Impedance spectroscopy characterization of relaxation mechanisms in gold–chitosan nanocomposites

Investigation of polymer dynamics in chitosan-maghemite nanocomposites: a potential green superparamagnetic material

“…This is attributable to modification in σ relaxation of chitosan due to maghemite nanoparticles. This is similar to the modifications in σ relaxation observed when gold nanoparticles were incorporated in chitosan films [57] The other had relaxation time value in the range 1.75 × 10 −6 s to 5.95 × 10 −7 s with E a = 47 kJ/mol. Since the E a for CF1 is greater than that of chitosan at the same temperature range, this indicates that the relaxation due to bound water is affected by maghemite nanoparticles.…”

“…Since the activation energy is close to that of bound water, this relaxation is due to water trapped in the film. The α relaxation has been reported for chitosan between 50 and 85°C in low frequency [57]. We however could only detect a very mild shoulder peak and hence have not included it in the Fig.…”

“…In the temperature range of 60-80°C two relaxations, both with negative activation energy values were observed for CF1. The first relaxation corresponding to low frequency range had relaxation time value from 3.4 × 10 −6 s to 3.7 × 10 −6 s indicating α relaxation [57]. Since the peak is somewhat more prominent than that of chitosan film at the same temperature and frequency range this indicates that the presence of maghemite could favour α relaxation between 50 and 80°C.…”

“…One of it had nearly constant relaxation time (5.26 × 10 −4 s). This is attributable to σ relaxation [57]. The second relaxation was observed between 105°C-150°C with relaxation time in the range 3.3 × 10 −6 s to 1.16 × 10 −6 s with E a = 37 kJ/mol.…”

Dielectric properties, Impedance analysis, and electrical conductivity of Ag doped radiation grafted polypropylene

“…These plots exhibit two distinguished semicircles: the characteristic depressed semicircle at high frequencies and the quasi-linear response at low frequencies. According to previously reported studies, a depressed semicircle describes properties of the bulk material, and the quasi-linear response at low frequencies is associated with the interfacial polarization and/or the surface and electrode effects (J. Betzabe Gonz´alez-Campos, 2012, Alexandra Neagu, 2015). The intercepts of the semicircles on low frequency end gives the bulk resistance (R b ) of the sample at different temperatures.…”