CONFORMATION OF ETHYLENE PROPYLENE COPOLYMERS (RANDOM OR BLOCK) AS SEEN BY C-13 NMR, IR AND THERMAL METHODS

Selected random and block ethylene/propylene (E/P) copolymers have been investigated thoroughly using 13C NMR, IR, DSC and dynamic mechanical analysis (DMA). The ethylene content in the range 1-6% in random E/P copolymers can be quantified with good agreement by NMR relative intensity of PEP triad, by IR band intensity of the isolated ethylene units, and by DSC melting peak depression. The toughened polypropylenes containing E/P blocks show the expected "run" sequence of five or more methylene groups of intense PEE and EEE triads sequence in NMR and in IR bands. The glassy-rubbery transitions of the two-phase-structure block E/P copolymers are clearly demonstrated by DMA damping signals. © 1990.