Extendability and von Neuman–Morgenstern stability of the core

This paper introduces a strengthening of the notion of a stable core and characterizes it in terms of Kikuta and Shapley’s extendability condition.     

Study on the compatibility of unbleached and bleached bamboo-fiber with LLDPE matrix

This article presents the comparative study on the compatibility of unbleached and bleached bamboo-fibers (UBF and BBF) with LLDPE matrix. Thermal characterization of composites was conducted by differential scanning calorimetry and thermogravimetric analysis. The results suggested that BBF are more compatible with matrix than the unbleached ones. The X-ray diffraction pattern shows no change in the intensity peak position of matrix in the presence of bamboo fibers. Morphological studies were done by scanning electron microscopy to get an idea of the compatibility of the fibers with the matrix. This study gives us the idea of using the bleached fiber for the preparation of the composites.     

Jetting of dilute polymer solutions

Light emitting devices containing conjugated polymers are conveniently fabricated using ink-jet printing. A common problem in the processing of these materials is that the Newtonian viscosity of the polymer solution is not sufficient to describe the jetting performance because the molecular weights and concentrations employed are such that the resulting solutions are elastic. These differences in fluid elasticity levels cannot be measured using traditional techniques like dynamic mechanical experiments or the first normal stress difference in shear, but strongly impact the jetting behavior of the liquid. In this study, a variety of polystyrene solutions in DECALIN having a shear viscosity of ~5 mPa s but different elasticity levels were examined for their jetting behavior. The jetting behavior of these solutions was studied visually using drop-on-demand jetting equipment and their rheology was characterized using a custom extensional rheometer designed for measuring the elasticity of such low viscosity liquids. If elasticity effects are absent as in Newtonian liquids (corresponding to a Trouton ratio of 3) satellite drops are formed resulting in loss of liquid and poor positioning. On the other hand, if elasticity effects are very large (Trouton ratios ≫4) separation problems occur at the nozzle with undesirable “tailing.” The optimum range for stable, efficient jetting occurs at Trouton ratios in a narrow band between 3 and ~5. A very slight degree of elasticity corresponding to a Trouton Ratio around four thus seems to be optimum for the jetting process. This appears to be the first time that such a design criterion has been outlined for this process. Such an approach complements thermal techniques for elucidating the role of molecular and flow properties on the processing behavior of polymeric systems.     

Modification of isotactic polypropylene film by radiation-induced graft copolymerization

In the present communication we report on the radiation induced grafting of methyl methacrylate (MMA) onto irradiated isotactic polypropylene film (IPP) by Peroxidation method to prepared grafted membrane (IPP-g-MMA). The radioactive isotope ⁶⁰Co was used as the source of gamma radiation. A plausible mechanism of grafting has been proposed. Optimum conditions pertaining to maximum percentage of grafting were evaluated as a function of different reaction parameters such as radiation dose, inhibitor concentration, monomer concentration, reaction time and reaction temperature respectively. Maximum percentage of grafting (85%) was obtained at [radiation dose] = 25 kGy, [inhibitor concentration] = 0.04 wt%, [MMA] = 6 wt%, [Reaction Temperature] = 60 °C in a [Reaction time] of 120 min. The evidence of grafted membrane was characterized by Fourier transform infrared spectroscopy, Atomic force microscopy method, Scanning electron microscopy which indicates that MMA has been grafted onto IPP. Hydrolysis of the grafted membranes in 1 N NaOH transformed ester groups of the grafted membranes to carboxylic acid and hydroxyl groups to form hydrolyzed grafted membranes. Hydrolyzed grafted membranes were investigated for their swelling behavior. Swelling properties of the hydrolyzed grafted membranes were performed in different solvents such as water, N,N-dimethylformamide (DMF) and dimethylsulfoxide (DMSO). Maximum percentage swelling value of IPP-g-MMA was observed in pure DMSO, followed by DMF and water.     

Terphenyl based ‘Turn On’ fluorescent sensor for mercury

New terphenyl-based derivative 4 with pyrene as a fluorophore has been synthesized and examined for its cation recognition abilities toward various cations by NMR and fluorescence spectroscopy. The results show that it has very high binding affinity (log β = 5.12) and selectivity for mercury. A fluorescence enhancement of 375% was observed for the 4-Hg²⁺ system in THF. A Hg²⁺ selective electrode (ISE) was also formed which showed excellent selectivity over all the other cations tested. The lower limit of detection is 2.1 × 10⁻⁶ M.     

Rheology of polycarbonate reinforcedwith functionalized and unfunctionalized single-walled carbon nanotubes

Nanocomposites of polycarbonate (PC) containing low concentrations of pristine and COOH and OH functionalized single-walled carbon nanotubes (SWNTs, COOH-SWNTs and OH-SWNTs) were prepared by melt-mixing and analyzed using rheology and scanning electron microscopy (SEM). The steady state and linear viscoelastic behavior of each nanocomposite material is presented and compared to that of the neat PC. SEM analysis revealed that samples containing functionalized SWNTs were more dispersible than samples containing the pristine SWNTs.     

Room-temperature electrochemical reduction of epitaxial magnetite films to epitaxial iron films

The electrochemical reduction of oxides to metals has been studied for decades. Earlier work produced polycrystalline bulk metals. Here, we report that pre-electrodeposited epitaxial face-centered cubic magnetite thin films can be electrochemically reduced to epitaxial body-centered cubic iron thin films in aqueous solution on single-crystalline gold substrates at room temperature. This technique opens new possibilities to produce special epitaxial metal/metal oxide heterojunctions and a wide range of epitaxial metallic alloy films from the corresponding mixed metal oxides.