Crystallinity and transitions in ethylene hexene copolymers

✍ Scribed by B. Florin; R. Spitz; A. Douillard; A. Guyot; R.F. Boyer; L. Richards Denny; P.L. Kumler

• Publisher: Elsevier Science
• Year: 1980
• Tongue: English
• Weight: 666 KB
• Volume: 16
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(80)90228-1

✦ Synopsis

Abstraet--Copolymers of ethylene with hexene-1 have been prepared by catalytic polymerization. Three types of specimens were studied: (a) as the polymerized material; (b) the same after extraction with heptane; (c) the low molecular weight extract. These specimens were subjected to one or more of the following characterization techniques: M, by several methods, X-ray diffraction, GPC, DSC, Rheovibron at 110 Hz, and To by an ESR spin probe technique. The hexene content of the extracted polymer did not exceed 4 mol~,~; that in the extract was as high as 89.5~,~. The characterization data and dynamic mechanical loss results in this paper have been examined in the context of an exhaustive study of ethylene-ethylene-~-olefin copolymers by Shirayama et al. with some additional details by Wilson et al. All T 9 data are summarized in the form of a plot of temperature vs log (wt°/o hexene-I). It is emphasized that increasing hexene content decreases crystallinity, crystallite size and molecular weight, so that caution is required in interpreting results. For high mol wt low hexene-I whole and extracted polymers, the spin probe method gives T 9 for the amorphous phase whereas Rheovibron data reflect Ta(> T 9) for the composite amorphous-crystallite specimens. The ESR data indicate that T~ for amorphous PE, called .T0(L), is very close to 200 K which is above and distinct from T at c. 150 K. It would still be desirable to investigate a series of ethylene-hexene-I copolymers over the entire composition range at essentially constant, high molecular weight.