Spectroscopic investigations on polypropylene‐carbon nanofiber composites. I. Raman and electron spin resonance spectroscopy

Abstract

Isotactic polypropylene‐vapor grown carbon nanofiber composites containing various fractions of carbon nanofibers, ranging from 0 to 20 wt %, have been prepared. Raman spectroscopy was used to analyze the effect of the dispersion of carbon nanofibers within polypropylene and the interactions between carbon nanofibers and macromolecular chains. The as‐recorded Raman spectra have been successfully fitted by a linear convolution of Lorentzian lines. Changes of the Raman lines parameters (position, intensity, width, and area) of polypropylene and carbon nanofibers were analyzed in detail. The Raman spectra of the polymeric matrix—at low concentrations of nanofibers—show important modifications that indicate strong interactions between carbon nanofibers and the polymeric matrix reflecting by vibrational dephasing of macromolecular chains. The Raman spectrum of carbon nanofibers is sensitive to the loading with carbon nanofibers, showing changes of the resonance frequencies, amplitudes, and width for both D‐ and G‐bands. Raman data reveals the increase of the disorder, as the concentration of carbon nanofibers is increased. The presence of the typical ESR line assigned to conducting electrons delocalized over carbon nanofibers is confirmed and the presence of a spurious magnetic line due to catalyst's residues is reported. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1644–1652, 2009

Polyoctenamer - Single Walled Carbon Nanotube Composites: Spectroscopic Investigations

“…However, this interpretation is rather qualitative as the position of Raman lines are affected also by additional parameters as the conductivity of carbon nanotubes [9][10]. Two contributions are affecting the position and width of SWCNTs lines.…”

“…A, B, and C are constants that defines the base line correction, w is the Raman shift and p j is a parameter that characterizes the asymmetry of the Raman line. As expected, the total areas corresponding to breathing modes, DG bands, and G' line are enhanced as the concentration of SWCNTs is increased [7][8][9]. its lineshape degenerates into a Lorentzian one.…”

“…The addition of nanometer-sized fillers increases the strength of polymeric materials and in most cases results in a decrease of the elongation at break. Recent studies [2][3][4][5][6][7][8][9][10][11][12] indicated that the dispersion of nanometer-sized fillers such as carbon nanotubes and carbon nanofibers enhances the mechanical properties, the thermal and thermo-oxidative stability, improves the thermal conductivity, and eventually adds electrical conducting features to typically insulating polymeric matrices. Carbon nanotubes are among the most frequently used nanofillers due to their huge aspect ratio, excellent mechanical strength (large high modulus), large thermal conductivity, and electrical features ranging from semiconductor to metal (pending on the chirality of the nanotubes) [1][2][3][4][5].…”

Fourier transform infrared spectroscopy and wide‐angle X‐ray scattering: Investigations on polypropylene–vapor‐grown carbon nanofiber composites

“…The resonance line shape suggested a percolating transition from an insulator toward a conducting nanocomposite. The Raman spectroscopy data revealed4 that the addition of VGCNF to iPP dramatically affected the dynamics of the macromolecular chains. It was concluded4 that the loading of iPP with VGCNFs resulted in a rapid drop in the intensity of Raman lines assigned to the polymeric matrix, which was accompanied by a fast broadening of these lines.…”

“…The Raman spectroscopy data revealed4 that the addition of VGCNF to iPP dramatically affected the dynamics of the macromolecular chains. It was concluded4 that the loading of iPP with VGCNFs resulted in a rapid drop in the intensity of Raman lines assigned to the polymeric matrix, which was accompanied by a fast broadening of these lines. Such a fast vibrational dephasing of the macromolecular chain demonstrated the strong interaction between the VGCNFs and iPP chains, making difficult the study of both the polymeric matrix and filler over a wide range of VGCNF concentrations with Raman spectroscopy 4.…”