Abstract: Several propylene copolymers with high impact strength and high flowability were characterized using nuclear magnetic resonance, dynamic mechanical analysis, differential scanning calorimeter, and rheological properties. Sample 1# had a high ethylene content and high isotacticity, low xylene solubility, the homopolymer and copolymer phases showed good compatibility, provided the best comprehensive mechanical properties. Sample 3# had higher content of PE node and ethylene, so it possessed the highest impact strength. Gel permeation chromatography data showed that sample 4# and 5# had a wide molecular weight distribution and displayed good processing property at high shear rates. The comparison showed that the high melt flow impact propylene copolymer should contain a high fraction of ethylene-propylene rubber segments, a high isotactic index in the homopolymer phase, and a good compatibility between the two phases. Molecular weight distribution should be moderately wide, so that good processing behavior could be obtained, and dimensional stability of the products could be increased.

Key words: high flowability, propylene copolymer, structure, property, high impact strength