Heat Shrinkable Behaviour of Supramolecular Hydrogen Bonded Maleated Ethylene Propylene Diene Rubber and Maleated High Density Polyethylene Blend

Maleated high density polyethylene and maleated ethylene propylene diene rubber (50 wt%/50 wt%) was blended in presense of 3-amino-1,2,4-triazole (ATA). The supramolecular hydrogen bonding was characterized by FTIR and dynamic mechanical analysis. The crystallinity of the blend system was studied by XRD and it was observed that supramolecular hydrogen bonding decreases the crystallinity of the blend. The supramolecular hydrogen bonded network improves heat shrinkability of the blend.     

FT-Raman and FT-IR vibrational spectroscopic studies of nanocrystalline Ba2RESbO6 (RE = Sm, Gd, Dy and Y) perovskites

The nanoparticles of Ba₂RESbO₆ (RE = Sm, Gd, Dy and Y) were synthesized using auto ignition combustion process. The structure and phase purity of the as-prepared nanopowders were examined by X-ray diffraction pattern. A systematic analysis of the structure of the four compounds was carried out for the first time by recording Raman and IR spectra. The four Raman active modes A_1g, E_g and 2F_2g were observed as strong or medium intense bands in the Raman spectra and the IR active F_1u(1) mode is obtained as a strong absorption band around 630 cm⁻¹ in all the four compounds. Hence it is confirmed that the above compounds were crystallized in the cubic symmetry with space group.     

Synthesis,structural analysis and microwave dielectric properties of Bi<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Ln<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>TiTaO<Subscript>6</Subscript> (Ln = Ce,Pr and Nd) Ceramics

Bi substituted LnTiTaO₆ (Ln = Ce, Pr and Nd) ceramics are prepared using the conventional solid state ceramic route. The materials are calcined at 1,150°C and sintered at 1,375°C. The structure is analysed using X-ray diffraction technique and the microstructure using scanning electron microscopy. The microwave dielectric properties of the samples are measured using the cavity resonator method. Substitution of Bi increases the dielectric constant and improves the thermal stability. A number of samples with improved quality factor are obtained and can be used in practical microwave circuits.     

Photoluminescence and dielectric properties of Eu<Superscript>3+</Superscript> substituted microwave ceramics

Ln_0.9Eu_0.1TiNbO₆ (Ln = Pr, Nd, Sm, Dy and Y) ceramics have been prepared through the solid state ceramic route. The samples are calcined at about 1,250 °C and sintered between 1,370 and 1,425 °C for 4 hours. Structure of the samples is analyzed using X-ray diffraction method. Pr, Nd, Sm and Y based compounds form solid solutions while Dy based compound is a composite. The microstructure is analyzed using Scanning Electron Microscopy. All the compositions have strong photoluminescence in the visible region. The dielectric constant (ε _r ), the unloaded quality factor (Q _u ) and the temperature coefficient of resonant frequency (τ _f ) are measured in the microwave frequency region. The samples have relatively high ε _r , high Q _u  × f and good thermal stability. Hence these materials are suitable for optoelectronic and dielectric resonator applications.     

Structural and functional properties of sol-gel synthesized and microwave heated Pb0.8 Co0.2-zLazTiO3 (z = 0.05–0.2) nanoparticles

The present work reports the effect of La-substitution on structural and functional properties of lead cobalt titanate (PCT) perovskite structure as a function of variation of Co-content. The sol-gel synthesized and microwave heated Pb_0.8 Co_0.2-zLa_zTiO₃ (z?=?0.05, 0.1, 0.15 & 0.2) (PCLT) nanoparticles showed the presence of complete cubic phases while few were noted to be tetragonal lead titanate (PT) phases. The surface morphology was examined by field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM). The HRTEM revealed fibers like nanoparticles at z?=?0.15 and 0.2. The Fourier transform infrared spectra attributed the presence of metal oxide bonds. Furthermore, the wide optical band gap energy (E_op) was acquired to be changing from 2.32 to 3.20?eV. In addition, the electrical parameters such as dielectric constant (ε'), dielectric loss (ε"), ac & dc-electrical conductivity (σ_ac & σ_dc), complex dielectric modulus (M^*) and complex impedance (Z^*) were studied as a function of frequency (f) and composition. Using power law fitting, the σ_dc values were determined. The z?=?0.15 content exhibited high σ_dc of ~ 2.51?×?10^?7 S/cm among all compositions. Besides, the results expressed the existence of short range and long range hopping conduction regions in dielectric modulus spectra. The Nyquist plots were drawn to elucidate the electrical conduction and relaxation mechanism. Later on, ferroelectric hysteresis loops were recorded for z?=?0.05–0.2.     

Synthetic resins: II: Preparation and characterization of resins prepared from aminoacetophenone

A number of resins were prepared by condensing m-aminoacetophenone with substituted aromatic compounds and formaldehyde in the presence of acids and bases as catalyst. The resins were characterized by infrared spectra. The solubility parameters were calculated from Small's group contribution which agreed well with the experimental value. The bacteriocidal properties of the resins have been studied.     

Buccoadhesive Tablets of Nifedipine: Standardization of A Novel Buccoadhesive-Erodible Carrier

Buccoadhesive tablets of nifedipine were obtained by incorporation of nifedipine in suitable carrier systems standardised based on bioadhesion and dissolution. The carrier systems were formulated using sodium alginate as the bioadhesive. Mannitol, lactose, polyethylene glycol 6000 and polyethylene glycol 4000 were incorporated as solubilisers, singly or in combination. Carrier systems having a diameter of 11 mm and weighing about 200 mg were obtained by standard tabletting techniques using polyvinylpyrolidone as the binder. The systems were evaluated for bioadhesion and dissolution, 'in vitro' and 'in vivo' in seven normal healthy human volunteers. Based on these studies, nifedipine (5 mg) was incorporated in selected carrier systems to obtain buccoadhesive tablets of nifedipine. These tablets exhibited rapid 'in vitro' drug release.     

Radiation induced graft copolymerization V. Graft copolymerization of methyl acrylate onto nylon-6 fiber

The radiation induced graft copolymerization of methylacrylate onto nylon-6 fiber at room temperature and in nitrogen medium was investigated. The effects of monomer, dose rate, inhibitor etc. on the graft yield have been investigated. The effect of solvents on the rate of grafting was studied from which the chain-transfer constant (C_s) of the solvent has been evaluated. Addition of certain inorganic salts was found to act as scavengers. The value of G_b, the number of branches per 100 eV of energy absorbed in the substrate polymer, was calculated. The density, moisture regain, alkali solubility, dyeability and thermal properties of the grafted nylon-6 fiber have been evaluated.     

Synthetic resins. V. Preparation and properties of substituted benzoic acid,hydroxyacetophenone and aniline/formaldehyde resins

A number of resin copolymers have been prepared by condensation of substituted aromatic compounds with formaldehyde in the presence of different acid catalysts. The resin copolymers were characterized by IR, thermal, X-ray diffraction, and by their reactivity ratios. The resins were found to possess high thermal stability. Activation energies of resin degradation were computed using the Freeman–Anderson method. The antifungal activities of several previously synthesized resins were studied.