Effect of γ-irradiation on thermally stimulated depolarization current spectra of polyethylene-grafted-poly(Acrylic acid)

Abstract

The graft copolymerization process of polyethylene (PE) with acrylic acid is performed using a ⁶⁰Co-gamma irradiator, and the samples are irradiated at different doses, 30, 50, 70 and 100 kGy with a dose rate of 0.55 Gy/s. Global thermally stimulated discharge current (TSDC) spectrum of irradiated and non-irradiated PE-g-AAc has been investigated from RT to ∼ 440K. The TSDC spectrum of non-irradiated PE-g-AAc exhibited two relaxation processes. The first process is located at ∼ 329 K, and the second one is at ∼390 K. These processes are called dipolar and space charge relaxation, i.e. α- and ρ-relaxation, respectively. On the other hand, the position of these processes is shifted towards a higher temperature for irradiated samples. The activation energy for α-relaxation process of non-irradiated samples is ∼ 0.21 eV, while for irradiated samples, it is 0.34 eV. The thermal sampling technique (TS) has been applied to decompose the global TSDC spectrum of all samples into its elementary peaks. The molecular parameters, such as activation energy (E_a), pre-exponential factor (τ₀), enthalpy (ΔH), entropy (ΔS) and Gibbs free energy (ΔG), are estimated for all samples. The compensation phenomenon has been verified for all samples in different ways, such as plotting ln τ₀ against E_a or entropy versus enthalpy.

KEYWORDS:

• PE-g-AAc
• irradiation
• TSDC
• enthalpy
• entropy
• compensation

Acknowledgements

W. B. Elsharkawy and M. T. Ahmed thank Scientific Research Deanship (SRD) at Prince Sattam bin Abdulaziz University, KSA. Also, one of the authors (ZME) would like to thank the Deanship of Scientific Research (DSR) in Princess Nourah bint Abdulrahman University, Saudi Arabia, for funding this research through the fast-track research funding programme.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

W. B. Elsharkawy

W. B. Elsharkawy got PhD in Medical Biophysics from Cairo University, Cairo, Egypt in 2013. She is working now as assistance professor of biophysics at Physics Dept., College of Science and humanities, Prince Sattam bin Abdulaziz University, Alkharj, Kingdom of Saudi Arabia. Currently, her research interests focus on polymer properties and x-ray scattering and Monte Carlo simulation in the medical biophysics field.

M. T. Ahmed

M. T. Ahmed got PhD degree in 1992 from Mansoura University in cooperation with the Max Planck Institute (Stuttgart) in Germany. He is working now a professor of material science at Physics Dept., College of Science and humanities, Prince Sattam bin Abdulaziz University, Alkharj, Kingdom of Saudi Arabia. Currently, his research interests focus on studying the phenomenon of relaxation, optical, electrical properties, radiology and antibacterial activity of polymers and their nanocomposites.

E. O. Abdelmuttlib

E. O. Abdelmuttlib got PhD degree in 2018 (Biophysics) from Mansoura University, Egypt. He is working now in Mansoura Specialized Hospital.

Z. M. Elqahtani

Z. M. Elqahtani got PhD degree in 2005 from the College of Education, Princess Nourah Bint Abdulrahman University, Riyadh, Saudi Arabia. She is working now an assistant professor at Physics Department, College of Science, Princess Nourah Bint Abdulrahman University, Riyadh, Saudi Arabia. Currently, her research interests focus on studying the phenomenon of dielectric, optical, electrical properties of polymers and their nanocomposites.

M. A. Azzam

M. A. Azzam got PhD degree in 2019 (inorganic chemistry) from Menofia University, Egypt. He is working now a lecturer at Chemistry Dept., College of Science and humanities, Prince Sattam bin Abdulaziz University, Alkharj, Kingdom of Saudi Arabia. Currently, his research interests focus on inorganic synthesis of metal complexes of pharmaceutical interest, water purification, molecular modelling and medicinal chemistry.

T. Fahmy

T. Fahmy got PhD degree in 1996 from Mansoura University in cooperation with the Max Planck Institute (Stuttgart) in Germany. He is working now a professor of experimental physics (Polymer Physics) at Physics Dept., Faculty of Science, Mansoura University, Mansoura, Egypt. Currently, his research interests focus on studying the phenomenon of dielectric relaxation spectroscopy, optical, electrical properties, piezoelectricity and antibacterial activity of polymers and their nanocomposites.