Cellulose hybrid nanocomposites using Napier grass fibers with in situ generated silver nanoparticles as fillers for antibacterial applications.

Initially silver nanoparticles (AgNPs) were in situ generated in Napier grass fibers (NGFs) and these nanocomposite NGFs were used as fillers (by 1 wt% to 5 wt%) in cellulose matrix to make hybrid nanocomposite films. The formation of in situ generated AgNPs on the surface of the NGFs was studied using scanning electron microscope (SEM), high resolution transmission electron microscope (HR-TEM), Energy dispersive X-ray spectroscope (EDX) and X-ray photoelectron spectroscope (XPS). The HR-TEM analysis indicated the presence of spherical AgNPs on the surface of the fillers with a size ranging from 10 to 100 nm but majority of them in the 11 to 20 nm range. The POM images indicated the randomly oriented fillers in the hybrid composite films. Though the inflection temperatures of the hybrid composites were lower than for the matrix (due to catalytic activity of the AgNPs), the residual weight for them was higher than that of the matrix. The tensile strength of the hybrid nanocomposites varied between 73 MPa and 40 MPa while their tensile modulus between 4350 MPa and 2580 MPa for various filler contents. The hybrid nanocomposite films showed good antibacterial activity against Gram negative (E. coli) and Gram positive (S. aureus) bacteria.

Assimilation of NH4Br in Polyvinyl Alcohol/Poly(N-vinyl pyrrolidone) Polymer Blend-Based Electrolyte and Its Effect on Ionic Conductivity.

Biodegradable polymer blend electrolyte based on ammonium based salt in variation composition consisting of PVA:PVP were prepared by using solution casting technique. The obtained films have been analyzed by various technical methods like as XRD, FT-IR, TG-DSC, SEM analysis and impedance spectroscopy. The XRD and FT-IR analysis exposed the amorphous nature and structural properties of the complex formation between PVA/PVP/NH4Br. Impedance spectroscopy analysis revealed the ionic conductivity and the dielectric properties of PVA/PVP/NH4Br polymer blend electrolyte films. The maximum ionic conductivity was determined to be 6.14 × 10-5 Scm-1 for the composition of 50%PVA: 50%PVP: 10% NH4Br with low activation energy 0.3457 eV at room temperature. Solid state battery is fabricated using highest ionic conducting polymer blend as electrolyte with the configuration Zn/ZnSO4 · 7H2O (anode) ∥ 50%PVA: 50%PVP: 10% NH4Br ∥ Mn2O3 (cathode). The observed open circuit voltage is 1.2 V and its performance has been studied.

Investigation of Electrochemical Studies of Magnesium Ion Conducting Poly(vinyl alcohol)-Poly(vinyl pyrrolidone) Based Blend Polymers.

Polymer blend electrolytes based on magnesium ion conducting PVA-PVP-MgCl2 polymer were prepared at different compositions by solution casting techniques. The prepared films were characterised by various techniques such as XRD and FTIR. Amorphous nature and structural coordination of polymer electrolyte were confirmed by X-ray diffraction and Fourier transform infrared spectroscopy studies. The ionic conductivity of the prepared polymer electrolytes were analysed through ac impedance spectroscopy. The highest conductivity was found to be in the order of ~10-6 Scm-1 at an ambient temperature for the composition of 50PVA:50PVP:5 wt% MgCl2. Conductivity versus temperature plot was found to follow an Arrhenius nature. The dielectric behaviour and ionic transport properties of the polymer electrolytes were also analyzed.

Dimensional changes of alginate dental impression materials.

The weight loss and corresponding dimensional changes of two dental alginate impression materials have been studied. The weight loss kinetics indicate this to be a diffusion controlled process, but with a boundary condition at the surface of the concentration decreasing exponentially with time. This is in marked contrast to most desorption processes, where the surface concentration becomes instantaneously zero. The appropriate theory has been developed for an exponential boundary condition, and its predictions compared with experimental data; the agreement was satisfactory. The diffusion coefficients for two thicknesses of the same material were not identical as predicted by theory; the possible reasons for this are discussed.