The measurement of compositional heterogeneity in a propylene–ethylene block copolymer |
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Authors: | Y Feng JN Hay |
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Affiliation: | School of Metallurgy and Materials, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK |
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Abstract: | 13C nuclear magnetic resonance (n.m.r.) and Fourier transform infra-red (FTi.r.) spectroscopies, as well as wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (d.s.c.) and temperature rising elution fractionation (TREF), have been combined to measure the composional heterogeneity of a commercial propylene–ethylene block copolymer. It has been shown that the copolymer contains molecular species with a wide variation in composition, and the copolymer products range from amorphous ethylene–propylene rubbers (EPR) to crystallisable propylene–ethylene statistical copolymers, polyethylene and polypropylene homopolymers 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. |
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Keywords: | Block copolymers Polypropylenes Polyethylenes Molecular structure Crystallization Melting Monomers Fourier transform infrared spectroscopy X ray diffraction analysis Differential scanning calorimetry Nuclear magnetic resonance spectroscopy Monomer sequence distribution Compositional heterogeneity |
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