Morphology of High Impact Polypropylene Particles

Abstract

An extensive characterization (SEM, AFM, mercury porosimetry, sorption, and 13C NMR) of the particle morphology prior (isotactic PP particles) and after the gas phase reaction (hiPP particles) was performed in an attempt to gain some knowledge of the gas phase reaction of the hiPP process. It was found that the majority of the elastomer was finely dispersed in the i-PP matrix, but breaking the i-PP matrix and flowing into its pores. It was also found that the interior of the particles was readily accessible to the monomers because of the existence of a network of pores. The catalyst fragmented into small pieces with about ≈210 atoms of Ti per fragment. The copolymer is richer in ethylene than in propylene although the monomer concentration around the active center is [C3]/[C2] = 2.75. This behavior could not be justified on the basis of a faster diffusivity of the ethylene with respect to the propylene and hence must be due to higher activity of the catalyst for ethylene.