h i g h l i g h t s " TCMCs were synthesized by graft copolymerization for the first time. " The ... more h i g h l i g h t s " TCMCs were synthesized by graft copolymerization for the first time. " The processing property of TCMC was characterized. " Electrospinning of TCMC was explored and nanofibers were obtained. " The results showed that TCMC exhibited thermoplastic property and spinnability. g r a p h i c a l a b s t r a c t New thermoplastic carboxymethyl cellulose (TCMC) was synthesized by graft copolymerization. The main objective of this study was to investigate the thermoplastic and spinnability of thermoplastic carboxymethyl cellulose (TCMC). We found that TCMC exhibited thermoplastic property, and nanofibers with diameters from 250 nm to about 4 lm were obtained through electrospinning.
Corn cob and tea leaves waste are used as raw materials for condensed phenolic structures. In thi... more Corn cob and tea leaves waste are used as raw materials for condensed phenolic structures. In this study phenolics were extracted from these waste materials, characterized, and modified to obtain surface active materials. The phenolic structures of corn cob were HGS-type lignin with 10% by mass of initial dry weight, while of tea waste were condensed tannin with catechin-like fragments with 15% by mass. Hydroxymethylation reactions were carried out to increase the reactive sites and also the water solubility. The phenolics of the corn cob were hydroxymethylated to a higher rate than the phenolics of the tea leaves waste (85 vs. 48%). Subsequent modification with maleic anhydride was carried out at a rate of about 40% for both types. Visual determinations indicated that all the materials obtained behaved like non-ionic surfactants. However, sulfonation of tannin structure (at a rate of 40%) resulted in an anionic surfactant structure, as expected.
Journal of the Turkish Chemical Society, Section A: Chemistry, Feb 28, 2022
This study covers the synthesis and release behavior of chitosan-graft-polyacrylamide copolymers ... more This study covers the synthesis and release behavior of chitosan-graft-polyacrylamide copolymers in aqueous media at different pH values. The copolymers were synthesized using redox polymerization with ceric ammonium nitrate (CAN) in 1% aqueous acetic acid solution as the initiator. Optimum condition for the graft copolymer synthesis was determined as 3.85 g/L chitosan, 0.27 M acrylamide (AAm) monomer at 40 °C with a CAN per gram chitosan as 6 mmol using 0.05 M stock solution in 0.1 N HNO3. Then the crosslinked copolymers were synthesized using methylenebisacrylamide (MBA) as a crosslinker varying mass proportions of AAm:MBA as 15:1, 20:1, and 30:1. Obtained material amount (polymer yield) and molecular weight of crosslinked copolymers were lower than the graft copolymer as expected. Acetylsalicylic acid (ASA) release behaviors of all copolymers were monitored with UV-visible spectroscopy at different pH values (2, 6, and 8.5) corresponding to different media in the body (stomach, skin, and intestine, respectively). According to the results, the release behavior changed the least among the samples with respect to medium pH and of was the most affected.
Centrifugal spinning is a fast and safe nanofiber production technique and polyacrylonitrile (PAN... more Centrifugal spinning is a fast and safe nanofiber production technique and polyacrylonitrile (PAN) nanofibers have been widely studied for many applications including energy storage, filtration, sensors, and biomedical applications. Nanofiber morphology, specific surface area, porosity and average fiber diameter are important to determine the performance of nanofibers in these fields. In centrifugal spinning, nanofiber morphology and average fiber diameter are influenced by solution properties and process parameters including rotational speed, feeding rate, collector distance, and nozzle diameter. In this study, the effect of solution concentration, rotational speed, feeding rate, collector distance and nozzle diameter on average fiber diameter and fiber morphology were studied and statistical analysis was performed to determine the main factors. Optimum solution and process parameters were determined as well. Increased average fiber diameter was seen with increasing polymer concentration and nanofibers produced at 4000 rpm with the feeding rate of 60 ml/h had the lowest average fiber diameter for all studied nozzle sizes (0.3 mm, 0.5 mm and 0.8 mm). 8 wt. % PAN solution was centrifugally spun with the rotational speed of 4000 rpm, feeding rate of 60 ml/h, collector distance of 20 cm and nozzle diameter of 0.3 mm and bead free nanofibers with the average fiber diameter of 680 ± 87 nm was observed.
