Thermal stability, mechanical strength, and ionic conductivity of hematite nanoparticle/CS nanocomposites

Chitosan (CS)-based nanocomposite films were successfully fabricated by incorporating hematite (Fe 2 O 3 ) nanoparticles (HNPs) as reinforcing fillers at varying weight percentages ( x = 0, 1, 3, and 10) using the solution casting method. The HNPs were synthesized through a chemical route utilizing naturally occurring ferruginous laterites. Fourier-transform infrared spectroscopy (FTIR) confirmed the effective integration of HNPs into the CS matrix, while differential scanning calorimetry (DSC) revealed an increase in the glass transition temperature ( T g ) from 121°C for pure CS to 132°C for the x = 3 nanocomposites. Mechanical testing demonstrated a threefold increase in tensile strength and a significant improvement in elastic modulus from 1.67 GPa for pure CS to 2.34 GPa for x = 3 nanocomposites. Electrical properties, including capacitance, impedance, and AC conductivity, were evaluated across a frequency range of 50 Hz–100 kHz and temperatures from 300 K to 390 K. The results for x = 3 sample exhibited an increased dielectric constant and the smallest semicircular arc in the Nyquist plot, signifying the lowest resistance and highest ionic conductivity. The AC conductivity analysis, modeled using Jonscher’s universal power law and the Arrhenius equation, demonstrated that incorporating HNPs reduced activation energy from 0.99 eV for pure CS to 0.53 eV for the x = 3 nanocomposites. Additionally, the correlated barrier hopping (CBH) mechanism was confirmed through S parameter analysis, with the maximum barrier height decreasing from 0.42 eV to 0.13 eV for x = 3. These findings highlight the substantial improvements in the thermal, mechanical, and electrical properties of CS-based nanocomposites, particularly at x = 3, making them promising candidates for advanced applications requiring superior thermal stability, mechanical strength, and ionic conductivity.