Browsing by Author "Mange, Siyabonga"

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    Structure-property relationships in poly-(propylene-ethylene) copolymers
    (1999) Mange, Siyabonga; Marcus, Kashif
    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.