Thermal Stability, Dielectric Behavior and Structural Relaxation in Cross-Linked and Grafted Chitosan Polymer Composites

Abstract

Biopolymer-based materials have attracted increasing attention for advanced functional applications due to their eco-friendly nature and tunable physicochemical properties. In the present investigation, pure chitosan, cross-linked chitosan and grafted chitosan polymer composites were synthesized and systematically studied with respect to their thermal stability, dielectric behavior and structural relaxation characteristics. Structural modifications were confirmed using FTIR and X-ray diffraction techniques, while thermal transitions and degradation behavior were analyzed using DSC and TGA. Dielectric parameters such as dielectric constant, dielectric loss and AC conductivity were evaluated over a wide frequency range. Cross-linking and grafting significantly improved thermal resistance and reduced crystallinity, leading to enhanced dielectric stability and reduced energy loss. The observed dielectric relaxation phenomena are attributed to restricted segmental mobility and enhanced interfacial polarization effects in modified chitosan systems. The results demonstrate that chemically modified chitosan composites possess improved thermal endurance and dielectric performance, making them promising candidates for bio-based insulating and packaging applications.