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Structure-property relationships in PVC-lubricant compounds
Thesis (DSc)--Stellenbosch University, 2021.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2021
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| _version_ | 1867613908018135040 |
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| access_status_str | Open Access |
| author | Barnard, Johannes Lodewiekus |
| author2 | Van Reenen, A. J. |
| author_browse | Barnard, Johannes Lodewiekus Van Reenen, A. J. |
| author_facet | Van Reenen, A. J. Barnard, Johannes Lodewiekus |
| author_sort | Barnard, Johannes Lodewiekus |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (DSc)--Stellenbosch University, 2021. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/110468 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:43:36.943Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/110468 Structure-property relationships in PVC-lubricant compounds Barnard, Johannes Lodewiekus Van Reenen, A. J. Robertson, D. D. Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. Tracking lubricants UCTD Polyvinyl chloride Nuclear magnetic resonance Fourier transform infrared spectroscopy Waxes industry Thesis (DSc)--Stellenbosch University, 2021. ENGLISH ABSTRACT: This thesis was constructed with the aim of developing and improving current methods for tracking lubricants during the single screw extrusion of unplasticized polyvinyl chloride (uPVC). First a set of commercial waxes were selected to develop this method. These waxes were sourced from industries making use of different production technologies and therefore varied widely in chemical composition and morphology. The lubricant behaviour was monitored over three stages. In stage 1, it was essential to fully characterize the waxes according to their chemical composition and morphological properties. During stage 2, it was necessary to evaluate any inherent chemical or physical association interactions between any of the components within a uPVC formulation. For stage 3, full uPVC formulations were extruded using a single screw Brabender extruder and subsequently analysed. In stage 1 the waxes were characterized using various analytical techniques such as High-temperature size exclusion chromatography (HT-SEC), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, 13C nuclear magnetic resonance (13C-NMR) spectroscopy, solid state NMR (SS-NMR), differential scanning calorimetry (DSC) and, X-ray diffraction (XRD) spectroscopy. In stage 2, uPVC formulations were hot-melt mixed at high speed and evaluated using scanning electron microscopy coupled to energy dispersive X-ray spectroscopy (SEM-EDS). This allowed for the effective determination of additive positions before extrusion. In stage 3 the extrudates were also analysed using SEM-EDS. This technique helped to establish the additive positions after PVC fusion, effectively tracking additive migration. At this point it was established that calcium stearate (CaSt) facilitated the dispersion of the nonpolar wax across the surface of a PVC particle and that there exists a competition effect between polar waxes and CaSt. The extrudates showed some interesting results such as a complete phase separation for formulations containing CaSt and a polar wax. The method was further refined using a screw-freezing technique which allowed in-extruder sampling to be done. The method was applied to a second set of polar and nonpolar waxes (Wax set 2). No trends could be observed at this stage due to the waxes differing too much in chemical composition and morphology. It was therefore decided to synthesize a new set of polar waxes and fully characterize them. A new set of waxes were successfully synthesized by ozonolysis of FT (Fischer-Tropsch) waxes. These waxes were fully characterized, and an attempt was made to track the lubricants’ migration. Migration could not be track and the samples were subjected to commercial testing. Through combining the stage 3 experiments and commercial fusion studies a deeper understanding of the currently accepted model for lubricant migration was gained. Additionally, the model was expanded to include the effect of oxidized waxes. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar Doctoral 2021-05-18T09:52:18Z 2021-05-18T09:52:18Z 2021-03 Thesis http://hdl.handle.net/10019.1/110468 en_ZA Stellenbosch University 135 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Tracking lubricants UCTD Polyvinyl chloride Nuclear magnetic resonance Fourier transform infrared spectroscopy Waxes industry Barnard, Johannes Lodewiekus Structure-property relationships in PVC-lubricant compounds |
| title | Structure-property relationships in PVC-lubricant compounds |
| title_full | Structure-property relationships in PVC-lubricant compounds |
| title_fullStr | Structure-property relationships in PVC-lubricant compounds |
| title_full_unstemmed | Structure-property relationships in PVC-lubricant compounds |
| title_short | Structure-property relationships in PVC-lubricant compounds |
| title_sort | structure property relationships in pvc lubricant compounds |
| topic | Tracking lubricants UCTD Polyvinyl chloride Nuclear magnetic resonance Fourier transform infrared spectroscopy Waxes industry |
| url | http://hdl.handle.net/10019.1/110468 |
| work_keys_str_mv | AT barnardjohanneslodewiekus structurepropertyrelationshipsinpvclubricantcompounds |