Investigation of the effect of aluminum oxide nanoparticle additives and gamma irradiation on the thermal behavior of syndiotactic polystyrene

Syndiotactic polystyrene (sPS) containing 3, 5, 7, and 10 wt% of aluminum oxide (Al ₂ O ₃ ) nanoparticles were prepared following the melt‐mixing technique. The thermal behavior of the sPS/Al ₂ O ₃ nanocomposites was investigated through differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and melt flow index (MFI). The DSC results indicated that for all sPS/Al ₂ O ₃ nanocomposites, the melting temperature (T _m ), the melting enthalpy (ΔH _m ), the crystallization temperature (T _c ), and the glass transition temperature (T _g ) increased with an increase in the Al ₂ O ₃ nanoparticles content. The TGA analysis indicated that the thermal stability of all nanocomposites is significantly enhanced after the addition of Al ₂ O ₃ nanoparticles with different contents. The activation energy was determined through two different models: the Coats–Redfern model and Broido's models were utilized to measure the activation energy of thermal decomposition by assuming first‐order kinetics. The results of both methods have displayed a high level of agreement. Our study extended to study the MFI of the sPS/Al ₂ O ₃ nanocomposites. The MFI reduced when the Al ₂ O ₃ nanoparticles content increased. The effect of gamma irradiation on the thermal behavior of the sPS/Al ₂ O ₃ nanoparticles was also investigated at different gamma‐absorbed doses. Significant modifications were observed in the thermal behavior of sPS/Al ₂ O ₃ nanocomposites after the irradiation process, and the experimental data indicated that the addition of Al ₂ O ₃ nanocomposites in small loading contents and gamma irradiation can significantly help improve the thermal properties of sPS. POLYM. COMPOS., 40:3588–3600, 2019. © 2019 Society of Plastics Engineers