The present study covers the preparation and the characterisation of ï¢-nucleated impact
polypropylene copolymer (NA-IPC), and its fractions prepared through temperature rising
elution fractionation (TREF). Calcium stearate (CaSt), as well as pimelic (Pim) and adipic
(Adi) acids, were doped into IPC as a mono- or bi-component nucleating agents (NAs) at
varying mass ratios. The non-isothermal crystallisation kinetics, and the effect of the NAs on
the morphology, thermal and mechanical properties were investigated. However, only
thermal properties of the fractions were investigated on. DSC and XRD results revealed that
IPC nucleated with Pim and Pim-CaSt nucleants induced up to 90% β-crystals, while Adi and
Adi-CaSt formed only about 17% β-crystals. This was associated with the strong nucleation
efficiency (NE) of Pim. The 110C and 120C fractions treated with Pim-based NAs were the
only fractions that formed β-crystals, probably due to their higher isotacticity. The nonisothermal
crystallisation kinetics showed that the crystallization of IPC and NA-IPC
followed a three-dimensional growth with athermal nucleation mechanism. The SEM images
showed no changes in the distribution and size of the rubber phase after treatment with NAs.
FTIR showed that none of the NAs chemically reacted with IPC, and the chemical structure
of the polymer was thus intact during the treatment. Formation of β-crystals in the samples
with Pim and Pim-CaSt improved the impact strength by more than 50%. However,
incorporation of Adi, CaSt, and Adi-CaSt nucleants had little effect on the impact resistance
of IPC. The tensile properties such as Youngâs modulus, yield stress and stress at break
changed very little for the nucleated samples. On the other hand, the elongation at yield and
at break increased. This is an indication of the strong ductility of IPC caused by the formation
of β-crystals. The glass transition temperatures shifted slightly to higher temperatures with
increasing β-crystal contents, due to the immobilization of the chains in the amorphous phase
in the vicinity of the β-lamellae.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-08262013-151910 |
| Date | 26 August 2013 |
| Creators | Motsoeneng, Teboho Simon |
| Contributors | Prof AJ van Reenen, Prof AS Luyt |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-08262013-151910/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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