Crystallization of polydisperse polyethylene fractionated according to pennings' method

It is shown that the molten state and the semi‐crystalline state of polydisperse polyethylene are interrelated. Large polydisperse fractions obtained according to Pennings' fractionation method were studied by small angle X‐ray scattering and differential thermal analysis; the long period, depending on the molecular weight distribution, is shown to be given by the weight average end‐to‐end distance of the coils; the long chains with molecular weights M > 105 behave as a series of “sub‐chains” with molecular weight M* = 105 which crystallize independently. The same result is found for fractions with narrow molecular weight distribution and for mixtures of polyethylene fractions.