فهرست نشریات علمی دسترسی آزاد ایران

This study aims to evaluate the thermal decomposition behavior and kinetic parameters of chitosan/polyethylene oxide (CS/PEO) blend films reinforced with different concentrations (1%, 3%, and 5%) of silver nanoparticles (AgNPs). Samples were fabricated using the solution casting method and characterized via thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC), and kinetic modeling using the Coats–Redfern method; the degradation took place using a heat rate of 10◦ C/min in a nitrogen atmosphere. DSC results supported the thermal stability evaluation by revealing a progressive increase in the glass transition temperature (Tg), from 156.7 °C for pure chitosan (S1) to 192.3 °C for the CS/PEO blend (S3), with a peak of 214.5 °C for the 3% AgNP-reinforced sample (S5), indicating enhanced polymer chain restriction and improved thermal resistance. The activation energies (Ea) varied significantly across the samples: 73.59 kJ/mol for pure chitosan (S1), 81.07 kJ/mol for pure PEO (S2), and 79.89 kJ/mol for the 50:50 CS/PEO blend (S3). Upon AgNP incorporation, the highest value of Ea was found at 3% concentration to be (78.76 kJ/mol). The results demonstrate a non-linear behavior, indicating that AgNPs contribute to thermal stability at moderate concentrations but catalyze degradation at higher amounts. Thermodynamic parameters revealed positive enthalpy (ΔH) and negative entropy (ΔS) values, indicating an endothermic degradation process with a more ordered transition state. A strong linear correlation between Ea and ln A confirmed the presence of a kinetic compensation effect, reflecting the complex interplay between structural reinforcement and catalytic facilitation.