Yazar "Kursun, Fatma" seçeneğine göre listele

Listeleniyor 1 - 4 / 4
  • Küçük Resim
    Öğe
    Development of thermo-responsive poly(vinyl alcohol)-g-poly(N-isopropylacrylamide) copolymeric membranes for separation of isopropyl alcohol/water mixtures via pervaporation
    (Elsevier Science Inc, 2016) Kursun, Fatma; Isiklan, Nuran
    This study aims to develop thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm) grafted poly(vinyl alcohol) (PVA-g-PNIPAAm) copolymer membranes for separation of isopropyl alcohol (IPA)/water mixtures via pervaporation. PVA-g-PNIPAAm copolymers were synthesized by microwave supported graft copolymerization. Structure of copolymers was characterized by element analysis, FTIR, TGA/DTG/DSC, C-13 NMR and SEC. PVA-g-PNIPAAm membranes prepared with casting technique were characterized by SEM-AFM. Effects of grafting yield, operation temperature, and feed concentration on separation factor and flux were investigated to determine the membrane performance. The maximum separation factor was 95 with flux of 0.011 kg/m(2) h at 87.4% IPA. Thermo-responsive PVA-g-PNIPAAm membranes developed in this study are promising for pervaporation. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
  • Küçük Resim
    Öğe
    Graft copolymerization of itaconic acid onto sodium alginate using benzoyl peroxide
    (Elsevier Sci Ltd, 2010) Isiklan, Nuran; Kursun, Fatma; Inal, Murat
    Graft copolymers of sodium alginate (NaAlg) with itaconic acid (IA) were prepared in aqueous solution using benzoyl peroxide (BPO) as the initiator. Grafted copolymers (NaAlg-g-PIA) were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy scanning electron, microscopy and thermogravimetric analysis. The grafting parameters, including the graft yield (GY%) of the graft copolymer and the grafting efficiency (GE%) of the reaction were evaluated comparatively. The effects of the reaction variables such as the reaction time, temperature, percentage of sodium alginate, monomer and initiator concentrations on these parameters were studied. It was observed that GY and GE first increased and then decreased with increasing polymerization temperature, concentrations of IA, and BPO. The optimum grafting conditions for maximum graft yield were obtained with reaction time of 1 h, reaction temperature of 85 degrees C. IA concentration of 1.38 M. BPO concentration of 1.82 x 10(-2) M and percentage of NaAlg 1.5 g/dL. (C) 2009 Elsevier Ltd. All rights reserved.
  • Küçük Resim
    Öğe
    Graft Copolymerization of Itaconic Acid onto Sodium Alginate Using Ceric Ammonium Nitrate as Initiator
    (John Wiley & Sons Inc, 2009) Isiklan, Nuran; Kursun, Fatma; Inal, Murat
    Graft copolymers of sodium alginate (NaAlg) with itaconic acid (IA) were prepared in aqueous solution using ceric ammonium nitrate (CAN) as the redox initiator under N(2) atmosphere. The carboxylic acid groups of IA were neutralized with sodium hydroxide before grafting process. Grafted copolymers as sodium salts (NaAlg-g-PIA) were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, intrinsic viscosity measurement, differential scanning calorimetry, and thermogravimetric analysis. The graft yield (GY %) of the graft copolymer and the grafting efficiency (GE %) of the reaction were evaluated comparatively. The effects of the reaction variables such as the reaction time, temperature, percentage of NaAlg, monomer and initiator concentrations on these parameters were studied. It was observed that GY% and GE% increased and then decreased with increasing concentrations of IA and polymerization temperature. The optimum grafting conditions for maximum GY were obtained with a reaction time of 5 h, reaction temperature of 30 degrees C, IA concentration of 0.23 M, CAN concentration of 9.12 X 10(-2) M and percentage of NaAlg 0.5 g/dL. The overall activation energy for the grafting was also calculated to be 1135 cal/mol. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 40-48, 2009
  • Küçük Resim
    Öğe
    pH responsive itaconic acid grafted alginate microspheres for the controlled release of nifedipine
    (Elsevier Sci Ltd, 2011) Isiklan, Nuran; Inal, Murat; Kursun, Fatma; Ercan, Gulden
    A series of pH responsive alginate-g-poly(itaconic acid) (NaAlg-g-PIA) microspheres were prepared as drug delivery matrices of nifedipine cross-linked by glutaraldehyde (GA) in the hydrochloric acid catalyst. Graft copolymers of sodium alginate with itaconic acid were synthesized using ceric ammonium nitrate. The chemical stability of the nifedipine after encapsulation into microspheres was confirmed by FTIR, DSC and X-RD analysis. The preparation conditions of the NaAlg-g-PIA microspheres such as graft yield, GA concentration, exposure time to GA and drug amount were optimized by considering the percentage entrapment efficiency, particle size, swelling capacity and their release data. The results showed that NaAlg-g-PIA microspheres are pH responsive. The release of nifedipine from grafted microspheres was slower for the pH 1.2 solution than that of the pH 7.4 buffer solution. It has been observed that an increase in exposure time, drug amount, GA and NaAlg-g-PIA concentrations causes a decrease in the nifedipine release from the microspheres, whereas an increase in graft yield leads to an increase in the nifedipine release. (C) 2010 Elsevier Ltd. All rights reserved.