Nahit AKTAŞ

Article | 2021 | Journal of Polymers and the Environment36 ( 11 )

Recently, the use of polymers in agricultural and horticultural applications has been seen as a solution to reduce water consumption and excess fertilizer use in particularly. In this study, macrogels were synthesized to allow fertilizer species and water to be controlled and released in the soil. A natural macrogel derived from N,N-Dimethylacrylamide (DMAAm), Maleic Acid (MA) and Citric Acid (CA) was selected because of its ability to absorb/release a large amount of water and to have modifiable functional groups. Urea, which is an abundant source of nitrogen, was chosen to model the fertilizer. The macrogel was prepared using easi . . .ly available, low-cost, modifiable starting materials by redox polymerization technique. p(DMAAm-co-MA-co-CA) (DMC1) surface was modified by hydrochloric acid (HCl) and sodium hydroxide (NaOH) to obtain p(DMAAm-co-MA-co-CA)/HCl (DMC2) and p(DMAAm-co-MA-co-CA)/NaOH (DMC3), which have positively and negatively charged, respectively. After being analyzed for intermolecular interactions (Fourier-Transform Infrared Spectroscopy,FT-IR) and thermal properties (Thermogravimetric Analysis,TGA), the macrogels were tested in terms of sorption isotherms and thermodynamic parameters. However, in order to examine the urea release mechanism, the macrogels were tested using four release models such as Zero Order Kinetic Model(Z-O), First Order Kinetic Model(F-O), Higuchi(H) and the Korsmeyer-Peppas(K-P) power law. Cumulative urea release values for DMC1, DMC2 and DMC3 macrogels were calculated as 100?t pH 4 and 10, 100?t pH 6, 8 and 10, 100?t pH 4, 6, 8 and 10, respectively. Analyzes confirmed that synthesized macrogels can be good water holder for soil and can be a slow release of urea More less

Nahit AKTAŞ

Article | 2022 | Journal of Polymers and the Environment30 ( 9 )

Novel metal-free catalysts were synthesized form maleic acid (MA) and citric acid (CA) based polymers for hydrogen generation form NaBH4. Surfactant-free-self-emulsion polymerization technique was used to synthesize poly(Maleic acid)(poly(MA)), poly(Citric acid)(poly(CA)) and poly(Maleic acid-co-Citric Acid) poly(MA-co-CA)) polymeric micro-particles in a single step. The prepared catalysts were characterized by zeta potential, SEM, FTIR and TGA. The hydrodynamic diameter of the poly(MA), poly(CA) and poly(MA-co-CA) micro-particles were found to be 0.681, 1.273, 1.604 mu m and the zeta potential of this micro-particles were found to . . .be -6.90, -5.69 and -7.73 mV, respectively. Various parameters affecting the rate of H-2 production of polymeric catalysts, such as the amount of microparticles, the amount of NaBH4 and the ambient temperature were investigated. Hydrogen generation rate(HGR) was calculated as 84 /- 44 ml H-2 g(-1) min(-1) for 50 mg poly(MA-co-CA)micro-particles in the hydrolysis of 50 mM NaBH4. The activation energy(E-a) of hydrolysis of NaBH4 catalyzed by poly(MA-co-CA)micro-particles was calculated as -1.66 /- 0.76 kJ mol(-1), which is much lower than similar studies reported in the literature. The prepared poly(CA), poly(MA) and poly(MA-co-CA) micro-particles were shown to be very effective catalysts in H-2 generation by hydrolysis of NaBH4 More less

Mustafa DOLAZ

Article | 2021 | Journal of Polymers and the Environment29 ( 7 )

The utilization of forest auxiliary products and their conversion into products with higher added value is important for the use of renewable resources. For this purpose, acorns belonging to the Q. coccifera species were collected in November, which is their ripening period, and dried and ground in the laboratory. Then, acorn starch (AS) was isolated from the sieved acorn flour. For 5 g of this isolated AS, hydroxypropyl acorn starch (HPAS) with the highest molar substitution (MS = 0.319) was synthesized by optimizing at 45 degrees C for 5 h with 30 g of propylene oxide and 1.88 g of NaOH. The structures of HPASs synthesized were ch . . .aracterized by FT-IR, XRD and H-1 (C-13)-NMR spectroscopy, and their MS values were determined. In addition, surface morphologies with SEM images and thermal stability with DTA-TG thermograms were examined. Since hydroxypropyl acorn starch has not been synthesized from acorn starch before, this study contributed to the literature and science. It has been understood that HPASs can also be used in many areas where hydroxypropyl starch is used More less

Nahit AKTAŞ

Article | 2021 | Journal of Polymers and the Environment30 ( 2 )

In this study, it was aimed to investigate the synthesis, characterization and drug release behaviors of organo-hydrogels containing pH-sensitive Agar (A), Glycerol (G), Sweet Almond oil (Wu et al. in J Mol Struct 882:107-115, 2008). Organo-hydrogels, which contained Agar, Glycerol and different amounts of Sweet Almond oil, were synthesized via the free-radical polymerization reaction with emulsion technique using glutaraldehyde or methylene bis acrylamide crosslinkers. Then, the degree of swelling, bond structures, blood compatibility and antioxidant properties of the synthesized organo-hydrogels were examined. In addition, Organo- . . .hydrogels which loaded with Ceftriaxone and Oxaliplatin were synthesized with the same polymerization reaction and release kinetics were investigated. In vitro release studies were performed at media similar pH to gastric fluid (pH 2.0), skin surface (pH 5.5), blood fluid (pH 7.4) and intestinal fluid (pH 8.0), at 37 degrees C. The effects on release of crosslinker type and sweet almond oil amount were investigated. Kinetic parameters were determined using release results and these results were applied to zero and first-order equations and Korsmeyer-Peppas and Higuchi equations. Diffusion exponential was calculated for drug diffusion of organo-hydrogels and values consistent with release results were found More less

