Tensile performance improvement of low nanoparticles filled-polypropylene composites

It was found beforehand that low nanoparticles loaded polymer composites with improved mechanical performance can be prepared by conventional compounding technique in which the nanoparticles are pre-grafted by some polymers using irradiation. To examine the applicability of the approach, a tougher polypropylene (PP) was compounded with nano-silica by industrial-scale twin screw extruder and injection molding machine in the present work. The results of tensile tests indicated that the nanoparticles can simultaneously provide PP with stiffening, strengthening and toughening effects at a rather low filler content (typically 0.5% by volume). The presence of grafting polymers on the nanoparticles improves the tailorability of the composites. Due to the viscoelastic nature of the matrix and the grafting polymers, the tensile performance of the composites filled with untreated and treated nanoparticles is highly dependent on loading rate. With increasing the crosshead speed for the tensile tests, the dominant failure mode changed from plastic yielding of the matrix to brittle cleavage.