Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006. / Rectangular components were produced by both standard injection moulding and by a
process called Lomolding. Both moulding grade polypropylene homopolymer and
glass-filled polypropylene were used. The effect of processing parameters on material
properties, as measured by tensile and impact strength, and warpage were determined
for both injection moulding and lomolding, for both unfilled and glass-filled
polypropylene materials. Sampling of the components allowed for critical evaluation of
processing parameters’ effect on material properties at points close to and distant from
the injection point, as well as in the direction of materials flow and transverse to
material flow.
Glass-filled components were also evaluated in terms of glass fibre length and fibre
distribution (post-injection). Overall conclusions could be drawn with respect to the 2
different processes and the materials used. It was seen, inter alia, that the specimen
orientation had no effect on the mechanical properties when using unfilled
polypropylene, but that the orientation of the glass fibres in the testing direction
resulted in an increase in the tensile strength and the impact strength for the injection
moulded samples. Similar results were seen for lomolded samples, except that the
fibre orientation effects were different. In the same vein, other notable differences
could be observed for samples produced by lomolding and injection molding. Fibre
length and distributions obtained by polymer burn-off experiments served to help
explain differences in properties of glass-filled products produced by the two
processes.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/1534 |
| Date | 03 1900 |
| Creators | Johnson, B. A. |
| Contributors | Van Reenen, A. J., Basson, A. H., 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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