TSDC of Irradiated and Non-Irradiated Cellulose Acetate

Abstract

Films of cellulose acetate (CA) have been prepared by casting method using tetrahydrofuran (THF). CA films are γ-irradiated with varying radiation doses of 10, 20, 30, 40, 50 and 60 kGy using cobalt-60 ( 60 Co) source. Global thermally stimulated depolarization current (TSDC) of non-irradiated and irradiated CA samples has been investigated under the effect of various poling electric field (Ep) in a temperature range from 300 K to 440 K. It is observed that, global TSDC spectra of non-irradiated and irradiated CA samples are characterized by two relaxation peaks. One in the low temperature range ~321 K and the other in the high temperature range ~ 376-383 K are observed for non-irradiated sample. On the other hand, these temperatures are shifted towards lower temperature for irradiated samples to be located at 317 K and ~371 K. These relaxations are assigned as  and -relaxation and attributed to molecular motion of the polar acetate groups, C2H3O2 and polarization of the space charges, respectively. TStechnique has been carried out to decompose global TSDC spectra of all samples into its elementary peaks and the molecular parameters such as, activation energy and pre-exponential factor are calculated for each TS peak. Relaxation map (RM) of all samples has been analyzed using Eyring transformation and thermodynamic parameters such as, enthalpy activation (H), entropy activation (S) and Gibbs free energy (G) are estimated. The compensation phenomenon was verified by the linear relationship between both enthalpy and entropy.

Enhanced molecular structure, thermal stability, and linear/nonlinear optical characteristics of chitosan/titanium dioxide nanocomposite films

“…This linear relation may be due tostructural changes that occur when increasing the temperature of the polymeric material to achieve equilibrium. A similar tendency has already been seen for other polymer composites(Fahmy et al 2021;Elsharkawy et al 2022;Abdelfattah et al 2023). The acquired results could be employed in thermal degradation optimization, as well as to improve the thermal stability of the nanocomposite under examination, potentially leading to intriguing technological applications.…”

Enhancement of the Structure, Thermal, Linear/Nonlinear Optical Properties, and Antibacterial Activity of Poly (vinyl alcohol)/Chitosan/ZnO Nanocomposites for Eco-Friendly Applications

“…The observed linear relationship between (ΔS) and (ΔH) indicated the existence of the compensation phenomenon in PVA/Cs/ZnO nanocomposites, as shown in Figure 8a-c. Such behavior has been reported for various polymer blends and polymer composites [54][55][56]. Structural changes that may arise when increasing the temperature of the polymeric material to reach equilibrium is the reason for the existence of the linear relationship between ΔH and ΔS, i.e., the variation in ΔH values is compensated by the variation in ΔS values [57].…”

Rate Theory and Relaxation Map Analysis of Iodine-Doped Poly(Ethyl Methacrylate) composite films using Thermally Stimulated Depolarization Current-Thermal Sampling (TSDC-TS) Technique

“…0 (sec) Pure PEMA 7x10 6 324-333 0.13 3.60x10 -2 349 0.15 1.40x10 -2 9x10 6 324-333 0.17 1.00x10 -3 347 0.12 1.68x10 -2 1x10 7 324-333 0.12 8.80x10 -2 351 0.17 Fig. 3 shows TSDC spectra of PEMA and doped samples polarized with negatively corona.…”

“…Thermally stimulated depolarization currents technique is applied to investigate the electrical properties of polymeric materials and their changes when are exposed to treatments that lead to formative changes. TSDC method is highly sensitive to probe the motions of polar groups or space charges in polymers [2][3][4][5][6][7].…”