Miscibility and fracture toughness of thermoplastic polyurethane/poly(vinyl chloride)/nitrile rubber ternary blends with special reference to the blend composition

Ternary blends of thermoplastic polyurethane and a poly(vinyl chloride)/nitrile rubber blend were investigated in this work. The blends, with weight ratios of 100/0, 80/20, 40/60, 60/40, 80/20, and 0/100, were prepared via melt blending. Dynamic mechanical analysis showed that the blends with ratios of 20/80 and 80/20 were miscible, whereas the 40/60 and 60/40 blends were partially miscible. IR spectroscopy studies showed shifts in the peaks due to specific interactions in the blends. The blends showed degradation behavior between the blend components. The fracture toughness was investigated with the J‐integral by the locus method; the components and the miscible blends had good fracture toughness, whereas the other blends had lower toughness. Similar behavior was observed for the tensile properties. Scanning electron microscopy studies showed the morphological variations in the blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1763–1770, 2005     

Biocompatible antimicrobial cotton fibres for healthcare industries: a biogenic approach for synthesis of bio‐organic‐coated silver nanoparticles

Cotton fibres coated with biogenically fabricated silver nanoparticles (SNPs) are most sought material because of their enhanced activity and biocompatibility. After successful synthesis of SNPs on cotton fibres using leaf extract of Vitex negundo Linn, the fibres were studied using diffuse reflectance spectroscopy, scanning electron microscopy, nanoparticle tracking analysis, energy dispersive X‐ray, and inductively coupled plasma atomic emission spectrometry. The characterisation revealed uniformly distributed spherical agglomerates of SNPs having individual particle size around 50 nm with the deposition load of 423 μg of silver per gram of cotton. Antimicrobial assay of cotton–SNPs fibres showed effective performance against pathogenic bacteria and fungi. The method is biogenic, environmentally benign, rapid, and cost‐effective, producing highly biocompatible antimicrobial coating required for the healthcare industry.Inspec keywords: cotton, health care, nanoparticles, coatings, silver, fibres, nanofabrication, scanning electron microscopy, X‐ray chemical analysis, atomic emission spectroscopy, plasma applications, microorganisms, biotechnologyOther keywords: biocompatible antimicrobial cotton fibre coating, healthcare industry, bioorganic‐coated silver nanoparticle synthesis, biogenically fabricated silver nanoparticle, SNP, leaf extraction, Vitex negundo Linn, diffuse reflectance spectroscopy, scanning electron microscopy, nanoparticle tracking analysis, energy dispersive X‐ray spectrometry, inductively coupled plasma atomic emission spectrometry, uniformly distributed spherical agglomerate, antimicrobial assay, pathogenic bacteria, fungi, Ag     

Polyaniline–CdS nanocomposites: effect of camphor sulfonic acid doping on structural, microstructural, optical and electrical properties

Nanocomposites of CdS nanocrystals with conducting polyaniline doped with camphor sulfonic acid (CSA) have been prepared by spin coating technique and investigated by X-ray diffraction, field emission scanning electron microscopy (FESEM), fourier transform infra red spectroscopy (FTIR), UV–visible spectroscopy and electrical transport method. The X-ray diffraction patterns showed broad peaks due to formation of nanoparticles of CdS in polyaniline matrix. FESEM showed that the transformation of morphology from agglomeration to nanopetals. The FTIR spectra confirmed the interaction between CSA and polyaniline (PANi)–CdS nanocomposite. The UV–visible spectrums revealed the enhancement of doping level for the PANi–CdS nanocomposites which is assigned to the existence of greater number of charges on the polymer backbone. DC electrical conductivity studies showed an increase in conductivity of PANi–CdS nanocomposites from 6.9?×?10^?6 to 3.14?×?10^?4 due to addition of CSA (10–50?%).     

