Browsing by Author "Hojiyev, Rustam"

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Changes on montmorillonite characteristics through modification
(Elsevier, 2016-03-27) Ersever, Gafure; Karaağaçlıoğlu, İbrahim Ethem; Karakaş, Fırat; Boylu, Feridun; Hojiyev, Rustam; Uludağ Üniversitesi/Mühendislik Mimarlık Fakültesi/Tekstil Mühendisliği Bölümü.; 0000-0002-2047-3169; 36026524100
Since montmorillonite (Mt) and organomontmorillonite (O-Mt) are widely used in many different areas from ordinary to high technological applications, there are lots of studies about them in the literature. However, its unique characteristic and different interaction mechanism with additives make those studies continue in order to explain much more detail on it In this study effect of hexadecyltrimethylammonium bromide (HDTMA) on Mt through modification process has revealed in detail. Adsorption, electrokinetic, rheology and structural aspects of the system were considered in together to explain the interaction mechanism between Na-Mt and HDTMA. Mt suspensions show four different characteristics that are dependent on the HDTMA concentration as dispersion, coagulation-precipitation, coagulation-flotation and re-dispersion. It is found that sedimentation behavior at this regions are in a good agreement with adsorption isotherm, zeta potential, apparent viscosity, X-ray diffraction patterns, swelling index and filtration losses.
Development of a clay-polymer compatibility approach for nanocomposite applications
(Elsevier, 2017-07-05) Çelik, Mehmet S.; Hojiyev, Rustam; Ulcay, Yusuf; Uludağ Üniversitesi/Mühendislik Fakültesi/Tekstil Mühendisliği Bölümü.; 0000-0002-2047-3169; 36026524100; 6601918936
Na-montmorillonite (Na-Mt) from Resadiye Region of Turkey was modified by three different cationic and two different nonionic surfactants. The raw Na-Mt was purified before modification in order to remove mineral impurities other than Mt. The intercalation ability of surfactants into Na-Mt interlayer was investigated by X-ray diffractometry (XRD). Interaction of surfactant with Na-Mt surface was examined by various techniques involving Fourier Transform Infrared Spectroscopy (FTIR), thermal stability by Thermal Gravimetric Analysis (TGA), and the clay-polymer compatibility using surface energy and solubility parameters approaches. The present study was mainly focused on the evaluation of clay-polymer compatibility due to the lack of knowledge in this research field. It was found that different type of surfactants required different methodologies to evaluate the clay-polymer compatibility. It is proposed that the surface energy approach is very suitable for cationic surfactants used in this study due to their hydrophobic nature, however, such approach is not suitable for relatively less hydrophobic nonionic surfactants. The possibility of using the surface energy approach for cationic surfactants and that of solubility parameter for nonionic surfactants is discussed in the light of experimental data and theoretical considerations.
Effect of CEC coverage of hexadecyltributylphosphonium modified montmorillonite on polymer compatibility
(Elsevier, 2017-02-28) Çelik, Mehmet S.; Carty, William M.; Hojiyev, Rustam; Ulcay, Yusuf; Uludağ Üniversitesi/Mühendislik Fakültesi/Tekstil Mühendisliği Bölümü.; 0000-0002-2047-3169; 36026524100; 6601918936
The present work was aimed to investigate polymer compatibility of hexadecyltributylphosphonium bromide (HDTBPh) modified Na-montmorillonite (Na-Mt) at different cation exchange capacity (CEC) coverages. The Na-Mt was modified at five different CEC coverages in the range of 60%-150%. The morphology, porosity, and thermal and surface properties of HDTBPh in Na-Mt interlayer were investigated. The intercalation behavior of HDTBPh investigated by X-ray diffractometry showed that the door-value reached a maximum of 23.4 angstrom at 125% CEC coverage. The specific surface area (SSA) and porosity were investigated by N-2 adsorption at -197 degrees C temperature. The SSA decreased from 57.19 m(2)/g to 24.11 m(2)/g at 150% CEC coverage, as opposed to the porosity which increased upon interaction with HDTBPh and led to a more open structure. The thermal stability, investigated by themogravimetry (TGA), slightly decreased with increasing CEC coverage. The CEC coverage of HDTBPh was found to play an important role in the clay-polymer compatibility. A simple acid-base approach involving the calculation of total energy of interaction between Na-Mt surface and polymer surface (Delta G(clay)(IF)/(poiymer/clay)) was developed to evaluate the clay-polymer compatibility. While the positive value of Delta G(clay/Polymer/Clay)(IF) indicated the clay-polymer compatibility, the negative value was ascribed to no polymer compatibility. The calculated value of Delta G(clay/Polymer/Clay)(IF) was critical for proper selection of CEC coverage for each polymer.
