Browsing by Author "Alma, M.hakki"

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Design, Synthesis and Antimicrobial Activities of New Carbon Nanotubes Derivatives
(2021) Alma, M.hakki; Yiğit, Aybek; Akinay, Yuksel; Menges, Nurettin
Even though natural products or crops have been more common and popular in the recent, the chemicals without side-effects have been also addressed in various fields of industries due to possibility obtaining the large quantity and more bio-efficacy. In that context, many drugs have been developed for antibacterial activities but the over-uses of those relevant drugs have caused that microorganisms have adapted and evolved resistance against those drugs. Those lead to the researchers to focus on newly synthesized or functionalized molecules. In that context, nanotechnology, especially modified nanocarbon tubes (NCTs), are of the great interest of the various industries. Along with the current study, multi-walled carbon nanotubes (MWCNTs) were functionalized with three steps. Firstly, the carbon nanotube with a carboxylic acid tip on its surface was commercially purchased and then converted into acyl chloride, and later converted into a more reactive group. Then, the nucleophilic amino group such as diethylene triamine is bonded onto the carbon nanotube. Finally, after the carbon nanotube material with amine groups was functionalized with boric acid, carbon nanotube molecules carrying boric acid molecules were synthesized. Following modification and functionalization of MWCNTs, the newly synthesized molecules were characterized using FT-IR, SEM, TEM and XPS. After chemical characterization, the relevant molecules were screened for their anti-bacterial activities in comparison to those of well-known antibiotics. For anti-bacterial assays, molecules were tested against K. pneumoniae, E. coli, P.aeruginosa, S. aureus and B. subtilis. Concerning the findings of the antibacterial assays, concentrations of 40 and 80 μg /mL exhibited a range of activities but in parallel with those of standard antibiotics whereas the lower concentration, viz. 5, 10 and 20 μg / mL did not exhibit any activities. The highest activity was noted for 80 μg / mL, in comparison to those of antibiotics and other concentrations, against B. subtilis, with a 23 mm inhibition zone.
Preparation and Characterization of Potato Crust-Based Polyurethane Foam-I
(2023) Gürsoy, Tülay; Alma, M.hakki; Altuntas, Ertugrul; Karaoğul, Eyyüp
Polyurethanes (PUs) are polymers obtained by reacting diisocyanates with a group of polyols. The first synthesized PU compounds were prepared using petroleum subproduct compounds. In this research study, biomass-containing polyols, which have been studied by other scientists, were prepared using potato crust and polymerized with diisocyanates to produce PU foam. Polyol reactions were carried out using the microwave heating method. Synthesis reactions and structural properties of polyols have been studied in many aspects. The most available polyol was used for PU synthesis. Different formulations were tried for PU synthesis and as a result, PU foam containing nearly 25% starch-polyol was synthesized. The chemical structure of PU polymer was identified by ATR-FTIR spectroscopy and crystallographic properties by WA-XRD analysis. The physical and mechanical properties of PU foam, which is used as a large number of building and construction materials, including thermal insulation materials, were evaluated by comparing them with a commercial PU foam. According to the results of our research, it was detected that the incorporation of biomass into the structure of PU polymer improved its density, heat conduction coefficient, pressure based mechanical properties. PU foam derived from potato waste has a WA XRD-ray diffraction peak between 13.1-28.5o. This data is between 12.5-23o in synthetic commercial foam and has been positively improved in the product we synthesized as a result of combining biomass into the structure. The synthesized biomass-based PU foam can be used as thermal insulation material. Biomass-based PU foam has been synthesized with features that can be used as a thermal insulation material.
Preparation and Characterization of Potato Crust-Based Polyurethane Foam-Ii
(2023) Gürsoy, Tülay; Alma, M.hakki; Altuntas, Ertugrul; Karaoğul, Eyyüp
In this research study, environmentally friendly and biodegradable PU polymer foam was synthesized from starch-containing potato crust to be used as a thermal insulation material by reducing reliance on fossil resources and utilizing biomass resources. Biopolyols were obtained by reacting with active solvents at different reaction times, in the presence of different catalysts and at different catalyst concentrations. The most suitable polyol in terms of biomass content, density, viscosity and acid-hydroxyl number was selected for PU foam synthesis. Reactions for PU synthesis were tried and PU foam was synthesized. The synthesized PU foam was examined by Scanning Electron Microscope (SEM) and Thermo Gravimetric Analysis (TGA). Its morphological structure, thermal degradation properties, sound transmission coefficient and water absorption properties were determined by comparing it with a commercial PU foam. SEM images showed a heterogeneous pore distribution with closed and open cells, the majority of which were closed. From the TGA results, it was determined that a two-step degradation occurred and incorporating biomass into its structure improved the total thermal degradation properties. The sound transmission rate of starch-containing PU foam, when used as a thermal insulation material, was measured to be lower than the concrete structure, but partially close to and higher than that of commercial PU foam. The water absorption properties of the synthesized PU foam were found to be significantly higher compared to commercial PU foam and and contributed to its usability as a thermal insulation material. Thermal insulation material PU foam is synthesized in terms of its properties.