Structure and properties of polyethylene ionomer based nanocomposites

Li and Zn ionomers of poly(ethylene‐co‐methacrylic acid) were modified by two organically modified montmorillonites by melt mixing. In the nanocomposites (NCs), the increase in the loss tangent main peak temperature indicated a reduction in the mobility of the long‐chain segments containing neutralized acid groups. The stack compaction observed by wide‐angle X‐ray scattering and transmission electron microscopy in the Cloisite 30B based NCs was attributed to the partial degradation of the surfactant and to the irreversible character of the ion‐exchange process of the ammonium cation of the surfactant with the Li cation. The considerable dispersion that occurred in the poly(ethylene‐co‐methacrylic acid) zinc salt (PEMA–Zn)/Cloisite 20A (20A) NCs was attributed to the high volume of the surfactant, which reduced undesired interactions between the inorganic clay surface and the ionomer. The ductile nature of the matrix remained in all of the NCs, and the increase in the modulus of elasticity of the PEMA–Zn/20A NCs reached a value five times greater than that of the PEMA–Zn matrix. The results suggest that this ionomer is suitable for use both as a matrix for 20A NCs and as a compatibilizer of polyolefin‐based NCs with 20A. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of the processing temperature on the nanostructure and mechanical properties of PCTG‐based nanocomposites

The influence of the processing temperature on both the dispersion level and the mechanical properties of the amorphous copolyester (PCTG)/organoclay (Cloisite® 20A) nanocomposite (NC) is studied in this article. At high processing temperatures, no change in the chemical nature of the matrix was observed, but its molecular weight decreased. Widely dispersed structures were observed by wide angle X‐ray diffraction (WAXD) and transmission electron microscopy whatever the processing temperature might be. Dispersion was greatest for the samples processed at 200°C due to the highest viscosity of these samples and decreased at higher processing temperatures (T_p). These different dispersion levels led to a large modulus increase (71%) after processing at 200°C and to lower ones (about 50%) after processing at 230 and 260°C. The ductility of the NCs decreased at lower processing temperatures. The decrease was attributed to the greater stiffness of the matrix, and was not significant enough to modify the ductile nature of the NCs, which showed clear yield points even at the lowest processing temperature (200°C). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Off-diagonal magnetoimpedance in NiFe-Au-NiFe layered film and its application to linear magnetic sensors

We have measured the field dependence of the off-diagonal impedance in the megahertz frequency range for a NiFe-Au-NiFe layered film using a helical microcoil. The film and the coil were deposited by means of radio-frequency sputtering, and a transverse anisotropy in magnetic layers was established by applying a dc magnetic field during the deposition and by postproduction annealing. The film had 5 mm length, 50 /spl mu/m width, and 1.5 /spl mu/m total thickness. The helical microcoil had 23 turns with a 50 /spl mu/m turn width. We applied high-frequency excitation by means of the coil current and measured the induced voltage across the film stripe. This voltage response is directly proportional to the off-diagonal component of the total impedance tensor. We found that the plots of the real and imaginary parts of the off-diagonal impedance, as functions of the applied dc magnetic field, are antisymmetrical with respect to the field direction. The dc bias current through the film plays an important role: without the bias current, the measured signal is very small and irregular. The field antisymmetry demonstrated by the off-diagonal impedance can be utilized in highly sensitive and linear magnetic sensors, and we discuss the principles of operation of such sensors here.     

Molecular dynamics study of thermal properties of noble metals

Molecular dynamics simulations have been applied to investigate thermal properties of Ag and Au. Semi-empirical potentials, based on the embedded atom method (EAM) have been employed to calculate lattice parameter, energy per atom, mean square displacements and radial distribution function for the two metals. Thermal properties like specific heat, thermal coefficient of linear expansion and melting temperature are deduced from the calculated parameters. Results are found to compare well with the experimental results.     