Abstract In this review, the recent developments on centrifugal spinning and characteristics of c... more Abstract In this review, the recent developments on centrifugal spinning and characteristics of centrifugally-spun fibers are reviewed. In recent years, there have been great efforts to develop high performance materials for different applications including energy storage, tissue engineering, drug delivery and aerosol filtration. The performance of these materials is greatly influenced by the material type; structure; mechanical, chemical, thermal stability and physical properties such as porosity and surface area. This review introduces the principles of centrifugal spinning with recent developments in manufacturing. The structures, characteristics and performance of centrifugally spun fibers are described in this review. Furthermore, the perspective on the current challenges and promising research directions that could lead to further advancements on centrifugal spinning is provided.
Journal of the Turkish Chemical Society, Section A: Chemistry, 2018
This study is about the preparation of two different organoclays with cationic surfactants and th... more This study is about the preparation of two different organoclays with cationic surfactants and their poly(vinyl alcohol) nanocomposites with increased thermal and mechanical behavior. Organoclays were prepared to modify clay mineral with solution intercalation method using aqueous solutions of cationic surfactants dodecyltrimethylammonium bromide (DTABr) and cetylpyridinium bromide (CPBr). Obtained organoclays (D-MMT and C-MMT for DTABr/MMT and CPBr/MMT, respectively) were characterized using different methods including zeta potential and XRD. Results indicated an absolute decrease in zeta potential about 20 mV for C-MMT and 14 mV for D-MMT indicating flocculation and coating of the surface. Moreover, measurements indicated that interlayer distance increased based on basal spacing peak shift whose value was 1.27 nm for NaMMT, whereas 1.40 nm for D-MMT, and 1.75 nm for C-MMT. The organoclays were used in the preparation of PVA/clay nanocomposites; thermal stability of the nanocomposites was determined using TGA, while mechanical strength measurements were done using DMA. The maximum thermal decomposition temperature of the pristine PVA and nanocomposites were compared, and an average increase of 4°C was observed. Also, the activation energy of the decomposition was observed ca. 40 kJ.mol-1 higher than pristine PVA.
Polyester and/or polythioester grafted chitosan copolymers were synthesized. For that, poly(ε-cap... more Polyester and/or polythioester grafted chitosan copolymers were synthesized. For that, poly(ε-caprolactone) (PCL), poly(ε-thiocaprolactone) (PTCL), and their copolymers were first synthesized by ring opening polymerization. Copolymers with caprolactone:thiocaprolactone (CL:TCL) molar ratios of 2:1, 1:1, 1:2 were synthesized. All of the synthesized macromolecular architectures were characterized using different spectral (Fourier transform infrared (FTIR), proton nuclear magnetic resonance (1H-NMR), X-Ray diffraction (XRD)) and thermal (Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA)) methods. Grafting was then performed according two distinct routes: (i) using a blend of both homopolymers (PCL and PTCL) or (ii) using pre-synthesized copolymers with controlled CL:TCL ratios. Hexamethylene diisocyanate was used as a grafting/coupling agent through urethane bonds with high yield. Grafting preferentially occurred at sulfur sites. The results indicated that PTCL ...
Restaurator. International Journal for the Preservation of Library and Archival Material, 2017
A Koran written by Mehmed Şevki is the subject of this comparative analysis. This manuscript disp... more A Koran written by Mehmed Şevki is the subject of this comparative analysis. This manuscript displayed an extensive degree of deterioration in 28 of the folios, while the rest of the manuscript is in considerably better condition. The aforementioned deteriorated sections of the book proved to be brittle and much darker in colour compared to the rest of this manuscript. The possible cause for this condition was ascertained using complementary techniques including the utilisation of micro-chemical (spot) tests, SEM-EDS, FTIR and Raman spectroscopy. The Micro-chemical Herzberg test indicated rag fibres in the paper used for the Koran, while the Raspail test #1 revealed rosin only in the sizing material of the deteriorated folios. SEM-EDS identified the presence of iron in all layers of the deteriorated folios but not in the stable folios. These results led subsequently to the conclusion that the deterioration of the folios was in fact related to the acid-catalysed hydrolysis due mainly...
Journal of the Turkish Chemical Society Section A: Chemistry, 2018
This study is about preparation of two different organoclays with cationic surfactants and their ... more This study is about preparation of two different organoclays with cationic surfactants and their poly(vinyl alcohol) nanocomposites with increased thermal and mechanical behavior. Organoclays were prepared modifying clay mineral with solution intercalation method using aqueous solutions of cationic surfactants dodecyltrimethylammonium bromide (DTABr) and cetylpyridinium bromide (CPBr). Obtained organoclays (D-MMT and C-MMT for DTABr/MMT and CPBr/MMT, respectively) were characterized using different methods including zeta potential and XRD. Results indicated an absolute decrease in zeta potential about 20 mV for C-MMT, and 14 mV for D-MMT indicating flocculation and coating of the surface. Moreover measurements indicated that interlayer distance increased based on basal spacing peak shift whose value was 1.27 nm for NaMMT, whereas 1.40 nm for D-MMT, and 1.75 nm for C-MMT. The organoclays were used in preparation of PVA/clay nanocomposites; thermal stability of the nanocomposites were...
