This study was undertaken to prepare polystyrene (PS)/montmorillonite (MMT) nanocomposites by different methods, including melt intercalation, in-situ polymerization and masterbatch methods. The in-situ polymerization method
consisted of dispersing the styrene monomer into the galleries of MMT followed by subsequent polymerization. The PS/MMT nanocomposites formed by melt intercalation method were prepared on a twin-screw extruder. The masterbatch method was in fact a two-step process. As the first step, a high clay content composite of polystyrene (masterbatch) was prepared by in-situ polymerization, and then the prepared masterbatch was diluted to desired compositions with commercial polystyrene in a twin-screw extruder.The structural, thermal and mechanical properties of the nanocomposites were examined. X-Ray diffraction (XRD) analysis showed that the d-spacing of the
in-situ formed nanocomposites containing 0.73 and 1.6 wt. %organoclay increased from 32.9 & / #506 / to 36.3 and 36.8 & / #506 / respectively, indicating intercalation while the dspacing
of the other prepared materials remained nearly unchanged compared to pure organoclay. At low clay content,
(< / 1 wt.%), in-situ formed nanocomposites showed
the best improvement in mechanical properties including tensile, flexural, impact strength and Young&rsquo / s modulus. In all the three methods, the addition of organoclay
increased the Young&rsquo / s modulus compared to neat resin, but the maximum improvement was 88.5 %, obtained at 0.73 wt. % organoclay in the in-situ formed material. In-situ polymerization method did not prove to be efficient at high clay loadings in terms of mechanical properties.
At high clay loadings, the effects of the three methods on promoting mechanical properties were not significantly different from each other. The glass transition temperature increased from 105.5 oC in the pure polystyrene to 108.4 oC
in the in-situ formed nanocomposite at 0.73 wt % organoclay due to the restricted mobility of the polymer chains within the organoclay layers.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12605132/index.pdf |
| Date | 01 July 2004 |
| Creators | Ozden, Gulsum |
| Contributors | Yilmazer, Ulku |
| 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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