The effect of catalyst composition on the fundamental properties of isotactic polypropylene
Date
2019-03
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Abstract
ENGLISH ABSTRACT: Isotactic polypropylene is an important commercial polymer in the world today. Falling under the group of polyolefins, polypropylene serves as the largest commercial polymer worldwide
together with polyethylene. Isotactic polypropylene is typically produced by a multi-sited
Ziegler-Natta catalyst, the composition of which plays a critical role in the molecular properties
of the final sample.
The work in this study was done in order to set up a baseline of results of five different grades of
isotactic polypropylene, varying in their final form (reactor powder and extruded pellet forms), as
well as the catalyst composition used during polymerisation (Lynx and NHP catalysts). There
were four variations possible of each different grade of isotactic polypropylene, which lead to the
investigation of twenty different bulk polymer samples. Extensive analysis and characterisation was done on each of these bulk samples, as well as the fractions of each bulk sample which resulted from performing preparative temperature rising elution fractionation (p-TREF). The full
analytical toolbox was implemented for the characterisation of these samples, which include
SEM, DSC, HT-SEC, XRD, SSA, solution- and solid-state 13C NMR spectroscopy. By obtaining
and investigating the results it was able to investigate the effect that the catalyst composition
has on the fundamental properties of isotactic polypropylene samples, such as percentage
isotacticity, crystallinity, molar mass, crystal structure and surface morphology.
This study was performed to serve as a starting point for future projects related to these isotactic
polypropylene samples investigated, such as for example the production of heterophasic
ethylene propylene copolymers (HECOs). The main theme throughout this study will thus be to set up a baseline of results, for future project based on the same materials.
AFRIKAANSE OPSOMMING: Geen opsomming
AFRIKAANSE OPSOMMING: Geen opsomming
Description
Thesis (MSc)--Stellenbosch University, 2019.
Keywords
Polypropylene, Catalysis, Isotactic polypropylene, Ziegler-Natta catalysts, Polimerization