Journal of the Turkish Chemical Society Section A: Chemistry, 2021
This study covers the synthesis and release behavior of chitosan-graft-polyacrylamide copolymers ... more This study covers the synthesis and release behavior of chitosan-graft-polyacrylamide copolymers in aqueous media at different pH values. The copolymers were synthesized using redox polymerization with ceric ammonium nitrate (CAN) in 1% aqueous acetic acid solution as the initiator. Optimum condition for the graft copolymer synthesis was determined as 3.85 g/L chitosan, 0.27 M acrylamide (AAm) monomer at 40 °C with a CAN per gram chitosan as 6 mmol using 0.05 M stock solution in 0.1 N HNO3. Then the crosslinked copolymers were synthesized using methylenebisacrylamide (MBA) as a crosslinker varying mass proportions of AAm:MBA as 15:1, 20:1, and 30:1. Obtained material amount (polymer yield) and molecular weight of crosslinked copolymers were lower than the graft copolymer as expected. Acetylsalicylic acid (ASA) release behaviors of all copolymers were monitored with UV-visible spectroscopy at different pH values (2, 6, and 8.5) corresponding to different media in the body (stomach, skin, and intestine, respectively). According to the results, the release behavior changed the least among the samples with respect to medium pH and of was the most affected.
In this study, the effect of the two cationic surfactants (benzyldimethyltetradecylammonium chlor... more In this study, the effect of the two cationic surfactants (benzyldimethyltetradecylammonium chloride (BDTDACl) and dodecyltrimethyl-ammonium bromide (DTABr)) on the electrokinetic and rheologic properties of Na-montmorillonite dispersion (3% w/w) has been investigated at their concentrations between 0 and 10 mmol/L. Experimental results reveal that cationic surfactants are attached on the surface of negatively charged clay particles and also they penetrate into the interlayer of clay particles. The intercalation of surfactants with clay minerals is shown to lead to an increase in the interlayer spacing of montmorillonites by X-ray diffraction. The Fourier transform infrared (FTIR) spectra obtained from the modified bentonite products reveal the characteristic absorption bands. The morphology of bentonite dispersions was analyzed by scanning electron microscopy (SEM). Both X-ray diffraction data and scanning electron micrographs of intercalated montmorillonites indicate that most of ...
In this study, the rheologic and colloidal characterizations of sodium montmorillonite (NaMMT) we... more In this study, the rheologic and colloidal characterizations of sodium montmorillonite (NaMMT) were examined. Hexadecylamine (CH 3 (CH 2) 15 NH 2 , HDA) was added to the bentonite water dispersion (2%, w/w) in different concentrations in the range 5⋅ ⋅6 × 10-4-9⋅ ⋅4 × 10-3 m mol/l. The rheological and electrokinetic behaviour of aqueous montmorillonite dispersions was investigated as a function of solid content and HDA concentration. The basal spacings of the HDA/NaMMT composites were studied by X-ray diffraction. The FTIR spectra were obtained from the modified bentonite products, which revealed the characteristic absorbances after treatment with HDA.
Recycled paper cellulose has some drawbacks, for example loss in mechanical strength, to use in p... more Recycled paper cellulose has some drawbacks, for example loss in mechanical strength, to use in paper industry alone. However, derivatives of cellulose can find applications in other industrial areas. Carboxymethylcellulose (CMC) is one of the most used cellulose derivatives and can be obtained by heterogeneous modification of cellulose. In general carboxymethylation of cellulose achieved in alkaline alcoholic dispersions. In this work modification of cellulose from recycled newspaper in aqueous alkaline solution was aimed. First cellulose was recovered from newspaper under oxidative alkaline conditions. Cellulose recovery was determined as 75-90% (w/w) of starting material. Carboxymethylation reactions were carried out to find optimum conditions for derivatization, changing concentrations of components and reaction temperature. Obtained CMC samples had a DS of 0.3-0.7% and 84-94% CMC content. As a result, carboxymethylation of cellulose from recycled newspaper was achieved in aqueous alkaline dispersion giving commercial grade CMC for industrial use.
