Piezoelectric Ba and Ti co-doped BiFeO3 textured films: selective growth of solid solutions or nanocomposites

Accurate control of the MOCVD process parameters results selectively and reproducibly in the formation of two different systems: a single-phase solid solution film and a nanocomposite sample formed by nanocolumns embedded in a solid solution film.

Study on Atomic Oxygen Exposure and Hard Particle Impact of Polyimide Nanocomposites

Atomic oxygen (AO) exposure and hard microparticle impact on polyimide nanocomposites were performed by a ground-based magnetoplasmodynamic accelerator and electrostatic accelerator, respectively. The computer simulation of the AO erosion of polyimide nanocomposites was carried out with Monte Carlo method. It is found that the polyimide nanocomposites are significantly more durable to AO exposure than the pure polyimide material. Besides, in the case of combined hard microparticle impact and AO exposure, the regions around craters created by hard microparticle impact are etched more intensively than the undamaged areas of the polyimide nanocomposite sample surface.

Single-walled carbon nanotubes–polyaniline composites: Synthesis and field-emission analysis

In this article, we report a facile synthesis and comparative analysis of field emission behavior of polyaniline (PANI)-coated as-received and annealed single-walled carbon nanotube (SWCNT) films by in-situ polymerization and ex-situ synthesis routes, respectively. Amongst all the samples, the sample prepared by in-situ polymerization method with more fraction of annealed SWCNTs in the composite gave an enhanced field emission characteristics with E to = 3 V/μm and β = 1.2 × 104 probably because of good formation of pi-pi non-covalent bonds between the SWCNTs and PANI represented by pi-pi interaction between the quinoid rings of PANI and π bond of the SWCNTs lattice. A significant increase in the threshold field is observed after annealing and doping of nanocomposite films. Field emission behavior of as-prepared nanocomposite samples are also analyzed and discussed with two PANI forms: micro-PANI particles and PANI nanofibers. It is also speculated that PANI may have helped in lowering the overall work function of the composite structure which gave an enhanced field emission. The stability of all the samples are also presented and it is analyzed that nanocomposite sample films synthesized by in-situ polymerization method showed a stability for at least 8 h. The surface morphology analysis by field emission scanning electron microscopy of nanocomposite sample films reveal an increase in SWCNTs diameter upon PANI wrapping. The high-resolution transmission electron microscopy and Raman spectra and X-ray diffraction analysis are also presented.

Electrical Tree Growth in Silicone Rubber/Organo-Montmorillonite Nanocomposites under AC Ramp Voltage

This paper presents the results of the study on the electrical tree growth of organo-montmorillonite (OMMT) nanofillers in silicone rubber under ac ramp voltage of 0.5 kV per second. This study investigates the ability of OMMT to retard the growth of electrical tree in silicone rubber. Samples of silicone rubber nanocomposites (two filled with 1% and 3% OMMT respectfully while the third is unfilled silicone rubber), were used in this experimental study and the growth rate of the electrical tree and its length were observed in both samples. .The result of this study has revealed that in the filled nanocomposite sample, the OMMT acts as barrier which slows down the growth rate of electrical tree. This makes OMMT a potential material to use as fillers in polymeric insulations for the purpose of retarding electrical tree growth.

Fire Retardancy and Morphology of Nylon 6-Clay Nanocomposite Compositions

ABSTRACTWe investigated the effect of organically modified clay on the thermal and flammability behavior of nylon 6 nanocomposites. We also used zinc borate along with layered silicate with an aim of achieving synergistic effect in flame retardancy. It is found that addition of 10 wt% clay reduced the onset decomposition (5% wt loss) temperature of nylon 6 by 20°C, while addition of 5 wt% zinc borate and 5 wt% clay in combination reduced it by around 10°C. Differential thermogravimetric analysis indicated that the peak decomposition temperature was not affected by the addition of clay, but the rate of weight loss decreased with increasing clay concentration. The horizontal burning behavior of the nanocomposite films of approximately 0.5mm thickness changed with additive concentration. The nanocomposites with 2.5 wt% and 5 wt% clay burned for almost the same duration as neat nylon 6 but dripping was reduced. The 10 wt% clay nanocomposite sample burned without any dripping and the flame spread rate was reduced by 25-30%. The burn rate of 5 wt % zinc borate/5 wt% clay nanocomposite sample was about 20% higher than that of 10 wt% clay nanocomposite sample, which could be attributed to varying char morphology. Scanning electron microscopy images of the 10wt% clay nanocomposite char surface and cross- section revealed an integrated layer of clay platelets with increasing density gradient from the center to the surface, while the 5 wt% zinc borate/5 wt% clay nanocomposite char appeared foamy and porous. The 5 wt% zinc borate and 5 wt% clay sample developed into a very good intumescent system in cone calorimeter test, swelling about 10-13mm height prior to ignition forming a cellular char structure. This was as effective as the 10wt% clay nanocomposite sample in reducing the heat release and mass loss rate of nylon 6 by around 65%. Fourier transform infrared spectroscopy of the 10 wt% clay nanocomposite char showed the presence of amides, indicating possible residual polymer within the shielded char.