Ceramic Composite
G. Upender; V. Chandra Mouli; V. Sreenivasulu; Praveena Kuruva; M. Prasad
Abstract
The new tellurite glasses with chemical composition 64TeO2-15CdO-(20-x) ZnO-xLi2O-1V2O5 (x= 0, 5, 10, 15 and 20 mol %) were synthesized by traditional melt quench hardening method. The glass samples showed broad humps of typical amorphous phase in the X- ray diffraction patterns. The physical properties ...
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The new tellurite glasses with chemical composition 64TeO2-15CdO-(20-x) ZnO-xLi2O-1V2O5 (x= 0, 5, 10, 15 and 20 mol %) were synthesized by traditional melt quench hardening method. The glass samples showed broad humps of typical amorphous phase in the X- ray diffraction patterns. The physical properties of glass samples such as density (ρ), molar volume (Vm), oxygen packing density (OPD), refractive index (n), molar refractivity (Rm) and metallization parameter (M) were estimated. The Fourier transform infrared spectroscopy (FTIR) studies exhibited that replacement of ZnO by Li2O forms significantly some basic structural units of TeO4, TeO3/TeO3+1 and ZnO4. Differential scanning calorimetry (DSC) was employed to find out the glass transition temperature (Tg) and thermal stability ( ). The optical enthrallment studies exhibited that the cut-off wavelength (λ) decreases while optical energy gap (Eopt) and Urbach energy ( ) values increases with an increase an escalation of Li2O content. This tellurite glasses possess an important use such as sensor devices, storage of data system and industrial applications etc.
N. Rajeswara Rao; T. Venkatappa Rao; S.V.S. Ramana Reddy; B. Sanjeeva Rao
Abstract
Thermal, morphological and antioxidant properties of lignin irradiated with electron beam (EB) of doses 30, 60 and 90 kGy have been investigated by Electron spin resonance (ESR), Fourier transform infrared spectroscopy, Differential scanning calorimetry, Scanning electron microscope and Spectrophotometer ...
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Thermal, morphological and antioxidant properties of lignin irradiated with electron beam (EB) of doses 30, 60 and 90 kGy have been investigated by Electron spin resonance (ESR), Fourier transform infrared spectroscopy, Differential scanning calorimetry, Scanning electron microscope and Spectrophotometer techniques. ESR studies confirm the presence of poly-conjugated radicals in unirradiated lignin; whereas irradiated lignin posses both poly-conjugated and peroxy radicals. The peroxy radicals decay near the glass transition point on thermal heating while poly-conjugated radicals are stable even up to a temperature of 450K. Presence of conjugated structures is confirmed by the presence of 1604 cm -1 absorption band whose concentration increases following radiation dose. Up to a radiation dose of 60 kGy the fall in glass transition temperature (Tg) is very slow, while at 90 kGy Tg decreased abruptly. The decrease in Tg is assigned to be due to intermolecular chain interactions or plasticization effect. Granular structure of lignin is found to be effected by EB irradiation. Cracks were generated on lignin granules on EB irradiation. Due to increase in poly-conjugation, amorphous nature and granular cracks the antioxidant property is observed to increase. The current research trends in lignin materials include modification of lignin, fabrication of biodegradable thermoset/thermoplastic and use of lignin as stabilizers and dispersants.
Ranjana Singh; S. G. Kulkarni; N. H. Naik
Abstract
A number of nanocomposites have been synthesized biomimetically by embedding various transition metal salts in polyvinyl alcohol (PVA) as the preorganised matrix. The metal salts were reduced to metallic form using aqueous sodium borohydride solution. In the present paper, very comprehensive studies ...
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A number of nanocomposites have been synthesized biomimetically by embedding various transition metal salts in polyvinyl alcohol (PVA) as the preorganised matrix. The metal salts were reduced to metallic form using aqueous sodium borohydride solution. In the present paper, very comprehensive studies on thermal decomposition behavior of these composites have been carried out using thermogravimetric and differential scanning calorimetric studies. The transition metal salts/ metals based composites exhibit increased thermal stability as indicated by shift in the decomposition temperature of pure PVA. The DSC data show increase in glass transition temperature of all composites, except the one containing iron, in comparison with neat PVA.The improvement in the thermal stability is explained in terms of decrease in the segmental mobility of polymer chains due to entrapment of metal salt / metal forming a complex with the hydroxyl group of the polymer chains and thus decreasing heat transfer process for decomposition of polymer composites.