In vitro biocompatibility and antimicrobial activity of chitin monomer obtain from hollow fiber membrane

This study for the first time shows the effective utilization and production of chitin monomers at laboratory level, with immense potential for its biomedical application. Low molecular weight (LMW) N-acetylglucosamine (GlcNAc) is prepared by depolymerization of chitin using chemical method coupled with a physical separation method. A novel filtration strategy exploiting polysulfone hollow fiber membrane is used for the preparation of GlcNAc particles with 94% yield within 8.5 ± 0.5 h. This high efficiency is analyzed using high-pressure liquid chromatography. The GlcNAc obtained was further analyzed using dynamic light scattering, first derivative Fourier transform infrared spectroscopy, and X-ray diffraction techniques. The antimicrobial properties of GlcNAc, chitin, and GlcNAc/chitin mixture were investigated using minimal inhibitory concentration against S. aureus and E. coli. Bacteriostatic property was exhibited by high molecular weight chitin, while GlcNAc and GlcNAc/chitin mixture (LMW) demonstrated bactericidal activity. Blood biocompatibility below 0.25 g/ml and cytocompatibility with NIH3T3 fibroblast cells and the proliferative efficacy suggested its utilization and suitability of these particles in biological applications.     

Selective transport of radio-cesium by supported liquid membranes containing calix[4]crown-6 ligands as the mobile carrier

Facilitated transport of Cs-137 across supported liquid membranes (SLM) containing a calix-crown ligand viz. caliz[4]arene-bis(crown-6) (CC), calix[4]arene-bis(o-benzocrown-6) (CBC) or calix[4]arene-bis(napthocrown-6) (CNC) was investigated. The feed consisted of dilute nitric acid solutions while the carrier solutions contained mainly CNC in several organic diluents inside the pores of polypropylene (PP) as well as PTFE flat sheet membranes. PTFE membranes containing CNC in a diluent mixture of 2-nitrophenyloctyl ether (NPOE) and n-dodecane were found to have high stability. Selectivity studies were carried out using simulated high level waste (SHLW) as well as fission products obtained from an irradiated natural uranium target.     

Extraction of Uranyl Ion Using 2-Thenoyltrifluoro Acetone (HTTA) in Room Temperature Ionic Liquids

The extraction of UO₂²⁺ ion was studied using six different solvent systems containing 2-thenoyltrifluoroacetone (HTTA) in room temperature ionic liquids such as [C_nmim][X] (where, n = 4, 6, or 8 and X^? = PF₆^? or NTf₂^?) from low to moderate pH solutions for the first time. The extraction kinetics studies indicated rather slow attainment of equilibrium which in some cases improved if the solutions were pre-equilibrated with the aqueous phase prior to the actual experiments. The D_U values were found to increase with increasing pH and leading to a plateau like profile at higher pH values. The D values were quite high as compared to that obtained with molecular diluents. The nature of the extracted species was ascertained by slope analysis method which suggested species of the type: UO₂(TTA)⁺_IL, UO₂(TTA)_2,IL, and UO₂(TTA)₂(HTTA)_IL in different ionic liquid based solvents. Temperature variation studies on UO₂²⁺ ion extraction were also carried out and the thermodynamic parameters were calculated which indicated high endothermicity of the reactions with large positive entropy values.     

Room temperature H2S gas sensing characteristics of platinum (Pt) coated porous alumina (PoAl) thick films

