Spectroscopic investigations on Polypropylene-Carbon Nanofiber Composites: I. Raman and Electron Spin Resonance Spectroscopy

Authors

• Mircea Chipara, University of Texas Pan AmericanFollow
• John R. Villarreal, University of Texas Pan American
• Magdalena Dorina Chipara, University of Texas Pan AmericanFollow
• Karen Lozano, University of Texas Pan American
• Alin Cristian Chipara, University of Texas Pan AmericanFollow
• David J. Sellmyer, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

7-2009

Comments

Published in Journal of Polymer Science Part B: Polymer Physics 47:17 (2009), pp. 1644–1652; doi: 10.1002/polb.21766 Copyright © 2009 Wiley Periodicals, Inc. Used by permission.

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.