Chitosan polymer was added to the montmorillonite (MMT) dispersions in different concentrations i... more Chitosan polymer was added to the montmorillonite (MMT) dispersions in different concentrations in the range of 1 × 10 −2 50 × 10 −2 g/L (in 1% acetic acid solution). The rheological behaviours and colloidal properties of the clay dispersions were determined as a function of ...
In this study synthesis and characterization of biopolymer/clay biocomposites was aimed using nat... more In this study synthesis and characterization of biopolymer/clay biocomposites was aimed using naturally occurring polysaccharide (xylan) as biopolymer and montmorillonite type clay (NaMt). Xylan was extracted from corn cobs via alkaline oxidative treatment. Maximum solubility of xylan was determined as 1% (w/v) in water at room temperature. Thus synthesis was realized following two routes; first NaMt concentration was kept constant at 2.0×10−2g/ml and xylan concentration was changed. Latter xylan concentration was kept constant at 1.0×10−2g/ml and NaMt concentration was changed. Natural xylan, NaMt and biocomposites were examined in terms of their spectral, electrokinetic, rheologic, morphologic and thermal properties. Results showed that lower amounts of xylan interacted with NaMt on the surface, however, when the xylan amount was increased also intercalation of NaMt has occurred. Biocomposites showed better thermal and rheologic behaviors with respect to the starting materials.
The influence of polymer on flow behaviour of Balikesir, Turkey bentonite dispersions (2%, w/w) w... more The influence of polymer on flow behaviour of Balikesir, Turkey bentonite dispersions (2%, w/w) was studied for non-ionic polymer, polyvinyl alcohol (PVA). In a range of 3⋅3 × 10 -6 -3⋅3 × 10 5 mol/l, PVA was added to the bentonite dispersions in different concentrations and its behaviour was observed on rheology parameters. Thixotropy was detected by a hysteresis loop of the flow curves. The data were interpreted taking into account the interactions of colloidal clay particles, bentonitic clay concentrations, structure, and concentrations of added PVA. The particle size analysis was explained by surface orientation of PVA to the clay particles dispersed in aqueous solution. Zeta potential determination also emphasized that PVA molecules got attached on the face and edge surface of clay particles. The morphology of bentonite dispersions was analysed by scanning electron micrograph (SEM). FTIR studies carried out in parallel to rheology studies showed that hydrogen bonds were formed between surface of the clay, and absorbed PVA molecules and adsorbed water. The presence of PVA did not prevent extensive swelling of bentonite.
In this study, the effect of the two cationic surfactants (benzyldimethyltetradecylammonium chlor... more In this study, the effect of the two cationic surfactants (benzyldimethyltetradecylammonium chloride (BDTDACl) and dodecyltrimethyl-ammonium bromide (DTABr)) on the electrokinetic and rheologic properties of Na-montmorillonite dispersion (3% w/w) has been investigated at their concentrations between 0 and 10 mmol/L. Experimental results reveal that cationic surfactants are attached on the surface of negatively charged clay particles and also they penetrate into
In this study, the rheologic and colloidal characterizations of sodium montmorillonite (NaMMT) we... more In this study, the rheologic and colloidal characterizations of sodium montmorillonite (NaMMT) were examined. Hexadecylamine (CH 3 (CH 2 ) 15 NH 2 , HDA) was added to the bentonite water dispersion (2%, w/w) in different concentrations in the range 5⋅ ⋅6 × 10 -4 -9⋅ ⋅4 × 10 -3 m mol/l. The rheological and electrokinetic behaviour of aqueous montmorillonite dispersions was investigated as a function of solid content and HDA concentration. The basal spacings of the HDA/NaMMT composites were studied by X-ray diffraction. The FTIR spectra were obtained from the modified bentonite products, which revealed the characteristic absorbances after treatment with HDA.
In this study modification of xylan via Mannich reaction in aqueous basic solution to obtain dime... more In this study modification of xylan via Mannich reaction in aqueous basic solution to obtain dimethylaminomethylated products and characterization of modified xylan were examined. Components were xylan (obtained from corn cob and used without modification) as active hydrogen containing compound, formaldehyde as carbonyl compound having no ˛-hydrogen and dimethylamine. Mannich reaction was used with different parameters such as component concentration, reaction temperature, and time. The highest modification was observed about 35 • C with a nitrogen content of 4.6% by weight indicating successive modification. Both 1D and 2D NMR measurements displayed new signals related with aminomethyl groups. Spectral characterizations indicated that aminomethylation took place on oxygen sites. Moreover modified xylan could form film while xylan could not without an auxiliary agent. Antimicrobial activity tests indicated that modified xylan acted as a bacteriostatic material.
