Structure and morphology of polyethylene/polypropylene in‐reactor alloys synthesized by spherical high‐yield Ziegler–Natta catalyst

A series of spherical polyethylene/polypropylene (PE/PP) in‐reactor alloys were synthesized with spherical high‐yield Ziegler–Natta catalyst by sequential multistage polymerization in slurry. The morphology of PE/PP alloy granule was evaluated by optical microscopy, scanning electron microscopy, and transmission electron microscopy. The results show PE/PP in‐reactor alloy with excellent morphology, high porosity, and narrow distribution of the particle size. The PE/PP in‐reactor alloys show excellent mechanical properties with good balance between toughness and rigidity. It was fractionated into five fractions by temperature‐gradient extraction fractionation, and every fractionation was analyzed by FTIR, ¹³C‐NMR, DSC, and WAXD. The PE/PP in‐reactor alloy was found to contain mainly five portions: PP, PE, segmented copolymer with PP and PE segment of different length, ethylene‐b‐propylene copolymer, and an ethylene–propylene random copolymer. The characteristic chain structure leads to good compatibility between the fractions of the alloy that shows a multiphase structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2075–2085, 2007