Hydrophobicity and polymer compatibility of POSS-modified Wyoming Na-montmorillonite for developing polymer-clay nanocomposites
(Elsevier, 2017-03-05) Hojamberdiev, Mirabbos; Çelik, Mehmet S.; Carty, William M.; Hojiyev, Rustam; Ulcay, Yusuf; Uludağ Üniversitesi/Mühendislik Fakültesi/Tekstil Mühendisliği Bölümü.; 000-0002-2047-3169; 36026524100; 6601918936
The aim of the present work was to investigate the hydrophobicity and polymer compatibility of aminopropylisooctyl polyhedral oligomeric silsequioxane (POSS) - modified Na-montmorillonite (Na-MMT) towards developing polymer-clay nanocomposites. The effect of different concentrations of POSS on properties of Na-MMT was studied. The intercalation ability of the POSS molecules into the Na-MMT interlayer was analyzed by X-ray diffraction. It was found that the d(001) value was increased with increasing the POSS concentration, indicating the successful intercalation of the POSS molecules into the Na-MMT interlayer. The d(001) value was 4.12 nm at 0.4 cation exchange capacity (CEC) loading of POSS, increased at a slight rate upon further increase of CEC loading, and finally reached 4.25 nm at 1.0 CEC loading of POSS. The results of the thermogravimetric (TGA) analysis confirmed the high thermal stability of the POSS-MMT. The thermal stability was defined as a 5% mass loss (T-5) at 0.2 CEC loading of POSS was observed at 352 degrees C and slightly decreased with further increase in the POSS concentration. The porous properties, such as specific surface area (SSA), pore volume, and pore size were estimated by the adsorption of N-2 molecules on the Na-MMT surface. The SSA and pore volume were reduced with increasing the concentration of the POSS molecules due to the adsorption of the POSS molecules on the Na-MMT, while the pore size was increased upon the formation of macroporous structure. The interfacial interaction energy between water and POSS-MMT (Delta G(Clay/Water/Clay)(IF)) was used to evaluate the surface hydrophobicity, and a similar approach was also applied to assess the polymer compatibility of the developed composite. The obtained results confirm that the polymer compatibility of POSS-MMT prepared in this study is better than that of commonly used HDTMA-MMT.
Nano kil takviyeli poliester liflerinin performans özelliklerinin iyileştirilmesi
(Uludağ Üniversitesi, 2013) Hojiyev, Rustam; Ulcay, Yusuf; Uludağ Üniversitesi/Fen Bilimleri Enstitüsü/Tekstil Mühendisliği Anabilim Dalı.
Doktora tezi çalışmasında PET-kil nanokompozitlerin performans özellikleri incelenmiştir. Araştırmada Nanomer I30P ve Nanomer I44P gibi ticari nanokiller kullanılarak PET-kil nanokompozit iplikler üretilerek mekaniksel, dispersiyon ve ısıl özellikleri incelenmiştir. PET-kil nanokompozit iplikler eriyikten üretim yöntemlerinden olan ve çift karıştırma metodu olarak bilinen masterbatch yöntemi ile üretilmiştir. Öncelikle kil miktarı yüksek olan konsantreler (masterbatch) çift burgulu ekstruder kullanılarak hazırlanmıştır. Masterbatch aşamasında PET yerine PBT kullanılmıştır. İkinci aşamada ise üretilen konsantreler lif çekim makinesinde tamamen oryante iplik (FDY-fully drawn yarn) haline getirilerek bobinlere sarılmıştır. PET polimeri olarak lif için uygun ve IV değeri 0,64 dL/g'a eşit olan polimer kullanılmıştır. Üretilen FDY ipliklerin numarası 300 denye ve 96 filamandan oluşmaktadır. Mekaniksel özellikler olarak kopma mukavemeti ve kopma uzamaları kullanılan kil miktarına göre değişimleri incelenmiştir. İpliklerin dispersiyon özellikleri ise XRD ve SEM yöntemleri kullanılarak incelenmiştir. Isıl özelliklerin incelenmesinde ise TGA, DTA ve DSC yöntemleri kullanılmıştır. Ticari nanokillerin polimer ile uyumluluğunu incelenmek için test sıvılarıyla temas açıları ölçülerek yüzey enerji değerleri hesaplanarak etkileşim enerjileri hesaplanmıştır. Ticari killerin yanında Tokat Reşadiye bölgesinden Na-bentonitlerin saflaştırılması ve modifikasyonlar yapılarak polimerler ile uyumluluğu, ısıl özellikleri ve morfolojileri incelenmiştir. Modifikasyon için PVP ve PEG gibi noniyonik YAM'ler ve HDTPhBr, CPB ve Ethoquad C12 gibi kayonik YAM'ler kullanılmıştır.
