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 a 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 com parison, 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. © 2005 Wiley Periodicals, Inc.