h i g h l i g h t s " TCMCs were synthesized by graft copolymerization for the first time. " The ... more h i g h l i g h t s " TCMCs were synthesized by graft copolymerization for the first time. " The processing property of TCMC was characterized. " Electrospinning of TCMC was explored and nanofibers were obtained. " The results showed that TCMC exhibited thermoplastic property and spinnability. g r a p h i c a l a b s t r a c t New thermoplastic carboxymethyl cellulose (TCMC) was synthesized by graft copolymerization. The main objective of this study was to investigate the thermoplastic and spinnability of thermoplastic carboxymethyl cellulose (TCMC). We found that TCMC exhibited thermoplastic property, and nanofibers with diameters from 250 nm to about 4 lm were obtained through electrospinning.
Corn cob and tea leaves waste are used as raw materials for condensed phenolic structures. In thi... more Corn cob and tea leaves waste are used as raw materials for condensed phenolic structures. In this study phenolics were extracted from these waste materials, characterized, and modified to obtain surface active materials. The phenolic structures of corn cob were HGS-type lignin with 10% by mass of initial dry weight, while of tea waste were condensed tannin with catechin-like fragments with 15% by mass. Hydroxymethylation reactions were carried out to increase the reactive sites and also the water solubility. The phenolics of the corn cob were hydroxymethylated to a higher rate than the phenolics of the tea leaves waste (85 vs. 48%). Subsequent modification with maleic anhydride was carried out at a rate of about 40% for both types. Visual determinations indicated that all the materials obtained behaved like non-ionic surfactants. However, sulfonation of tannin structure (at a rate of 40%) resulted in an anionic surfactant structure, as expected.
Journal of the Turkish Chemical Society, Section A: Chemistry, Feb 28, 2022
This study covers the synthesis and release behavior of chitosan-graft-polyacrylamide copolymers ... more This study covers the synthesis and release behavior of chitosan-graft-polyacrylamide copolymers in aqueous media at different pH values. The copolymers were synthesized using redox polymerization with ceric ammonium nitrate (CAN) in 1% aqueous acetic acid solution as the initiator. Optimum condition for the graft copolymer synthesis was determined as 3.85 g/L chitosan, 0.27 M acrylamide (AAm) monomer at 40 °C with a CAN per gram chitosan as 6 mmol using 0.05 M stock solution in 0.1 N HNO3. Then the crosslinked copolymers were synthesized using methylenebisacrylamide (MBA) as a crosslinker varying mass proportions of AAm:MBA as 15:1, 20:1, and 30:1. Obtained material amount (polymer yield) and molecular weight of crosslinked copolymers were lower than the graft copolymer as expected. Acetylsalicylic acid (ASA) release behaviors of all copolymers were monitored with UV-visible spectroscopy at different pH values (2, 6, and 8.5) corresponding to different media in the body (stomach, skin, and intestine, respectively). According to the results, the release behavior changed the least among the samples with respect to medium pH and of was the most affected.
Centrifugal spinning is a fast and safe nanofiber production technique and polyacrylonitrile (PAN... more Centrifugal spinning is a fast and safe nanofiber production technique and polyacrylonitrile (PAN) nanofibers have been widely studied for many applications including energy storage, filtration, sensors, and biomedical applications. Nanofiber morphology, specific surface area, porosity and average fiber diameter are important to determine the performance of nanofibers in these fields. In centrifugal spinning, nanofiber morphology and average fiber diameter are influenced by solution properties and process parameters including rotational speed, feeding rate, collector distance, and nozzle diameter. In this study, the effect of solution concentration, rotational speed, feeding rate, collector distance and nozzle diameter on average fiber diameter and fiber morphology were studied and statistical analysis was performed to determine the main factors. Optimum solution and process parameters were determined as well. Increased average fiber diameter was seen with increasing polymer concentration and nanofibers produced at 4000 rpm with the feeding rate of 60 ml/h had the lowest average fiber diameter for all studied nozzle sizes (0.3 mm, 0.5 mm and 0.8 mm). 8 wt. % PAN solution was centrifugally spun with the rotational speed of 4000 rpm, feeding rate of 60 ml/h, collector distance of 20 cm and nozzle diameter of 0.3 mm and bead free nanofibers with the average fiber diameter of 680 ± 87 nm was observed.
