Effect of temperature and frequency on the dielectric properties of cellulose nanofibers from cotton

Abstract

The present work has been carried out to evaluate the dielectric properties and ac-electrical conductivity of cellulose nanofibers. The cellulose nanofibers (CNF) described in this work are the ones extracted from cotton via a simple acid hydrolysis method and are characterized with X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and UV-Visible diffuse reflectance spectroscopy. The optical band gap of CNF found out using the Kubelka-Munk plot is 3.30 eV. The dielectric constant, dielectric loss, and ac-electrical conductivity of the prepared CNF have been investigated in the temperature range from 30 °C to 300 °C and in the frequency range from 50 Hz to 5 MHz. The synthesized system exhibits a higher dielectric constant value for all temperatures in the low-frequency (0.1 kHz) region and a frequency-independent behavior above 10 kHz. In the high-frequency region, the dielectric constant is independent of temperature. Also, the study shows that the conductivity increases with increasing frequency and temperature. The maximum values of ac-conductivity at room temperature (30 °C) and high temperature (300 °C) are found to be 4.58 9 10 -5 S/cm and 2.26 9 10 -4 S/cm, respectively. In brief, the studies point to the application potential of CNF for future flexible electronics.

Dielectric and electrochemical performance of rhombohedral lanthanum manganite perovskite nanostructures

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Dielectric Properties of Cellulose and Nanocellulose-Based Materials

“…In the latest study by Jose et al (2021) obtained nanocellulose from cotton and studied the dielectric properties of CNF in the temperature range of 30 °C to 300°C and the frequency range of 50 Hz to 5 MHz. The dielectric constant of CNF varies obviously with the temperature at low frequency (<1 kHz).…”

Decomposable Flexible Organic Transistors with a Cellulose-Based Gate Dielectric and Substrate for Biodegradable Electronics

“…The capacitance increases due to the adsorption of water molecules in a humid enviornment, leading to enhancement in ionic conduction . The k value of cellulose-based dielectrics is found to increase up to an annealing temperature of 50 °C, possibly due to the reduction in the dipole–dipole interaction and an increased motion of polar groups and water dipoles. , An improvement in the electrical performance of transistors with cellulose-based dielectrics had been reported upon heating up to the temperature of 50 °C, though a degradation in performance had been observed upon heating at higher temperatures due to the water release leading to loss of ionic conductivity and also due to issues like adhesion to the semiconductor surface …”

“…This phenomenon enables the formation of an electric double layer (EDL) and helps in enhancing the gate capacitance density significantly, which effectively lowers the operating voltage in transistors. The migration of mobile ions and effective capacitance density are influenced by various factors, including frequency, humidity, and temperature, ,, and are strongly dependent on the frequency. The capacitance of these dielectrics is high at very low frequencies, but sharply decreases at high frequencies as the dipoles cannot follow the changes in the electric field .…”

“…The capacitance of these dielectrics is high at very low frequencies, but sharply decreases at high frequencies as the dipoles cannot follow the changes in the electric field . Moreover, it had been observed that both humidity and temperature significantly affect the dielectric properties specifically at low frequencies . The capacitance increases due to the adsorption of water molecules in a humid enviornment, leading to enhancement in ionic conduction .…”