In the first part of this dissertation, poly(methylsilyne) was produced both in small and large-scales. In the small-scale, the aim was to synthesize the polymer by electrochemical polymerization of methyltrichlorosilane at a constant potential of -6 V supplied by batteries, using sodium dodecyl sulfate (SDS) as the supporting electrolyte. The polymer was characterized by 1H-NMR, FTIR, UV-Visible Spectroscopy and GPC in addition to its distinctive yellow color. The yellow color and the 1H-NMR, FTIR, UV-Visible and GPC results proved that poly(methylsilyne) was produced successfully in small-scale.
In the second part of the synthesis, the objective was to scale-up the electrochemical synthesis of poly(methylsilyne) while investigating the effects of the parameters like the electrode, solvent and supporting electrolyte types, monomer/solvent ratio and reaction time on the synthesis. Although successful results were obtained in large-scale synthesis with acetonitrile and SDS, the
problems with the reproducibility of the synthesis were solved using a system containing 1.2-dimethoxyethane (DME) and tetrabutylammonium perchlorate (TBAP).
In the second part of the dissertation, the aim was to prepare polypropylene/silicon-based preceramic polymer blends and to characterize them in terms of flammability, thermal and mechanical properties and morphologies. In order to investigate the effect of the silicon-based preceramic polymers, two different polymers were used: poly(methylsilyne) (PMSy) and allylhydridopolycarbosilane (SMP-10) where the latter was a commercially available silicon carbide precursor. Triphenylphosphate (TPP) and a metal complex were also used in polypropylene based composites to gain a synergy with the silicon containing polymers. The polymer composites were prepared using a twin-screw extruder and molded in an injection molding machine.
As a result of the flammability tests, it was seen that in order to achieve a significant decrease in the flammability of polypropylene, at least 20 wt% additive was needed. Furthermore, it was observed that the most significant improvement in flame retardancy was obtained in PP/10SMP/5TPP/5M sample containing 10 wt% SMP-10, 5 wt% TPP and 5 wt% metal complex with a limiting oxygen index (LOI) value of 23.5%. This was explained by the synergy obtained by SMP-10, TPP and the metal complex. With the addition of these silicon containing polymers, thermal properties of the composites increased to a great extent. For the mechanical properties, it was seen that impact strength of the composites significantly increased with the addition of SMP-10, PMSy and TPP.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/3/12609878/index.pdf |
| Date | 01 September 2008 |
| Creators | Eroglu, Damla |
| Contributors | Bayram, Goknur |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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