Abstract In this review, the recent developments on centrifugal spinning and characteristics of c... more Abstract In this review, the recent developments on centrifugal spinning and characteristics of centrifugally-spun fibers are reviewed. In recent years, there have been great efforts to develop high performance materials for different applications including energy storage, tissue engineering, drug delivery and aerosol filtration. The performance of these materials is greatly influenced by the material type; structure; mechanical, chemical, thermal stability and physical properties such as porosity and surface area. This review introduces the principles of centrifugal spinning with recent developments in manufacturing. The structures, characteristics and performance of centrifugally spun fibers are described in this review. Furthermore, the perspective on the current challenges and promising research directions that could lead to further advancements on centrifugal spinning is provided.
Journal of the Turkish Chemical Society, Section A: Chemistry, 2018
This study is about the preparation of two different organoclays with cationic surfactants and th... more This study is about the preparation of two different organoclays with cationic surfactants and their poly(vinyl alcohol) nanocomposites with increased thermal and mechanical behavior. Organoclays were prepared to modify clay mineral with solution intercalation method using aqueous solutions of cationic surfactants dodecyltrimethylammonium bromide (DTABr) and cetylpyridinium bromide (CPBr). Obtained organoclays (D-MMT and C-MMT for DTABr/MMT and CPBr/MMT, respectively) were characterized using different methods including zeta potential and XRD. Results indicated an absolute decrease in zeta potential about 20 mV for C-MMT and 14 mV for D-MMT indicating flocculation and coating of the surface. Moreover, measurements indicated that interlayer distance increased based on basal spacing peak shift whose value was 1.27 nm for NaMMT, whereas 1.40 nm for D-MMT, and 1.75 nm for C-MMT. The organoclays were used in the preparation of PVA/clay nanocomposites; thermal stability of the nanocomposites was determined using TGA, while mechanical strength measurements were done using DMA. The maximum thermal decomposition temperature of the pristine PVA and nanocomposites were compared, and an average increase of 4°C was observed. Also, the activation energy of the decomposition was observed ca. 40 kJ.mol-1 higher than pristine PVA.
Polyester and/or polythioester grafted chitosan copolymers were synthesized. For that, poly(ε-cap... more Polyester and/or polythioester grafted chitosan copolymers were synthesized. For that, poly(ε-caprolactone) (PCL), poly(ε-thiocaprolactone) (PTCL), and their copolymers were first synthesized by ring opening polymerization. Copolymers with caprolactone:thiocaprolactone (CL:TCL) molar ratios of 2:1, 1:1, 1:2 were synthesized. All of the synthesized macromolecular architectures were characterized using different spectral (Fourier transform infrared (FTIR), proton nuclear magnetic resonance (1H-NMR), X-Ray diffraction (XRD)) and thermal (Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA)) methods. Grafting was then performed according two distinct routes: (i) using a blend of both homopolymers (PCL and PTCL) or (ii) using pre-synthesized copolymers with controlled CL:TCL ratios. Hexamethylene diisocyanate was used as a grafting/coupling agent through urethane bonds with high yield. Grafting preferentially occurred at sulfur sites. The results indicated that PTCL ...
Restaurator. International Journal for the Preservation of Library and Archival Material, 2017
A Koran written by Mehmed Şevki is the subject of this comparative analysis. This manuscript disp... more A Koran written by Mehmed Şevki is the subject of this comparative analysis. This manuscript displayed an extensive degree of deterioration in 28 of the folios, while the rest of the manuscript is in considerably better condition. The aforementioned deteriorated sections of the book proved to be brittle and much darker in colour compared to the rest of this manuscript. The possible cause for this condition was ascertained using complementary techniques including the utilisation of micro-chemical (spot) tests, SEM-EDS, FTIR and Raman spectroscopy. The Micro-chemical Herzberg test indicated rag fibres in the paper used for the Koran, while the Raspail test #1 revealed rosin only in the sizing material of the deteriorated folios. SEM-EDS identified the presence of iron in all layers of the deteriorated folios but not in the stable folios. These results led subsequently to the conclusion that the deterioration of the folios was in fact related to the acid-catalysed hydrolysis due mainly...
Journal of the Turkish Chemical Society Section A: Chemistry, 2018
This study is about preparation of two different organoclays with cationic surfactants and their ... more This study is about preparation of two different organoclays with cationic surfactants and their poly(vinyl alcohol) nanocomposites with increased thermal and mechanical behavior. Organoclays were prepared modifying clay mineral with solution intercalation method using aqueous solutions of cationic surfactants dodecyltrimethylammonium bromide (DTABr) and cetylpyridinium bromide (CPBr). Obtained organoclays (D-MMT and C-MMT for DTABr/MMT and CPBr/MMT, respectively) were characterized using different methods including zeta potential and XRD. Results indicated an absolute decrease in zeta potential about 20 mV for C-MMT, and 14 mV for D-MMT indicating flocculation and coating of the surface. Moreover measurements indicated that interlayer distance increased based on basal spacing peak shift whose value was 1.27 nm for NaMMT, whereas 1.40 nm for D-MMT, and 1.75 nm for C-MMT. The organoclays were used in preparation of PVA/clay nanocomposites; thermal stability of the nanocomposites were...
