Tailoring the performance of boehmite nanoparticles reinforced carboxymethyl chitosan/cashew gum blend nanocomposites via green synthesis

The main motivation for this study stemmed from the demand for bio-friendly polymeric materials with enhanced properties in various fields of application. Biopolymer blend nanocomposite films based on carboxymethyl chitosan (CMCS) and cashew gum (CG) with different contents of boehmite nanoparticles were prepared via a purely green method using water as the solvent. The successful inclusion of boehmite nanoparticles in the CMCS/CG blend was verified by Fourier transform infrared (FTIR) analysis. Scanning electron microscopy (SEM) and optical microscopy were used to analyze the surface microstructure of prepared films. SEM and optical images revealed a uniform distribution of nanofillers in the blend because of the strong interactions between nanoparticles and the CMCS/CG blend segments. The thermogravimetric analysis demonstrates that the addition of boehmite nanoparticles increased the thermal stability of the biopolymer blend films. Differential scanning calorimetry (DSC) showed a small shift in the glass transition and melting temperature of pristine blend to higher values with the addition of boehmite. The correlation of AC conductivity with varying frequency and temperature was evaluated. The maximum conductivity was shown by CMCS/CG blend with 7 wt % boehmite, which was further supported by their lowest activation energy value. Nyquist plots were used to illustrate the complex impedance of prepared nanocomposite films. A decrease in the area under the semicircular arc with temperature suggested an increase in conductivity with temperature. The dielectric constant and dielectric loss factor of blend and its nanocomposite films were found to increase with temperature. Boehmite addition increased tensile strength and hardness while lowering elongation at break up to a specific concentration. The synthesized CMCS/CG/boehmite films can be used as environmentally friendly alternatives in the development of flexible organic electronics and charge harvesting devices.