Structure and morphology of a commercial high-impact polypropylene in-reactor alloy synthesized using a spherical Ziegler-Natta catalyst

A commercial high-impact polypropylene (hiPP) was fractionated by temperature-gradient elution fractionation into nine fractions. All fractions were studied using Fourier transform infrared spectroscopy and differential scanning calorimetry. The amount of ethylene in the fractions was also determined. The results demonstrate that the ethylene-propylene statistical copolymer (or ethylene-propylene rubber, EPR) content in this hiPP is rather low and the amounts of ethylene-propylene segmented copolymer and ethylene-propylene block copolymer (that act as adhesive and compatibilizer between elastomeric phase and matrix, respectively) are negligible. Furthermore, the morphology of the resin was studied using scanning electron microscopy observations of microtome-cut original and etched samples, which reveals that EPR particles are too large and their distribution inside the matrix is not uniform. (C) 2010 Society of Chemical Industry