Novel water-soluble polymer coatings control NPK release rate,improve soil quality and maize productivity

We investigated different combinations of polymers (5% each) (i) starch, gelatin (polymer coating; PC-1), (ii) polyvinyl alcohol (PVA), gum Arabica (PC-2), (iii) PVA, gelatin (PC-3), (iv) starch, gum Arabica (PC-4), (v) gelatin, gum Arabica (PC-5), (vi) starch, PVA (PC-6), for coating NPK (17, 17:17) in a fluidized bed granulator. Morphological characterization indicated a uniform coating of all formulations on NPK granules. A slow release of N (PC-3), P (PC-6), and K (PC-3) was observed in water. In soil, high mineral N (63%), plant-available P (72%), and K (24%) were observed in PC-3, PC-5, and PC-6, respectively than uncoated fertilizer. Microbial biomass NPK was also higher in these treatment. This resulted in higher maize yield (66%), N (114%), P (164%), and K (137%) uptakes and apparent N (267%), P (196%), and K (358%) recoveries from applied fertilizer in these treatments. Among these, PC-3 resulted in an increase of 115% shoot N, 169% P and 138% K uptakes and 268% apparent N, 206% P and 361% K recoveries than uncoated fertilizer. Hence, coating of NPK with this biodegradable polymer combination controlled N, P, and K release and synchronized these nutrients availabilities with maize nutrients demand therefore resulted in higher maize crop yield and nutrient utilization efficiencies.     

Dynamic Stability Improvement of Decentralized Wind Farms by Effective Distribution Static Compensator

Dynamic instability of decentralized wind energy farms is a major issue to deliver continuous green energy to electricity consumers. This instability is caused by variations of voltage and frequency parameters due to intermittencies in wind power. Previously, droop control and inverter-based schemes have been proposed to regulate the voltage by balancing reactive power, while inertial control, digital mapping technique of proportional-integral-differential (PID) controller and efficiency control strategy have been developed to regulate the frequency. In this paper, voltage stability is improved by a new joint strategy of distribution static compensator (DSTATCOM) six-pulse controller based reactive power management among decentralized wind turbines and controlled charging of capacitor bank. The frequency stability is ensured by a joint coordinated utilization of capacitor bank and distributed wind power turbines dispatching through a new DSTATCOM six-pulse controller scheme. In both strategies, power grid is contributed as a backup source with less priority. These new joint strategies for voltage and frequency stabilities will enhance the stable active power delivery to end users. A system test case is developed to verify the proposed joint strategies. The test results of the proposed new schemes are proved to be effective in terms of stability improvement of voltage, frequency and active power generation.     

Structure and mechanical properties of new hybrid composites based on polyamide 6,6 reinforced with both glass fibers and a semiaromatic liquid crystalline polyester

Polyamide 6,6 (PA66) composites with 30% glass fiber (GF) were blended with a semiaromatic liquid crystalline copolyester (Rodrun 5000 (R5)) up to 40% R5 by injection molding. The composites showed two amorphous phases. Interchange reactions took place between the two polymers, leading to good interfacial adhesion. The addition of 20% R5 was enough to counteract the viscosity increase provided by the GF. The synergistic increases in the modulus of elasticity were attributed to the increase in the skin thickness at increasing R5 content. The tensile strength of the composites remained constant on LCP addition, despite the lower tensile strength of R5 compared with that of PA66/GF. The notched impact strength increased notably at increasing R5 content. Polym. Compos. 25:601–608, 2004. © 2004 Society of Plastics Engineers.     

Processability,Structure and Mechanical Properties of Poly(ether imide)/Amorphous Copolyester Blends

Blends of PEI with an amorphous copolyester (PCTG) were obtained by melt‐mixing followed by injection molding. The processability of PEI increased several times upon addition of just 10% PCTG, thus expanding the applications of PEI. All the blends showed a single T_g and most of them were transparent. However, they were biphasic as suggested by the widening of the T_g's and proved by SEM. A fine dispersed particle size and good adhesion level were also observed by SEM. The values of the modulus of elasticity and the yield stress appeared close the additivity rule, and were attributed to the combined effects of the density increase and orientation decrease in the blends. These morphological changes had a slightly negative influence on ductility which was nevertheless high.