PP ELASTOMER/FILLER HYBRIDS .2. MORPHOLOGIES AND FRACTURE/

Three microstructures of polypropylene (PP)/elastomer/filler hybrids w ere obtained by processing control and elastomer or PP surface modific ation: (a) filler and elastomer particles are dispersed in a PP matrix to form separate particles; (b) elastomer particles with a filler cor e are distributed in a PP matrix; or (c) there are mixed microstructur es of (a) and (b). Morphologies and fracture of different components a nd microstructures were studied by SEM. When the lower-temperature cut samples were carefully etched, the differences between the various mi crostructures were clearly observed under SEM. The core-shell microstr ucture provided an elastomer interlayer between the filler and the PP matrix, which resulted in changing the fracture mechanism from microcr ack to shear yield. The SEM micrographs were digitized and analyzed by IMAGE 1.52. Rubber particle size and distribution were studied. The r elationship between the morphologies and mechanical properties, especi ally the brittle-toughness transition, was discussed. DSC was used to confirm the difference of microstructures, crystallization behavior, a nd compatibility. (C) 1996 John Wiley & Sons, Inc.