• AC conductivity and dielectric relaxation of chitosan/poly(vinyl alcohol) biopolymer polyblend

• # Fulltext

https://www.ias.ac.in/article/fulltext/boms/043/0243

• # Keywords

Chitosan/PVA; AC conductivity; dielectric constant; dielectric relaxation; dipolar relaxation.

• # Abstract

Polyblend samples of chitosan/poly(vinyl alcohol) (PVA) have been prepared using a casting technique. Scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis measurementsrevealed that chitosan and PVA are compatible with each other. Alternate current (AC) conductivity and dielectric relaxation features of pure and polyblend samples are analysed in the frequency range of 0.1 Hz to 100 kHz covering abroad temperature range from room temperature to 423 K. Variation of AC conductivity, $\rho_{\rm AC}$, of pure and chitosan/PVA polyblend samples is found to be characterized by a plateau region at low frequency and high temperature, and this plateau region increases with increase in temperature. Based on the behaviour of the exponent $s$ $vs$. temperature, AC conductivitydependence on frequency is found to be correlated with overlapping-large polaron tunnelling (OLPT) model. The polyblend samples showed an improvement in their dielectric properties compared to the pure materials. The dielectric constant, $\epsilon '$, of polyblend samples was increased by increasing the content of PVA. The dielectric dispersion was observed in the variation of $\epsilon '$ against frequency for all samples. The high values of $\epsilon '$ for all samples at high temperature and low frequency are attributed to space charge polarization. Also, loss tangent-frequency behaviour of pure chitosan, PVA andall polyblend samples showed two distinguished relaxation peaks with different values of activation energies. The first relaxation peak is termed as interfacial polarization or Maxwell–Wagner–Sillars polarization due to heterogeneity of thepolyblend samples, whereas, the second relaxation peak is termed as $\delta$-relaxation and $\alpha$-relaxation, for pure chitosan and PVA, respectively.

• # Author Affiliations

1. Physics Department, College of Science and Humanities, Prince Sattam bin Abdulaziz University, 11942 Al-Kharj, Kingdom of Saudi Arabia
2. Polymer Research Group, Physics Department, Faculty of Science, Mansoura University, 35516 Mansoura, Egypt
3. Department of Basic Science, Delta Higher Institute for Engineering and Technology, 11152 Mansoura, Egypt
4. Physics Department, Faculty of Science, Mansoura University, 35516 Mansoura, Egypt

• # Bulletin of Materials Science

Volume 44, 2021
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020