Effects of Copolymerization on Space Charge in Polypropylene

The DSC curve, the DC current and the space charge distribution have been measured on polypropylene (H-PP), block copolymer (B-PP) and random copolymer (Z-PP) copolymerized with Ziegler catalyst, and M-PP copolymerized with metallocene catalyst. The copolymers have 3.0~4.5 wt% of ethylene. B-PP with 4.5 wt% of ethylene had similar DSC curve and space charge distribution to H-PP. The magnitude of DC current is in the order of M-PP>Z-PP>B-PP>H-PP. Space charge in PP and PP copolymers depended on copolymerization, electrode, temperature and so on. The effects of copolymerization on morphology, DC current and space charge distribution of PP and PP copolymers have been also discussed