Raman spectroscopic investigation of carbon-based materials and their composites. Comparison between carbon nanotubes and carbon black (original) (raw)
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Raman spectroscopic characterization of multiwall carbon nanotubes and of composites
Express Polymer Letters, 2012
In this work Raman spectroscopy was used for extensive characterization of multiwall carbon nanotube (MWNTs) and of MWCNTs/rubber composites. We have measured the Raman spectra of bundled and dispersed multiwall carbon nanotubes. All the Raman bands of the carbon nanotubes are seen to shift to higher wavenumbers upon debundling on account of less intertube interactions. Effects of laser irradiation were also investigated. Strong effects are observed by changing the wavelength of the laser excitation. On the other hand, at a given excitation wavelength, changes on the Raman bands are observed by changing the laser power density due to sample heating during the measurement procedure.
Raman Spectroscopy of Polymer–Carbon Nanomaterial Composites
Rubber Chemistry and Technology, 2017
Raman spectroscopy is potentially useful in the analysis of polymer composites filled with carbon materials. These carbon materials that display strong resonance-enhanced Raman scattering effects give rise to strong bands even if used at very low filler loading, thus making Raman spectroscopy one of the most important techniques for the analysis of various properties of the composites. Factors that influence the Raman signal are presented and discussed for correct acquisition and interpretation of the spectra of polymer composites. Special attention is given to the characterization of the polymer–filler interface, which has been shown to play a crucial role in the extent of property improvement of the polymeric matrix.
C, 2015
Carbon-based nanomaterials have emerged as a subject of enormous scientific attention due to their outstanding mechanical, electrical and thermal properties. Incorporated in a polymeric matrix, they are expected to significantly improve physical properties of the host medium at extremely small filler content. In this work, we report a characterization of various carbonaceous materials by Raman spectroscopy that has become a key technique for the analysis of different types of sp 2 nanostructures, including one-dimensional carbon nanotubes, two-dimensional graphene and the effect of disorder in their structures. The dispersion behavior of the D and G' Raman bands, that is, their shift to higher frequencies with increasing laser excitation energy, is used to assess the interfacial properties between the filler and the surrounding polymer in the composites.
A Raman Investigation of Carbon Nanotubes Embedded in a Soft Polymeric Matrix
Journal of Inorganic and Organometallic Polymers and Materials, 2011
Raman spectroscopy has been used to characterize multiwall carbon nanotubes (MWNTs) styrenebutadiene rubber (SBR) composites. Raman spectra of the MWNTs/SBR composites excited at different excitation wavelengths show that the dependence of the D band of carbon nanotubes on the laser energy has the same behavior as that of pure MWNTs. Raman spectra are shown to be sensitive to the state of dispersion of carbon nanotubes in the polymeric medium. On the other hand, analysis of Raman spectra of uniaxially stretched composites reveals a weak interface between the polymer and the nanotube surface.
Carbon, 2014
A new Raman spectroscopic methodology is proposed to monitor the weight fraction of Multi-Walled Carbon Nanotubes (MWCNTs) in polymeric nanocomposites. In order to disentangle the parameters affecting the frequency of the Raman bands and their intensity, this methodology involves the acquisition of sets of Raman spectra as a function of MWCNTs loading, excitation laser power and temperature. In the specific case of isotactic polypropylene (iPP), any interaction of the carbon nanotubes with the polymeric host has minimal effect on the frequency of the MWCNTs G band ($1584 cm À1); the same holds for the influence of residual stresses acting on the MWCNTs. The parameter that primarily alters the CNTs Raman bands frequency is temperature, determined by the excitation laser intensity, the MWCNTs concentration and the thermal properties of the polymer matrix. This is demonstrated by confocal micro-Raman spectra collected from agglomerates and from micro-Raman spectra of samples containing either poorly or well dispersed MWCNTs. A direct correlation of the G band frequency with the effective MWCNT wt% loading in the nanocomposites is confirmed after careful and systematic experiments performed on prototype well-dispersed samples.
Diagnostics of carbon nanotube composites by Raman spectroscopy
We use Raman imaging as diagnostic tool to assess the degree of interaction of double wall carbon nanotubes with the composite matrix. The local environment of the carbon nanotube has a strong influence on the Raman G and D band shape, spectral position and relative intensity. Additional spectral lines are observed due to the interaction of amphiphilic molecules with carbon nanotubes. We use high pressure experiments on carbon nanotubes using different pressure transmitting media and correlations in the observed peak shifts to estimate the local pressure in carbon nanotubes composites.
Characterization of carbon nanotubes by Raman spectroscopy
MATERIALS SCIENCE-POLAND
Application of Raman spectroscopy to analyse carbon nanotubes has been presented. Having a mixture of various carbon nanotube samples, one can easily distinguish, in a quick experiment, presence of singlewalled, doublewalled and multiwalled carbon nanotubes (SWCNT, DWCNT, MWCNT, respectively). The so-called G-line is a characteristic feature of the graphitic layers and corresponds to the tangential vibration of carbon atoms. Another characteristic mode is a typical sign of defective graphitic structures (D-line). A comparison of the intensity ratios of these two peaks gives a measure of the quality of the bulk samples. In addition, there is a third mode, named the radial breathing mode (RBM) which is very sensitive to the diameter of SWCNT and DWCNT. Additional option is application of Raman microscopy for mapping analysis and depth profiling to view the changes of intensity in various directions in the sample.
Laser excited Raman scattering was measured from various carbon nanotube samples, as well as high purity graphite using an Ar + laser at different wavelengths and the variation of the band parameters was studied as a function of the excitation laser wavelength. Features in the Raman scattering have been identified and assigned to known structural and dynamical sources. Scanning electron microscopic and tunnelling microscopic pictures of two different nanotube samples contributed to the characterization of the samples as multiwalled and singlewalled carbon nanotube bundles and helped identify Raman spectral features.