Materials Science

TiO₂ and TiO₂-SiO₂ nanocomposite was synthesized by sol-gel method at room temperature using titanium tetraisopropoxide with ethanol and water mixture as Titania source and Silicic acid as Silica source. Characterization of the product was carried out by means of X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared (FT-IR). An average grain size of ~13nm was obtained for TiO₂ and ~2nm for TiO₂-SiO₂, as estimated by the Debye-Scherrer’s equation. From the FTIR results, peaks were observed at 3408 cm^-1 and 1627 cm^-1 in both samples due to stretching and bending vibrations of -OH groups. 

Polypyrrole-TiO₂ nano composite samples with various dopant percentages of TiO₂ were synthesized by chemical oxidative method at room temperature. The samples were characterized by Fourier transforms infrared (FTIR), SEM with EDAX, UV vis Spectrum, X-ray diffraction (XRD), Photoluminescence (PL) and Conductivity measurements. Electrical conductivity measurements indicate that the conductivity of nano composites increases with TiO₂ content. The doped H₂SO₄ may interact with PPy by donating either hydrogen sulfate (HSO₄) or sulfate (SO₄^2-) ions as dopants. SEM images confirm that introduction of higher content of TiO₂   leads to the formation of nano spheres.

AC-5%Co has been synthesized successfully by impregant method using Tra Bac activated carbon (AC) and cobalt chloride as precursors. The characterization of prepared materials showed that Co species which exists in oxide form (denoted as CoOx) distribute on surface of AC with the size ranging from 20 to 25 nm. The CoOx almost does not affect to the m-xylene adsorption of AC and m-xylene adsorption processes occurred mainly at micropores with two types of AC adsorption sites. The study on the catalytic activity revealed that the oxidation of m-xylene by oxygen in the air occurred mainly at cobalt oxide sites with the conversion degree ranging from 23.2 to 51.8% at the temperature range of 180-250oC with the WHSV of 1941.75 hour-1 and relatively low activation energy (21.16 kJ mol-1? 5 kcal mol-1).

Chicken feather disposal has contributed significantly in the galloping elephantiasis in our society; hence this research work was targeted on recycling chicken feathers into a more useful material that would find its applications in virtually all discipline. These natural Fibres are low-cost with low density and good mechanical properties. This study uses Taguchi’s robust design on the basis of the higher the better to investigate the effect of (A: Volume fraction, B: Fibre length and C: Fibre orientation) to determine the optimum Tensile strength, Flexural strength and Hardness strength of the chicken feather barbs (CFB) and chicken feather rachis (CFR) when reinforced with epoxy. The optimum tensile strength, flexural strength and hardness strength of the chicken feather barbs are (34.40MPa, 60.05MPa and 18.87MPa) while that of the chicken feather rachis are (34.00MPa, 70.30MPa and 19.1MPa), respectively. This study shows that the composite of the CFB are better in tensile, while the CFR are better both in flexural and hardness strength. The young’s Moduli of the CFB ranges from 0.81GPa to 1.63GPa, while that of the CFR ranges from 0.58GPa to 1.90GPa. Higher proportion of the chicken feather barbs, however, showed significant reduction in the density and void fraction of the composite material. It can therefore be concluded that a low cost composite material could be processed from the chicken feather thereby reducing the risk of pollution and disease associated with it.

These studies focus on firing temperature and mineralogical analysis of the ancient pottery sample collected from the recently excavated site Pilaiyarpalaiyam in Tamilnadu, India. Clay was prepared which consists of quartz, kaolinite, illite, chlorite, feldspars and iron oxides. The samples were subjected analysis as in the received state. The characterization studies for the analysis of the composition of the pottery using FT-IR and XRD analysis reveals the skill and style of the artisan lived in the ancient civilization. The firing temperature and the firing conditions adopted at the time of manufacturing of the pottery also determined. The Pilaiyarpalaiyam samples might have been fired in the range of 800 °C.

The conduction polymer Polypyrrole base is soluble in selected organic solvents. The Polypyrrole becomes conductive upon partial oxidation or reduction by a processcommonly known as doping. The Polypyrrole base was doped by chemical method usingHydrochloric acid (HCl) as a dopant. The doped conducting polymer was dissolved inthree selective organic solvents namely p-Cresol (PCL), Dimethyl sulphoxide (DMSO)and 2-Chlorophenol (2CPL). The variation in the ultrasonic velocity values measured using fixed frequency (3MHz) continuous wave ultrasonic interferometer techniquewith temperature and their related thermodynamic parameters have been discussed with a view to understand the molecular interactions of the conduction polymers in solutions. Hence the acoustic properties of Polypyrrole base and its doped polymer in solutions will pave the way to obtain possibly a new product ideas and benefits over the traditional polymers.

PbS_xO_1-x (x = 0.0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0) nanocomposites were prepared by the microwave assisted solvothermal method using a domestic microwave oven for the first time. The yield percentage and the preparation time were noted. The samples were annealed at 200 ^oC for 1 hr to improve the ordering.  Grain sizes and lattice parameters were determined by carrying out X-ray powder diffraction measurements. AC and DC electrical measurements were carried out on palletised samples at various temperatures ranging from 40-150 ^oC.  Results of the present study reveal that the space charge contribution plays a significant role in the charge transport process and polarizability in all the seven nanocrystals studied. The electrical parameters increase with increasing temperature. Results of the present study reveal that the space charge contribution plays a significant role in the charge transport process and polarizability in all the seven nanocrystals studied.

Polymers, the synthetic materials have truly unique properties.  The polymers are a very special kind of compounds, which do not behave like small molecules do, but the properties of polymers depend on molecular weight and molecular weight distribution (MMD). The molecular characterization of PANi base synthesized chemically by condensation method is attempted using MALDI-TOF MS technique.  Further the study is extended on doped PANi with two different strengths (0.01N, 1 N) of dopant HClO₄. The detailed descriptions of the method of TOF (Time of Flight) and the molecular weight determination of the PANi base and its doped form as conducting polymers have been studied quantitatively and strength of the dopant on the molecular characterization is also identified.

Single crystals of L-arginine monohydrate of reasonable size and excellent quality were grown by the solution growth method. The powder XRD of the samples suggested no significant change in the unit cell dimensions and the presence of any extra phase. The structural analysis can be useful in the clarification of the role of hydrogen bonds in crystals exhibiting non-linear optical properties. The dielectric studies shows the the governance of various polarization mechanisms. The mechanical response of the crystal has been studied using Vickers microhardness technique.

The present work was aimed to evaluate the effects of shot peening on the mechanical properties and the fatigue life of 5052- H34 aluminum alloy at different shot peening time SPT. Shot peening to full coverage (100%) was performed using carbon steel shots with an average shot size of 0.6 mm and at shot peening times of 10, 15, 20, 25 and 30 min. The 10 minutes shot peening time gave the highest value of ( ) which is about 9.489% for ( ) and 10.36% for ( ). The fatigue endurance limit was raised by 10.93% at 10 minute shot peening time and then reduction was observed.