Degradation kinetics of PVC plasticized with different plasticizers under isothermal conditions

The aim of the present work is to elucidate the degradation kinetics of polyvinyl chloride (PVC) plasticized with some phthalate and nonphthalate plasticizers. A PVC thermomat instrument was utilized to maintain the isothermal degradation conditions at 140 and 160°C, and to suppress the oxidative degradation by means of nitrogen flow. The conductivity measurements were performed to follow hydrogen chloride (HCl) gas which is released upon PVC degradation and trapped in water. Dehydrochlorination of plasticized PVC films occurred with activation energies of about 23–160 and 26–117 kJ mol^?1 and the isokinetic temperatures, at which the dehydrochlorination rate constants of all p‐PVC films would have the same value, were found to be 171 and 128°C for initial and linear regions of dehydrochlorination curve, respectively. Plasticizer incorporation contributes to the stability of the films particularly after the consumption of stabilizer due to the dehydrochlorination. Influence of temperature rise by 20°C on the degradation rate constant is the lowest for DINCH having p‐PVC films as 0.36 and 0.42% increment at the initial region and linear region, respectively. On the other hand, DOTP reveals greater stability than the others do since the compensation ratio of the PVC film having DOTP is greater than the other films. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41579.     

Heterogeneous asymmetric reactions. 23. Enantioselective hydrogenation of ethyl pyruvate over cinchonine- and α-isocinchonine-modified platinum catalysts

The enantioselective hydrogenation of ethyl pyruvate to (S)-ethyl lactate over cinchonine- and -isocinchonine-modified Pt/Al₂O₃ catalysts was studied as a function of modifier concentration and reaction temperature. The maximum enantioselectivities obtained under the applied mild conditions were 89% ee using cinchonine (0.014 mmoldm^–3, 1 bar H₂, 23°C, 6% AcOH in toluene), and 76% ee in the case of -isocinchonine (0.14 mmoldm^–3, 1 bar H₂, –10°C, 6% AcOH in toluene). Since -isocinchonine of rigid structure exists only in anti-open conformation these data provide additional experimental evidence to support the former suggestion concerning the dominating role of anti-open conformation in these cinchona-modified enantioselective hydrogenations.     

Color of absence and presence: Reconsidering black in architecture

Abstract: This article explores the effects of using black on spatial experience by means of phenomenological analysis of its architectural examples with a special focus on Serpentine Gallery Pavilion designed by Peter Zumthor. Contrary to the growing interest in the color in contemporary architecture, black rarely found a place in architectural history and in studies on color design. Whereas, the distinct achromatic qualities of the color that appear highly self‐contradictory swinging back and forth from absence to presence cover a wide range of potentials to be used in architectural design. Through insights delved into the spatial experience constructed around these qualities, this paper attempts to analyze how black is used as a design element in built environments. This analysis revolves around Zumthor s pavilion, which stood as a uniform black box on the expanse of green grass of London Kensington Gardens for more than three months in 2011. Encompassing various oppositions, the box built to surround a hortus conclusus, an enclosed garden inside, provided its visitors with a unique spatial experience depending predominantly on the combination of its form, tectonics and the qualities of its color, black. The phenomenological analysis of these qualities manifests that the architect utilized the contradictory characteristics of the color intentionally in order to create a complex and manifold spatial experience for visitors in and outside the box. In an interplay of absence and presence, momentary crystallizations of the vision of black provide architects with uncharted opportunities for creative use of color in the design of built environments. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 378–387, 2017     

Effect of layer thickness on the electrical parameters and conduction mechanisms of conjugated polymer‐based heterojunction diode

In this study, thickness‐dependent current density–voltage (J–V) characteristics obtained for poly{(9,9‐dioctylfluorene)?2,7‐diyl‐(4,7‐bis(thien‐2‐yl) 2‐dodecyl‐benzo[1,2,3] triazole)} (PFTBT) conjugated copolymer based heterojunction diode fabricated on ITO were investigated in terms of electrical characteristics. In order to analyze J –V plots with ITO/PEDOT:PSS/PFTBT:PC₆₁BM/LiF/Al configuration, the thickness‐dependent J–V measurements were applied in the thickness range between 90 and 200 nm. The effect of PFTBT:PC₆₁BM layer thickness on the forward J –V characteristics were investigated by evaluating electrical parameters such as zero bias barrier height (Φ_Bo), ideality factor (n ), shunt resistance (R _sh), series resistance (R_s ), the interface states density (N _ss), and space‐charge limited mobility. The results show that at PFTBT:PC₆₁BM layer thickness of 90 and 200 nm, ideality factor for ITO/PEDOT:PSS/PFTBT:PC₆₁BM/LiF/Al heterojunction diodes ranged from 2.726 to 3.121 and the thermionic emission over the heterojunction diodes is crucial at low current densities and the intrinsic thermally generated charge carriers controlled the forward current this region of the heterojunction diode. At relatively higher voltage, the current mechanism of ITO/PFTBT:PC₆₁BM/PEDOT:PSS/LiF/Al heterojunction diodes were found to obey a space charge limited (SCLC) conduction mechanism. The values of N_ss and R_s in heterojunction diodes increase with increasing PFTBT:PC₆₁BM layer thickness and effect the main electrical parameters of diodes. In addition, the leakage current of heterojunction diodes are taken and interpreted via Poole‐Frenkel emission and Schottky emission. The leakage current was controlled in ITO/PEDOT:PSS/PFTBT:PC₆₁BM/LiF/Al heterojunction diodes by Poole‐Frenkel emission above 140 nm and by Schottky emission under 140 nm. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44817.     

