Date

2012

Author

Coniku, Anisa

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In the present study the effects of addition of organically functionalized boehmite nano-particles on the mechanical properties of epoxy polymers were analyzed. Nanosize platelets of boehmite powders were produced via a hydrothermal process from the raw material aluminum trihydroxide Al(OH)3 provided by a a chemical supplier, but which in future studies can be replaced by local resources of aluminum trihydroxide available in Seydişehir, Turkey. The ground aluminum trihydroxide particles were submitted to a two-step preliminary ageing procedure in different pH media. Particles were then converted to boehmite nanoparticles via hydrothermal ageing at high pressure and temperature. The product‘s chemical identity, size, structure and morphology were characterized with XRD, FT-IR, SEM and PSA analyses. By controlling the pH and the ageing time as parameters, hexagonal shaped nanoplatelets were obtained with dimensions ranging from 100 to 500 nm. Aiming at using these nanoparticles into surface coating polymers, the most favorable shape is the plate-like morphology, leading to adopting the last hydrothermal condition in the rest of the study. v The boehmite crystal surfaces are furnished with hydroxyls which can potentially be reacted with epoxy monomers of bisphenol A diglycidyl ether with the help of tin (II) chloride as catalyst through ring-opening reactions. The FT-IR and quantitative analyses indicated that this surface functionalization is possible under a temperature 80 oC and a weight ratio of 5:1 epoxy monomer to boehmite powder These novel inorganic/organic hybrid materials were then mixed with epoxy/hardener resin mixture to obtain nanocomposites. The properties of the composites were characterized accordingly with tensile, impact, micro hardness, micro-scratch tests, DMA analysis and observed with SEM analysis. A deterioration of the tensile strength from the neat polymer was observed, with a distinct trend between the functionalized and non-functionalized boehmite-epoxy polymers. The functionalized polymers showed a less deteriorative character. The tensile modulus instead showed a little improvement of (4%) in 5wt% loaded polymers. DMA analysis results revealed an improved glass transition temperature in the nanocomposites as well as in storage and loss modulus. As aimed in this work, the functionalized boehmite-epoxy polymers displayed a clear improvement in comparison to both non-functionalized and neat polymers in surface coating properties in hardness and scratch resistance.

Subject Keywords

Nanoparticles., Polymeric composites.

URI

http://etd.lib.metu.edu.tr/upload/12614037/index.pdf
https://hdl.handle.net/11511/21312

Collections

Graduate School of Natural and Applied Sciences, Thesis