Abstract-Alumina nanoparticles have been modified with polysulfone (PSU) chains via 1,3-dipolar cycloaddi-tion reaction between functionalized alumina with vinyl groups and terminal azide polysulfone chains of two differ-ent molecular weights. Homopolymer nanocomposites have been prepared for the first time by extrusion and microinjection. The effectiveness of the grafts on the dispersiblity has been analyzed in terms of the parameters that govern the wettability between grafted and matrix chains: graft density ( ), graft molecular weight (N) at constant matrix molecular weight (P).The dispersion state and interfacial adhesion of PSU grafted-nanoparticles have been evaluated from laser scanning confocal, FESEM and SEM microscopy. Results show that the incorporation of the modified g-alumina improves the dispersion state in comparison with bare alumina nanoparticles, reducing the aver-age particle size from 5±9 to 1.3±1 microns. Although aggregates are still present the size of the aggregates are also substantially reduced even with low or moderate graft density used in this work, but further improves the interfacial adhesion between nanoparticle and matrix when long PSU chains are grafted even with low-moderate grafting den-sity. These results can be explained by enthalpic compatibility between polysulfone grafted layer and host polysul-fone matrix
This work describes how a solid-state blending method such as jet milling can be used to successfully prepare polysulfone (PSU)/γ-alumina nanocomposites. For comparison purposes, conventional melt extrusion was used as well. Morphological analysis revealed how jet mill blending allows obtaining well-dispersed γ-alumina nanoparticles within a polysulfone matrix without any surface treatment, with an important decrease of particle size promoted by the breakup of agglomerates and aggregates due to the particle-particle impacts during processing, which was not observed in the extruded nanocomposites. DSC analysis demonstrated that jet-milling processing promoted Tg enhancements with alumina addition, while TGA experiments confirmed the increment of thermal stability of the nanocomposites prepared by jet milling when compared with the composites prepared by extrusion. The tensile tests showed that ductility remains at a high value for milled nanocomposites, which agreed with the fracture surface images revealing large plastic deformation as a function of the alumina content. This comparative study indicates that the dispersion of nanoparticles in PSU was more homogeneous, with smaller nanoparticles when preparing nanocomposites using jet milling, showing a strong correlation with the enhanced final properties of the nanocomposites.
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