▎ 摘　　要

In this work, we designed and studied two synthetic routes, based on modified Hummers method, to obtain graphene oxide (GO), and investigated their influence on the performance of polypropylene (PP)/GO nanocomposites. The two synthetic routes differed in the application condition of the oxidizing agent, potassium permanganate (KMnO4), which was added either as a powder (GO-P) or as a water solution (GO-S). This apparently subtle synthetic change yielded GOs with different degrees of oxidation and particle sizes, where GO-P presented a higher oxidation degree and smaller particles. The different GOs were then melt-blended with PP and the correlation between their different chemical/morphological structures and the nanocomposites' thermomechanical/rheological properties were evaluated. The milder oxidation process suffered by GO-S, and consequent less hydrophilic character, yielded a PP/GO-S nanocomposite with improved performance as the consequence of a better matrix/filler chemical affinity, mainly in compositions with lower GO-S contents. The thermal stability was increased by more than 10 degrees C when 0.1 wt% GO-S was inserted into PP. When compared to the composition with 0.1 wt% GO-P, the increase was 13 degrees C. Reinforcing effects were also observed in that sample (with 0.1 wt% GO-S), which exhibited the highest storage modulus and complex viscosity. These results suggest that tailoring the GO's oxidation degree and morphology is a key point to obtain an ideal interfacial interaction between phases.