Advanced Materials Research Vol. 716

Abstract: Ultrasonic welding have been studied using Polycarbonate (amorphous) and Polypropylene (semi-crystalline) in presence and absence of polymeric compatibilizer. A solution phase compatibilization has been used using Polycaprolactone, Polymethylmethacrylate and Maleic anhydride grafted Polypropylene. Cylindrical samples were used in the near and far field ultrasonication in order to achieve the better weldability. The welding strength was increased while utilizing the compatibilizer than that of un-compatibilized samples. Mixture of Polycarbonate and Polymethylmethacrylate on the PC phase enhanced the weld strength tremendously. The XRD analysis revealed the increase in crystallinity during the ultrasonication process resulting the enhanced weldability. The phase fusion is quite prominent from the SEM study of the fractured surface and also from the SEM of the welded portion. The FTIR study indicated the phase interaction through the compatibilizer thus enhancing the ultrasonic weldability of the thermoplastics.

Abstract: All the technologies of the melt quenching preparation ensure its time-temperature treatment to not only improve but also stabilize the metal structure and properties with every melt. The influence of annealing temperature of nanocrystalline alloy Fe_72.5Cu₁Nb₂Mo_1.5Si₁₄B₉ on the structure and magnetic properties has been investigated. The relation between numerical values of the coercive force, the initial magnetic permeability and the magnetic hysteresis loop rectangularity factor allows optimizing a mode of nanocrystalline alloy heat treatment.

Abstract: Gallium Phosphide (GaP) nanostructures were grown on p-Si substrates by Metal Organic Chemical Vapor Deposition (MOCVD) to study the structure of low dimensional IIIV semiconductor on Si substrates. It is found that at a temperature of 540 °C, nanostructures with diameter 4080 nm and height 515 nm were obtained. The density of the nanostructures was found to be 10¹⁴ m^-2. The UV-Vis-NIR spectra showed a blue shift of band gap. Photoluminescence measurements also confirmed the band gap enhancement.

Abstract: The aim of this work was focused on developing a hydrotalcite by chemistry coprecipitation, which one was tested with one agricultural herbicide used in the region of the "Bajío" of the state of Guanajuato in Mexico. The clay was synthesized by a method by chemical precipitation at vacuum, and it was exposed to an herbicide for cultures control. The results showed that the hydrotalcitestructure and the toxic basicity, define their absorption in the hydrotalcite, performance fulfilling a function of soil recuperation.

Abstract: This work consisted in the development and characterization of a bioactive coating on Ti6Al4V samples by flame spray projection. A synthetichidroxyapatite powder was used to form the coatings. Oxygen and acetylene gas were used as combustible, and the metallic substrate was Ti6Al4V with a roughness of 0.4 and 2.3 μm. The time process varied from 5 to 60 seconds. The projection distance was of 22 cm.The spray coatings were mechanical tested; in all cases, the results indicated that the coatings were well adhered to the metallic surfaces and the metallic subtracts did not present any degradation of the mechanical properties. In addition, the coatings were immersed in simulated body fluids for 21 days in physiological conditions to evaluate the bioactivity. The results demonstrated that the coatings are potentially bioactive through the formation of a dense and homogeneous apatite layer similar to the bone. Results of X-ray diffraction exhibited evidence of a hidroxyapatite layer and by energy dispersive spectroscopy, a Ca/P ratio of 1.57 was obtained. This is an indication of that the use of flame spray projection to coat Ti6Al4V substrates do not decompose the original hidroxyapatite powder. Compositional analysis of the remnant fluids, made by inductively coupled plasma spectrometry, showed that nonmetallic ions were present in the coatings.

Abstract: t is shown that the structure of phenilon-based nanocomposites filled with carbon tubes represents the synergetic system. The degree of polymers reinforcement with non-aggregated carbon nanotubes is comparable with the correspondent index for exfoliated layer silicates (organoclay). As it should be expected, based on the most general principles, the reinforcement degree of the investigated nanocomposites is determined by three groups of factors: properties of the polymer matrix and nanofiller, and their level of interaction.

Abstract: The boron-containing phenolic resin/high-silica fiberglass fabric ceramifying composites were prepared using muscovite micas loaded boron-containing phenolic resin (BPF) as matrix, high-silica fiberglass fabric as reinforcements. The boron-containing phenolic resin (BPF) reacted with the muscovite to form ceramic residue after thermal pyrolysis under high temperature. X-Ray Diffraction (XRD) analysis of the composites at different temperatures showed the formation of new crystalline phases as a result of reactions between the degradation residue of BPF and the muscovite. Electron probe micro-analyzer (EPMA) was used to explore the changes in microstructure and local micro-chemical composition after samples were pyrolyzed under high temperatures. The ceramic yield of the composites ranged from 84.39% to 75.23% when pyrolyzed 700 to 1300°C in air.

Abstract: Polybenzimidazole (PBI) with a high molecular weight of 69,000 was first synthesized. It was afterwards grafted with benzimidazole pendant groups on the backbones. The acid doped benzimidaozle grafted PBI membranes were investigated and characterized including fuel cell tests at elevated temperatures without humidification. At an acid doping level of 13.1 mol H₃PO₄ per average molar repeat unit, the PBI membranes with a benzimidazole grafting degree of 10.6% demonstrated a conductivity of 0.15 S cm^-1 and a H₂-air fuel cell peak power density of 378 mW cm^-2 at 180 °C at ambient pressure without humidification.

Abstract: Amino group-functionalized magnetic particles have wide applications in enzyme immobilization, DNA extraction, drug delivery, water purification, catalysis, and sensor. In this paper, Fe3O4/PPy microspheres with a well-defined coreshell structure have been prepared through an interfacial polymerization approach without surfactant. The magnetic composite spheres were characterized with XRD, FTIR, SEM, TEM, and magnetometry techniques, and further tested as the adsorbent to isolate plasmid DNA from Escherichia coli (E. coli) DH5α cells. The magnetic separation yields high-quality plasmid DNA in satisfying productivity as compared to the conventional phenolchloroform extraction.

Abstract: Hard aluminum 2A12 and super hard aluminum 7A04 were adopted to conduct tensile tests in different conditions of impulse current. Effects of current density on elongationtensile strength and hardness were analyzed. In this experiment, thermal effect that impulse current exerted on aluminum alloy had little impact to plasticity. After adding impulse current, the elongation of aluminum alloy increased, but the tensile strength and hardness decreased. The elongation of the hard aluminum 2A12 could increase 53.4% and the elongation of the super hard aluminum 7A04 could increase 69.5% in certain condition.