Effect of Ozonated Water Treatment on Fatty Acid Composition and Some Quality Parameters of Olive Oil

The organic olives from Çine-Ayd?n (Turkey) were washed with tap or ozonated water for 2 and 5 min, respectively, and pressed to olive oil. The effects of wash treatments on fatty acid composition and several quality parameters of the oils were determined. The maximum values after 2-min ozonated water washes were 9.58 meqO₂/kg, 0.73%, 2.44 and 0.16 for peroxide, free acid, K₂₃₂ and K₂₇₀ values, respectively, which were under the standard limits for extra-virgin olive oil. Five min of ozonated water washes also yielded acceptable results, except for a slight excess on K₂₃₂ value. Ozonated water washes had almost no effect on fatty acid composition.     

Spectroscopic and conductometric studies on the interactions of thionine with anionic and nonionic surfactants

In this study, the interaction of thionine, a cationic dye, with anionic [sodium dodecyl sulphate (SDS), lithium dodecyl sulphate (LiDS), and sodium dodecylbenzene sulphonate (SDBS)], nonionic (Tween 20 and Triton X‐100), and binary mixtures of anionic and nonionic surfactants was studied by conductometric and spectrophotometric measurements. The degree of ionisation, the counterion binding parameters, and the equilibrium constants in the premicellar region were obtained from conductivity data. Binding constants of thionine to anionic, nonionic, and mixtures of anionic and nonionic micelles were determined by spectrophotometric measurements. The binding tendency of thionine to anionic micelles followed the order SDBS > SDS > LiDS. The presence of nonionic surfactants increased significantly the binding affinity of thionine to anionic micelles, and the highest binding constant was calculated in the presence of Tween 20. The results obtained from conductometric studies correlated with those obtained from spectroscopic studies. Data concerning dye–surfactant interaction are important for a fundamental understanding of the performance of single and mixed surfactants and for their industrial application.     

Application of ozone gas for the stripping of fabric ink‐jet‐printed with reactive dyes

In this study, a novel process utilizing ozone was carried out for colour stripping of fabrics misprinted with reactive dyes in ink‐jet machines. The results of ozone applications were compared with conventional colour stripping process performed by thiourea dioxide (TUDO) and soda ash. In trials, cotton‐based and viscose‐based woven fabrics were used as these fabrics were the most utilized at the textile mill in which this study was performed. Different ozone treatment times (30, 45, 60 or 90 min) were tested to find optimum process time and it was found that process times depended on fabric type. Particularly, colour stripping on high density and thick fabrics were harder than low density and thin fabric types. Fabric strengths, whiteness indexes and chemical oxygen demand (COD) values were measured. Also energy, chemical and water consumptions were calculated. Consequently, it was found that the reduction of the COD value of effluent was up to 98%. The calculations showed that the savings in time and cost in ozone treatment were up to 77%. Satisfactory colour stripping and tensile strengths were achieved.     

Polymer Nanocomposite Hydrogels with Improved Metal Adsorption Capacity and Swelling Behavior: Influence of Spirulina Immobilization onto Montmorillonite Clay

Polacrylamide nanocomposite hydrogels were prepared by in situ free radical polymerization reaction in presence of Spirulina microalgae, which is immobilized in montmorillonite clay (Sp-MMT). The nanocomposite hydrogel having 1 wt.% Sp-MMT clay was found to have desired exfoliated structure, maximum swelling and improved thermal stability. It also showed maximum metal adsorption capacity, which is about 312% higher than that of neat PAAm hydrogel at the highest metal concentration. The presence of Spirulina's porous network structure where all potential binding sites are under receptive position was found to be responsible for the dramatic increase in the metal adsorption and swelling behavior.     

Dehydration,Water Vapor Adsorption and Desorption Behavior of Zn[B3O3(OH)5] · H2O and Zn[B3O4(OH)3]

The dehydration behaviors of two different hydrated zinc borate species, Zn[B₃O₃(OH)₅] · H₂O and Zn[B₃O₄(OH)₃], which are industrially important flame retardants, were studied by thermal gravimetric(TG) analysis and in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Dehydration onset temperatures of Zn[B₃O₃(OH)₅] · H₂O and Zn[B₃O₄(OH)₃] were 129 and 320°C, respectively, at a 10°C/min ramp rate. A very small amount of boric acid was volatilized in addition to water vapor when both samples were heated at 250°C. A significant amount of water vapor was adsorbed by Zn[B₃O₃(OH)₅] · H₂O from air at 25°C. However, Zn[B₃O₄(OH)₃] adsorbed a very small amount of water under the same conditions. Both zinc borates did not have a tendency to cake during storage.