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Öğe Aluminyum için korozyon inhibitorü olarak kullanılan bazı proton pump inhibitörlerinni kuantum kimyasal olarak incelenmesi(Bursa Teknik Üniversitesi, 2016) Topal, Emre; Gece, Ender GökhanAlüminyum ve alaşımları, düşük maliyetlerinin yanı sıra gösterdikleri yüksek termal iletkenlik ve elektriksel iletkenlik ve hafiflik gibi önemli özellikler sayesinde endüstriyel teknolojinin temelini oluşturan malzemelerin başında gelmektedir. Bu önemli malzeme ayrıca yüzeyinde oluşan sıkıca tutunmuş halde bulunan görünmez bir koruyucu oksit film tabakasının oluşmasından dolayı korozyon direncine sahiptir. Alüminyum metalinin HCl çözeltisi içerisinde korozyonunu azaltan ya da önleyen bu tür tabakalar belirli ortam koşullarında kararlı bir biçimde kalabilmesine karşın endüstriyel çalışma ortamlarında daha ekstrem koşullarda kullanılabilmesi için çeşitli inhibitörlerin kullanılması tercih edilmektedir. Ancak bu geleneksel inhitörlerin çevreye verdikleri zararlar düşünüldüğünde yeni yeşil inhibitörlerin geliştirilmesi önemli bir araştırma konusu haline gelmiştir. Özellikle ilaçlar içerdikleri azot, oksijen, fosfor ve kükürt atomlarının fazla olması nedeniyle bu bağlamda ilgi çekici bir aday olarak düşünülmektedir. PPI grubu olarak adlandırılan ve anti-ülser ilacı olarak kullanılmakta olan prazol bileşiklerinin çok iyi korozyon inhibisyonu özelliği sergilediği deneysel olarak ortaya konmakla beraber bu inhibisyon mekanizması hakkında bir açıklama getirilmemiştir. Bu çalışmada, bu mekanizmayı açıklamak için kuantum kimyasal hesaplama yöntemi kullanılmış ve hesaplamalar yoğunluk fonksiyonel teorisi kullanılarak B3LYP/6-311G++(d,p) baz seti seviyesinde gerçekleştirilerek molekül yapısı ve inhibisyon etkinliği arasındaki korelasyon incelenmiştir. En yüksek dolu moleküler orbital enerjisi (EHOMO), en düşük boş moleküler orbital enerjisi (ELUMO), enerji boşluğu (?E), dipol momenti (µ), elektronegativite (?) ve sertlik (?) gibi kuantum kimyasal parametreler hesaplanmış ve teorik datalar ile deneysel sonuçlar arasında iyi bir korelasyon olduğu bulunmuştur.Öğe Investigation of Mechanical Properties of Graphene and Reduced Graphene Oxide Reinforced Epoxy Matrix Composites(Amer Soc Testing Materials, 2016) Topal, Emre; Şam Parmak, Ebru Devrim; Uzunsoy, Deniz; Cakir, O. ColakGraphene has generated great excitement in the scientific community due its unique mechanical and electronic properties, and also the availability of bulk quantities of graphene as both colloidal dispersion and powder. With the development of relatively high yield and defect-free synthesis methods, this exciting material is ready for practical application in the preparation of polymer nanocomposites. Here, we reported on the mechanical performances of epoxy nanocomposites which have been reinforced with exfoliated graphene nano platelet (GNP) and reduced graphene oxide (RGO) at a loading of 0 to 0.5 wt. %. A soft molding method was used for the preparation of epoxy nanocomposites. The reinforcing effects of GNP and RGO on epoxy resin were examined by tensile testing and dynamic mechanical analysis (DMA). The morphology of the epoxy/GO and epoxy/RGO nanocomposites were investigated using a scanning electron microscope (SEM). A significant improvement on mechanical properties of epoxy/GO and epoxy/RGO nanocomposites was observed at low GNP and RGO loading. Contrary to the literature, the ultimate tensile strength values have mainly decreased, although the Young's modulus has improved. Dynamic mechanical analysis has shown that with the addition of both GNP and RGO, storage modulus was significantly enhanced at 40 degrees C. The loss factor was almost not affected by both RGO and GNP loading. SEM investigation of the fractured surface indicates that GNP and RGO fillers are dispersed uniformly in the epoxy matrix.Öğe A Theoretical Study on Chemically Elegant Proton Pump Inhibitors in Search of Novel Green Corrosion Inhibitors(Maik Nauka/Interperiodica/Springer, 2017) Topal, Emre; Gece, Ender GökhanAluminum and its alloys exhibit remarkable corrosion resistance property due to its ability to form a tightly adhered, invisible protective oxide layer. Although this layer prevents or decelerates the corrosion of aluminum in HCl solution under certain conditions, they have to be used with inhibitors in very extreme circumstances of industrial applications. However, traditional inhibitors normally include environmentally hazardous substances, and therefore the development of novel green inhibitors becomes an important and vogue research subject. In this work, quantum chemical calculation approach was deployed and the density functional theory at B3LYP/6-311G++(d,p) basis set level calculations were performed on PPI drugs for the purpose of investigating the relation between their molecular structure and inhibition efficiency. Quantum chemical parameters such as the highest and lowest occupied molecular orbital energy, energy gap, dipole moment, electronegativity and hardness were calculated and a favorable correlation between the theoretical data and the experimental results was found.Öğe UNTANGLING THE INHIBITION EFFECTS OF ALIPHATIC AMINES ON SILVER CORROSION: A COMPUTATIONAL STUDY(Acad Sciences Moldova, Inst Chemistry, 2017) Topal, Emre; Gece, Ender GökhanThe topic of corrosion inhibition of different metals by organic compounds has been the focus of intense scrutiny for decades. The enormity of the problem is reflected in the need to understand the underlying inhibition mechanisms of such compounds, one of which is the class of aliphatic amines. Electrochemical measurements represent protective effect of these compounds at ever-increasing levels of detail but these methods lack the resolution to represent inhibition efficiency-molecular structure relations adequately. In this study, the dependence of inhibition effect of four aliphatic amines (methylamine, ethylamine, n-propylamine, and n-butylamine), on their molecular and electronic structure is analysed using quantum chemical calculations. The obtained results of these calculations were found to be consistent with the experimental findings.