Journal of the Turkish Chemical Society Section A: Chemistry, 2021
This study covers the synthesis and release behavior of chitosan-graft-polyacrylamide copolymers ... more This study covers the synthesis and release behavior of chitosan-graft-polyacrylamide copolymers in aqueous media at different pH values. The copolymers were synthesized using redox polymerization with ceric ammonium nitrate (CAN) in 1% aqueous acetic acid solution as the initiator. Optimum condition for the graft copolymer synthesis was determined as 3.85 g/L chitosan, 0.27 M acrylamide (AAm) monomer at 40 °C with a CAN per gram chitosan as 6 mmol using 0.05 M stock solution in 0.1 N HNO3. Then the crosslinked copolymers were synthesized using methylenebisacrylamide (MBA) as a crosslinker varying mass proportions of AAm:MBA as 15:1, 20:1, and 30:1. Obtained material amount (polymer yield) and molecular weight of crosslinked copolymers were lower than the graft copolymer as expected. Acetylsalicylic acid (ASA) release behaviors of all copolymers were monitored with UV-visible spectroscopy at different pH values (2, 6, and 8.5) corresponding to different media in the body (stomach, skin, and intestine, respectively). According to the results, the release behavior changed the least among the samples with respect to medium pH and of was the most affected.
In this study, the effect of the two cationic surfactants (benzyldimethyltetradecylammonium chlor... more In this study, the effect of the two cationic surfactants (benzyldimethyltetradecylammonium chloride (BDTDACl) and dodecyltrimethyl-ammonium bromide (DTABr)) on the electrokinetic and rheologic properties of Na-montmorillonite dispersion (3% w/w) has been investigated at their concentrations between 0 and 10 mmol/L. Experimental results reveal that cationic surfactants are attached on the surface of negatively charged clay particles and also they penetrate into the interlayer of clay particles. The intercalation of surfactants with clay minerals is shown to lead to an increase in the interlayer spacing of montmorillonites by X-ray diffraction. The Fourier transform infrared (FTIR) spectra obtained from the modified bentonite products reveal the characteristic absorption bands. The morphology of bentonite dispersions was analyzed by scanning electron microscopy (SEM). Both X-ray diffraction data and scanning electron micrographs of intercalated montmorillonites indicate that most of ...
In this study, the rheologic and colloidal characterizations of sodium montmorillonite (NaMMT) we... more In this study, the rheologic and colloidal characterizations of sodium montmorillonite (NaMMT) were examined. Hexadecylamine (CH 3 (CH 2) 15 NH 2 , HDA) was added to the bentonite water dispersion (2%, w/w) in different concentrations in the range 5⋅ ⋅6 × 10-4-9⋅ ⋅4 × 10-3 m mol/l. The rheological and electrokinetic behaviour of aqueous montmorillonite dispersions was investigated as a function of solid content and HDA concentration. The basal spacings of the HDA/NaMMT composites were studied by X-ray diffraction. The FTIR spectra were obtained from the modified bentonite products, which revealed the characteristic absorbances after treatment with HDA.
Recycled paper cellulose has some drawbacks, for example loss in mechanical strength, to use in p... more Recycled paper cellulose has some drawbacks, for example loss in mechanical strength, to use in paper industry alone. However, derivatives of cellulose can find applications in other industrial areas. Carboxymethylcellulose (CMC) is one of the most used cellulose derivatives and can be obtained by heterogeneous modification of cellulose. In general carboxymethylation of cellulose achieved in alkaline alcoholic dispersions. In this work modification of cellulose from recycled newspaper in aqueous alkaline solution was aimed. First cellulose was recovered from newspaper under oxidative alkaline conditions. Cellulose recovery was determined as 75-90% (w/w) of starting material. Carboxymethylation reactions were carried out to find optimum conditions for derivatization, changing concentrations of components and reaction temperature. Obtained CMC samples had a DS of 0.3-0.7% and 84-94% CMC content. As a result, carboxymethylation of cellulose from recycled newspaper was achieved in aqueous alkaline dispersion giving commercial grade CMC for industrial use.
