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- Gromov, Andrei, 1959, et al.
(författare)
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Covalent Amino functionalisation of single walled carbon nanotubes
- 2005
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Ingår i: J. Materials Chem. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 15, s. 3334-3339
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Tidskriftsartikel (refereegranskat)abstract
- Chemical transformation of single-wall carbon nanotubes (SWNT), edge-terminated with carboxylic groups, to SWNT species with amino groups directly attached to the tube open ends has been performed. Different synthetic approaches have been investigated. The reaction products were characterised by FTIR, Raman spectroscopy, XPS and SEM.
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- Licea Jimenez, Liliana, 1977
(författare)
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Carbon nanotube/MF composites
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A new generation of composites, frequently referred to as nanocomposites, are making research and engineering impact worldwide. Particularly, the incorporation of carbon nanotubes (CNT) into polymers is attractive, due to the generally good processability of polymers and the unprecedented properties of nanotubes. Stiffness and strength enhancement, favourable processing characteristics as well as increased functionality are being imparted to a growing range of polymers, by filling them with carbon nanotubes. Some of the so-far studies have focused on coating polymers filled with CNT. However, melamine-formaldehyde (MF), an important coating polymer, has not been studied as a matrix for CNT composites.In this work, MF filled with single-wall (SWNT) and filled with multi-wall nanotubes (MWNT), is studied. Low amounts of nanotubes are used. Alpha-cellulose is added to MF in order to improve the processing conditions, and to enhance the performance in the solid state. Thus a ternary CNT/cellulose/MF composite is prepared and analysed MWNT are carboxilized, and X-ray photoelectron spectroscopy (XPS) is used to characterise the carboxilation. Next, the functionalised nanotubes are dispersed in MF aqueous solution. An anionic sodium dodecyl sulphate (SDS) surfactant is used to assist the dispersion. Viscosity of the dispersion is measured. A manufacturing technique developed by us earlier for carbonaceous micro fillers in MF is adapted. A dispersion is deposited on alpha-cellulose papers, impregnated papers are stacked and hot-pressed to form a solid nanocomposite.Electron and light microscopy is used to observe the composite solid state morphology and dispersion in the liquid-phase. Solid state mechanical properties are measured and analysed.
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- Licea Jimenez, Liliana, 1977
(författare)
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Carbon Nanotube Polymer Composites: Mechanical, Electrical and Photorefractive Properties.
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Incorporation of carbon nanotubes (CNT) into polymers is attractive due to the generally good processability of polymers and unprecedented properties of nanotubes. In this work, preparation and matrix known earlier but not employed so-far for nanocomposites are studied towards enhanced mechanical and electrical performances. For another CNT composite, the photorefractive behaviour is studied. Commercial single-wall (SWNT) and multi-wall nanotubes (MWNT) grown by arc discharge and Chemical Vapour Deposition (CVD) of diameter 1.4 nm (average value) and 10-30 nm, respectively, were used. They were purified and functionalised by acid reflux, and characterised by X-ray Photoelectron Spectroscopy (XPS). From the C1s spectrum, the peak corresponding to carboxylic group increased from 7% (for as–received) to 16%, and similarly from 0% to 9%, for oxidised MWNT and SWNT, respectively. The presence of carboxylic moieties plays a role in the composite preparation and properties.Films containing 0-1.5 wt% CNT were synthesized by hot pressing from melamine-formaldehyde (MF) with -cellulose, using a film stacking route with layered cellulose, and using milled cellulose. Sonication, mechanical mixing and surfactant assistance were used in the low viscosity (~30 mPa·s) aqueous MF solution to de-agglomerate and disperse the nanotubes. Electron and optical microscopy was performed to observe the morphology. Also, composites containing 0.2-0.3 wt% untreated SWNT in aromatic polyimide (API) were prepared by coating.Obtained results for both, SWNT and MWNT MF composites demonstrate that improvements in stiffness and strength, practically without embrittlement (MWNT), can be achieved; for example improvements by around 40-50% at 0.1 wt% CNT. Continuum mechanics calculations of the modulus gave underestimated values. Superior stiffening of the structure is explained in terms of constituents linking (immobilisation).Conductive behaviour was found for SWNT/MF at filler content >1 wt% and >1.5 wt% (MWNT), and statically dissipative behaviour for CNT/cellulose/MF at filler content >0.05 wt%. From the percolation theory, a threshold of 0.13 wt% (SWNT) and 0.2 wt% (MWNT) were calculated.For SWNT/API, improvement in the photorefractive performance was observed at 1062 nm wavelength with 0.25 wt% CNT. The gain coefficient of 90 cm-1 and net gain coefficient of 65 cm-1 at 80 V/μm were obtained.
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