Browsing by Subject "Clay"
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Item Open Access Bio-based polymer nanocomposites based on layered silicates having a reactive and renewable intercalant(Wiley, 2013) Albayrak, O.; Şen, S.; Çaylbox, G.; Ortaç, B.Soybean oil-based polymer nanocomposites were synthesized from acrylated epoxidized soybean oil (AESO) combined with styrene monomer and montmorillonite (MMT) clay by using in situ free radical polymerization reaction. Special attention was paid to the modification of MMT clay, which was carried out by methacryl-functionalized and quaternized derivative of methyl oleate intercalant. It was synthesized from olive oil triglyceride, as a renewable intercalant. The resultant nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effect of increased nanofiller loading in thermal and mechanical properties of the nanocomposites was investigated by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The nanocomposites exhibited improved thermal and dynamic mechanical properties compared with neat acrylated epoxidized soybean oil based polymer matrix. The desired exfoliated nanocomposite structure was achieved when the OrgMMT loading was 1 and 2 wt % whereas partially exfoliated nanocomposite was obtained in 3 wt % loading. It was found that about 400 and 500% increments in storage modulus at glass transition and rubbery regions, respectively were achieved at 2 wt % clay loading compared to neat polymer matrix while the lowest thermal degradation rate was gained by introducing 3 wt % clay loading. © 2013 Wiley Periodicals, Inc.Item Open Access Electrospinning of nanocomposite nanofibers from cyclodextrin and laponite(Elsevier, 2018) Topuz, Fuat; Uyar, TamerHerein, the electrospinning of nanocomposite nanofibers from a non-polymeric system using cyclodextrin (CD)and Laponite was reported. Laponite, a hectorite-type synthetic clay, was used as an additive in the aqueoussolutions of CD molecules, and its influence on the polymer-free electrospinning of CD was investigated. Flowtests showed that the viscosity of CD solutions increased with a Laponite content rise at low shear rates and anunequalled degree of shear thinning at high shear rates. The morphology of the CD/Laponite nanofibers wasexplored by SEM, which revealed the formation of smooth nanofibers at low Laponite content (0.62 wt%) andnon-smooth nanofibers at Laponite content over 1.56 wt% due to enhanced electrostatic interactions betweenthe charged surface of Laponite and hydroxyl groups of CD. Further increasing Laponite content to 12.5 wt% ledto only micro-sized beads instead offibers due to electrospraying, suggesting that the embedded Laponite sig-nificantly disturbed hydrogen bonds among CD molecules. The presence of Laponite in the nanofibers wasconfirmed over chemical analysis by EDX and XPS. TEM analysis displayed homogeneous distribution of theexfoliated Laponite in the CD nanofibers, as supported by the disappearance of the diffraction patterns ofLaponite by WAXS. The nanocomposite CD/Laponite mats with Laponite content of≤1.56 wt% maintained theirself-standing andflexible structure to some extent, as revealed by tensile tests. In brief, this study reports thepolymer-free electrospinning of nanocomposite nanofibers based on CD and Laponite and investigates the impactof the incorporated clay on the polymer-free electrospinning of CD molecules.Item Open Access Property enhancement in unsaturated polyester nanocomposites by using a reactive intercalant for clay modification(Wiley, 2013) Şen, S.; Gündem, H. B.; Ortaç, B.Polymeric nanocomposites were synthesized from unsaturated polyester (UPE) matrix and montmorillonite (MMT) clay using an in situ free radical polymerization reaction. Organophilic MMT was obtained using a quaternary salt of coco amine as intercalant having a styryl group making it a reactive intercalant. The resultant nanocomposites were characterized via X-ray diffraction and transmission electron microscopy. The effect of increased nanofiller loading on the thermal and mechanical properties of the nanocomposites was investigated. All the nanocomposites were found to have improved thermal and mechanical properties as compared with neat UPE matrix, resulting from the contribution of nanolayer connected intercalant-to- crosslinker which allows a crosslinking reaction. It was found that the partially exfoliated