Effect of Melt Mixing Processing conditions on the Flexural and Morphological Properties of Polypropylene Reinforced with Mesoporous Silica/Hydroxyapatite Nanoparticles

The polypropylene (PP) nanocomposite reinforced with the composite of mesoporous silica and hydroxyapatite (MH), were prepared by melt mixing in an internal mixer and melt extrusion in a twin screw extruder. The influence of processing parameters on the flexural performance of the nanocomposite was studied by varying the mixing temperature and rotor speed of internal mixer. Maleic anhydride grafted polypropylene (PP-g-MA) was used as compatibilizer. The nanocomposites were characterized by performing flexural testing and Scanning Electron Microscopy (SEM) analysis. It was found that PP/MH prepared by two techniques were effectively enhanced the flexural properties of neat PP. The enhancement of flexural strength was about 33% by melt extrusion and 17.8% by melt mixing compared with neat PP. Therefore, by incorporating MH nanoparticles in PP, we could achieve a new hybrid nanocomposite with high flexural properties. Also, the optimum temperature of 180°C and rotor speed of 100 rpm obtained and applied to the extruder to achieve higher flexural properties. A higher shear rate of the twin screw extruder and more efficient sol-gel reaction led to better dispersion and higher flexural properties. From SEM images, it was observed that nanoparticles were distributed reasonably uniformly indicating a good dispersion of nano phase in the PP matrix by using extruder.