Sustainable conductive polylactic acid/cashew gum/polypyrrole nanocomposites reinforced with boehmite for multifunctional applications

Abstract

Biopolymer‐based conductive nanocomposite films composed of polylactic acid (PLA), cashew gum (CG), and polypyrrole (PPy), reinforced with varying concentrations of boehmite (BHM) nanoparticles, were successfully fabricated and systematically investigated for their structural, morphological, thermal, electrical, dielectric, and mechanical properties. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of characteristic functional groups. Field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) revealed a homogeneous morphology at optimal filler loading, while higher concentrations led to slight agglomeration. X-ray diffraction (XRD) analysis indicated a semi-crystalline nature of the composites, with modifications in crystallinity upon BHM incorporation. Thermogravimetric analysis (TGA) demonstrated enhanced thermal stability of the BHM-filled nanocomposite films and increased char residue. AC electrical conductivity at room temperature exhibited frequency-dependent behavior, consistent with Jonscher’s universal power law. The Arrhenius plot revealed that the activation energy decreased with increasing BHM loadings up to an optimal concentration. Low-frequency dielectric measurements showed a high dielectric constant due to a significant Maxwell–Wagner–Sillars effect. The nanocomposite film containing 2 wt% BHM exhibited optimum electrical performance, with a maximum AC conductivity of 10^–7 Scm⁻¹ and a dielectric constant of 18.5 at 10² Hz, indicating the formation of efficient charge-transport pathways and enhanced polarization effects within the nanocomposite system. Mechanical characterization revealed significant improvements in tensile strength from 38.04 MPa for the parent matrix to 47.77 MPa (2 wt%), Young’s modulus, and Shore hardness with BHM nanofiller incorporation. PLA/CG/PPy/BHM nanocomposite films exhibit enhanced thermal, electrical, dielectric, and mechanical properties, making them suitable for flexible electronics and sustainable multifunctional materials.