6 research outputs found
Optimization of Near Infrared Cured Polyester/Melamine Coil Coatings by the Use of Near Infrared Absorbing Primers
Near Infrared (NIR) radiative curing is a fastthermal curing technology used to cure 25 micron polyestermelamine industrial coil coatings on galvanized steel substrate.The cure is optimized when the top coat is relatively transparentto NIR and with most NIR absorption taking place at thesubstrate surface. In this study UV/Vis/NIR spectroscopy andlab scale curing trials with a white top coat were used to showthat absorption in the bottom most layers of the coating systemcan be taken a stage further by the addition of NIR absorbingpigment to the primer layer. The results show energy efficiencybenefits for NIR cure by increasing the amount of incidentradiation absorbed without altering the colour properties of thecoating. A similar smaller benefit is also evident with aconventional convection cure
Surface-initiated growth of copper using isonicotinic acid-functionalized aluminum oxide surfaces
Isonicotinate self-assembled monolayers (SAM) were prepared on alumina surfaces (A) using isonicotinic acid (iNA). These functionalized layers (iNA-A) were used for the seeded growth of copper films (Cu-iNA-A) by hydrazine hydrate-initiated electroless deposition. The films were characterized by scanning electron microscopy (SEM), electron-dispersive X-ray spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and advancing contact angle measurements. The films are Cu0 but with surface oxidation, and show a faceted morphology, which is more textured (Rq = 460 ± 90 nm) compared to the SAM (Rq = 2.8 ± 0.5 nm). In contrast, growth of copper films by SnCl2/PdCl2 catalyzed electroless deposition, using formaldehyde (CH2O) as the reducing agent, shows a nodular morphology on top of a relatively smooth surface. No copper films are observed in the absence of the isonicotinate SAM. The binding of Cu2+ to the iNA is proposed to facilitate reduction to Cu0 and create the seed for subsequent growth. The films show good adhesion to the functionalized surface
Optimization of near infrared cured polyester/melamine coil coatings by the use of near infrared absorbing primers
Near Infrared (NIR) radiative curing is a fastthermal curing technology used to cure 25 micron polyestermelamine industrial coil coatings on galvanized steel substrate.The cure is optimized when the top coat is relatively transparentto NIR and with most NIR absorption taking place at thesubstrate surface. In this study UV/Vis/NIR spectroscopy andlab scale curing trials with a white top coat were used to showthat absorption in the bottom most layers of the coating systemcan be taken a stage further by the addition of NIR absorbingpigment to the primer layer. The results show energy efficiencybenefits for NIR cure by increasing the amount of incidentradiation absorbed without altering the colour properties of thecoating. A similar smaller benefit is also evident with aconventional convection cure
Understanding the effect of functional groups on the seeded growth of copper on carbon nanotubes for optimizing electrical transmission
We present a study of the seeded growth of copper on the surface of two classes of single-walled carbon nanotubes (SWNTs) in order to compare the effects of surface functional groups. Pyridine-functionalized HiPco SWNTs and ultrashort SWNTs (US-SWNTs) were synthesized (py-SWNTs and py-US-SWNTs, respectively), and the functionality was used as seed sites for copper, via an aqueous electroless deposition reaction, as a comparison to the carboxylic acid functionality present on piranha-etched SWNTs and the native US-SWNTs. UV–vis spectroscopy demonstrated the take-up of Cu(II) ions by the functionalized SWNTs. TEM showed that the SWNTs with pyridine functionality more rapidly produced a more even distribution of copper seeds with a narrower size distribution (3–12 nm for py-US-SWNTs) than those SWNTs with oxygen functional groups (ca. 30 nm), showing the adventitious role of the pyridine functional group in the seeding process. Seed composition was confirmed as Cu(0) by XPS and SAED. Copper growth rate and morphology were shown to be affected by degree of pyridine functionality, the length of the SWNT, and the electroless reaction solvent used
Electrodeposition of Cu–SWCNT Composites
Single walled carbon nanotubes (SWCNTs) are used as a component of a plating solution of CuSO4 for direct current electrodeposition of Cu–SWCNT composites with varying nanotube proportions without the use of either a surfactant, a dispersing agent, or functionalization of the SWCNTs. The Cu–SWCNT composites are characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy. The composites are comprised of metallic Cu and SWCNTs with minor oxide impurities, as well as the residual (Fe) catalyst from the unpurified SWCNTs, in addition to displaying nanotube-mediated morphological differences. EDX analysis of carbon (wt%) is close to quantitative with respect to the wt% of SWCNTs added to the electrolysis solution. The presence of SWCNTs decreases the oxidation of the copper, as well as changing the identity of the oxide from CuO, for electrolysis of Cu, to Cu2O. Hard adherent Cu–SWCNT coatings are prepared by the addition of Cu powder to the electrolysis solution. The approach described in this paper will enable controlled synthesis of metal-nanomaterial composites that can potentially be processed further into high ampacity electrical conductors
Spatial and Contamination-Dependent Electrical Properties of Carbon Nanotubes
Two-point probe and
Raman spectroscopy have been used to investigate
the effects of vacuum annealing and argon bombardment on the conduction
characteristics of multiwalled carbon nanotubes (MWCNTs). Surface
contamination has a large
effect on the two-point probe conductivity measurements which results
in inconsistent and nonreproducible contacts. The electric field under
the contacts is enhanced which results in overlapping depletion regions
when probe separations are small (<4 μm) causing very high
resistances. Annealing at 200 and 500 °C reduced the surface
contamination on the MWCNT, but high resistance contacts still did
not allow intrinsic conductivity measurements of the MWCNT. The high
resistance measured due to the overlapping depletion regions was not
observed after annealing to 500 °C. Argon bombardment reduced
the surface contamination more than vacuum annealing at 500 °C
but caused a slight increase in the defects concentration, enabling
the resistivity of the MWCNT to be calculated, which is found to be
dependent on the CNT diameter. The observations have significant implications
for future CNT-based devices