The study reports H₂S gas sensing characteristics of platinum (Pt) coated porous alumina (PoAl) films. The porous alumina (PoAl) thick layers were formed in the dark on aluminum substrates using an electrochemical anodization method. Thin semitransparent platinum (Pt) films were deposited on PoAl samples using chemical bath deposition (CBD) method. The films were characterized using energy dispersive X-ray analysis (EDAX) and scanning electron microscopy (SEM). The thicknesses of coated and bare films were measured using ellipsometry. The sensing properties such as sensitivity factor (S.F.), response time, recovery time and repeatability were measured using a static gas sensing system for H₂S gas. The EDAX studies confirmed the purity of Pt–PoAl film and indicated the formation of pure platinum (Pt) phase. The ellipsometry studies revealed the thickness of PoAl layer of about 15–17 μm on aluminum substrates. The SEM studies demonstrated uniform distribution of spherical pores with a size between 0.250 and 0.500 μm for PoAl film and nearly spherical platinum particles with average particle size ∼100 nm for Pt–PoAl film. The gas-sensing properties of these samples were studied in a home-built static gas characterization system. The H₂S gas sensing properties of Pt–PoAl at 1000 ppm of H₂S gave maximum sensitivity factor (S.F.) = 1200. The response time and recovery time were found to be 2–3 min and ∼1 min respectively. Further, the measurement of H₂S gas sensing properties clearly indicated the repeatability of gas sensing response of Pt–PoAl film. The present study indicated the significant potential of Pt coated PoAl films for H₂S gas sensing applications in diverse areas.     

Formulation,in vitro evaluation and study of variables on tri-layered gastro-retentive delivery system of diltiazem HCl

Context: Tri-layered floating tablets using only one grade of polyethylene oxide (PEO) would enable easy manufacturing, reproducibility and controlled release for highly soluble drugs.

Objective: To evaluate the potential of PEO as a sole polymer for the controlled release and to study the effect of formulation variables on release and gastric retention of highly soluble Diltiazem hydrochloride (DTZ).

Methods: Tablets were compressed with middle layer consisting of drug and polymer while outer layers consisted of polymer with sodium bicarbonate. Design of formulation to obtain 12?h, zero-order release and rapid floatation was done by varying the grades, quantity of PEO and sodium bicarbonate. Dissolution data were fitted in drug release models and swelling/erosion studies were undertaken to verify the drug release mechanism. Effect of formulation variables and tablet surface morphology using scanning electron microscopy were studied.

Results and discussion: The optimized formula passed the criteria of USP dissolution test I and exhibited floating lag-time of 3–4?min. Drug release was faster from low molecular weight (MW) PEO as compared to high MW. With an increase in the amount of sodium bicarbonate, faster buoyancy was achieved due to the increased CO₂ gas formation. Drug release followed zero-order and gave a good fit to the Korsmeyer–Peppas model, which suggested that drug release was due to diffusion through polymer swelling.

Conclusion: Zero-order, controlled release profile with the desired buoyancy can be achieved by using optimum formula quantities of sodium bicarbonate and polymer. The tri-layered system shows promising delivery of DTZ, and possibly other water-soluble drugs.     

X-Ray Diffraction and Cation Distribution Studies in Zinc-Substituted Nickel Ferrite Nanoparticles

Structural and cation distribution studies on Ni_1?x Zn _x Fe₂O₄ (with x=0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) ferrite nanoparticles by using X-ray diffraction analysis are reported. In this work the Nickel–Zinc ferrites nanoparticles are synthesized by sol–gel auto combustion using respective metal nitrates and citric acid as fuel for the auto combustion reaction. Formation of ferrite nanoparticles having single-phase spinel structure is evident from the obtained X-ray diffraction patterns. Lattice constant values of the Ni_1?x Zn _x Fe₂O₄ ferrite system are found to increase with increase of zinc substitution x. Broad and intense XRD peaks in the patterns indicate the nanocrystalline nature of the produced ferrite samples. Average particle size calculated from most intense Bragg’s reflection (311) using Debye–Scherrer’s formula is found to be 30 nm. The particle size is found to decrease with increase in zinc substitution x. Observed X-ray density is found to decrease with increase in zinc substitution x. Bulk density, porosity, and unit cell volume are also calculated from the XRD data. Distribution of metal cations in the spinel structure estimated from X-ray diffraction data show that along with Ni²⁺ ions most of the Zn²⁺ ions also occupy the octahedral [B] sites, which are attributed to nanosize dimensions of the ferrite samples.