Volume 2 Issue 2
Authors: Navin Chand; Archana Nigrawal
Abstract: This paper reports the Dielectric, a.c. conductivity and DMA results of nano alumina filled PVA composites. Dielectric, a.c. conductivity, Dynamical mechanical measurements were performed on these composites. Effects of temperature and frequency variation on dielectric constant (ε’), dielectric dissipation factor (tan δ) and on a. c. conductivity (σa.c.) were determined. With the increase of nano alumina content, the dielectric constant increased. tan δ peak temperature shifts towards higher temperature side for all samples in both the cases of dielectric and DMA. This shows that increase in nano alumina concentration initially increased the relaxation temperature towards higher temperature. The detailed analysis of the results showed that dielectric dispersion consists of both dipolar and interfacial polarization. The Linchtenecker model fits well for the dielectric data obtained experimentally for these composites.
Keywords: PVA; Nano Alumina; Dielectric; Ac Conductivity; Composite
Authors: M.A. Wahab; J.B.M. Krishna; N.P. Sharma; Sidd hartha; S.K. Raghuvanshi; Bashir Ahmed
Abstract: Physical and chemical changes induced in poly vinylidene fluoride (PVDF) polymer by 1.25 MeV gamma radiations have been investigated.These changes were studied for the optical and chemical response using UV-VIS and FTIR techniques respectively.In this paper, we have studied the optical and chemical properties of virgin and gamma irradiated PVDF polymer samples in the dose range from 500to 2000kGy.The optical study of polymer samples shows a gradual increase in the absorption edge from 280 to 400nm with increasing gamma dose. Further, the direct energy band gap (Eg) found to be decreasedat higher dose. The recorded UV-visible spectra clearly show two characteristic peaks at320 and 360 nm in the pristine sample.However,in irradiated samples the position of the peaks is shifted slightly, their intensity decreases and finally disappearsat 2000kGy of higher dose. The direct energy band gap has been observed in PVDF polymer samples. In the FTIR spectra, an appreciable change in peak intensity and broadening of peaks has been observed due to irradiation. The development of a new peak at 1700 cm-1indicates the evolution of the HF group during irradiation.
Keywords: Gamma Radiation; PVDF (Polymer); Optical Properties; FTIR Analysis
Authors: Saravanan Nagappan; Elamathi Swaminathan; Padmavathi Rajangam; Sangeetha Dharmalingam
Abstract: Waste water from industrial areas contains many toxic heavy metal ions, which are carcinogenic and need to be removed before water recycling. In this study, complexation microfiltration technique was used to separate the metal ions. Initially, known concentrations of metal ions were complexed with polyethylene glycol (PEG) and polyacrylic acid (PAA). Polymer enhanced microfiltration process has been investigated for removal of toxic heavy metals such as Ni2+, Cu2+ and Cr6+ from synthetic waste water solutions. The concentration of metal ions in the sample water was analyzed by UV–Vis spectrophotometer. The effects of pH and polymer/metal ratio using two different membranes such as nylon and cellulose nitrate (CN) were investigated. The membranes were characterized by FTIR to identify the functional groups present in the membrane matrix and SEM analysis used to find the pore size and the metal deposition present over the membrane. Among the various combinations, PAA as the complexing agent at pH ≥ 8 proved to be most effective for the removal of nickel (II) and copper (II), and pH ≤ 4 for chromium (VI) metal ions.
Keywords: Micro filtration; Heavy Metalion Separation; Polymeric Membrane; Complexation Process