Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 2Citation - Scopus: 2Hybrid Preceramic Aerogels for Oil and Solvent Cleanup(Wiley-v C H verlag Gmbh, 2025) Icin, Oyku; Vakifahmetoglu, CekdarThis study presents the first synthesis and characterization of monolithic hybrid preceramic aerogels using distinct drying techniques: ambient pressure (ambigels) and CO2 supercritical drying. Polymeric ambi/aerogels, derived from polyhydromethlysiloxane (PHMS) and divinylbenzene (DVB), are processed at 200 degrees C, while hybrid ceramic-polymer (ceramer) is produced through pyrolysis at 600 degrees C. Despite variations in drying methods, polymer and ceramer ambi/aerogels exhibit comparable microstructural characteristics, bulk density, pore size and volume, and specific surface area (542-841 m(2) g(-1)). Polymeric and ceramer ambigel with 90 vol% total porosity yield a compressive strength, reaching 2.5 MPa, demonstrating a low thermal conductivity of 0.046 W m-1 K-1. Sorption tests are conducted using oil and organic solvents in aqueous media to benefit their high hydrophobicity (112 degrees < theta < 142 degrees). Aerogels exhibit high sorption capacities: 13.17 g g(-1) for sesame oil, 11.74 g g(-1) for toluene, and 9.19 g g(-1) for n-hexane. The sorption rate for the oil is nearly 10 times slower than that for toluene and n-hexane. Regarding regeneration and reusability, polymer and ceramer aerogels show consistent sorption properties cycles tested for n-hexane and toluene.Article Citation - WoS: 5Citation - Scopus: 5Sioc Foam-Aerogel Composites: Optimal Balance of Lightness and Excellent Thermal Insulation(Wiley, 2024) Icin, Oyku; Abebe, Adane Muche; Soraru, Gian Domenico; Vakifahmetoglu, CekdarFoam-aerogel composites are synthesized in polymeric, hybrid, and ceramic states by completing the open cells of the foam with a solution forming a wet gel, carbon dioxide (CO2) supercritically dried, and pyrolyzed. Thermal diffusivity measurements are conducted using the laser flash, and for mechanical performance, cold crushing tests are done to obtain compressive strengths. Samples possess a range of specific surface area (SSA) values up to similar to 650 m2/g contingent upon the material state, that is, polymeric, hybrid, or ceramic. While SSA values can be deliberately altered, almost all samples demonstrated a total porosity of similar to 90 vol%, with superb specific compressive strength reaching around 2 MPa. In addition to adjustable surface characteristics granting hydrophobic and hydrophilic features, the study revealed the potential use of these foam-aerogel composites as thermal insulators with low thermal conductivities of 0.02 W<middle dot>m-1<middle dot>K-1 at RT and 0.05 W<middle dot>m-1<middle dot>K-1 at 500 degrees C. When exposed directly to a butane flame gun with a flame temperature reaching similar to 1200 degrees C, from the backside of a 5 mm-thick foam-aerogel composite, only similar to 200 degrees C is recorded, which is lower than a comparable commercial insulator panel tested under the same conditions.