THE MEASUREMENT OF COMPOSITIONAL HETEROGENEITY IN A PROPYLENE-ETHYLENE BLOCK-COPOLYMER

C-13 nuclear magnetic resonance (n.m.r.) and Fourier transform infra-r ed (FTi.r.) spectroscopies, as well as wide-angle X-ray diffraction (W AXD), differential scanning calorimetry (d.s.c.) and temperature risin g elution fractionation (TREF), have been combined to measure the comp osional heterogeneity of a commercial propylene-ethylene block copolym er. It has been shown that the copolymer contains molecular species wi th a wide variation in composition, and the copolymer products range f rom amorphous ethylene-propylene rubbers (EPR) to crystallisable propy lene-ethylene statistical copolymers, polyethylene and polypropylene h omopolymers as well as blocks of various lengths. The so-called block copolymer was composed of about 15% amorphous EPR, 5% random copolymer , 28% block copolymers with long propylene and long ethylene sequences , and 52% homopolypropylene. The crystallisation and melting behaviour of these fractions have been investigated. (C) 1998 Elsevier Science Ltd. All rights reserved.