Compatibilizing effect of maleated polypropylene on the mechanical properties of injection molded polypropylene/polyamide 6/functionalized-TiO2 nanocomposites

TiO2 nanoparticles were pretreated with excessive toluene-2,4-diisocyanate to synthesize TDI-functionalized TiO2 (TiO2-NCO), and then the polypropylene/polyamide 6/(PP/PA6, 70/30 wt%) blends containing 3 phr of the TDI-functionalized TiO2 were prepared using twin-screw extruder followed by injection molding. Maleated polypropylene (PP-g-MAH) was used to compatibilize the blends. The mechanical properties of PP/PA6 blends based nanocomposites were studied through tensile and flexural tests. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to assess the fracture surface morphology and the dispersion of the TDI-functionalized TiO2, respectively. The dynamic mechanical properties of PP/PA6 based nanocomposites were analyzed by using dynamic mechanical thermal analyzer (DMTA). The strength and stiffness of the PP/PA6 compounds were improved significantly in the presence of PP-g-MAH. This has been attributed to the synergistic effect of TDI-functionalized TiO2 and PP-g-MAH. The PP-g-MAH compatibilized PP/PA6 compounds showed a homogeneous morphology supporting the compatibility improvement between PP, PA6 and TDI-functionalized TiO2. TEM results revealed that the TDI-functionalized TiO2 nanoparticles were exfoliated and uniformly dispersed in blends matrix. Possible chemical interactions between PP, PA6, TDI-functionalized TiO2 and PP-g-MAH were proposed based on the experimental work.