Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006. / Isotactic polypropylene (iPP) exists in four different crystalline phases: α-, β-, γ- and
the mesomorphic (smectic) form. The α-phase is probably the most predominant form
of iPP with a monoclinic unit cell, whereas the unit cell of the γ-phase is
orthorhombic. The aim of this study was to examine the ability of AFM to identify
the α and γ crystalline forms of polypropylene and polypropylene copolymers that
were not especially treated.
Spherulites imaged on propylene-ethylene random copolymer surfaces had diameters
ranging from 10-30μm and predominantly radial lamellae. The cross-hatching
phenomenon of isotactic polypropylene was observed for samples containing both the
α- and γ-phase. Two types of γ-phase spherulites were observed, namely a featherlike
form for samples with a high content of the γ-phase and a bundle-like form with
varying sizes, which is typical for the mixed structure of both α- and γ-forms. In some
images of polypropylene-ethylene copolymer sample lozenge-shaped structures could
be observed between the γ-spherulites, which might be single polyethylene crystals.
Both the α- and γ-phase of iPP were successfully imaged and identified with AFM
without prior treatment of the surface. The degree of crystallinity obtained from AFM
images was calculated as a percentage of the surface area exhibiting regular
structures. The results compared well to X-ray results.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/3007 |
| Date | 03 1900 |
| Creators | Klash, Abdalah |
| Contributors | Meincken, M., Van Reenen, A., University of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
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