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Crystallinity and amorphous segmental properties in random propylene–ethylene copolymers: NMR correlation
Author(s) -
Dujourdy L,
Bazile J P,
CohenAddad J P
Publication year - 1999
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/(sici)1097-0126(199907)48:7<558::aid-pi196>3.0.co;2-4
Subject(s) - crystallinity , amorphous solid , crystallization , materials science , annealing (glass) , ethylene , melting point , copolymer , relaxation (psychology) , polymer chemistry , polymer , crystallography , chemistry , organic chemistry , composite material , catalysis , psychology , social psychology
We present a characterization of the state of semi‐crystallization of random propylene–ethylene copolymers, observing the transverse relaxation of protons attached to the chains. The degree of crystallinity was determined step by step, from NMR, during the progressive annealing of the copolymers, quenched at room temperature from the melt. The ethylene content varied over the range 0–4.7 (w/w). It is shown that the empirical temperature dependence of the degree of crystallinity, as detected by NMR, obeys a single curve; this curve is translated along the temperature axis in accordance with the melting point depression when the ethylene content varies. The degree of crystallinity is primarily a function of the undercooling, whatever the ethylene content. Considering any state of semi‐crystallization, a strong correlation between the degree of crystallinity and the relaxation rate of the protons attached to amorphous segments is established; the NMR sensitivity to crystallinity is considerably enhanced when detected by amorphous properties. © 1999 Society of Chemical Industry