Effects of urea formaldehyde resin to film properties of alkyd–melamine formaldehyde resins containing organo clay

Organo clay modified alkyd resins were prepared and these modified alkyd resins were cured with different ratios of melamine formaldehyde and urea formaldehyde resins in this work. Alkyds formulated to have oil content 40% were prepared with phthalic anhydride (PA), glycerine (G), coconut oil fatty acid (COFA), dipropylene glycol (DPG) and organo clay. “K alkyd constant system” was used for the formulation calculations of the alkyd resins. Alkyd resins were blended with 40% of a commercial melamine formaldehyde. The films of the alkyd–amino resins were prepared from 60% solid content xylene solutions using 50 μm applicators. After the films were cured at 140 °C for 2 h in an oven, properties of the films were determined. The film properties of the alkyd–amino resins such as drying degree, hardness, adhesion strength, abrasion resistance, water, acid, alkaline, solvent resistance, and resistance to environmental conditions were investigated. The addition of the urea formaldehyde resin and organo clay has positive effect on the physical and chemical resistance of the alkyd–amino resins.     

Cost analysis of wind-electrolyzer-fuel cell system for energy demand in Pınarbaşı-Kayseri

In this study, the hydrogen production potential and costs by using wind/electrolysis system in P?narba??-Kayseri were considered. In order to evaluate costs and quantities of produced hydrogen, for three different hub heights (50 m, 80 m and 100 m) and two different electrolyzer cases, such as one electrolyzer with rated power of 120 kW (Case-I) and three electrolyzers with rated power of 40 kW (Case-II) were investigated. Levelised cost of electricity method was used in order to determine the cost analysis of wind energy and hydrogen production. The results of calculations brought out that the electricity costs of the wind turbines and hydrogen production costs of the electrolyzers are decreased with the increase of turbine hub height. The maximum hydrogen production quantity was obtained 14192 kgH₂/year and minimum hydrogen cost was obtained 8.5 $/kgH₂ at 100 m hub height in the Case-II.     

Highly efficient orange–red electroluminescence from a single layer MEH-PPV-POSS:CdS0.75Se0.25 hybrid PLED

In this study, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] end capped with polyhedral oligomeric silsesquioxanes (MEH-PPV-POSS): cadmium sulfide selenide quantum dots (CdS_0.75Se_0.25 QDs) nanocomposites based OLEDs were fabricated. By the addition of CdS_0.75Se_0.25 QDs into the polymer active layer, a considerable enhancement was observed in terms of hole and electron injection in devices. Additionally, the presence of QDs reduced the interchain interaction of polymer that resulted in narrower electroluminescence (EL) spectrum. The device structure of ITO/PEDOT: PSS/MEH-PPV-POSS: 25 wt% CdS_0.75Se_0.25/Ca (40 nm)/Al demonstrated the best performance with a brightness of 8672 cd/m² at 10 V, current efficiency of 2.5 cd/A at 8 V, and an EQE of 0.55% at 150 mA/cm².     

Removal of acidic dye from aqueous solutions using poly(DMAEMA–AMPS–HEMA) terpolymer/MMT nanocomposite hydrogels

In this study, poly(DMAEMA–AMPS–HEMA) terpolymer/montmorillonite nanocomposite hydrogels were prepared by in situ polymerization technique using 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA), 2-acrylamido-2-methlypropane sulfonic acid (AMPS), 2-hydroxyethyl methacrylate (HEMA) monomers in clay suspension media. N,N-methylenebisacrylamide (NMBA) was used as crosslinker and potassium persulfate/potassium bisulfide were used as initiator and accelerator pair. The water absorption capacities and acidic dye (indigo carmine) adsorption properties of the nanocomposite hydrogels were investigated. Adsorption properties of the hydrogels were investigated at different conditions such as different initial dye concentration and contact time. The concentrations of the dyes were determined using UV/Vis Spectrophotometer at wavelength 610 nm. Langmuir and Freundlich isotherm models were used to describe adsorption data and the results clarified that these models were the best-fit for the adsorption of indigo carmine.     

Coke minimization via SiC formation in dry reforming of methane conducted in the presence of Ni-based core–shell microsphere catalysts

Mesoporous Ni/Si microsphere catalysts were synthesized with a modified sol–gel microencapsulation method and their activity was tested in dry reforming of methane (DRM) reaction. Results indicated comparable conversion values and H₂/CO ratios with other catalysts reported in literature. Activity loss of 5% determined with time on stream analysis of 5% Ni/Si catalyst revealed that sustainable production could have been possible in the presence of these catalysts. Coke deposition which was frequently stated as the reason of activity loss was not observed with Ni/Si microsphere catalysts. Taking into account the impossibility of eliminating methane cracking and Boudard reaction during DRM, we should come up with an explanation of the absence of coke. This explanation was provided by silicon carbide (SiC) formation which consumed the coke deposited on the catalyst. Characterization analyses conducted at spent catalysts validated both the absence of coke and formation of SiC during DRM.     

Development of a new two‐enzyme biosensor based on poly(pyrrole‐co‐3,4‐ethylenedioxythiophene) for lactose determination in milk

A new lactose biosensor was developed by preparing a suitable copolymer of polypyrrole and poly(3,4‐ethylenedioxythiophene) synthesized using the electropolymerization method. Pyrrole and 3,4‐ethylenedioxythiophene monomers were deposited in the presence of sodium dodecylbenzene sulphonic acid on a platinum disc electrode, which was used as the working electrode. The sensor is based on the serial reactions of β‐galactosidase and galactose oxidase immobilized on a copolymer‐modified platinum disc electrode. Successful synthesis of the enzyme‐immobilized copolymer was confirmed by FT‐IR spectrometry, SEM, and electrochemical analysis. The response of the enzyme electrode to lactose was determined by cyclic voltammetry at + 0.40 V. The response time of the biosensor was found to be from 8 to 10 s, and the upper limit of the linear working portion was found to be at a lactose concentration of 2.30 mM with a detection limit of 1.4 × 10^?5 M. The apparent Michaelis–Menten constant was found to be 0.65 mM of lactose. The effects of interferents were also investigated. Lactose concentrations determined by the biosensor were in good agreement with those measured by the reference methods. Our results show that the developed biosensor has a significant potential to the determination of lactose concentration in milk. POLYM. ENG. SCI., 58:839–848, 2018. © 2017 Society of Plastics Engineers     

Ozonation as an Environmentally Friendly Method to Decolorize the Leather Products

In this study, ozonation as an environmentally friendly bleaching method was studied for decolorization of leather products. The effect of ozonation time (3, 5, 10, 15 and 30 min) and water pick-up value (WPV) (0%, 20%, 40%, 60%, 80% and 100%) were investigated on decolorization effect. For this aim, the color measurement and tensile strength tests were performed, and also structural changes were determined by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) after ozonation process. The results of color measurements showed that 30 min for ozonation and 60% WPV were optimum parameters to obtain maximum decolorization effect. SEM images of the ozonated leathers showed some deformations on the collagen fibers and resulted with the slightly decreases in tensile strength of the products. On the other hand, decreases in the tensile strength values were not statistically important levels.