The fractionation of polypropylene

Abstract

Abstract Polypropylene has been fractionated by two methods of column fractionation. One, a gradient elution fractionation at 150°C., fractionates according to molecular weight only; the other, elution with one solvent at increasing temperatures separates also according to crystallinity. The two methods are compared and it is shown that polypropylene is best characterized by applying the two methods successively. It is demonstrated that fractions obtained in this way between 60 and 95°C. in an increasing temperature fractionation consist of material possessing a wide range in molecular weight and in crystallinity.