Chitosan polymer was added to the montmorillonite (MMT) dispersions in different concentrations i... more Chitosan polymer was added to the montmorillonite (MMT) dispersions in different concentrations in the range of 1 × 10 −2 50 × 10 −2 g/L (in 1% acetic acid solution). The rheological behaviours and colloidal properties of the clay dispersions were determined as a function of ...
In this study synthesis and characterization of biopolymer/clay biocomposites was aimed using nat... more In this study synthesis and characterization of biopolymer/clay biocomposites was aimed using naturally occurring polysaccharide (xylan) as biopolymer and montmorillonite type clay (NaMt). Xylan was extracted from corn cobs via alkaline oxidative treatment. Maximum solubility of xylan was determined as 1% (w/v) in water at room temperature. Thus synthesis was realized following two routes; first NaMt concentration was kept constant at 2.0×10−2g/ml and xylan concentration was changed. Latter xylan concentration was kept constant at 1.0×10−2g/ml and NaMt concentration was changed. Natural xylan, NaMt and biocomposites were examined in terms of their spectral, electrokinetic, rheologic, morphologic and thermal properties. Results showed that lower amounts of xylan interacted with NaMt on the surface, however, when the xylan amount was increased also intercalation of NaMt has occurred. Biocomposites showed better thermal and rheologic behaviors with respect to the starting materials.
The influence of polymer on flow behaviour of Balikesir, Turkey bentonite dispersions (2%, w/w) w... more The influence of polymer on flow behaviour of Balikesir, Turkey bentonite dispersions (2%, w/w) was studied for non-ionic polymer, polyvinyl alcohol (PVA). In a range of 3⋅3 × 10 -6 -3⋅3 × 10 5 mol/l, PVA was added to the bentonite dispersions in different concentrations and its behaviour was observed on rheology parameters. Thixotropy was detected by a hysteresis loop of the flow curves. The data were interpreted taking into account the interactions of colloidal clay particles, bentonitic clay concentrations, structure, and concentrations of added PVA. The particle size analysis was explained by surface orientation of PVA to the clay particles dispersed in aqueous solution. Zeta potential determination also emphasized that PVA molecules got attached on the face and edge surface of clay particles. The morphology of bentonite dispersions was analysed by scanning electron micrograph (SEM). FTIR studies carried out in parallel to rheology studies showed that hydrogen bonds were formed between surface of the clay, and absorbed PVA molecules and adsorbed water. The presence of PVA did not prevent extensive swelling of bentonite.
In this study, the effect of the two cationic surfactants (benzyldimethyltetradecylammonium chlor... more In this study, the effect of the two cationic surfactants (benzyldimethyltetradecylammonium chloride (BDTDACl) and dodecyltrimethyl-ammonium bromide (DTABr)) on the electrokinetic and rheologic properties of Na-montmorillonite dispersion (3% w/w) has been investigated at their concentrations between 0 and 10 mmol/L. Experimental results reveal that cationic surfactants are attached on the surface of negatively charged clay particles and also they penetrate into
In this study, the rheologic and colloidal characterizations of sodium montmorillonite (NaMMT) we... more In this study, the rheologic and colloidal characterizations of sodium montmorillonite (NaMMT) were examined. Hexadecylamine (CH 3 (CH 2 ) 15 NH 2 , HDA) was added to the bentonite water dispersion (2%, w/w) in different concentrations in the range 5⋅ ⋅6 × 10 -4 -9⋅ ⋅4 × 10 -3 m mol/l. The rheological and electrokinetic behaviour of aqueous montmorillonite dispersions was investigated as a function of solid content and HDA concentration. The basal spacings of the HDA/NaMMT composites were studied by X-ray diffraction. The FTIR spectra were obtained from the modified bentonite products, which revealed the characteristic absorbances after treatment with HDA.
In this study modification of xylan via Mannich reaction in aqueous basic solution to obtain dime... more In this study modification of xylan via Mannich reaction in aqueous basic solution to obtain dimethylaminomethylated products and characterization of modified xylan were examined. Components were xylan (obtained from corn cob and used without modification) as active hydrogen containing compound, formaldehyde as carbonyl compound having no ˛-hydrogen and dimethylamine. Mannich reaction was used with different parameters such as component concentration, reaction temperature, and time. The highest modification was observed about 35 • C with a nitrogen content of 4.6% by weight indicating successive modification. Both 1D and 2D NMR measurements displayed new signals related with aminomethyl groups. Spectral characterizations indicated that aminomethylation took place on oxygen sites. Moreover modified xylan could form film while xylan could not without an auxiliary agent. Antimicrobial activity tests indicated that modified xylan acted as a bacteriostatic material.
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