Changanācheri, India
Changanācheri, India

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Mathew V.,St Aloysius College | Jacob S.,St Aloysius College | Mahadevan C.K.,Physics Research Center | Abraham K.E.,Sb College
Materials Letters | Year: 2011

Single crystals of copper malonate trihydrate were grown in silica gel by slow diffusion of copper nitrate by sodium metasilicate gel impregnated with malonic acid. The grown crystal was subjected to dielectric studies and magnetic studies. The dielectric properties of the crystal were analyzed as a function of frequency and temperature. A vibrating sample magnetometer was used to determine the hysteresis properties of the crystals by measuring the magnetic moment for different applied fields. The crystal is found to be weakly ferromagnetic. © 2011 Elsevier B.V. All rights reserved.


Mathew V.,St Aloysius College | Joseph J.,St Aloysius College | Jacob S.,St Aloysius College | Abraham K.E.,Sb College
Indian Journal of Pure and Applied Physics | Year: 2011

Growth of single crystals of strontium malonate has been accomplished using silica gel in glass test tubes. The powder XRD pattern of the sample reveals the strong crystalline nature. The FTIR and FT Raman spectra of the strontium malonate crystals are recorded and the vibrational assignments have been made with possible explanations. From diffuse reflectance spectroscopic (DRS) studies, the band gap of the material is also determined.


Mathew V.,St Aloysius College | Jacob S.,St Aloysius College | Xavier L.,St Aloysius College | Abraham K.E.,Sb College
Journal of Rare Earths | Year: 2012

Lanthanum malonate crystals were grown by single tube ionic diffusion through silica gel. The crystallinity of the grown crystals was analyzed by powder X-ray diffraction studies. Fourier transform infrared spectroscopy (FTIR) and fourier transform (FT) Raman studies confirmed the presence of functional groups in the title compound. The optical band gap energy of the material was extracted from diffuse reflectance spectrum.


Mathew V.,St Aloysius College | Joseph J.,St Aloysius College | Jacob S.,St Aloysius College | Abraham K.E.,Sb College
Bulletin of Materials Science | Year: 2010

The preparation of manganese malonate crystals by gel method and its spectroscopic studies are reported. X-ray diffraction (XRD) pattern reveals the crystalline nature. The FTIR and FT Raman spectra of the crystals are recorded and the vibrational assignments are given with possible explanations. Diffuse reflectance spectroscopy (DRS) is used to measure the bandgap (Eg) of the material. © Indian Academy of Sciences.


Idicula M.,Mar Thoma College | Joseph K.,SB College | Thomas S.,Mahatma Gandhi University
Journal of Reinforced Plastics and Composites | Year: 2010

Short randomly oriented banana and sisal hybrid fiber reinforced polyester composites, banana/polyester composites and sisal/polyester composites were fabricated at different fiber loading say, 0.20 to 0.50 Vf. Composites were prepared by varying the relative volume fraction of the two fibers at each fiber loading. When the fiber loading was increased; tensile, flexural, and impact properties increased. Better performance was shown by composites having volume fraction, 0.40 Vf. Tensile strength, tensile modulus, flexural strength, and flexural modulus showed a positive hybrid effect when the volume ratio of the fiber was varied in the hybrid composites at each fiber loading. Maximum tensile strength was observed in composites having volume ratio of banana and sisal 3:1. When the volume ratio of sisal was increased, the impact strength of the composite increased. Different layering patterns were tried at 0.40 Vf, keeping the volume ratio of fibers 1:1. Tensile properties were slightly greater in the trilayer composite with banana as the skin material. Bilayer composites showed higher flexural and impact property. SEM studies were carried out to evaluate fiber/matrix interactions. Experimental results were compared with theoretical predictions. © 2010 SAGE Publications.


Thomas S.P.,Bam College Thuruthicad | Ettolil M.J.,Sb College
Journal of Applied Polymer Science | Year: 2010

This study explored the possibility of preparing a new thio accelerator, N-benzylimine aminothioformamide to investigate its synergic accelerator activity in three conventional binary accelerator systems, N-cyclohexyl benzothiazyl sulfenamide, mercapto benzothiazyl disulfide, and tetramethylthiuram disulfide in the sulfur vulcanization of natural rubber. Each system was found effective in reduction of cure time as a further proof of the nucleophilic mechanism suggested in the earlier reports. The vulcanizates of the mixes of the three systems were experimented for evaluating their physicomechanical properties. Most of the properties were found better than those of the reference mixes. Crosslinks were also evaluated for correlating the properties. Based on the evaluated properties, optimum dosage of the new binary systems were derived. © 2010 Wiley Periodicals, Inc.


