Long single-walled carbon nanotubes, with lengths >10 μm, can be spontaneously dissolved by stirring in a sodium naphthalide N,N-dimethylacetamide solution, yielding solutions of individualised nanotubide ions at concentrations up to 0.74 mg mL. This process was directly compared to ultrasonication and found to be less damaging while maintaining greater intrinsic length, with increased individualisation, yield, and concentration. Nanotubide solutions were spun into fibres using a new reactive coagulation process, which covalently grafts a poly(vinyl chloride) matrix to the nanotubes directly at the point of fibre formation. The grafting process insulated the nanotubes electrically, significantly enhancing the dielectric constant to 340% of the bulk polymer. For comparison, samples were prepared using both Supergrowth nanotubes and conventional shorter commercial single-walled carbon nanotubes. The resulting nanocomposites showed similar, high loadings (ca. 20 wt%), but the fibres formed with Supergrowth nanotubes showed significantly greater failure strain (up to ∼25%), and hence more than double the toughness (30.8 MJ m), compared to composites containing typical ∼1 μm SWCNTs.

Please cite this article as: Fisher SJ, Shaffer MSP, Rapid quantitative mapping of multi-walled carbon nanotube concentration in nanocomposites, Composites Science and Technology (2018), Abstract 23 Inhomogeneous distributions of nanoparticles in polymer nanocomposites have a strong 24 influence on final material properties. Quantitative methods to characterise particle 25 dispersion are rarely applied but are critical for advancing understanding of material 26 behaviour, developing accurate computer models, and optimizing processing. Two 27 complementary quantitative methods were developed to map local concentration, based 28 on Raman spectroscopy and simple optical absorbance, respectively. The approaches 29 are demonstrated for a model multi-walled carbon nanotube (MWNT) epoxy 30 nanocomposite, but should be widely applicable. Maps of absolute concentration can be 31 produced with submicron resolution, allowing analysis of the uniformity of MWNT 32 concentration distribution via the coefficient of variation. The two approaches correlate 33 closely, providing validation of both methods. However, the optical absorbance 34approach is likely to be more practical, in most cases, as it uses a standard laboratory 35 microscope to analyse large areas rapidly. 36

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A comparative simultaneous evaluation of the Optimate and the TDX analyzers was performed according to guidelines proposed by the National Committee for Clinical Laboratory Standards. Statistically significant (P less than 0.05) better precision was demonstrated for the TDX analyzer with both commercial controls and patient pools. No statistically significant difference was found between the analyzers in terms of linearity, accuracy, and curve stability. Technologists judged the TDX to be superior in ease of start-up and shutdown procedures, loading and unloading, test changeover, time for a stat specimen, and time for an average run. In general, the TDX analyzer required less operator interaction for routine performance, but its consumable expenses were about 50% greater than those for the Optimate analyzer.

In recent years carbon nanotubes (CNT) have attracted significant research into their processing, properties and applications due to their extraordinary mechanical [1], electrical [2] and thermal properties [3]. Incorporating CNTs into polymer matrices to produce composite materials is one strategy to harness the potential of these materials. The development of a powder based processing route for thermosetting nanocomposites allows the manufacture of materials with high loading fractions (up to 20wt%) of CNTs [4]. Typically, nanocomposites with randomly dispersed CNTs show a decline in strength and plateau in elastic modulus beyond a few volume percent CNTs, as well as severe embrittlement [5, 6]. However, in recent work, the highest strength and modulus of the powder‐based composites increased up to the highest loading [4]. Differential interference contrast (DIC) optical reflective microscopy of these nanocomposites have revealed a texture with domains on the length scale of the original powder particles, suggesting the migration of resin out of the nanocomposite particles to fill voids at particle interfaces. Raman spectroscopy combined with scanning electron microscopy is a powerful tool to identify the presence of epoxy rich regions and variations in CNT density. The correlated chemical and morphological analysis provides insight into the unique microstructure of the nanocomposite not possible by elemental analysis methods, such as EDS. Using correlated Raman and SEM techniques, the relationship between CNT loading on the “grain size” is quantified and calibrated resulting in an enhanced understanding of how the microstructure affects the macro mechanical properties of the nanocomposite.