modified with hexadecyltrimethylammonium bromide by cation exchange capacity method, along with aluminum trihydroxide and magnesium hydroxide were dispersed in vinylester and tested. Addition of 30% aluminum trihydroxide and 4 wt% Indian bentonite increased the glass transition temperature of vinylester by 24.4%; decreased thermal degradation by 47%, vertical burning rate by 54% and horizontal burning rate by 72%; and increased limiting oxygen index by 56.6% and microhardness by 49.6%.

DEVELOPMENT AND CHARACTERIZATION OF TITANIUM PHOSPHATES (TIP2O7) AND LITHIUM TITANIUM PHOSPHATE (LITIP2O7) AND THEIR THERMAL AND ELECTRIC PROPERTIES.

In this present study, the Titanium phosphates (TiP2O7) and Lithium titanium phosphate (LiTiP2O7) materials were synthesized by using soft hydrothermal method at moderate pressure and temperature conditions. The resultant materials were characterized by using P-XRD, SEM, EDAX, FTIR, TGA, DSC and Electrochemical impedance spectra (EIS). From P-XRD, confirms the well crystalline rhombohedral phase and was found to be in the range below 100 nm. FTIR spectra indicated that there is an increase in the degree of splitting and stretching of the vibration bands, whereas the splitting of vibration bands and polymerization of [PO4] decreased as the Ti ions. The TGA/DSC studies revealed that, these materials display endothermic reactions due to the liberation of ligands and diffusion. Thermal stability of the materials improved and the dielectric constant decreases. AC conductivity measurements for both the samples were carried and results are plotted. From AC conductivity studies, it is observed that the ionic conductivity of dc conductance of sample was measured show the frequency dependence dc capacitance of LiTiP2O7 material. The frequency response dc capacitance also depends on doping with titanium.

Synthesis and characterization of nano ZnO and MgO powder by low temperature solution combustion method: studies concerning electrochemical and photocatalytic behavior

Research Centre, Department of Science, EWIT, Bengaluru-560091, India Research and Development Centre, Bharathiar University, Coimbatore-641046, India Department of Chemistry, Dayananda Sagar College of Engineering, Bengaluru-78, India Dr. Premachandra Sagar Center for Advance Functional Materials, DSCE, Bengaluru-78, India Research Centre, Department of Chemistry, AMC Engineering College, Bengaluru-83, India Department of Studies and Research in Chemistry, B.H Road, Tumkur University Tumkur, Karnataka, India Department of Chemistry, Jyothi Institute of technology, Bengaluru-560062, India ∗nagaswarupa77@gmail.com

A facile hydrothermal recovery of nano sealed MnO2 particle from waste batteries: An advanced material for electrochemical and environmental applications

This work deliberates a method for manganese (Mn) recovery as manganese oxide obtained by leaching of waste batteries with 3M sulphuric acid. The Experimental test for the recovery of Mn present within the waste dry cell batteries were carried out by a reductive leachant. Elemental composition of leached sample was confirmed by Energy Dispersive X-ray analysis (EDAX), and Surface morphology of the recovered MnO2 was examined by using Scanning Electron microscopy (SEM). Phase composition was confirmed from X-ray Diffractro meter (XRD). The obtained leached solution was treated with 4M NaOH, yielded to Manganese Dioxide with high extraction degree, while it do not touches the Zn content within the solutions. The recovered samples were characterized using XRD, EDAX, SEM and Fourier transform infrared spectrometry (FTIR). The electrochemical properties of the as-recovered sample from leached solution was examined used cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Remarkably, the 80 wt.% MnO2 displays reversibility, diffusion constant, smaller equivalent series resistance and charge transfer resistance in 0.5M NaOH showed superior results as compared to alternative electrolytes. The ideal capacitive behaviour of MnO2 electrode and nano particle was applied to photocatalytic degradation of dyes.

Organomodified Clay and its Influence on Thermal and Fire Behaviors of Clay/Fire Retardant/Poly Vinyl Ester Composites

The objective of this research was to examine the synergistic effect of organomodified nanoclay and fire retardants on the thermal decomposition, glass transition temperature and fire retardation behaviour of nanoclay/Poly vinyl ester composites. The two nanoclays such as Cloisite-15A and Cloisite-Na are used along with two fire retardants as Aluminium Tri Hydroxide (ATH) and Magnesium Hydroxide (MH) in the present study. The nanoclay/fire retardants were dispersed in poly vinyl ester using twin screw extrusion. TEM and AFM of nanoclay/Poly vinyl ester specimens revealed that 4 wt% Cloisite-15A/Poly vinyl ester exhibited exfoliation and distribution of nanoclay which were superior to that of Cloisite-Na/Poly vinyl ester. The synergistic effect of Cloisite-15A and 30 % ATH increased glass transition temperature by 18 % and reduced thermal degradation by 47 % and Limiting Oxygen Index (LOI) by 52 % when compared with that of Poly vinyl ester after the curing process in all the cases.