Saritha A.,Amrita University | Saritha A.,Sb College | Joseph K.,Indian Institute of Space Science and Technology | Thomas S.,Mahatma Gandhi University | Muraleekrishnan R.,VSSC
Composites Part A: Applied Science and Manufacturing | Year: 2012

The field of polymer nanocomposites has attracted attention as a method of enhancing polymer properties and extending their utility by using molecular or nanoscale reinforcements rather than conventional particulate filled nanocomposites. These materials exhibit behavior different from conventional composite materials with micro scale structure due to small size of structural unit and high surface to volume ratio. Chlorobutyl rubber nanocomposites were prepared using organically modified cloisite 15 A and characterized using XRD and TEM. The gas barrier properties of the nanocomposites were modeled using the composite theories of permeation and the tortousity factors were predicted. Analysis of mechanical properties, transport and gas barrier properties of the nanocomposites as well as the calculation of break through times show the effectiveness of the material to be utilized as potential gas as well as VOC barrier materials. © 2012 Elsevier Ltd. All rights reserved.


Chandran A.,SB College | George K.C.,SB College
Journal of Nanoparticle Research | Year: 2014

Zinc sulfide nanoparticles (particles size range 10-20 nm) and nanorods (particles size range 20-35 nm) were prepared through a hydrothermal method. The influence of surface defects and lattice strain on the optical, dielectric, and electrical transport properties was investigated. The spectral shifts and modification in bandgap are explained based on effective mass approximation model. Photoluminescence and ESR studies clearly showed the presence of large density of surface defects in the samples. The Raman spectra were thoroughly studied using the Gaussian confinement model. Dielectric studies using impedance and electric modulus spectroscopy showed enhanced grain boundary conductivity. Both nanoparticles and nanorods were found to exhibit Cole-Cole type dielectric relaxation. The enhanced ac electrical conductivities observed in both the nanostructures were successfully explained using the correlated barrier hopping model. Parameters like hopping time, barrier width, and defect densities were calculated. © 2014 Springer Science+Business Media.


Soosen Samuel M.,Sb College | Koshy J.,Sb College | Chandran A.,Sb College | George K.C.,Sb College
Physica B: Condensed Matter | Year: 2011

Highly optical, good crystalline and randomly aligned ZnO nanorods were synthesized by the hydrothermal method. The dielectric properties of ZnO nanorods were attributed to the interfacial polarization at low frequencies (below 10 kHz) and orientational polarization at higher frequencies. The observed ω (n-1) dependence of dielectric loss was discussed on the basis of the Universal model of dielectric response. Dielectric loss peak was composed of the Debye like loss peak at higher frequencies and interfacial loss peak at lower frequencies. Charge transport through the grain and grain boundary region was investigated by impedance spectroscopy. At higher temperatures the conductivity of the nanorod was mainly through the grain interior and the overall impedance was contributed by the grain boundary region. The activation energy of nanorod was calculated as 0.078 eV, which is slightly higher than the reported bulk value. © 2011 Elsevier B.V.


Kannan M.,Amrita University | Bhagawan S.S.,Amrita University | Jose T.,SB College | Thomas S.,Mahatma Gandhi University | Joseph K.,Indian Institute of Space Science and Technology
Polymer Engineering and Science | Year: 2010

Ester-based thermoplastic polyurethane (TPU) nanocomposites were prepared by melt blending at 190°C, using 3 wt% Cloisite 10A (organically modified montmorillonite clay) as the nanoscale reinforcement [TPU(C10A)]. The nanocomposites were subsequently melt-blended with polypropylene (PP) using maleic anhydride-grafted polypropylene (MA-g-PP) as a compatibilizer [in the ratio of 70/30-TPU/PP, 70/25/5-TPU/PP/MA-g-PP, 70/25/5-TPU (C10A)/PP/MA-g-PP]. Besides giving substantial increase in modulus, tensile strength, and other properties, organoclay reinforcement functions as a surface modifier for TPU hard segment resulting in improved dispersion. The morphology and other characteristics of the nanocomposite blends were investigated in terms of X-ray diffraction, fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, tensile properties, scanning electron microscopy, and atomic force microscopy. The results indicate that the ester-TPU(C10A)/PP/MA-g-PP exhibited better dispersion than other blend systems; abrasion resistance and water absorption resistance were also better for this system. © 2010 Society of Plastics Engineers.

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