Abstract: Structure of three kinds of industrial polypropylene random copolymer（PPR） with different impact property was characterised in this paper. Morphology of fracture shown by SEM indicates that
the PPR2 has brittleness fracture, PPR1 has toughness fracture and PPR3 has both brittleness fracture and toughness fracture. Results of Polarizing microscope observation show that PPR1 has more and bigger spherulite than PPR2 has, and PPR3 has a large number of small spherulite. From the results of SEM and Polarizing microscope observation, we can safely draw the conclusion that existing of a small sum of insufficiently modified PP in samples leads to the different impact property of three kinds of industrial PPR. Insufficiently modified PP can also be observed by 13C-NMR and DSC characterisation.

Key words: Polypropylene random copolymer, Structural characterisation, Polypropylene