Metal coordinated polymer nanocomposites have gained great attention due to their
superior characteristics. Polymethylmethacyrlate (PMMA) is the most commonly
used polymer since it is easily processed. In this study, modified TiO2 nanoparticles
prepared by insitu and exsitu methods were embedded into PMMA in order to
improve its thermal stability and the effects of TiO2 nanoparticles on thermal characteristics of PMMA were investigated by direct pyrolysis mass spectrometry.
The insitu method which is a sol gel method, TiO2/SiO2 nanoparticles were synthesized by mixing titanium(IV) tetraisopropoxide, TTIP, with silane coupling agent, 3-(3-methoxysilyl)methylmetacrylate, MSMA in absolute ethanol. In exsitu method, TiO2 powder was directly mixed with silane coupling reagent. TiO2/SiO2 nanoparticles were embedded into the PMMA by direct mixing resulting in exsitu
and insitu TiO2/SiO2/PMMA nanocomposites. The synthesized TiO2/SiO2/PMMA
nanocomposites were characterized by TEM, ATR-FT-IR and analyzed for the
investigation of their reaction mechanism and thermal characteristics by pyrolysis
mass spectroscopy.
iv
TEM images confirmed the formation of TiO2/SiO2 nanoparticles and TiO2/SiO2/PMMA nanocomposites and indicated that the average particle size of TiO2/SiO2 nanoparticles was around 6 nm whereas average particle size of SiO2/TiO2/PMMA nanocomposites were around 25 nm. The increase in the size of nanoparticles is associated with incorporation of TiO2/SiO2 nanoparticles into PMMA matrix.
ATR-FTIR spectrum of 5% TiO2/SiO2/PMMA nanocomposites showed the formation of TiO2/SiO2 nanopartciles clearly.
Pyrolysis mass spectrometry analysis revealed that incorporation of TiO2/SiO2 nano-
particles into PMMA resulted in higher thermal stability only for low weight percentage
insitu TiO2/SiO2/PMMA. At high weight percentages a decrease in thermal stability
was detected. On the other hand, in case of exsitu TiO2/SiO2/PMMA, contrary to our
expectations a decrease in thermal stability was detected. The decrease in thermal
stability was attributed to evolution of methacrylic acid during thermal degradation of
silane groups.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12613752/index.pdf |
| Date | 01 October 2011 |
| Creators | Karabulut, Meryem |
| Contributors | Kayran, Ceyhan |
| 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 METU campus |
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