Morphologies of microporous polyethylene and polypropylene crystallized from solution in supercritical propane

The morphologies of solvent‐free, microporous, mechanically self‐supporting cylinders of linear polyethylene and isotactic polypropylene, crystallized from solution in supercritical propane, were examined by an SEM technique. The morphology of gels (or foams), obtained with little or no shrinkage fr...

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Bibliographic Details
Published in:Journal of polymer science. Part B, Polymer physics Polymer physics, 1995-05, Vol.33 (7), p.1053-1063
Main Authors: Pradhan, Debjeet, Ehrlich, Paul
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
microporosity
morphology
Organic polymers
Physicochemistry of polymers
polyethylene
polypropylene
Properties and characterization
Structure, morphology and analysis
supercritical propane
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Summary:The morphologies of solvent‐free, microporous, mechanically self‐supporting cylinders of linear polyethylene and isotactic polypropylene, crystallized from solution in supercritical propane, were examined by an SEM technique. The morphology of gels (or foams), obtained with little or no shrinkage from 2% to 35% solutions by weight of polyethylene (99% to 85% porosities), is shown in some detail. Lamellae with very little or considerable mutual organization occur, often in the form of stacks with straight or coiled axes (axialites). Further growth of these can lead to particles with a roughly spherical overall shape and a predominantly radial orientation of the lamellae at the particle surface. Subcooled isotactic polypropylene, on the other hand, crystallizes in the form of perfectly shaped birefringent microspheres of very uniform size. ©1995 John Wiley & Sons, Inc.
ISSN:0887-6266
1099-0488
DOI:10.1002/polb.1995.090330709