ISSN:
0098-1273
Schlagwort(e):
Physics
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
The broad-line proton NMR spectra of melt-crystallized samples of polyethylene covering a very wide range in molecular weight have been analyzed in terms of contributions from three components: (1) a crystalline region with crystals of orthorhombic form; (2) a noncrystalline region with liquid-like character which produces a Lorentzian contribution to the spectrum; and (3) an intermediate region in which the rotation of methylene groups about C - C bonds is partly hindered. The relative mass fractions as well as the character of these components depend greatly on the molecular weight. Samples of low molecular weight (e.g., ≤30,000) are predominantly composed of lamellar crystalline regions with a minor amount of interfacial regions and no liquid-like interzonal regions. As the molecular weight increases beyond 45,000, an interzonal region with a liquid-like character associated with a higher molecular mobility is produced. Above a molecular weight of 100,000, this liquid-like character becomes pronounced with an increase in molecular mobility in the interfacial region.
Zusätzliches Material:
6 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1977.180150506
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