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Aluminum oxide nanoparticles (Al 2 O 3 ) were prepared and the obtained structure and size of the prepared Al 2 O 3 nanoparticles were studied via X-ray diffraction (XRD) and transmission electron microscopy. The effect of adding various concentrations of the Al 2 O 3 and gamma radiation on the structural and optical properties of syndiotactic polystyrene (sPS) were investigated using XRD and UV-spectroscopy. XRD data showed that the addition of the various concentrations of the Al 2 O 3 influenced the crystallinity of the nanocomposites. A significant change in the lattice structure and the optical parameters were observed. The results showed that a sample with the Al 2 O 3 concentration of 10% achieved a higher refractive index and optical conductivity. Effect of gamma irradiation on sPS sample loaded with 10% Al 2 O 3 was studied. The results showed several changes in the structure and optical properties of the resulting films due to crosslinking between the polymer chains. This result reflects that the polymer suffered from structural rearrangement due to the irradiation treatments. POLYM. ENG. SCI., 59:555-565, 2019.

Some composites were prepared depending on ethylene vinyl acetate (EVA) copolymer with 18% VA content and titanium dioxide (TiO2). These composites were prepared in the ratios of 100/0, 90/10, 80/20, 70/30, and 60/40 by melt mixing method. Gamma radiation at differing doses was applied on pure EVA and composites to investigate the impact on modification of composites. Gel percentage and the Charlesby‐Pinner equation were used to confirm crosslinking increases. X‐Ray diffraction measurement (XRD), scanning electron microscope (SEM), and mechanical testing were all used to investigate the varying effects of the different processes on the structure, morphology, and mechanical behavior of EVA. It was observed that the addition of TiO2 and gamma irradiation both have a significant effect on the structure and, therefore, the composites' surface morphology. Notable changes of the lattice structure were revealed by the XRD results for both unirradiated and irradiated composites, which were also confirmed by examination of the samples' surface morphology. It was found that the presence and amount of TiO2 along with the irradiation process has a significant influence upon the EVA's mechanical behavior. When compared with the pure EVA, the results demonstrated a significant enhancement in the mechanical parameters of both unirradiated and irradiated composites, except elongation at break. The mechanical results were in line with gel content analysis. The reliability of gamma radiation as an applied method for controlling long‐term properties is clearly demonstrated. J. VINYL ADDIT. TECHNOL., 26:224–235, 2020. © 2019 Society of Plastics Engineers

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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 gammaabsorbed 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.FIG. 3. (a) The changes in melting temperature (tm) and (b) the changes in melting enthalpy (Hm) as a function of Al 2 O 3 nanoparticles content for the pure sPS and sPS/Al 2 O 3 nanocomposites before and after gamma irradiation. FIG. 7. Some plots of the Coats-Redfern method of thermal decomposition for (a) pure sPS, (b) sPS/3%Al 2 O 3 nanocomposite, and (c) sPS/5% Al 2 O 3 nanocomposite.