Structure-property relationships in poly-(propylene-ethylene) copolymers

This thesis examines the relationship between the microstructural and the mechanical properties of poly-(propylene-ethylene) bi-phasic copolymers. The copolymers investigated covered a comonomer content ranging between 4 and 23 percent ethylene. Nine grades were considered, with variables such as the melt flow index, the degree of crystallinity, the molecular weight distribution and the effect of a nucleating agent being examined. These copolymers have been characterised in order to gain a better understanding of the interrelationship between the morphological structure and their physical, mechanical, thermal and thermo-mechanical properties. The toughness of the copolymers can be enhanced at low temperatures by increasing the ethylene content, at the expense of a loss in stiffness. A study of the microstructure using the scanning electron microscope indicates that a good balance between these two properties can be achieved through a uniform size and spatial distribution of the ethylene-propylene rubber particles within the polypropylene homopolymer matrix. The transmission electron microscope shows the ethylene-propylene rubber (EPR) to be agglomerates of smaller particles, with some crystallinity within the EPR being evident.

Grantor dc:publisher.institution

Centre for Materials Engineering

Year dc:date.issued

1999

Author dc:creator

• Mange, Siyabonga

Advisor dc:contributor.advisor

• Marcus, Kashif

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/19804

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/19804