Nahit AKTAŞ

Article | 2022 | Journal of Polymers and the Environment31 ( 3 )

The use of the metal free catalysts synthesized form natural and environmental friendly materials for fast generation of hydrogen is accomplished form sodium borohydride (NaBH4) methanolysis assays. Thus, green and metal free-catalysts were prepared form natural resources of ginger oil (GO). Polymeric GO particles were synthesized via emulsion polymerization technique and characterized in detail. The hydrodynamic diameters of p(GO) particles were found to be in the 220 nm and the zeta potential was - 162.48 mV. TGA results showed that thermal decomposition of microparticles was gradually continuing up to 700 degrees C. The catalytic . . . performance of the metal-free p(GO) particles were studied under various conditions such as changing NaBH4 concentrations, amount of p(GO) and media temperature. A fast hydrogen production rate of 617.8 mL min(-1) gcat(-1) is achieved at 20 degrees C by methanolysis of 50 mM NaBH4 and 0.1 g p(GO) particles. Factors are regularly investigated to reveal methanolysis kinetic properties. The activation energy is found 24 /- 0.9 kJ mol(-1). Thanks to this study, the p(GO) particle obtained from GO has been transformed into a product with high energy value More less

Nahit AKTAŞ

Article | 2021 | Journal of Polymers and the Environment30 ( 2 )

In this study, six different organo-hydrogel containing Agar-Glycerol (AG) based Coconut Oil (CnO) were synthesized using different crosslinkers to ensure the controlled release of D-3 Vitamine and 5-Fluorouracil (5-Flu). Synthesized organo-hydrogels were characterized by FT-IR, Afterwards, swelling behaviors were investigated in ethanol, acetone, ethanol/ID water (1:1), acetone /ID water (1:1) and gasoline environments and different pH. As a result of hemolysis, blood clotting and antioxidant analysis, organo-hydrogels have been shown to have blood compatibility and antioxidant properties. The effects of the initial pH of the solut . . .ion on the drug release process were investigated. It was observed that the most release occurred at pH 2 and glutaraldehyde crosslinker. Release kinetics models were applied to understand the mechanism of the release system of D-3 Vitamine and 5-Flu (anti-cancer) with poly(Agar-co-Glycerol-co-Coconut Oil) (p(AG-co-CnO)) organo-hydrogel. The value of the correlation coefficient (R-2) was used as the best model fit indicator of different models and it was determined that the balance data fit the Korsmeyer-Peppas with large R(2)s and the Higuchi kinetic model. The results showed that the p(AG-co-CnO) organo-hydrogel can be used as a suitable carrier for the controlled release of D-3 Vitamin and 5-Flu More less

Nahit AKTAŞ

Article | 2022 | Journal of Polymers and the Environment30 ( 11 )

In this study, the poly (Castor Oil) (p(CO)) organo-particle from natural castor oil (CO) was synthesized for the first time in literature for sodium boron hydride (NaBH4) methanolysis hydrogen production. As is known, catalysts are used in most reactions performed in the chemical industry. Here, by analytical method, Fourier Transform Infrared Spectroscopy (FT-IR), Thermal Gravimetric Analyzer (TGA) and Ultra Field Emission Energy Dispersive Spectroscopy (SEM) analyzes of the catalyst were performed and the characteristics of the catalyst were determined. Also for the methanolysis of the p(CO) catalyst NaBH4; The effect of the opti . . .mum NaBH4 concentration, catalyst amount and kinetic parameters at different temperatures were investigated. In the methanolysis reaction, the reaction rates for 0 and 30 degrees C were found to be 96.9 and 527.1 ml min(- 1) gcat(- 1), respectively. The activation energy of the p(CO) catalyst was calculated as 24 +/- 0.01 kJ mol(- 1) More less

Mustafa DOLAZ

Article | 2020 | Journal of Polymers and the Environment29 ( 3 )

This article focuses on the synthesis of hydroxyethyl potato starch (HEPS) for liquid hand soap by evaluating waste potato starch (WPS), a byproduct in potato chips production. It is a cheap, biodegradable, non-toxic and renewable natural polymer, available in great quantities on a global level. In a factory producing potato chips, WPS, which remained in the aqueous medium during peeling, slicing, and washing the potatoes, was purified at the desired temperature with H2O2 and NaOH. HEPSs with the molar substitution (MS) in the range from 0.298 to 0.670, were synthesized under microwave irradiation in isopropanol (IPA) and NaOH solut . . .ion by adding ethylene oxide (EO) to WPS. The selected reaction parameters were the concentration of NaOH, the proportion of EO, and reaction time in an attempt to understand their effects on the reaction. Considering all the studied conditions, the highest viscosity was reached at 250 cP for the highest MS in the sample of HEPS-4 when 15 g EO was used in 20 mL solution of 40?aOH at 40 degrees C for 40 min under microwave irradiation. The structure of synthesized HEPSs has been characterized by FT-IR, XRD, H-1(C-13)-NMR spectroscopic methods, and the degree of molar substitution was calculated from H-1-NMR spectra. In addition, thermal stability and surface morphology of characterized HEPSs were studied by DTG-TG and SEM, respectively. The thickener effect of hydroxyethyl starch in liquid hand soap was investigated. In this way, it has been understood that in the production of liquid hand soaps, hydroxyethyl potato starch can be used instead of coco diethanolamide (CDEA) More less