Poliester liflerinin iç yapısındaki değişikliklerin mekaniksel özelliklere ve boya alımına etkisinin incelenmesi
(Uludağ Üniversitesi, 2005-06-15) Hojiyev, Rustam; Polat, Hülya; Uludağ Üniversitesi/Fen Bilimleri Enstitüsü/Tekstil Mühendisliği Ana Bilim Dalı.
PET esaslı poliester lifleri dünyada en çok üretilen sentetik lifleridir. Bu yüzden hem araştırmacıların hem de üreticilerin ilgisini çekmektedir. Üreticilerin istenen özelliklerde lif üretebilmek için, lifterin ince yapısı hakkında geniş bilgiye sahip olmaları gerekmektedir, özellikle kullanım yerine uygun mamullerin elde edilmesini ve son işlemlerin nasıl bir şekilde yapılması gerektiği belirlemek için ince yapının nasıl değiştiğini bilmek gerekmektedir. Yapılan çalışmada poliester lifterin çekimi, germesi ve termofıksajı sırasında ince yapısında meydana gelen değişiklikler teorik olarak incelenmiştir. Ayrıca ince yapı değişikliklerine bağlı olarak hem mekaniksel özelliklerinde hem de boya alımında meydana gelen değişiklikler incelenmiştir. Daha fazla bilgi edinmek için kaynakların özüne inilmeye çalışılmıştır. Ayrıca Korteks İplik fabrikasından FDY ve teksture iplikleri alınarak dört farklı sıcaklıkta ve üç farklı sürede fikse edilerek, ince yapıya bağlı mekaniksel özelliklerin ve boya alımının nasıl değiştİkleri hakkında deneysel çalışma yapılmıştır.
Poly(ethylene terephthalate)-clay nanocomposite multifilament yarn: Physical and thermal properties
(Maik Nauka/Interperiodica/Springer, 2020-07) Çelik, Mehmet Sabri; Hojiyev, Rustam; Ulcay, Yusuf; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Tekstil Mühendisliği Bölümü; 0000-0002-2047-3169; AFP-6442-2022; GHA-2068-2022; 36026524100; 6601918936
Poly(ethylene terephthalate)/clay nanocomposite multifilament yarn was manufactured by conventional masterbatch approach. Poly(butylene terephthalate) was used as a carrier polymer in masterbatch steps. The masterbatches were diluted into pilot melt spinning machine and subsequently drawn with 2.65 ratios to prepare fully oriented yarn. The degree of dispersion in nanocomposite fibers was analyzed by X-ray diffractometry and scanning electron microscopy. Even though the addition of nanoclay reduced mechanical properties of nanocomposite fibers, dimensional stability could be improved at certain clay contents. The flammability properties were sufficiently improved, and no significant changes were observed with increasing clay content. The main novelty of this paper is the development of a proper approach for the selection of optimum carrier polymer for nanoclay in masterbatch preparation, as well as proper nanoclay for desired polymers. The acid-base approach is used in evaluating the surface free energy of commercial nanoclay and calculation the total interaction energies between polymer and clay surfaces. Such an approach gives adequate information about polymer-clay compatibility and provides a useful tool in the selection of optimum carrier polymer, as well as proper nanoclay for the desired polymer during masterbatch preparations.
