Date

2008

Author

Eroğlu, Damla

Metadata

Show full item record

Item Usage Stats

262
views

91
downloads

Cite This

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.

Subject Keywords

Chemical engineering., Polymers.

URI

http://etd.lib.metu.edu.tr/upload/3/12609878/index.pdf
https://hdl.handle.net/11511/18206

Collections

Graduate School of Natural and Applied Sciences, Thesis