NOPR Collection:

Dielectric dispersion and electrical conductivity of amorphous PVP–SiO2 and PVP–Al2O3 polymeric nanodielectric films

Mon, 01 Jun 2020 00:00:00 GMT

Title: Dielectric dispersion and electrical conductivity of amorphous PVP–SiO2 and PVP–Al2O3 polymeric nanodielectric films Authors: Choudhary, Shobhna; Dhatarwal, Priyanka; Sengwa, R J Abstract: The biodegradable hybrid polymer nanocomposite (PNC) films comprising silica (SiO₂) and alumina (Al₂O₃) nanoparticles as inorganic nanofillers and the poly(vinyl pyrrolidone) (PVP) as organic host matrix (i.e., PVP–x wt% SiO₂ and PVP–x wt% Al₂O₃for x = 0, 1, 3 and 5) have been prepared by aqueous solution-casting method. X-ray diffraction (XRD) study reveals that these nanocomposite materials are highly amorphous. The dielectric spectroscopy of these different nanofiller concentrations PNC films has been carried out in the frequency range from 20 Hz to 1 MHz at a fixed temperature and also for 3 wt% nanofillers containing PNC films with the temperature variation. The results confirm that the complex dielectric permittivity of these hybrid films is influenced by the interfacial polarization in the low frequency range of 20 Hz to 1 kHz, whereas in the high frequency range up to 1 MHz permittivity is mainly governed by the molecular polarization and remains almost independent of the frequency. These SiO₂ and Al₂O₃ nanofillers containing PNC films at fixed temperature display anomalous behaviour of dielectric permittivity and ac electrical conductivity with the increase of nanofiller concentration, but these parameters significantly enhance at low frequencies with the increase of temperature of the films. The electric modulus spectra of Al₂O₃ containing PNC film exhibit relaxation peaks below 100 Hz at higher temperatures which attribute to the interfacial polarization relaxation process. The frequency independent dielectric permittivity and significantly low loss of these PNC materials at radio frequencies confirm their suitability as polymeric nanodielectric (PND) substrate and insulator in the design and fabrication of biodegradable electronic devices and electrical components. Page(s): 201-209

Modelling of heat integrated reactive distillation column (r-HIDiC): Simulation studies of MTBE synthesis

Fri, 01 May 2020 00:00:00 GMT

Title: Modelling of heat integrated reactive distillation column (r-HIDiC): Simulation studies of MTBE synthesis Authors: Ahmed, S A; Ahmad, S A Abstract: In the present study, heat integrated distillation column is modelled and simulated for the production of Methyl tert-Butyl Ether (MTBE) from methanol and isobutylene using ASPEN Plus®. Also, the objective of this study is to have comparative analysis between the reactive distillation process and an alternative intensified process (r-HIDiC) to produce MTBE.
Rigorous simulation study has been conducted to compare the optimal flow sheet of the above two designs. Temperature and composition profiles are studied and compared for both the models and found that the temperature at the last stage of the stripping section in r-HIDiC is 406 K while that of the stripping section in RDC is 427.24 K. This reduced temperature decreases the composition of methanol in bottom product in stripping column in case of r-HIDiC as methanol forms a homogenous azeotrope with MTBE at 408.53 K. Also, it is found that, although with nominal increase in TAC i.e. 16.56%, in r-HIDiC design as compared to the reactive distillation column design which is caused due to the high cost of the additional compressor needed in the vapour compression, however, the r-HIDiC design can save reboiler and condenser heat duties to a considerable amount i.e. by 35.06% and 36.65% respectively. Page(s): 210-218

Anionic natural graft copolymer used in removal of hazardous dye water pollutants

Fri, 01 May 2020 00:00:00 GMT

Title: Anionic natural graft copolymer used in removal of hazardous dye water pollutants Authors: Srivastava, Arti; Mandal, Pratibha; Kumar, Rajesh Abstract: The carboxymethyl cellulose (CMC), guar gum, sodium alginate and chitosan etc. are natural polysaccharides. This paper presents the synthesis and characterization of natural polymer carboxymethyl cellulose (CMC) and synthetic monomer acrylic acid (AA) based graft copolymer (CMC–g–AA) and its applications in removal of Methylene blue dye from industrial effluents. CMC–g–AA has been synthesized using free radical initiator and characterized by FTIR, TGA, and SEM analysis. The AA concentration has been varied from 5.5 x 10^-2 to 35.5 x 10^-2mol dm^-3to get maximum grafting of AA monomer onto CMC. The FTIR spectral analysis proves the successful grafting. The synthesized graft copolymer (CMC–g–AA) has been applied in adsorption of a water soluble monovalent cationic dye such as Methylene Blue. Page(s): 219-226

A simple strategy to increase inhibitory activity of chitosan towards iron corrosion in acidic media

Fri, 01 May 2020 00:00:00 GMT

Title: A simple strategy to increase inhibitory activity of chitosan towards iron corrosion in acidic media Authors: Yavari, Zahra; Nematiyan, Salameh; Saraveni, Hamideh; Noroozifar, Meissam Abstract: The chitosan as a natural and inexpensive polymer is considered as an appropriate choice towards the corrosion inhibitory. Here, the corrosion and inhibition efficacy of iron sheets is examined in the H₂SO₄ solution and the presence of chitosan and potassium iodide as an inhibitor through gravimetry, potentiodynamic polarization, and impedance analyses. The inhibition performance is found to be enhanced by adding chitosan concentration. The experimental data demonstrate that the doping iodide ion to chitosan is efficient on the surface coverage and the inhibition performance. The introduced inhibitors are of the interface inhibitors → liquid phase → mixed type with the physical adsorption. The adsorption of iodized chitosan on the iron surface is followed Langmuir isotherm. These inhibitors, by changing the electrical double layer, increase the resistance of charge transfer. The existence of iodide in the chitosan structure improves the electron density of polymer and strengthens the interaction between inhibitor and metal. Page(s): 227-234