GCRIS

Now showing 1 - 2 of 2

Enhancement of Thermal, Electrical and Optical Properties of Zinc Oxide Filled Polymer Matrix Nano Composites
(Izmir Institute of Technology, 2009) Özmıhçı, Filiz; Balköse, Devrim
The purpose of this study is to enhance the electrical, thermal and optical properties of polyethylene and polypropylene by the addition of zinc oxide (ZnO) filler.Embedding ZnO in a polymeric matrix could make an economic, weight saving, chemically resistive, optical, flexible and conductive materials which possesses the properties of zinc oxide.Composites with higher electrical and thermal conductivity having luminescence properties were prepared using commercial and hydrothermally synthesized ZnO powders with different particle size and conductivity. Effect of ZnO loading and surface treatment on composite properties was investigated. Luminescence effects in green and blue regions were detected in all powders due to the defects on the structure of ZnO.The powders were found to be moderately conductive materials, as well. Un-homogenously dispersed composites were prepared using rheomixer since especially nano powders tended to be agglomerated in the composite. On the other hand, different surface properties of powder and polymer caused adhesion and wetting problems. Microvoids were detected in the interphase, as well.Composites can be used as an electrostatic dissipation and moderate electrical conductive applications in the field of electrical conductivity, as a heat sink in the field of thermal conductivity and as a solid state lamp due to luminescence properties. Stiffness of the composites was very high compared to neat polymer and can be properly used as an engineering material.
Nanosized zing borate production
(Izmir Institute of Technology, 2009) Gönen, Mehmet; Balköse, Devrim
The present study covers both zinc borate synthesis from boric acid-zinc oxide and borax decahydrate-zinc nitrate hexahydrate pairs; treatment of those samples by supercritical carbon dioxide drying, supercritical ethanol drying, and freeze drying techniques to obtain nanosized products. Zinc borate samples before and after supercritical drying were characterized by analytical titration, SEM, XRD, TGA, DSC, FTIR, and N2 adsorption at 77 K.The use of oleic acid as a modifying agent, ultrasonic treatment and nanosized zinc oxide in the reaction of zinc oxide and boric acid did not make significant effect in controlling the particle size. However, particle size of zinc borate produced from borax and zinc nitrate has increased with reaction time. Interaction of zinc borates with CO2 or ethanol at supercritical conditions or compression of crystals by high pressure created by the expansion of water during freezing are possible side effects of the nanoparticle producing processes. Zinc borate (2ZnO.3B2O3.7H2O) having water of crystallization in its structure reacted partially with CO2 to produce zinc carbonate, however zinc borate (2ZnO.3B2O3.3H2O) containing only hydroxyl groups did not react with CO2 in supercritical CO2 drying. While zinc borate (2ZnO.3B2O3.3H2O) decomposed partially and formed anhydrous zinc borate and zinc oxide, zinc borate (ZnO.B2O3.2H2O) decomposed completely and formed only zinc oxide in the supercritical ethanol drying that was carried out at 6.5 MPa and 250aC. Boric acid formed from the decomposition of both zinc borates was separated by ethanol extraction. If the initial particle size of zinc borate sample was at nano level, it would be possible to obtain nano particles by freeze drying.

Phd Degree / Doktora

Browse

Filters

Settings

Sort By

Results per page

Search Results