Influence of SiO2 Nanoparticles on Mechanical Properties of PP/SEBS Blends at Intermediate and High Strain Rates

概要

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The objective is to characterize the effects of SiO2 nanoparticles on the mechanical properties of the thermoplastic polypropylene (PP) blended with two different styrene-ethylene-butadiene-styrene tri-block copolymer (SEBS) at the intermediate and high strain rates. Tensile tests are conducted at the nominal strain rates from 3 x 10-1 to 102 s-1. Phase morphology is investigated by transmission electron microscopy (TEM). In addition, the fracture surfaces are observed by scanning electron microscopy (SEM) to investigate the fracture mechanisms. The elastic modulus increased only when nanoparticles were blended in the small-diameter SEBS blended PP. Decreases in the rupture strain and the strain energy up to failure were prevented for the blend system where nanoparticles were blended in the large-diameter SEBS blended PP. This is because the nanoparticles located inside rubber particles lead to the ductile fracture mechanism while the nanoparticles located outside rubber particles lead to the debonding sites between SiO2 particles and PP matrix because of the stress concentration around them. The synergistic effect of these nanoparticles gives importance to the location of nanoparticles in PP/SEBS blend systems and the stiffness of SEBS particle.