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Long and porous Pt botryoidal nanowires (Pt BNWs) were facilely synthesized by combination of soft and hard templates accompanying chemical reduction of ascorbic acid and replacement of Te nanowires. This bis-template and bis-reductant method is proved to be an effective way to prepare nanowires with special structure. The scanning electron microscopy and transmission electron microscopy images show the as-prepared product is botryoidal nanowires with diameter of 20–30 nm and length of several micrometers. High resolution transmission electron microscopy shows the Pt botryoidal nanowires are composed of many small Pt nanoparticles (about 3 nm in diameter), which is just like that many grapes grow on the branch. These small nanoparticles make Pt nanowires have botryoidal and porous structure. Moreover, the diameter of Pt BNWs can be adjusted by changing the dosage of Pt precursor, polyvinylpyrrolidone and l -ascorbic acid. The electrocatalytic performance of Pt botryoidal nanowires is studied, which shows that the as-prepared Pt botryoidal nanowires have not only high activity but also good stability for oxygen reduction reaction. [ABSTRACT FROM AUTHOR]

Magnesium oxide modified reduced graphene oxide supported Pd nanocatalyst (Pd/MgO-RGO) was facilely prepared by a chemical approach. The as-prepared material was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction. The electrocatalytic behavior of Pd/MgO-RGO for methanol oxidation was studied using cyclic voltammetric and chronoamperometric methods. The results indicated that Pd/MgO-RGO nanocatalyst exhibits higher electrocatalytic activity and better stability than Pd/RGO. [ABSTRACT FROM AUTHOR]

Crosslinked fluorinated polyimides (CFPI) were successfully synthesized to study and explore the effect of cross-linkage on the migration of fluorinated segments and on the adhesion strength. Characterization by dynamic thermomechanical analysis (DMA) and thermo gravimetric analysis (TGA) confirmed good thermal properties of CFPI. X-ray photoelectron spectroscopy (XPS) results showed that the ratio of fluorinated component (6FDA-ODA) concentration of the surface to the bulk decreased with the crosslink density. The water contact angle of CFPI was lower than that of non-crosslinked fluorinated polyimide, indicating that the migration of fluorinated groups to the surface was reduced by the presence of cross-linkage. Therefore, CFPI, with no fluorine segregation on the surface, exhibited excellent wetting of adherent surfaces and adhesion strength, which was proved by lap shear strength (LSS) measurements and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

A novel curing agent, poly (amide-amidic acid) (PAA), was used to cure tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM). The initial cure and exothermic peak temperatures increased with increase in PAA content. The mechanism for the cure of TGDDM/PAA was proposed which involved, besides TGDDM cure, PAA imidization in the system. Examination of the morphology of the fractured surface using scanning electron microscopy showed that curing with PAA improved more the fracture toughness as compared to the conventional 4,4′-diaminodiphenylsulfone (DDS), and rendered TGDDM more fire resistant with higher char yield. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

Reinforced phenolic resin (PF) was prepared by in situ polymerization of different fractions of carbon nanotubes (CNTs) that had undergone oxidation. The compressive strength and hardness of the material, according to mechanical property testing, was improved by the modified CNTs. The tribological properties of PF composites were investigated by a block-on-ring friction and wear tester. The results indicated that CNTs reinforced PF showed lower friction coefficient and higher wear resistance, compared with pure PF. The morphologies of the worn surfaces, debris, and transfer films were observed by scanning electron microscopy (SEM) and optical microscopy (OM). A continuous and thinner transfer film formed during the friction test of the composites led to the significant improvement of the tribological properties. [ABSTRACT FROM PUBLISHER]