ESR Spectroscopy in Polymer Research

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

“…The free-radical concentration in ESR spectroscopy is proportional to the double integral of the resonance spectrum. 20 For a simple Lorentzian line, the double integral of the resonance spectrum, is proportional to the amplitude of the ESR line and the square of the peak to peak linewidth. 20,21 As it is observed from Figure 8, the intensity of the resonance line located near g = 2.00 and the double integral of this line are increasing as the concentration of VGCNF is increased, confirming that this signal originates from VGCNF.…”

“…17 Pristine polymers such as iPP show no ESR spectra. 20 Under certain circumstances, residual ESR spectra may point either to catalyst residues or to trapped free radicals generated by mechanical, thermal, or oxidative processes. 20 VGCNFs show ESR spectra almost identical to the ESR spectra of carbon nanotubes.…”

“…20 Under certain circumstances, residual ESR spectra may point either to catalyst residues or to trapped free radicals generated by mechanical, thermal, or oxidative processes. 20 VGCNFs show ESR spectra almost identical to the ESR spectra of carbon nanotubes. 21 Typically, the ESR spectrum of carbon nanotubes contains several contributions [22][23][24] ; a very broad line characterized by g > 2.00 assigned to catalyst's impurities (magnetic nanoparticles), a narrow line (sometimes asymmetric) located near g = 2.0023 and assigned to conducting electrons delocalized over carbon nanotubes or carbon nanofibers.…”

Analysis of Relaxation Behavior of Free Radicals in Irradiated Cellulose Using Pulse and Continuous-Wave Electron Spin Resonance

“…Furthermore, according to a monograph on the ESR studies of irradiated polymers (Rånby, 1977), the majority of references have concluded that, among other candidate radicals, a radical at the C(5) position of the glucose unit is the most plausible one in irradiated cellulose. In general, hydrogen abstraction occurs at various chemical bonds by the gammairradiation.…”

“…Thus starch molecules do not form regular sheets and H-bonding is very different. Even though cellulose and starch have similar chemical formulas, their radical formation process may differ due to their structures (Rånby, 1977). It has been reported that the triplet ESR spectrum of cellulose (pure cotton) is due to the equal interaction of the two hydrogen atoms at the C6 position with the unpaired electron formed by the removal of the hydrogen atom at the C5 position of the glucose unit (Rånby, 1977;Arthur, 1971;Arthur & Hinojosa, 1971;Arthur et al, 1966;Baugh et al, 1967) (see Fig.…”