Lamellar morphology of random metallocene propylene copolymers studied by atomic force microscopy
Hosier, I.L., Alamo, R.G. and Lin, J.S. (2004) Lamellar morphology of random metallocene propylene copolymers studied by atomic force microscopy. Polymer, 45, (10), 3441-3455.
Four sets of propylene based random copolymers with co-units of ethylene, 1-butene, 1-hexene and 1-octene, and a total defect content up to similar to 9 mol% (including co-unit and other defects), were studied after rapid and isothermal crystallization. Etched film surfaces and ultrarnicrotomed plaques were imaged so as to enhance contrast and minimize catalyst and co-catalyst residues. While increasing concentration of structural irregularities breaks down spherulitic habits, the formation of the gamma polymorph has a profound effect on the lamellar morphology. Lamellae grown in the radial axis of the spherulite and branches hereon are replaced in gamma-rich copolymers with a dense array of short lamellae transverse or tilted to the main structural growth axis. This is the expected orientation for gamma iPP branching from a seeds. Spherulites are formed in copolymers with non-crystallizable units ( 1-hexene and 1-octene) up to similar to 3 mol% total defect content and were observed up to similar to 6 mol% in those with partially crystallizable comonorners (ethylene and 1-butene). However, lamellae were observed in all the copolymers analyzed, even in the most defective ones, highlighting the important role of the gamma polymorph in propagating lamellar crystallites in poly(propylenes) with a high concentration of defects. Long periods measured from AFM and SAXS are comparatively analyzed.
|Divisions:||Faculty of Physical Sciences and Engineering > Electronics and Computer Science
Faculty of Physical Sciences and Engineering > Electronics and Computer Science > EEE
|Date Deposited:||15 May 2008 09:47|
|Last Modified:||18 Aug 2012 04:10|
|Further Information:||Google Scholar|
|ISI Citation Count:||41|
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