nanocomposite structure with an exfoliation dominant morphology was achieved when the MMT loading was 1 wt %. This nanocomposite exhibited the highest thermal stability, the best dynamic mechanical performance and the highest crosslinking density, most probably due to more homogeneous dispersion and optimum amount of styrene monomer molecules inside and outside the MMT layers at 1 wt % loading. Copyright © 2013 Wiley Periodicals, Inc.Item Open Access The sorption behavior of CS + ion on clay minerals and zeolite in radioactive waste management: sorption kinetics and thermodynamics(Springer, 2011) Yildiz, B.; Erten, H. N.; Kış, M.In this work, Cs+ ion sorption on some clays and zeolite were investigated. 137Cs was used as a tracer. Activities were measured with a NaI crystal gamma counter. The particle size distribution was determined by a laser sizer. Surface area of the particles were determined by BET (Brunauer, Emmett and Teller method). Structure analysis was made by using X-ray diffraction. The chemical compositions of the solid samples were determined using a ICAP-OE spectrometer. Kinetic and thermodynamic parameters were determined. Due to very high uptake results; clay and zeolite can be proposed as a good sorbents in waste management considerations.Item Open Access Study of physical and mechanical properties of aerogel-modified expanded perlite aggregate and clay (AEP/C) board(Elsevier, 2022-12-26) Mercan, Elif; Yilmazer, SemihaThe aerogel-modified expanded perlite aggregate and clay (AEP/C) composite boards were produced, and physical and mechanical properties were investigated. The aerogel modification of expanded perlite aggregate was carried out with optimization of the two-step acid-base catalyzed sol–gel method. The perlite shrinkage under high-temperature annealing was prevented by covering perlite surfaces with aerogel modification. The boards with aerogel-modified expanded perlite aggregate (AEP) wrapped by clay matrix were successfully produced. The unit volume mass (UVM) and specific gravity (SG) of AEP/C boards slightly increased to 0.55 ± 0.01 g/cm3 and 2.36 ± 0.01, respectively. On the other hand, produced AEP/C boards’ volume of voids of 36.23 ± 1.05 and water absorption (WA) of 83.91 ± 0.49 % were moderately lower than EPA/C. The mechanical strength of the AEP/C composite boards remained almost unchanged with 0.73 ± 0.04 N/mm2, and the aerogel modification had practically no effect on the mechanical strength of composite boards.Item Open Access Surface spectroscopic studies of Cs+, and Ba2+ sorption on chlorite-illite mixed clay(De Gruyter Oldenbourg, 2000) Shahwan, T.; Sayan, S.; Erten, H. N.; Black, L.; Hallam, K. R.; Allen, G. C.The sorption behavior of Cs+, and Ba2+ on natural clay was investigated using ToF-SIMS, XPS, and XRD. The natural clay was composed mainly of chlorite and illite in addition to quartz and calcite. Depth profiling up to 70 Å was performed at 10 Å steps utilizing ToF-SIMS to study the amount of sorbed Cs+ and Ba2+ as a function of depth in the clay matrix. The results suggest that Cs+ and Ba2+ ions were sorbed primarily by ion exchange coupled with hydrolytic sorption. According to ToF-SIMS and XPS results, the total sorbed amount of Ba2+ was larger than that of Cs+. Quantitative determination of the primary cations within the analyzed clay before and after sorption indicated that for Ba2+ sorption, Ca2+, Mg2+ and for Cs+ sorption Ca2+, K+ were the major exchanging ions. The XRD spectra of Ba-sorbed clay contained new peaks that were identified as BaCO3.Item Open Access Thermodynamic parameters of Cs+ sorption on natural clays(Akademiai Kiado Rt., 2002) Shahwan, T.; Erten, H. N.The sorption behavior of Cs+ on kaolinite, chlorite-illite, and bentonite clays as a function of time, cation concentration, and temperature was studied using the radiotracer method. Sorption data were well represented by Freundlich and Dubinin-Radushkevich type isotherms. Bentonite was found to have the highest sorption capacity and the highest exchange affinity to Cs+. In all three cases Cs+ sorption was found to be exothermic with ΔH° (kJ/mol) -13, -8, -19 and ΔS° (J/mol·K) -15, 31, and -3 for kaolinite, chlorite-illite, and bentonite, respectively. Negative ΔG° values were obtained in all cases, indicating the spontaneity of sorption. The magnitudes of ΔG° suggest that ion exchange is the primary sorption mechanism.