Polyester yarns reinforced by nanoclays
(Maik Nauka/interperiodica/springer, 2021-05-01) Ulcay, Yusuf; ULCAY, YUSUF; Hojiyev, Rustam; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Tekstil Mühendisliği Bölümü.; AFP-6442-2022
In the present study, poly(ethylene terephthalate)-clay nanocomposite multifilament yarns were prepared using two commercial and four nanoclays synthesized from Resadiye Na-montmorillonite (Na-MMT). Two type multifilament yarns, i.e., fully drawn yarn (FDY) and partially oriented yarn (POY), were melt spun. The FDY yarns were prepared using pilot type Buschaert SpinBoy II CC melt spinning machine with a masterbatch feeding ratio of 4-5% in order to meet industrial machine requirements. The POY spinning was made on the Barmag industrial machine, and the POY yarn was subsequently texturized. All multifilament yarns were prepared via the masterbatch approach, similarly used for the preparation of colored dope dyed yarns. The mechanical properties, flame retardancy, thermal stability, and morphology of produced yarns on melt spinning experiments were analyzed and discussed along with the effect of nanoclay properties such as thermal stability, polymer-clay compatibility, and particle size distribution.
Production of ultrapure bentonite clays through centrifugation techniques
(Taylor & Francis, 2012) Boylu, Feridun; Ersever, Gafure; Çelik, Mehmet Sabri; Hojiyev, Rustam; Ulcay, Yusuf; Uludağ Üniversitesi/Mühendislik Fakültesi/Tekstil Mühendisliği Bölümü.; 0000-0002-2047-3169; 36026524100; 6601918936
In this study, the production of ultrapure Na-bentonite by centrifuge based techniques for organo and nano composite bentonite industry was investigated. Various parameters including centrifuging time, solids content, and g force were studied to determine the set points (cut size) for theoretical CEC (cation exchange capacity) and recovery limits. The experimental results were modeled using Response Surface Method (RSM) with high responses (regression > 85% and correlation coefficients > 0.85). it is shown that the commercial centrifugation equipment operating with residence time of 10-15 seconds and g values lower than 300 g such as Multi Gravity separator (MGS), Hydrocyclones and Falcon/Knelson concentrators are not suitable for obtaining pure quality Na-bentonite, since the set point size (5-8 mu m) is higher than 2 mu m which is defined for bentonite of high smectite contents. The RSM models demonstrate that only the kind of separators such as decanter centrifuges with operational g forces higher than 600 may exhibit the closest set point to 2 lm and thus enable the achievement of an ultra pure quality bentonite product. These assumptions obtained from the developed model were confirmed by running tests on Falcon and Mozley hydrocyclone separators.
Simultaneous removal of NH4+, H2PO4- and Ni2+ from aqueous sMark solution by thermally activated combinations of steel converter slag and spent alumina catalyst
(Elsevier, 2015-12-01) Kadirova, Zukhra C.; Hojamberdiev, Mirabbos; Bo, Longli; Okada, Kiyoshi; Hojiyev, Rustam; Uludağ Üniversitesi/Mühendislik Fakültesi/Tekstil Mühendisliği Bölümü.; GCT-0509-2022; 36026524100
Industrial wastes (spent alumina catalyst and steel converter slag) were utilized to prepare low-cost inorganic sorbents by thermal activation at temperatures ranging from 500 to 1000 degrees C. According to the results of X-ray diffraction analysis, high-temperature thermal activation of mixtures of spent alumina catalyst and steel converter slag in different ratios leads to the formation of new crystalline phases. The Ni2+, H2PO4- and NH4+ sorption properties of the prepared samples were investigated in separate batch experiments, employing initial analyte concentration of 10 mmol L-1. The steel converter slag samples calcined at 500 degrees C and 900 degrees C and the mixed sample (70% spent alumina catalyst and 30% steel converter slag) calcined at 1000 degrees C exhibited maximum ion sorption capacities of 3.56 mmol Ni2+ g(-1), 3.28 mmol H-2 PO4+ g(-1) and 2.21 mmol NH4+ g(-1), respectively. The principal mechanisms of Ni2+ sorption were the substitution of Ca2+ ions by Ni2+ ions, precipitation at high pH and sorption on Fe3O4 and SiO2 surfaces present in the samples. The H2PO4-sorption was due mainly to the formation of calcium phosphates and sorption on Fe2O3 and SiO2 surfaces, whereas the removal of NH4+ involved sorption on Al2O3 surfaces of the prepared samples. The results of the kinetics calculations showed that a second-order kinetic model offers a good fit for the present experimental data. The materials prepared from low-cost industrial wastes in this work have the ability to simultaneously remove NH4+, H-2 PO(4)(-)and Ni2+ ions from aqueous solution.