Competing effect between filled glass bead and induced β crystal on the tensile properties of polypropylene/glass bead blends

The blends of the polypropylene (PP‐1) with various glass bead contents were prepared via melt blending. Differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD) results indicated that the β crystal existed in PP‐1 and increased with increasing glass bead content up to 6 wt %. It was generally known that the stiffness of a polymer increased with introducing rigid particles, and the stiffness of the β crystal was less than that of the α crystal. This competing effect thus leads to the tensile modulus of PP‐1/glass bead blend decreasing with increasing glass bead content up to 6 wt %; thereafter, it increased with increasing glass bead content. For the purpose of comparison, the polypropylene (PP‐2) without the β crystal was employed to blend with glass bead. The tensile tests showed that the modulus of the PP‐2/glass bead blend increased continuously with increasing glass bead content. This result further supported that the tensile modulus behavior of PP‐1/glass bead blends resulted from the competing between the filled glass bead and the induced β crystal.