The study deals with the preparation and characterization of polystyrene (PS) capsules
containing M3 paraffin wax as phase change material for thermal energy storage embedded
in a polypropylene (PP) matrix. Blends of PP/PS:wax and PP/PS were prepared without and
with SEBS as a modifier. The influence of PS and PS:wax microcapsules on the morphology
and thermal, mechanical and conductivity properties of the PP was investigated. The SEM
images of the microencapsulated PCM show that the capsules were grouped in irregular
spherical agglomerates of size 16-24 μm. However, after melt-blending with PP the much
smaller, perfectly spherical microcapsules were well dispersed in the PP matrix. The results
also show fairly good interaction between the microcapsules and the matrix, even in the
absence of SEBS modification. The FT-IR spectrum of the microcapsules is almost exactly
the same as that of polystyrene, which indicates that the microcapsules were mostly intact
and that the FTIR only detected the polystyrene shell. The amount of wax in the PS:wax
microcapsules was determined as 20-30% from the DSC and TGA curves. An increase in
PS:wax content resulted in a decrease in the melting peak temperatures of PP for both the
modified and the unmodified blends due to the plasticizing effect of the microcapsules. The
thermogravimetric analysis results show that the thermal stability of the blends decreased
with an increase in PS:wax microcapsules content as a consequence of lower thermal stability
of both the wax and PS. The DMA results show a drop in storage modulus with increasing
PS:wax microcapsules content. The microcapsules acted as a plasticizer and thus enhanced
the mobility of the polymer chains. Generally the thermal conductivity of the unmodified and
modified blends decreased with increasing PS:wax microcapsule content when compared to
PP. The polystyrene shell has a lower conductivity than the PP matrix, which explains the
lower thermal conductivities of the blends with increasing PS content.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-09172013-093518 |
| Date | 17 September 2013 |
| Creators | Mochane, Mokgaotsa Jonas |
| Contributors | 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-09172013-093518/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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