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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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- Licea Jimenez, Liliana, 1977, et al.
(författare)
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MWNT reinforced melamine-formaldehyde containing alpha-cellulose
- 2007
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Ingår i: Composites Science and Technology. - : Elsevier BV. - 0266-3538 .- 1879-1050. ; 67, s. 844-854
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Tidskriftsartikel (refereegranskat)abstract
- Multi-wall carbon nanotubes (MWNT) were used as reinforcement for melamine-formaldehyde (MF). They were oxidised in HNO3/ H2SO4 mixture and analyzed by means of X-ray Photoelectron Spectroscopy (XPS). Two anionic surfactants: sodium dodecyl sulphate (SDS) and sodium dodecylbenzenesulfonate (NaDDBS) were used to assist the dispersion of nanotubes. The MWNT content was varied from 0 to 1.0 wt%, and the influence of nanotubes on viscosity (flow curves) was measured. The viscosity of SDS-assisted aqueous solution of MF containing a small amount (0.1 wt%) of MWNT is low, and thus promising towards manufacturing processes. A film stacking-like manufacturing route was adapted to prepare ternary MWNT/cellulose/MF thin composite layers. Transmission electron microscopy (TEM) and Light microscopy (LM) were used to observe dispersion. The addition of 0.1 wt% MWNT assisted with SDS increased the storage modulus and tensile strength by 50%. Conventional calculations of the Young's modulus were made. Values underestimating the modulus were found. The observed discrepancy was attributed to polymer chain immobilisation as a result of crosslinking.
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- Licea Jimenez, Liliana, 1977, et al.
(författare)
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Polymer Coatings Based on Nanocomposites
- 2020
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Ingår i: Polymer Coatings Technologies and Applications. - : CRC Press. - 9780429199226 ; , s. 31-52
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In particular, the development of polymeric nanocomposites has become an opportunity to meet the demands of functional materials. Polymer nanocomposites offer the possibility of new materials with a unique manifold of structure-property relationships. The formulation strategy of polymer coatings based on nanocomposites depends on the application and different approaches can be followed. In organic photovoltaics, the most important component is the active layer, which basically is a conjugated polymer nanocomposite coating. The development and design of polymer nanocomposites-enabled coatings has gained research importance as they offer the promise of incremental and disruptive improvements to products and processes. Polymer nanocomposite coatings represent properties with incredible practical applications for mechanical, optical, and electronic products. Over the last decades, the role of functional coatings has considerably changed. Polymer coating technology has evolved by the increase in scientific and technological understanding of important principles. Polymer coatings based on nanocomposites offer significant product performance and cost-saving advantages with functional features.
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- Rychwalski, Rodney, 1945, et al.
(författare)
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CF, CB and SWNT Polymer Composites
- 2003
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Ingår i: The National Conferences on Polymer Characterization, X Seminar TWORZYWA SZTUCZNE W BUDOWIE MASZYN (Plastics in Machine Design), Cracow University of Technology, Cracow (Poland), September 29-October 1, 2003. ; , s. 347-357
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Konferensbidrag (refereegranskat)
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- Rychwalski, Rodney, 1945, et al.
(författare)
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New polymeric micro-and nanocomposites
- 2003
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Ingår i: Proceedings of the Polish-Swedish Symposium: Materials-Energy Supply-Environment & Society, Chalmers University of Technology, Göteborg (Sweden), December 12, 2003. ; , s. 25 - 32
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Konferensbidrag (refereegranskat)
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- Velasco-Soto, M A, et al.
(författare)
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Carbon polymer nanocomposites
- 2016
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Ingår i: Nanocolloids. ; , s. 265-298
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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